U.S. patent application number 14/167097 was filed with the patent office on 2014-05-29 for method for the embedding and encapsulation of components.
This patent application is currently assigned to GENERAL MILLS, INC.. The applicant listed for this patent is GENERAL MILLS, INC.. Invention is credited to Bernhard H. VAN LENGERICH.
Application Number | 20140147501 14/167097 |
Document ID | / |
Family ID | 23028566 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140147501 |
Kind Code |
A1 |
VAN LENGERICH; Bernhard H. |
May 29, 2014 |
METHOD FOR THE EMBEDDING AND ENCAPSULATION OF COMPONENTS
Abstract
Controlled release, discrete, solid particles which contain an
encapsulated and/or embedded component such as a heat sensitive or
readily oxidizable pharmaceutically, biologically, or nutritionally
active component are continuously produced without substantial
destruction of the matrix material or encapsulant. A release-rate
controlling component is incorporated into the matrix to control
the rate of release of the encapsulant from the particles. The
additional component may be a hydrophobic component or a high water
binding capacity component for extending the release time. The
plasticizable matrix material, such as starch, is admixed with at
least one plasticizer, such as water, and at least one release-rate
controlling component under low shear mixing conditions to
plasticize the plasticizable material without substantially
destroying the at least one plasticizable material and to obtain a
substantially homogeneous plasticized mass. The plasticizer content
is substantially reduced and the temperature of the plasticized
mass are substantially reduced prior to admixing the plasticized
mass with the encapsulant to avoid substantial destruction of the
encapsulant and to obtain a formable, extrudable mixture. The
mixture is extruded through a die without substantial or
essentially no expansion and cut into discrete, relatively dense
particles. Release properties may also be controlled by precoating
the encapsulant and/or coating the extrudate particles with a
film-forming component.
Inventors: |
VAN LENGERICH; Bernhard H.;
(Plymouth, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL MILLS, INC. |
Minneapolis |
MN |
US |
|
|
Assignee: |
GENERAL MILLS, INC.
Minneapois
MN
|
Family ID: |
23028566 |
Appl. No.: |
14/167097 |
Filed: |
January 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09782320 |
Feb 13, 2001 |
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14167097 |
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09269763 |
May 17, 1999 |
6190591 |
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PCT/US97/18984 |
Oct 27, 1997 |
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09782320 |
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60052717 |
Jul 16, 1997 |
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60029038 |
Oct 28, 1996 |
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Current U.S.
Class: |
424/479 ;
424/493; 426/93 |
Current CPC
Class: |
B29B 7/823 20130101;
B29C 48/40 20190201; B29C 48/832 20190201; A61K 9/2086 20130101;
B29B 7/421 20130101; B29B 7/94 20130101; B01J 13/02 20130101; A23L
27/72 20160801; B29B 7/845 20130101; A23P 10/30 20160801; B29B 7/46
20130101; B29B 7/86 20130101; B29B 7/482 20130101 |
Class at
Publication: |
424/479 ; 426/93;
424/493 |
International
Class: |
A61K 9/20 20060101
A61K009/20; A23L 1/00 20060101 A23L001/00 |
Claims
1-24. (canceled)
25. An encapsulated product comprising discrete, solid particles
having a substantially uniform shape and a diameter of up to about
10 mm, wherein each particle comprises: a plasticized matrix
material in an amount of about 40% or more based on the weight of
the final product, the plasticized matrix comprising starch having
substantially intact molecules, at least one component for
controlling the rate of release of the encapsulant, at least one
plasticizer comprising water, and an encapsulant in an amount of
from about 1% to about 85% based upon the weight of the plasticized
matrix material, the encapsulant dispersed throughout the
plasticized matrix material and comprising is at least one
pharmaceutical component, neutraceutical component, nutritional
component, fragrance component, or biologically active component,
wherein the encapsulant and plasticized matrix material form an at
least substantially homogenous mixture.
26-27. (canceled)
28. An encapsulated product according to claim 25 wherein said
particles are in the form of a tablet, or a pellet.
29. An encapsulated product according to claim 28 wherein said
particles are coated with a film-forming material.
30. An encapsulated product according to claim 25 wherein said at
least one release-rate controlling component is a hydrophobic
component.
31. An encapsulated product according to claim 30 wherein said
hydrophobic component is at least one member selected from the
group consisting of fats, oils, waxes, fatty acids, emulsifiers,
polyolefins, paraffin, polyvinyl acetate and derivatives thereof,
and modified starches.
32-33. (canceled)
34. An encapsulated product according to claim 25 which has a
specific density of from about 800 g/liter to about 1500
g/liter.
35. An encapsulated product according to claim 25 wherein the
length-to-diameter ratio of said particles is from about 0.1 to
about 10.
36. (canceled)
37. An encapsulated product according to claim 25 wherein said
particles have a substantially non-expanded, substantially
non-cellular structure.
38. An encapsulated product according to claim 25 wherein said
encapsulant is released in an aqueous or gastric juice environment
in an amount of no more than from about 10% in about 1 hour to no
less than about 90% in about 24 hours.
39. An encapsulated product according to claim 25 wherein: the
amount of the plasticized matrix material is from about 60% by
weight to about 95% by weight, based upon the weight of the final
product, and the amount of said at least one component used to
control the rate of release of the encapsulant is from about 5% by
weight to about 50% by weight, based upon the weight of the matrix
material.
40. An encapsulated product according to claim 39 wherein said
particles have a diameter of from about 0.5 mm to about 5 mm and a
length-to-diameter ratio of about 0.5 to about 2.
41. (canceled)
42. An encapsulated product according to claim 25 wherein said
plasticized matrix material comprises durum wheat or semolina.
43-45. (canceled)
46. An encapsulated product according to claim 25 wherein said
encapsulant is at least one member selected from the group
consisting of antioxidants, phytochemicals, hormones,
microorganisms, prebiotics, probiotics, enzymes, formulations
containing zidovudine, macromolecular polypeptides, aromatic nitro
and nitroso compounds and their metabolites useful as anti-viral
and anti-tumor agents, HIV protease inhibitors, antibiotics,
viruses, steroids, oligopeptides, dipeptides, amino acids,
fragrance components, adenosine derivatives, sulfated tannins,
monoclonal antibodies, and metal complexes of water-soluble
texathyrin.
47-49. (canceled)
50. An encapsulated product according to claim 25 wherein said
plasticized matrix material further comprises at least one member
selected from the group consisting of cyclodextrins, dextrins,
monosaccharides, disaccharides, polyvinylpyrrolidone, copolymers of
N-vinylpyrrolidone and vinyl acetate, polyvinyl alcohol, cellulose
esters, cellulose ethers, and polyethylene glycol.
51. (canceled)
52. An encapsulated product comprising: discrete, solid particles
having a substantially uniform shape wherein each particle
comprises: a plasticized matrix material in an amount of about 40%
or more by weight, based on the weight of the final encapsulated
product, wherein said plasticized matrix material comprises starch
having substantially intact molecules, an encapsulant dispersed
throughout the plasticized matrix material, and at least one
component for controlling the rate of release of the encapsulant,
wherein said encapsulant comprises at least one pharmaceutical
component, neutraceutical component, nutritional component,
fragrance component, or biologically active component, wherein said
matrix material comprises at least one member selected from the
group consisting of durum wheat, semolina, wheat flour, wheat
gluten, soy protein, hydrocolloids, casein, and gelatin, and at
least one plasticizer comprising water, wherein the encapsulant and
plasticized matrix material form an at least substantially
homogeneous mixtures, and wherein the amount of said encapsulant is
from about 1% by weight to about 85% by weight, based upon the
weight of the matrix material.
53-54. (canceled)
55. An encapsulated product according to claim 52 wherein said
particles are in the form of a tablet, or a pellet.
56. An encapsulated product according to claim 52 wherein said
particles are spherical.
57. An encapsulated product according to claim 55 wherein said
particles are coated with a film-forming material.
58. An encapsulated product according to claim 52 wherein said at
least one release-rate controlling component is a hydrophobic
component.
59. An encapsulated product according to claim 58 wherein said
hydrophobic component is at least one member selected from the
group consisting of fats, oils, waxes, fatty acids, emulsifiers,
polyolefins, paraffin, polyvinyl acetate and derivatives thereof,
and modified starches.
60. (canceled)
61. An encapsulated product according to claim 52 which has a
specific density of from about 800 g/liter to about 1500
g/liter.
62. An encapsulated product according to claim 52 wherein the
length-to-diameter of said particles is from about 0.1 to about
10.
63. (canceled)
64. An encapsulated product according to claim 52 wherein said
particles have a substantially non-expanded, substantially
non-cellular structure.
65. An encapsulated product according to claim 52 wherein said
encapsulant is released in an aqueous or gastric juice environment
in an amount of no more than from about 10% in about 1 hour to no
less than about 90% in about 24 hours.
66. An encapsulated product according to claim 52 wherein the
amount of said at least one component for controlling the rate of
release of the encapsulant is up to about 70% by weight, based on
the weight of the matrix material.
67. An encapsulated product according to claim 52 wherein said
particles have a diameter of from about 0.5 mm to about 5 mm and a
length-to-diameter ratio of about 0.5 to about 2.
68. (canceled)
69. An encapsulated product according to claim 52 wherein said
matrix material comprises at least one member selected from the
group consisting of durum wheat, semolina, wheat flour, wheat
gluten, and soy protein.
70. An encapsulated product according to claim 52 wherein said
matrix material comprises at least one member selected from the
group consisting of durum wheat and semolina.
71-72. (canceled)
73. An encapsulated product according to claim 52 wherein said
discrete, solid particles have a diameter of up to about 10 mm.
74. (canceled)
75. An encapsulated product according to claim 52 wherein said
encapsulant is at least one member selected from the group
consisting of antioxidants, phytochemicals, hormones,
microorganisms, prebiotics, probiotics, enzymes, formulations
containing zidovudine, macromolecular polypeptides, aromatic nitro
and nitroso compounds and their metabolites useful as anti-viral
and anti-tumor agents, HIV protease inhibitors, antibiotics,
viruses, steroids, oligopeptides, dipeptides, amino acids,
fragrance components, adenosine derivatives, sulfated tannins,
monoclonal antibodies, and metal complexes of water-soluble
texathyrin.
76-78. (canceled)
79. An encapsulated product according to claim 52 wherein said
plasticized matrix material further comprises is at least one
member selected from the group consisting of cyclodextrins,
dextrins, monosaccharides, disaccharides, polyvinylpyrrolidone,
copolymers of N-vinylpyrrolidone and vinyl acetate, polyvinyl
alcohol, cellulose esters, cellulose ethers, and polyethylene
glycol.
80. (canceled)
81. An encapsulated product according to claim 52 wherein: the
amount of the matrix material is from about 60% by weight to about
95% by weight, based upon the weight of the final product, and the
amount of said at least one component used to control the rate of
release of the encapsulant is from about 5% by weight to about 50%
by weight, based upon the weight of the matrix material.
82. An encapsulated product according to claim 52 wherein said
encapsulant comprises at least one member selected from the group
consisting of enzymes and microorganisms.
83. An encapsulated product comprising discrete, solid particles
having a substantially uniform shape wherein each particle
comprises: an encapsulant dispersed throughout a plasticized matrix
material comprising starch which has substantially intact
molecules, said matrix material comprising at least one member
selected from the group consisting of durum wheat, semolina, vital
wheat gluten, soy protein, hydrocolloids, casein, and gelatin, and
at least one plasticizer comprising water, wherein said encapsulant
comprises at least one pharmaceutical component, neutraceutical
component, nutritional component, fragrance component, or
biologically active component, wherein the encapsulant and
plasticized matrix material form an at least substantially
homogeneous mixture, wherein the amount of said encapsulant is from
about 3% by weight to about 50% by weight, based upon the weight of
the matrix material, and wherein the amount of said matrix material
is about 40% or more by weight, based upon the weight of the final
encapsulated product.
84. An encapsulated product according to claim 83 wherein said
matrix material comprises semolina or durum wheat.
85. An encapsulated product according to claim 83 wherein said
encapsulant comprises at least one member selected from the group
consisting of enzymes and microorganisms.
86-89. (canceled)
90. An encapsulated product according to claim 25, comprising about
3% by weight to about 50% by weight of the encapsulant, based upon
the weight of the matrix material.
91. An encapsulated product according to claim 25, comprising about
5% by weight to about 20% by weight of the encapsulant, based upon
the weight of the matrix material.
92. An encapsulated product according to claim 25, wherein the
encapsulant is in liquid form.
93. An encapsulated product according to claim 25, wherein the
encapsulant is in solid form.
94. An encapsulated product according to claim 52, comprising about
3% by weight to about 50% by weight of the encapsulant, based upon
the weight of the matrix material.
95. An encapsulated product according to claim 52, comprising about
5% by weight to about 20% by weight of the encapsulant, based upon
the weight of the matrix material.
96. An encapsulated product according to claim 25, comprising said
plasticized matrix material in an amount of from about 60% by
weight to about 95% by weight based upon the weight of the final
encapsulated product.
97. An encapsulated product according to claim 52 comprising from
about 60% by weight to about 95% by weight of the matrix material,
based upon the weight of the final encapsulated product.
98. An encapsulated product according to claim 83 comprising from
about 60% by weight to about 95% by weight of the matrix material,
based upon the weight of the final encapsulated product.
99. An encapsulated product according to claim 25 wherein said
plasticized matrix material comprises at least one member selected
from the group consisting of durum wheat, semolina, wheat flour,
wheat gluten, native or modified starches, soy protein, casein, and
gelatin.
100. An encapsulated product according to claim 25 wherein said
plasticized matrix material comprises at least one member selected
from the group consisting of durum wheat, semolina, wheat flour,
wheat gluten, native starches and modified starches.
101. An encapsulated product according to claim 27 wherein said
plasticized matrix material comprises at least one member selected
from the group consisting of durum wheat and semolina.
102. An encapsulated product according to claim 25 wherein at least
a portion of the starch is not cooked.
103. An encapsulated product according to claim 25 wherein the
starch is not cooked or is cooked so that the specific energy input
during cooking is below about 100 Wh/kg.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a continuous process for
producing controlled release, discrete, solid particles which
contain an encapsulated and/or embedded component such as a heat
sensitive or readily oxidizable pharmaceutically, biologically, or
nutritionally active component.
BACKGROUND OF THE INVENTION
[0002] in encapsulating a component in a matrix, the matrix
material is generally heated to a sufficiently high temperature to
provide a plasticized mass which facilitates coating of the
component. Upon cooling, the matrix material hardens or becomes
solidified and protects the encapsulant from undesirable or
premature reaction. However, heating of the matrix to plasticize it
or to form a melt may deleteriously affect or decompose the
encapsulant as well as the matrix material. Additionally, the
mixing or high shear used to disperse the encapsulant uniformly
throughout the plasticized matrix material may likewise adversely
affect the matrix material or encapsulant. Furthermore, the use of
high temperatures to plasticize or melt the matrix material may
cause evaporation and loss of the encapsulant. The addition of
liquids to the matrix material to reduce its viscosity and to
facilitate mixing may require excessive drying or evaporation of
the plasticizing liquid for the attainment of a formable
composition capable of being formed into discrete, substantially
uniform pieces. Furthermore, removal of the plasticizing liquid may
adversely expand the product, decrease its density, and make the
encapsulated component more susceptible to attack or more easily
released.
[0003] The production of expanded products is disclosed in European
patent publication nos. EP 0465364 A1 (published Jan. 8, 1992) and
EP 0462012 A2 (published Dec. 18, 1991), U.S. Pat. No. 3,962,416 to
Katzen and U.S. Pat. No. 3,786,123 to Katzen. The two European
patent publications disclose the production of an anti-obesity food
and a method for making it by extrusion of starches with fatty
acids into an expanded product having densities between 0.1 and 0.3
g/cm.sup.3. U.S. Pat. No. 3,962,416 to Katzen discloses an expanded
product which contains at least one nutrient and one gelatinized
starch.
[0004] U.S. Pat. No. 3,786,123 to Katzen discloses a method for
producing encapsulated nutrients using extrusion temperatures of
between 250.degree. F. and 400.degree. F. and extrusion pressures
of between 200 psi to 2500 psi. A high protein encapsulating agent
containing up to 40% starch may be used. The starch is gelatinized
and extruded into an expanded product.
[0005] However, in producing a product having controlled release or
delayed release, excessive expansion or puffing may result in too
rapid release properties or may undersirably expose an encapsulant
to destructive reactions. For example, an edible composition for
delivering encapsulated pharmaceutically or nutritionally active
components or for a non-edible agricultural product for delivering
biocides or herbicides, it is desirable that the products have a
substantially spherical shape and a high density. Such products
exhibit a substantially low ratio between surface area and volume
and thus minimize or prevent surface related destructive reactions
that occur upon exposure to air or oxygen and light. The spherical
shapes and high densities also minimize the surface which would be
available to expose embedded material which is not encapsulated.
Furthermore, for edible products for delivering pharmaceutically or
nutritionally active components, it is desirable that the products
are capable of being consumed or swallowed without chewing or
substantially no chewing. Avoiding the need for mastication,
further assures that the products reach the digestive tract without
substantial enzymatic hydrolysis in the mouth. Furthermore, it
helps to control or reduce dissolution of the product in gastric
juice and to control the release of the embedded or encapsulated
components in the stomach and/or in the intestine.
[0006] International patent publication no. WO 92/00130 (published
Jan. 9, 1992) discloses a continuous process for obtaining an
encapsulated, biologically active product in a starchy matrix. A
biologically active agent and starch are mixed before extrusion and
extruded as a blend, with the encapsulant or biologically active
agent being heated together with the starch. Alternatively, a core
material to be encapsulated may be added and blended with an
aqueous dispersion of starch after the starch and water have been
subjected to an elevated temperature sufficient to gelatinize the
starch. The extrusion process, it is disclosed, exposes the mix to
high shear mechanical action at a temperature above the
gelatinization temperature of the starch. The use of extrusion
barrel temperatures of between about 58.degree. C. and 98.degree.
C. are disclosed. While these barrel temperatures may be above the
gelatinization temperature of starch, the extruder utilized has
barrel sections that are only three l/d long. The screw speeds
utilized, between 400 rpm and 200 rpm, result in a very short
residence time of the blend inside the extruder and barely allow
heating up of the starch water mix. As a result, the temperatures
obtained are generally too low to obtain substantial gelatinization
of native starches. Additionally, the barrel temperatures used are
particularly too low for substantial gelatinization of high amylose
starch which generally gelatinizes at temperatures substantially
above 100.degree. C., for example at 125.degree. C. The use of
extrusion barrel temperatures which are not sufficiently high to
substantially or completely gelatinize the starch may not form a
sufficiently continuous, plasticized and homogeneous matrix for
effective embedding or encapsulation.
[0007] In addition, the use of relatively low extrusion
temperatures, high speed mixing, and a high viscosity starch
composition generally requires a high mechanical energy input. High
shear is directly related to high specific mechanical energy, which
in turn increases the molecular destructurization and
dextrinization of starch. Breakdown of the starch molecules, and in
particular the amylopectin, increases the solubility of the
extruded starch composition in aqueous systems as described in P.
Colonna, et al., "Extrusion Cooking of Starch & Starchy
Products," Extrusion Cooking, C. Mercier, et al. pp. 247-319, AACC,
St. Paul, Minn. (1989) and F. Meuser, et al, "A Systems Analytical
Approach To Extrusion," Food Extrusion Science & Technology,
ed. J. Kokini, Dekker Publ., pp. 619-630 (1992). Increased
solubility of the extruded starch in aqueous systems decreases the
stability of the product against moisture and subsequently
diminishes or shortens the protection and controlled release of the
embedded or encapsulated substances. In addition, subjecting the
encapsulant to the same high shear and high temperature conditions
to which the starch is subjected may adversely affect the
encapsulant by at least partially destroying it or decomposing it
into unknown solid or volatile substances.
[0008] Pregelatinized starch is used in numerous applications in
the food industry as a swelling agent and for accelerated and
extended water absorption in foods such as soups, sauces, instant
puddings, baby food, and thickening agents. However, it has been
found that the use of pregelatinized starch or the use of starch as
the only matrix material during extrusion cooking generally results
in a matrix which releases the encapsulant too quickly. It has been
found that the penetration of water into a pure starch matrix
causes early release of the encapsulant into the environment.
Generally the time to release 100% of the encapsulant is too short
to provide a desirable time-release or controlled-release which is
effective for delivering the encapsulant at a desired location or
time.
[0009] International patent publication no. WO 95/26752 (published
Oct. 12, 1995) discloses the production of a food product for the
enteric supply of a fatty acid, a fatty acid containing substance,
an amino acid, or an amino acid containing substance by at least
partially complexing the fatty acid or amino acid in the amylose
helix of starch to mask the acid. The product may contain one or
more flavors and colors, fat soluble substances, anti-oxidants, or
pharmacologically effective substances. The components may be first
dry mixed and subsequently fed into an extruder where they are
substantially mixed and subsequently heated above the
gelatinization temperature of the starch to obtain an elasticized
mass which is extruded and formed into pellets. However,
heat-sensitive components would be destroyed during the heating
step.
[0010] International patent publication no. WO 85/04074 to
Flashinski, et al. (published Sep. 26, 1985) discloses an insect
bait containing an insect-controlling material in a gelatinized
starch matrix. The bait is made by coextruding starch with the
insect-controlling material at temperature and pressure conditions
sufficient to cook and gelatinize the starch. Alternatively, a
pregelatinized starch may be mixed with the insect-controlling
material and water to form a gel. In the formation of the insect
bait by mixing and extruding the components, it is disclosed, it is
essential to utilize additives, including the insecticides and
repellants which will withstand the extrusion temperatures of
starch without the degradation or vaporization. The extrusion
temperatures of the insect-bait mixture, depending upon the starch
content and other additives, ranges between about 160 to about
310.degree. F. at pressures of from about 300 through 800 psi.
[0011] U.S. Pat. No. 5,183,690 to Carr, et al. discloses a
continuous process for imparting predetermined release properties
to an encapsulated biologically active agent in a matrix of starchy
material. The starchy material, an active agent, and water are
continuously blended in an ingredient stream wherein the starchy
material is at a solids concentration of at least 40%. The
ingredients stream is continuously extruded as an extrudate and the
extrudate is continuously recovered. The conditions of blending,
extruding, and recovering are preselected to yield the
predetermined release properties. The temperature is elevated to at
least about 65.degree. C. to effect gelatinization of starch and
assure an essentially molecular dispersion of the starch in the
water. Alternatively, the core material to be encapsulated is added
and blended with the aqueous dispersion of starch after the starch
and water has been subjected to an elevated temperature sufficient
to gelatinize the starch. In this embodiment the aqueous starch
stream containing gelatinized starch may be lowered to a
temperature as low as about 25.degree. C. before the core material
to be encapsulated is added and subjected to high-shear mechanical
action. Under such low temperature conditions of admixture it is
disclosed, the activity of sensitive biological material, such as
bacteria and viruses, is preserved and loss of volatile organic
materials is minimized. The rate of swelling of the products in
water and the rate of release of active agents are controlled by
altering the amount of water present in the starch-agent-water
blend during processing. As the amount of water is decreased, both
the swelling rate and the release rate increase. The rate of
swelling of the products in water and the rate of release of active
agent are also controlled by passage of the extrudate containing
starch-agent-water through an exit die of various dimensions. As
the exit die is reduced in size, both the rate and extent of
swelling increase and the rate of release of agent increases.
[0012] The present invention provides a controlled release
particulate composition which contains a hydrophobic component for
controlling the release of an encapsulated and/or embedded active
component from a plasticized matrix. High water binding capacity
agents may also be used to delay or control the release of the
encapsulant from the matrix. Furthermore, in the process of the
present invention the amount of plasticizer is high to facilitate
plasticization of the matrix material at low shear and is then
reduced prior to adding the encapsulant to facilitate subsequent
forming and to reduce post extrusion drying. The controlled release
or delayed release composition may be produced without substantial
expansion of the matrix material to thereby avoid production of a
low density product which prematurely or too rapidly releases the
encapsulant or the embedded component. The products may be produced
using low shear mixing to avoid decomposition of the matrix
material and encapsulant or active component. However, even though
low shear mixing is utilized, substantial plasticization of the
matrix material and at least substantially uniform distribution of
the active component are achieved. Edible products produced in
accordance with the present invention for delivering
pharmaceutically or nutritionally active components may be consumed
or swallowed without chewing so that the products may reach the
digestive tract without substantial enzymatic hydrolysis in the
mouth. In addition, in embodiments of the invention, the
substantially spherical shape and high density of the products
reduce or prevent substantial surface related destruction of the
active components upon exposure of the particles to air, oxygen,
light, or water. Timing of the release of the embedded or
encapsulated component so that it is delayed until the product
reaches the stomach and/or the intestine may be controlled by the
use of varying amounts and types of hydrophobic components or high
water holding capacity components in the plasticized matrix. The
processes of the present invention may be used for the continuous
production of an edible composition for delivering pharmaceutically
or nutritionally active components, or for the production of an
agricultural product for the controlled release of biocides,
herbicides, fertilizers, growth stimulators, pesticides, or
products for other uses such as, for example, detergents which
release chemical and/or biological agents.
SUMMARY OF THE INVENTION
[0013] The present invention provides a continuous process for
producing controlled release, discrete, solid particles which
contain an encapsulated and/or embedded component. The particles
comprise a matrix material in which the active component is
encapsulated or embedded. The matrix material is plasticized upon
heating to form a melt. The active component is admixed with the
melt without substantially deleteriously affecting or decomposing
the encapsulant or the matrix material. The active component is
admixed with the plasticized matrix material at low temperatures
and under low shear mixing conditions to thereby avoid substantial
destruction of or volatilization of active components.
Additionally, high water contents may be employed so as to
substantially reduce viscosity and facilitate substantial
gelatinization of the starch without substantially destroying the
starch molecules. Subsequent removal of at least part of the water
prior to adding the encapsulant provides excessive drying or
evaporation of the plasticizing liquid which may adversely affect
the encapsulant content. The moisture reduction within the extruder
also provides for the attainment of a formable composition capable
of being formed into discrete, substantially uniform pieces.
Extrusion of the matrix and active component blend may be performed
without substantial expansion of the product thereby providing a
high density product which is less susceptible to attack by aqueous
or oxygen-containing mediums thereby providing a prolonged release
time. The process of the present invention may be used to
encapsulate heat sensitive components or readily oxidizable
components, for example, pharmaceutically or biologically or
nutritionally active components, without substantially destroying
their activity. The products of the present invention may be edible
for direct consumption or for incorporation into food products. In
other embodiments of the invention, products, such as chemical or
agricultural products such as pesticides, herbicides, fungicides,
insecticides, rodenticides, or other products like detergents or
flavorants, fragrances, and the like may be advantageously embedded
or encapsulated to control or delay their release from their
surrounding matrix.
[0014] In embodiments of the present invention, at least one
additional ingredient or component may be used to control the
release properties of the final product. The additional component
may manage, control or affect the flow, diffusion or distribution
of water or aqueous-based compositions into and within the final
product particles. The additional ingredient or component for
controlling the rate of release of the encapsulant may be a
hydrophobic agent such as polyethylene, polyurethane,
polypropylene, polyvinylchloride, polyvinylacetate, a fat, oil,
wax, fatty acid, or emulsifier which increases the hydrophobicity
of the matrix. The increased hydrophobicity helps to prevent or
delays penetration of water or gastric juice into the matrix. Other
ingredients which may be used to control the rate of the release
are components which have a high water binding capacity which delay
or prevent a fast dissolving of the matrix and thereby delay the
release of the encapsulant into the matrix. Exemplary of high water
binding capacity components which may be used are proteins, such as
wheat gluten, gelatin, and casein, hydrocolloid gums, and the
like.
[0015] In embodiments of the invention, matrix components may be
added to increase the rate of release of the encapsulant. These
rate increasing components may dissolve more readily in water than
does another matrix material. Upon dissolution, permeability of the
particles is increased, thereby increasing access to the
encapsulant by the penetrating aqueous-based solvent.
[0016] In accordance with the method of the present invention, at
least one plasticizable, matrix-forming material such as starch or
polyvinylpyrrolidone may be admixed with a sufficient amount of a
plasticizer such as water to reduce the melt or glass transition
temperature of the plasticizable material, together with the
additional release-rate controlling ingredient. The mix is heated
above the melt or glass transition temperature of the plastifiable
or matrix material, such as above the gelatinization temperature of
a starch matrix ingredient, while conveying and mixing the
ingredients within an extruder. The temperature is maintained
sufficiently high for a sufficiently long period of time to at
least partially gelatinize starch in the mixture. The additional
ingredient which is used to control the rate of release of the
encapsulant may be added before or after heating of the matrix
material, such as starch.
[0017] After the matrix material is plasticized at a high moisture
content to minimize molecular breakdown, at least some of the
moisture may then be removed from the plasticized mass or cooked
dough. The temperature of the plasticized mass may be reduced
either by the moisture removal and/or by additional barrel cooling,
the addition of inert gas, or by combinations of the above cooling
methods. The plasticized or gelatinized mass having a reduced
moisture content and lower temperature, is then conveyed toward a
subsequent extruder barrel section while maintaining sufficiently
low temperature to admix the encapsulant without thermally
destroying the encapsulant. The encapsulant is admixed with the
plasticized matrix under low temperature, low shear mixing
conditions to distribute, coat, embed, or encapsulate the added
active ingredient in the plasticized matrix material. Mixing is
continued towards the extruder die while adjusting the product
temperature for sufficient formability.
[0018] The admixture is extruded through the extrusion die and cut
or otherwise formed into pieces or pellets with no or substantially
no expansion of the extrudate. The extrudate or pieces may then be
dried and then surface treated with a film-building substance to
further encapsulate the extruded pellets or pieces. The
film-building substance may also contain additional components that
delay or prevent the access of light, oxygen, and/or water to the
matrix. In embodiments of the invention, the one or more
pharmaceutically, nutritionally, biologically or, chemically active
ingredients may be precoated with a coating material such as
shellac, zein, chitosan, chitin, an emulsifier or the like to
further control the release properties of the encapsulant from the
matrix material.
[0019] The products of the present invention may be in the form of
discrete particles, pellets, or tablets. They may be spherical in
shape, curvilinear or lens-shaped, flat discs, oval shaped, or the
like. The diameter of the particles may range from about 0.5 mm to
about 7 mm and the l/d ratio may be from about 0.1 to about 10. The
specific density of the pellets or particles may be from about 800
g/liter to about 1500 g/liter.
[0020] The amount of plasticizer such as water admixed with the
matrix material such as starch to form a plasticized mass may range
from about 20% by weight to about 50%/o by weight, preferably from
about 35% by weight to about 45% by weight, most preferably about
40% by weight, based upon the weight of the matrix material such as
starch. The amount of the ingredient used to control the rate of
release of the active component may range up to about 70% by
weight, preferably from about 5% by weight to about 50% by weight,
most preferably from about 10% by weight to about 35% by weight
based upon the weight of the matrix material such as starch. The
amount of the active component or encapsulant which may be
encapsulated or embedded into the matrix may be from about 1% by
weight to about 85% by weight, preferably from about 3% by weight
to about 50% by weight, most preferably from about 5% by weight to
about 20% by weight, based upon the weight of the matrix ingredient
such as starch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a schematic representation of the process of
the present invention.
[0022] FIG. 2 is a schematic overview of the extrusion process of
the present invention showing the screw configuration and barrel
temperature profile for the extruder.
[0023] FIG. 3 shows an alternative process, extruder screw
configuration and barrel temperature profile, where a
pregelatinized starch or hard durum wheat is fed to the extruder
using a relatively low temperature profile.
[0024] FIG. 4 shows a product in accordance with the present
invention having a primary outer coating and an encapsulant which
has a secondary coating.
[0025] FIG. 5 shows four basic release properties of an encapsulant
which is controllable by the use of optional coatings for the
extrudate and encapsulant in accordance with the present
invention.
[0026] FIG. 6 shows release data for encapsulated ascorbic acid
from various matrix compositions.
DETAILED DESCRIPTION OF THE INVENTION
[0027] An active component is encapsulated and/or embedded in a
plasticizable matrix component or material in an continuous process
to produce discrete, solid particles. Release of the active
component from the matrix is delayed or controlled over time so
that the active component is delivered when and where it is needed
to perform its intended function. The release of the active
component from the matrix may be controlled by an additional
ingredient or additive which affects the hydrophobicity of the
matrix or particle, the water binding capacity of the matrix or
particle, the solubility or porosity of the matrix material or
particle, or the glass transition (T.sub.g) of the matrix material
or particle. Pretreatment of the encapsulant, process conditions,
and the final shape of the discrete particles may also be used to
control the release of the active component from the matrix
material. The continuous process of the present invention
advantageously at least substantially uniformly distributes,
embeds, or encapsulates the active component in the matrix
material. The active components may be dispersed in the matrix
material on a microscopic or molecular level. Active components
which are dispersed on a molecular level may provide a higher
bioavailability when released, as compared to their crystalline
forms. The active components may be encapsulated or embedded either
in a solid form or liquid form. The encapsulants and encapsulated
products of the present invention may be edible such as
pharmaceutically or biologically or nutritionally active
components, or flavors or fragrances or they may be inedible
compositions such as a detergent, herbicide, fungicide, pesticide,
insecticide, or rodenticide, and the like. Release of the
encapsulant from the matrix material may also be controlled by the
use of a film or coating upon the encapsulant and/or upon the
discrete, solid matrix-encapsulated particles.
[0028] The matrix material may be a plasticizable biopolymer such
as a carbohydrate, such as a starch or cyclodextrin, or polymer
such as polyvinylpyrrolidone or other non-hydrophobic polymers such
as copolymers of N-vinylpyrrolidone (NVP) and vinylacetate,
polyvinyl alcohol, cellulose esters, cellulose ethers, and
polyethylene glycol. Exemplary starches which may be used in the
present invention are native or modified starches derived from
corn, wheat, rice, potato, tapioca, or high amylose starch. Sources
of starch which may be used also include flours from grains such as
corn, wheat, durum wheat, rice, barley, oat, or rye, and mixtures
thereof.
[0029] Additional matrix components which may be used include
carbohydrates which have a lower molecular weight than starches.
The lower molecular weight matrix components tend to dissolve more
readily than does the starch and increase the penetrability or
porosity of the matrix. As a result, access by the dissolution
medium, such as water or acid, to the encapsulant is increased
thereby permitting quicker release of the encapsulant from the
matrix material. Examples of carbohydrates other than starch which
may be used are sugars, such as mono- and di-saccharides, and
starch hydrolyzate products such as dextrins or syrups with
dextrose equivalent values (DE values) ranging from about 2 to
about 99, or from about 5 to 98, and mixtures thereof.
[0030] The matrix material is used in an effective encapsulating
amount. In embodiments of the present invention, the matrix
material content, such as the starch content of the particles may
be at least about 40% by weight, for example from about 60% by
weight to about 95% by weight, based upon the weight of the final
product.
[0031] The plasticizer or softener which may be used to lower the
melt temperature or glass transition temperature (T.sub.g) of the
matrix material and facilitate plastification is preferably water
but may be an aqueous-based composition such as a sugar solution,
alcohol, sorbitol, polyethylene glycol, polypropylene glycol,
silicone, hexanol, pentanol, dimethylsulfoxide (DMSO), hexane, or
an oil. The amount of plasticizer, such as water, should be
sufficient to substantially reduce the melt or glass transition
temperature of the plasticizable material such as starch so that it
may be admixed with the other ingredients at a sufficiently low
temperature and under sufficiently low shear conditions so as to
avoid substantial mechanical or thermal destruction of the
plasticizable material or matrix material. Exemplary amounts of
plasticizer, such as water, may range from about 20% by weight to
about 50% by weight, preferably from about 35% by weight to about
45% by weight, most preferably about 40% by weight based upon the
weight of the plasticizable material or matrix material such as
starch.
[0032] The additional ingredients which may be used to control the
release properties of the final product may be a hydrophobic agent
for slowing down the rate of release of the encapsulant. Exemplary
of components which may be added to affect the hydrophobicity of
the matrix include fats, oils, waxes, fatty acids, emulsifiers,
such as mono- or di-glycerides, synthetic polymers such as
polyolefins such as polyethylene or polypropylene, polyvinyl
chloride, polyvinyl acetate and derivatives thereof, paraffin, and
modified starches from plant sources that possess hydrophobic
properties that are obtained via either physical or chemical
modification, and mixtures of hydrophobic components. Plant lipids
or synthetic lipids with melting points up to about 65.degree. C.
may, for example, be employed as a hydrophobic agent. The
hydrophobic components increase the hydrophobicity of the matrix
and help to prevent or delay penetration of water or gastric juice
into the matrix by repelling water or aqueous acids, thereby
delaying the release of the encapsulant into the surrounding
media.
[0033] Additional components which may be used to delay or prevent
a fast release of the encapsulant from the matrix are components or
agents which have a high water binding capacity. The agents may
have a water binding capacity or water holding capacity which is
greater than the water binding capacity of the matrix material,
such as starch. The high water binding capacity component may bind
water which penetrates the particles, or prevent the water from
dissolving the matrix, thereby preventing or delaying the release
of the encapsulant from the matrix. Exemplary of high water binding
capacity agents which may be used in the present invention are
protein from animal sources such as gelatin, casein, and protein
from sources such as wheat, soy, corn, or other grains, and
hydrocolloids such as carrageenans, alginates, xanthan gum, gum
arabic, guar flour or guar gum, agar, tragacanth, karaya, locust
bean gum, pectin, soluble fiber, insoluble fiber and the like.
Exemplary proteins from grains which may be used are gluten, vital
wheat gluten, zein, and soy protein concentrate. The proteins from
plant sources may also be used to increase the tolerable addition
of lipids within the matrix composition and thereby indirectly
increase tie hydrophobicity of the matrix. The high water binding
capacity components may be used alone or mixtures thereof may be
employed.
[0034] The additional components or ingredients used to control the
rate of release of the encapsulant may be used in amounts up to
about 70% by weight, preferably from about 5% by weight to about
50% by weight, most preferably from about 10% by weight to about
35% by weight, based upon the weight of the matrix material, such
as starch.
[0035] Active components which may be encapsulated or embedded in
the matrixes in accordance with the present invention include
pharmaceutical compositions or compounds, nutraceutical
compositions or compounds, nutritional components, or biologically
active components, flavorants, fragrances, detergents or
surface-active compositions. The pharmaceutical compounds or
compositions may, for example, include antibiotics, analgesics,
vaccines, antiinflammatory agents, antidepressants, anti-viral
agents, anti-tumor agents, enzyme inhibitors, formations containing
zidovudine, macromolecular polypeptides, aromatic nitro and nitroso
compounds and their metabolites useful as anti-viral and anti-tumor
agents, HIV protease inhibitors, viruses, and steroids, mixtures
thereof, and the like.
[0036] Nutraceutical components may include components which
promote health or prevent disease or enhance well-being such as
antioxidants, phytochemicals, hormones, vitamins such as Vitamin C
and Vitamin E, pro-vitamins, minerals, microorganisms such as
bacteria, fungi, and yeast, prebiotics, probiotics, trace elements,
essential and/or highly unsaturated fatty acids such as omega-3
fatty acids, and mid-chain triglycerides, nutritional supplements,
enzymes, pigments, oligopeptides, dipeptides, and amino acids.
[0037] Biologically active components which may be encapsulated
include agriculturally useful compositions to either prevent
infestation such as herbicides, pesticides, insecticides,
rodenticides, fungicides, mixtures thereof, and the like or to
promote growth such as hormones, fertilizers, or other growth
stimulating agents.
[0038] Exemplary of the active components which may be encapsulated
or embedded in accordance with the present invention are:
acepromazine, acetaminophen, acetohexamide, acetohydroxamic acid,
acetylcholine, acetylcysteine acyclovir, albendazole, alclometasone
dipropionate, allopurinol, alprazolam, alprostadil, amcinoide,
amantadine, amdinocillin, amikacin amiloride, aminocaproic acid,
aminophylline, aminosalicylate, aminosalicylic acid, amitriptyline
hydrochloride, ammonium chloride, amobarbital, amodiaquine
hydrochloride, amoxapine, amoxicillin, amphetamine sulfate,
amphotericin, ampicillin amprolium, acetazolamide acetyldigoxin,
acetylsalicylic acid, anileridine, anthralin, antipyrine,
antivenin, apomorphine, apraclonidine, ascorbic acid, aspirin,
acromycin atropine, amoxycillin anipamil, azaperone azatadine
maleate, azathioprine, azithromycin, azrconam, bacampicillin,
bacitracin, baclofen, barium salts, beclomethasone diproionate,
belladonna extract, bendroflumethiazide, benoxinate hydrochloride,
benzethonium chloride, benzocaine, benzonatate benzthiazide,
benztropine mesylate, betaine, betamethasone, beaxolol, betanechol
chloride, biotin, biperiden, bisacodyl, bismuth, botulism
antitoxin, bromocriptine mesylate, bromodiphenhydramine
hydrochloride, bumetanide, bupivacaine, busulran butabarbital
sodium, butalbital, combinations of butalbital, caffeine and
aspirin and codeine, beta-carotene, calcifediol, calcium carbonate,
calcium citrate, calcium salts, candicidin, captopril, carbachol,
carbamazepine, carbenicillin indanyl sodium, carbidopa,
carbinoxamine maleate, carboprost tromethamine, carboxymethyl
cellulose, carisoprodol, casanthranol, cascara, castor oil,
cefaclor, cefadroxil, cefamandole nafate, cefazolin, cefixime,
cefoperazone, cefotaxime, cefprozil, ceftazidime, cefuroxime
axetil, cephalexin, cephradine, chlorambucil, chloramphenicol,
chlordiazepoxide, chloroquine phosphate, chlormadinone acetate,
chlorothiazide, chlorpheniramine maleate, chloroxylenol,
chlorpromazin, chlorpropamide, chlorprothixene, chlorprothixene,
chlortetracycline bisulfate, chlortetracycline hydrochloride,
chlorthalidone, chlorzoxazone, cholecalciferol, cholera vaccine,
chromic chloride, chymotrypsin, cimetidine, cinoxazin, cinoxate,
ciprofloxacin, cisplatin, clarithromycin, clavulanate potassium,
clemastine fumarate, clidinium bromide, clindamycin hydrochloride,
-palmitate and -phosphate, clioquinol, clofazimine, clofibrate,
clomiphene citrate, clonazepam, cinnarizine, clonidine
hydrochloride, clorsulon, clotrimazole, cloxacillin sodium,
cyanocobalamin, cocaine, coccidioidin, cod liver oil, codeine,
colchicine, colestipol, corticotropin, corisone acetate,
cyclacillin, cyclizine hydrochloride, cyclobenzaprine
hydrochloride, cyclophosphamide, cycloserine, cyclosporine,
cyproheptadine hydrochloride, cysteine hydrochloride, danazol,
dapsone, dehydrocholic acid, demeclocycline, desipramine,
desoximetasone, desoxycorticosterone acetate, dexamethasone,
dexchlorpheniramine maleate, dexpanthenol, dextroamphetamine,
dextromethorphan, diazepam, diazoxide, dibucaine, dichlorphenamide,
dicloxacillin sodium, dicyclomine, dienestrol, diethylpropion
hydrochlorid, diethylstilbestrol, diflunisal, digitalis,
dicoumarol, digitoxin, digoxin, dihydroergotamine,
dihydrostreptomycin, dihydrotachysterol, dihydroxyaluminium amino
acetate, dihydroxyaluminium sodium carbonate, diltiazem
hydrochloride, dimenhydrinate, dimercaprol, diphenhydramine
hydrochloride, diphenoxylate hydrochloride, diphteria antitoxin,
dipyridamole, disopyramide phosphate, disulfiram, dobutamine
hydrochloride, docusate calcium, docusate sodium, dopamine
hydrochloride, doxepin hydrochloride, doxycycline, doxycycline
hyclate, doxylamine cuccinate, dronabinol, droperidol, drotaverine,
dydrogesterone, dyphylline, guaifenesin, enalapril maleate,
analaprilat, ephedrine, epinephrine, equilin, ergocalciferol,
ergoloid mesylates, ergonovine maleate, ergotamine tartrate,
erythrilyl tetranitrate, erythromycin, estradiol, estriol,
estrogene, estrone, estropipate, ethcrynic acid, ethambutol
hydrochloride, ethchlorvynol, ethinyl estradiol, elthionamide,
ethopropazine hydrochloride, ethotoin, ethynodiol diacetate,
etidronate disodium, eoposide, eugenol, famotidine, fenoprofen,
ferrous fumatate, ferrous gluconate, ferrous sulfate, flucytosine,
fludrocortisone acetate, flunisolide, fluocinolone acetonide,
fluocinonide, fluorescein sodium, fluorometolone, fluorouracil,
fluoxymesterone, fluphenazine, flurandrenolide, flurazpam,
flurbiprofen, folic acid, furazolidone, flunitrazepam, furosemide,
gemfibrozil, gentamicin, gentian violet, glutarate, glutethimide,
glycopyrrolate, chorionic gonadotropin, gramicidin, griseofulvin,
guaifenesin, guanabenz, guanadrelsulfate, halazone, haloperidol,
haloprogin, halothane, heparin calcium, hepatitis virus vaccine,
hetacillin potassium, hexylresorcinol, histamine phosphate,
histidine, homatropine, histoplasmin, hydralazine hydrochloride,
hydrochlorothiazide, hydrocodone bitartrate, hydrocortisone,
hexobarbital, hydroflumethiazide, hydromorphone hydrochloride,
hydroquinone, hydroxocobalamin, hydroxyamphetamine,
hydroxychloroquine sulfate, hydroxyprogesterone caproate,
hydroxyurea, hydroxine hydrochloride, hydroxine pamoate,
hyoscyamine, hyoscyamine sulfate, ibuprofen, ifosfamide,
imipramide, imipramide hydrochloride, indapamide, indomethacin,
insulin, inulin, iocetamid, iodoquinol, ioliexol, iopamidol,
ipecac, ipodate calcium, ipodate sodium, isocarboxacid, isoetharine
hydrochloride, isoflurane, isoniacid, isopropamide iodine,
isoproterenol hydrochloride, isosorbide dinitrate, isotretenoin,
isoxsuprine hydrochloride, kanamycin sulfate, ketoprofen,
ketoconazole, labetalol hydrochloride, lanolin, leucine, leucovorin
calcium, levamisole hydrochloride, levocarnithine, levodopa,
levonorgestrel, levorphanol tartrate, levothyroxine sodium,
lidocaine, lincomycin hydrochloride, lindane, liothyronine sodium,
liotrix, lisinopril, lithium carbonate, loperamide hydrochloride,
loracarbef, lonetil, lorazepam, lovastalin, loxapine, lysine,
mafenide acetate, magaldrte, magnesium carbonate,
magnesiumchloride, magnesium gluconate, magnesium oxide, other
magnesium salts, malathinon, manganese salts, manganese,
maprotiline hydrochloride, mazindol, measle virus vaccine,
mebendazole, mebrofenin, mecamylamine hydrochloride, meclizine
hydrochloride, meclocycline, meclofenamate sodium,
medroxyprogesterone acetate, mefenamic acid, megestrol acetate,
meglumine, melphalan, menadiol sodium diphosphate, menadione,
menotropine, meperidine, mephenytoin, mephobarbital, meprednisone,
meprobamate, mercaptopurine, mesoridazine besylate, mestranol,
metaproterenol sulfate, metaraminol bitartrate, methacycline
hydrochloride, methadone hydrochloride, methamphetamine
hydrochloride, methazolamide, methdilazine, methenamine,
methicillin sodium, methimazole, methionine, methocarbamol,
methotrexate, methoxsalen, methoxyflurane, methsuximide,
methyclothiazide, methylbenzethonium chloride, methyldopa,
methylergonovine maleate, methylphenidate hydrochloride,
methylprednisolone, methyltestosterone, methysergide maleate,
metoclopramide, metolazone, meoprolol tartrate, metronidazole,
metyrapone, metyrosine, mexiletine hydrochloride, mexiletine
hydrochloride, miconazole, minocycline hydrochloride, minoxidil,
mitomycin, mitotane, molindone hydrochloride, monobenzone, morphine
sulfate, mupirocin, medazepam, mefruside, methandrostenolone,
methylsulfadiazine, nadolol, nafcillin, nafcillin sodium, nalidixic
acid, nalorphine, naloxone, nandrolone decanoate, nandrolone
phenpropionate, naproxen, natamycin, neomycin, neomycin sulfate,
neostimine bromide, niacin, nitrofurantoin, nalidixic acid,
nifedipine, nitrazepam, nitrofurantoin, nitroglycerine,
nitromerson, nizatidine, nonoxynol 9, norethindrone, norethindrone
acetate, norfloxacin, norgestrel, nortriptyline hydrochloride,
noscapine, novobiocin sodium, nystatin, opium, oxacillin sodium,
oxamniquine, oxandrolone, oxazepam, oxprenolol hydrochloride,
oxtriphylline, oxybenzone, oxybutynin chloride, oxycodone
hydrochloride, oxycodone, oxymetazoline hydrochloride,
oxymetholone, oxymorphone hydrochloride, oxyphenbutazone,
oxytetracycline, padimate, panreatin, pancrelipase, papain,
panthenol, papaverin hydrochloride, parachlorophenol, paramethasone
acetate, paregoric, paromomycin sulfate, penicillamine, penicillin,
penicillin derivatives, pentaerythritol tetranitrate, pentazocine,
pentazocine hydrochloride, pentazocine salts, pentobarbital sodium,
perphenazine, pertussis, phenacemide, phenazopyridine
hydrochloride, phendimetrazine tartrate, phenelzine sulfate,
phenmetrazine hydrochloride, phenobarbital, phenophtalein,
phenoxybenzamine hydrochloride, phentermine hydrochloride,
phenylalanine, phenylbutazone, phenylephrine hydrochloride,
phenylpropanolamine hydrochloride, physostigmine, phytonadione,
pilocarpine, pimozide, pindolol, piperazine, piroxicam plicamycin,
poliovirus vaccine inactivated, polycarbophil, polymycin b sulfate,
polythiazide, potassium chloride, potassium citrate, potassium
cluconate, potassium iodine, potassium sodium tartrate, povidone
iodine, pralidoxime chloride, pramoxine hydrochloride, pramezam,
prazepam, praziquantel, prazosin hydrochloride, prazosin
hydrochloride, prednisolone, prilocaine, primaquine, primidone,
probenecid, probucol, procainamide hydrochlorid, procaine
hydrochloride, procarbacine hydrochloride, prochlorperazine,
prochlorperazine maleate, procyclidine hydrochloride, progesterone,
proline, promazine, promazine hydrochloride, promazine,
promethazine, promethazine hydrochloride, propafenone
hydrochloride, propantheline, proparacaine hydrochloride,
propoxycaine hydrochloride, propoxyphene hydrochloride,
propoxyphene napsylate, propanolol hydrochloride, propyliodone,
propylthiouracil, propylthiouracil, protriptyline hydrochloride,
pseudoephedrine hydrochloride, pumice, pyrantel pamoate,
pyrazinamide, pyrethrum extract, pyridostigmine bromide, pyridoxine
hydrochloride, pyrilamine maleate, pyrimethamine, pyroxylin,
pyrvinium pamoate, phenacetin, phenytoin, prednisone, uinidine
gluconate, quinidine sulfate, rabies vaccine, racepinephrine
ranitidine, rauwolfia serpentina, resorcinol, ribavirin,
riboflavin, rifampin, ritodrine, rubella virus vaccine, saccharin,
saccharin sodium, salicylamide, salicylic acid, salsalata,
scopolamine, secobarbital sodium, selenius acid, selenium sulfate,
sennaserine, simethicone, sodium ascorbate, sodium bicarbonate,
sodium fluoride, sodium gluconate, sodium iodide, sodium lactate,
sodium nitrite, sodium ditroprusside, sodium salicylate,
spironolactone, stannozolol, streptomycin, sucralfate,
sulfacethmnide, sulfadiazine, reserpine, sulfadioxine,
sulfamerazine, sulfamethazine, sulfamethizole, sulfamethoxazole,
sulfamethoxydiazine, sulfapyridin, sulfasalazine, sulfaperin,
sulfathiazole, sulfisoxazole, sulfinpyrazone, sulindac, suprofen,
stilains, tamoxifen citrate, temacepam, terbutaline sulfate,
terfenadine, terpin, testolacton, testosterone, tolazamide,
tolbutamide, tetracaine, tetracycline, tetrahydrocycline,
theophylline, thiabendazole, thiamine hydrochloride, thiamin,
thiamylal, thiethylperazine thimerosal, thioguanine, thioridazine
hydrochloride, thistrepton, thiotepa, thiothixene, threonine,
thyroid, ticarcillin, timolol, tioconazole, titaniumdioxide,
tolazamide, tolbutamide, tolmetin, tolnaflate, trazodone
hydrochloride, tretinoin, triacetin, triamcinolone, triamterene,
triazolam, trichorfon, trichlormethiazide, trientine hydrochloride,
trifluoperazine hydrochloride, triflupromazine, trihexyphenidyl
hydrochloride, trimeprazine tartrate, trimethadione,
trimethobenzamide hydrochloride, trimethoprim, trioxsalen,
tripelennamine, triprolidine, risulfapyrimidine, tropicamide,
trypsin, tryptohan, tuberculin, tyloxapol, tyropanoate sodium,
tyrosine, tyrothricin, thyrothricin bethamethasone, thiotic acid,
sotalol, salbutamol, norfenefrine, silymarin, dihydroergotamine,
buflomedil, etofibrate, indometacin, urea, valine, valproic acid,
vancomycin hydrochloride, vasopressin, verapramil, vidarabine,
vinblastine, vincristine, vitamins, warfarin, yellow fever vaccine,
zinc acetate, zinc carbonate, zinc chloride, zinc gluconate, beta
acetyl digoxin, piroxicam, haloperidol, ISMN, amitriptylin,
diclofenac, nifedipine, verapamil, pyritinol, nitrendipin,
doxycycline, bromhexine, methylprednisolone, clonidine,
fenofibrate, allopurinol, pirenyepine, levothyroxin, lamoxifen,
metildigoxin, o-(beta-hydroxyethyl)-rutoside, propicillin,
aciclovir mononitrate, paracetamol, naflidrofuryl, pentoxifylline,
propafenone, acebutolol, L-thyroxin, tramadol, bromocriptine,
loperamide, ketotifen, fenoterol, cadobelisate, propanolol,
enalaprilhydrogen maleate, bezafebrate, ISDN, gallopamil, xantinol
nicotinate, digitoxin, flunitrazepam, bencyclane, dexapanthenol,
pindolol, lorazepam, diltiazem, piracetam, phenoxymethylpenicillin,
furosemide, bromazepam, flunarizin, erythromycin, metoclopramide,
acemetacin, ranitidin, biperiden, metamizole, doxepin, dipotassium
chloroazepate, tetrazepam, estramustine phosphate, terbutaline,
captopril, maprotiline, prazosin, atenolol, glibenclamide,
cefaclor, etilfrine, cimetidine, theophylline, hydromorphone,
ibuprofen, primidone, clobazam, oxaceprol, medroxyprogesterone,
flecainid, pyridoxal 5 phosphate glutaminate, hymechromone,
etofylline clofibrate, vincamine, cinnarizine, diazepam,
ketoprofen, flupentixol, molsimine, glibornuride, dimetinden,
melperone, soquinolol, dihydrocodeine, clomethiazole, clemastine,
glisoxepide, kallidinogenase, oxyfedrine, baclofen,
carboxymethylcysteine, thioridazine, betahistine, L-tryptophan,
murtol, bromelaine, prenylamine, salazosulfapyridine, astemizol,
sulpiride, benzerazide, dibenzepine, acetylsalicylic acid,
miconazol, nystatin, ketoconazole, sodium picosulfate, coltyramine,
gemfibrocil, rifampicin, fluocortolone, mexiletin, amoxicillin,
terfenadrin, mucopolysaccharide polysulfade, triazolam, mianserin,
tiaprofenic acid, amezinium metilsulfate, mefloquine, probucol,
quinidine, carbainazepine, L-aspartate, penbutolol, piretanide,
aescin amitriptyline, cyproterone, sodium valproinate, mebeverine,
bisacodyl, 5-aminosalicylic acid, dihydralazine, magaldrate,
phenprocoumon, amantadine, naproxen, carteolol, famotidine,
methyldopa, auranofine, estriol, nadolol, levomepromazine,
doxorubicin, medofenoxate, azathioprine, flutamide, norfloxacin,
fendiline, prajmalium bitartrate, lipid derivatives of
phosphonatides, amphiphilic polymers, adenosine derivatives,
sulfated tannins, monoclonal antibodies, and metal complexes of
water soluble texathyrin.
[0039] The amount of the active component or encapsulant which is
incorporated into the products of the present invention may be such
so as to provide or deliver an effective amount, such as a
pharmaceutically effective amount or a nutraceutically effective
amount of the active component at its intended location, such as
the small intestine. Exemplary amounts of the active component or
encapsulant which may be encapsulated or embedded into the matrix
may be from about 1% by weight to about 85% by weight, preferably
from about 3% by weight to about 50% by weight, based upon the
weight of the matrix ingredient, such as starch.
[0040] Film-building or film-forming substances which may be used
to coat the encapsulants prior to incorporation into the matrix
include commonly used coating materials such as zein, pectin,
shellac, gelatin, fats, oils, waxes, emulsifiers, native or
modified starch, chitosan, chitin, and mixtures thereof. The
film-building or film-forming substance may also be used to coat
the extruded, particulate product. Pretreatmnent of the encapsulant
by coating it with a film forming substance such as a high melting
fat or wax, or with an emulsifier such as glycerin monostearate, or
the like, tends to prevent unwanted interaction between an
encapsulant and the matrix. The encapsulants and the extrudate
particles may be coated with film-forming amounts of the substances
in aqueous or alcoholic solutions, or oleaginous compositions.
[0041] The film-forming substances or coatings may also contain
additional components that protect the particulates or pellets, or
encapsulant, from the influence of light, such as titanium dioxide,
or cocoa-based products. The coatings may also contain
anti-oxidants to protect the pellets or encapsulants from the
influence of oxygen or air.
[0042] In accordance with embodiments of the present invention, the
thickness of the coating upon the encapsulant may be used to
control the rate of release of encapsulant once the dissolving
media, such as water, reaches the encapsulant. For example,
increasing the thickness of the coating on the encapsulant slows
its rate of release into the media. Also, increasing the thickness
of the coating on the extrudate or pellet delays release of the
encapsulant from the matrix material.
[0043] In accordance with the method of the present invention, the
matrix material or plasticizable material and the plasticizer are
admixed and heated to plasticize and melt the matrix material under
low shear mixing conditions without substantially destroying or
decomposing the matrix material. In preferred embodiments, the
matrix material and the plasticizer may be added to the upstream
end of an extruder, mixed and heated above the melt temperature of
the plasticizable material or above the gelatinization temperature
of starch while mixing and conveying these ingredients inside the
extruder. In embodiments where starch is used as a matrix material,
the starch is at least partially gelatinized without substantially
destructurizing and dextrinizing the starch. The degree of
gelatinization may, for example, be at least about 75%, for
example, at least about 90%, or essentially completely gelatinized.
In embodiments of the invention, to achieve at least substantial
gelatinization of starch, the starch and plasticizer (preferably
water) admixture may be maintained at a temperature of the blend of
at least about 100.degree. C., preferably from about 120.degree. C.
to about 150.degree. C., for example, from about 125.degree. C. to
about 140.degree. C., for a period of time of at least about 3 l/d
preferably about 5 to 7 l/d of extruder length. For example, for
starches having an amylose content of snore than about 25%, for
example about 50% to about 70%, it may be necessary to maintain a
product temperature inside the extruder of about 125.degree. C. for
a sufficient amount of time, for example for about 4 l/d,
preferably about 7 to 8 l/d of extruder length at a low screw
rotational rate of about 150 to about 200 rpm using medium pitch
screw elements to assure at least substantial gelatinization of the
starch.
[0044] In embodiments of the invention, the pressure maintained
within the cooking section or gelatinization section or
plastification zone may be between about 5 to 100 bars, preferably
between about 10 and 35 bars.
[0045] An overall quantitative measure of the shear used inside the
extruder during the cooking process is the specific mechanical
energy input. In embodiments of the present invention, the specific
mechanical input during cooking may be below about 150 Wh/kg,
preferably below about 100 Wh/kg, and most preferably below about
50 Wh/kg.
[0046] In embodiments where durum wheat is used as the matrix
material, heating of the durum wheat and water mix to cook or
gelatinize the durum wheat may not be needed where an uncooked
pasta-type product is desired.
[0047] The at least one additional ingredient or component, such as
the hydrophobic component, or high water binding capacity component
for controlling the release properties of the final product, may be
dry blended or preblended with the matrix material such as starch.
In other embodiments of the invention, the additional component for
controlling the release properties may be added during heating in a
heating or gelatinization zone. Addition of the at least one
release-controlling component prior to substantial water
evaporation or cooling may also facilitate at least substantially
uniform dispersion of the component throughout the matrix.
[0048] The plasticized mass may be subjected to moisture reduction
during heating or gelatinization, downstream of the input of the
release-controlling components. In embodiments of the invention,
the water content may be substantially reduced so as to facilitate
forming and enable optional cutting without the material sticking
to the cutter. For example, the water content may be reduced by at
least about 10%, for example by about 25% to about 50%. For
example, a plasticized starch matrix having an initial moisture
content of about 43% by weight may have its moisture content
reduced to about 30% by weight. In other embodiments, a gelatinized
starch composition may have its moisture content reduced from about
30% by weight to about 18% by weight.
[0049] The removal of water may be achieved by passing the at least
partially plasticized or gelatinized mixture through an extruder
barrel section that is open to the atmosphere. In other
embodiments, the moisture may be removed by reducing the pressure
above the material while it moves underneath an open extruder
section or barrel that is connected to an external vacuum pump. A
plurality of open extruder barrel sections in series may also be
used. The plurality of open barrel sections may be open to the
atmosphere or connected to one or more vacuum pumps or combinations
thereof may be used. In another embodiment, the material may be
transferred from a first cooking extruder into a downstream or
subsequent mixing and forming device such as an extruder. During
the transfer, the material may be permitted to undergo a
temperature and moisture drop by exposure to the atmosphere or a
vacuum hood.
[0050] After heating and moisture content reduction, the
plasticized or gelatinized mass may be subjected to cooling to
substantially reduce the temperature of the mass for the subsequent
addition of the active component or encapsulant. In embodiments of
the invention, the temperature of the matrix material is
substantially reduced to avoid substantial destruction of the
encapsulant. The matrix material temperature may, for example, be
reduced by at least 5.degree. C., generally at least about
25.degree. C., preferably at least about 60.degree. C. In
embodiments of the invention, the temperature of the matrix
material may be cooled to substantially lower than 100.degree. C.,
for example, to a temperature of between about 25.degree. C. and
95.degree. C., in one or more extruder barrels. The material may be
transported through and exposed to the barrel walls of one or more
extruder barrels that are chilled with water or appropriate other
cooling liquids such as a glycol. In other embodiments of the
invention, the matrix material may be cooled or chilled by the
direct injection of gases such as carbon dioxide or nitrogen which
reduce the temperature of the matrix material by direct contact.
The matrix material, after moisture reduction and temperature
reduction, may be conveyed toward a subsequent extruder barrel
section for the addition of one or more active components.
[0051] After cooling the matrix material to a temperature which is
sufficiently low to avoid substantial thermal destruction and/or
volatilization of the active component or encapsulant, the
encapsulant may be added into a downstream barrel section of the
extruder. The added active component or encapsulant may be added as
a solid or liquid. For feeding the active components to an
extruder, for example, a feeding apparatus, commonly known as a
side feeder, may be used for feeding solids. Other conventional
solids feeding devices such as a volumetric or gravimetric feeder
may also be used. Liquid injection nozzles may be used for
injecting liquid active components or solutions, dispersions,
emulsions or suspensions. In embodiments of the invention, a side
feeder and liquid injection nozzles may be employed. If an
injection nozzle is used, the pressure for injecting the liquid
encapsulant should be sufficiently higher than the pressure in the
extruder so that the encapsulant can be injected into the extruder
barrel. For example, if the pressure of the plasticized mass inside
the extruder is 10 bars, the injection pressure may be about 2 to
about 5 bars higher, i.e. 12 to 15 bars.
[0052] In embodiments where the encapsulant is pre-coated with a
film-building material or coating material, the coating material
may be applied in conventional manner such as by spraying or
enrobing using conventional coating equipment. Commercially
available pre-coated active ingredients, such as precoated minerals
or vitamins may be employed.
[0053] The encapsulant which itself may be optionally coated, is
admixed with the matrix material without substantially destroying
the encapsulant or the precoated encapsulant. The mixing may be
conducted at a temperature which is substantially lower than the
degradation temperature of the encapsulant and its optional
precoating. For example, admixing of the encapsulant with the
matrix material may be performed at a temperature substantially
less than about 100.degree. C., preferably at a temperature less
than about 60.degree. C., most preferably less than about
40.degree. C.
[0054] The admixing of the added active ingredients or encapsulants
inside the extruder may be accomplished by using an appropriate
extrusion screw configuration for achieving low shear mixing. For
example, a combination of alternating small pitch conveying
elements with distributive mixing elements, that are staggered at
an angle to each other for providing axially oriented leakage flow
inside the extruder barrel may be employed. The combination of
alternating conveying elements with distributive mixing elements
cause the material flow to be continuously interrupted without
shearing of the mass thus resulting in mixing of the material at
low mechanical energy input.
[0055] In other embodiments of the invention, other extruder screw
configurations may be used that facilitate low shear distributive
mixing, such as screw elements of the type ZME, TME, SME, and
so-called IGEL elements commercially available from Werner and
Pfleiderer.
[0056] The total length of the distributive mixing section may be
about 3 to 12 l/d, preferably about 4 to 6 I/d to sufficiently
admix and distribute and embed or encapsulate the added active
components in the matrix.
[0057] The at least substantially homogeneous mixture of matrix
material and added active ingredient or encapsulant is then
conveyed towards an extruder die plate. The conveying may be
achieved by the use of low pitch extruder screw conveying elements
which build up sufficient pressure prior to extruding the mix so
that it can be forced through the apertures in the die plate.
Another function of the low pitch elements is that they increase
the degree of fill inside the last extruder barrel section. The
increased degree of fill enables control of the temperature profile
of the mix inside the extruder barrel for achieving optimum
viscosity adjustment and extrusion through the subsequent die
openings.
[0058] The mix may be extruded through extrusion dies having
aperture diameters of from about 0.5 mm to about 5 mm, preferably
from about 0.5 mm to about 1 mm. The diameter of the extrudate rope
and product may be larger than the diameter of the die apertures
due to deformation or swelling as the composition exits the die.
The increase in diameter upon exiting the die may occur without
substantial development of an expanded, puffed, foamy, or cellular
structure. The extruded rope may have a cross-sectional diameter of
from about 0.5 mm to about 7 mm, preferably from about 0.5 mm to
about 5 mm, most preferably from about 1 mm to about 3 mm.
[0059] The extrudate rope may be cut at the die face using a
rotating cutter, pelletizer, or rotating knives. In other
embodiments, the extrudate rope may be cut away from the die using
conventional cutting or forming means for producing pellets or
tablets. The cut pieces, pellets, or tablets, may have a
length:diameter ratio (l/d ratio) of about 0.5 to 10, preferably
about 1.
[0060] In accordance with the process of the present invention, the
particle size may be varied to control the surface to volume ratio
of the pellets or pieces for achieving a desired controlled release
of the encapsulant. The particle size may be varied, for example,
by the use of different diameters for the extrusion die openings.
Particle size may also be varied by the use of a variable speed
cutter either at the die plate at the end of the extruder or away
from the extruder after the ropes have been conveyed for a short
distance. By varying the speed of the cutter, the size of the cut
pieces may be varied for a given extruder throughput. The use of a
variable cutter which is spaced a short distance from the die
plate, for example, between about 0.5 meters to about 5 meters
permits further surface cooling, further surface drying, and
reduced stickiness to provide better cutting of the ropes into
pellets.
[0061] In producing products for human or animal consumption,
variation of particle size to control the surface to volume ratio
of the pellets is critical for achieving a controlled release of
tile encapsulant during passage of the pellets or particles through
the mouth, the stomach, and the intestine. Variation of particle
size is also critical for controlling the residence time of the
pellets inside the stomach. For example, particles smaller than 1
mm pass through the stomach or intestine faster than would
particles larger than for example 2.5 mm.
[0062] After cutting, the resulting pieces or pellets may be dried
to a sufficiently low moisture content which assures a sufficiently
prolonged storage stability or shelf life. For example, the pellets
may be dried to achieve a storage stability or shelf life of at
least about nine months, preferably at least about eighteen months,
most preferably at least about thirty-six months. In embodiments of
the present invention, the drying may be performed using
conventional drying equipment using drying temperatures which do
not adversely affect the thermal stability of the encapsulants.
Exemplary drying temperatures may range from about 10.degree. C. to
about 90.degree. C., preferably from about 20.degree. C. to about
60.degree. C. The drying may be conducted to achieve a moisture
content of less than about 30% by weight, preferably less than
about 12% by weight, for example, from about 6% by weight to about
9% by weight. In embodiments where no starch or substantially no
starch is used as a matrix material, the moisture content may be
less than about 6% by weight.
[0063] In embodiments where film-building substances or coatings
are applied to the particles or pellets, conventional spray nozzles
may be located close to the die or for spraying an aqueous or
alcoholic solution of the film-building substances onto the cut
pieces as they fall downwardly from the extruder die. In other
embodiments, the film-building substances may be applied after
drying of the pellets. For example, the film-building substances
may be applied using spray nozzles, conventionally known fluid bed
coating apparatus, or other conventional coating apparatus and
methods. If the application of the film-building substances
increases the moisture content above a shelf stable level, the
water or other volatile media may be removed from the surface of
the particles by additional drying.
[0064] In embodiments of the present invention, the extruded pieces
or pellets may be compressed in conventional tablet presses to
obtain compressed versions of the extruded pellets.
[0065] In other embodiments of the present invention, the mixture
may be extruded through a sheeting die into a sheet. The extruded
sheet may then be cut or molded into individual pieces, such as
tablets, or disks, using a rotary die or rotary cutter, or
reciprocating cutter or counterrotating drums conventionally known
as agglomeration drums or tabletting drums.
[0066] The products of the present invention comprise discrete
particles which may be spherical, lens-shaped, or flat discs having
diameters of from about 0.5 mm to about 7 mm, preferably from about
0.5 mm to about 5 mm, most preferably from about 1 mm to about 3
mm, exclusive of any optional exterior film-building substances or
coatings. In embodiments of the invention, the particles of the
invention may be in the form of tablets with diameters of up to
about 10 mm. The length-to-diameter ratio (l/d) of the particles
may be from about 0.1 to about 10, for example about 0.5 to about
2, preferably about 1. The particles are generally uniform in size,
dense, and granular to increase palatability to humans and animals
in a substantially compact form that is easy to swallow without
chewing. They are non-expanded, and exhibit a non-puffed,
substantially non-cellular, dense structure. The starch component
of the matrices is at least partially gelatinized and not
substantially destructurized or dextrinized. Exemplary specific
densities of the products of the present invention are between
about 800 g/liter and about 1500 g/liter (about 0.8 to about 1.5
g/c.sup.3).
[0067] FIG. 1 shows a simplified schematic representation of the
process of the invention using an extruder. A preblend that
contains at least one starch and one additional component is fed
into the upstream end of the extruder. Water is added into the same
or one of the next immediately following barrel sections of the
extruder. Co-rotating intermeshing twin screw extruders, such as
those available from Buhler, Switzerland, Clextral France, Werner
and Pfleiderer Germany, APV England or Wenger USA, or a Co-Kneader,
available from Buss, Switzerland are preferred, since they provide
superior mixing action compared to other single screw extruders.
The preblended matrix materials, plasticizer such as water,
additional components or matrix material are mixed in the extruder
and heated so that the starch is at least partially gelatinized. As
shown in FIG. 1, the additional ingredients for controlling release
properties may be fed into the extruder and mixed with the matrix
material before and/or after heating and plasticization of the
starch. The total mix may be plasticized and pressurized using
appropriate screw elements arranged in an appropriate matter.
[0068] After pressurizing and melting, the mass may be exposed to a
lower pressure and at least part of the moisture may be removed
from the matrix material. As illustrated in FIG. 1, in a subsequent
step the mass may be cooled in one or more subsequent extruder
barrels. After cooling of the mass, the optionally coated
encapsulant material may be added at a low temperature, i.e. room
temperature, so as to prevent thermal destruction of the
encapsulant. The added encapsulant may be mixed at low shear and
low temperature with the cooled, plasticized, matrix material. The
final plasticized mass may be mixed, conveyed and forced through
the extruder die. The mass may be formed into shapes that exit the
extruder as continuous ropes. The ropes may be sprayed with
liquids, that provide an additional coating or facilitate cutting
to separate the individual pieces from each other. In embodiments
of the invention, it is possible to perform the forming step using
a single screw extruder.
[0069] As shown in FIG. 1, after cutting, the product may be dried
using a conventional fluidized bed or other conventional drying
means. The product may be optionally coated after drying using
conventional coating equipment such as coating pans, coating drums,
or spray devices.
[0070] FIG. 2 shows schematically an overview of an extrusion
process, an exemplary extruder barrel configuration, and screw
configuration, in accordance with the present invention. Exemplary
barrel temperatures or temperature profiles, and moisture contents
along the length of the extruder are also shown in FIG. 2. A
preblend of starches or other plasticizable material such as PVP or
other matrix materials, with at least one more other component may
be prepared and stored or conditioned prior to feeding it into the
extruder. The dry blend is fed either gravimetrically or
volumetrically into the feeding section of the extruder in barrel
1. Temperatures at this barrel section are normally about room
temperature and can vary from about 0.degree. C. to about
85.degree. C. higher temperatures tend to cause steam to escape
from the feed port. Barrel (1) may be cooled with water to maintain
a temperature between about 10.degree. C. and 50.degree. C. Screw
elements with large pitch convey the dry blend into barrel 2.
Elements with less pitch than in Barrel 1 increases the degree of
fill in barrel 2. Offset forward pitch elements and small disk
kneading blocks cause distributive mixing of the added liquid that
may be added in barrels 1 and 2 with the dry blend. Simultaneously,
the temperatures of barrel 2 and 3 may be elevated to about between
60 and about 150.degree. C. to heat the wet blend, that is conveyed
using medium pitch screw elements into barrel 4. The barrel
temperature in barrels 4 and 5 may be between about 110.degree. C.
and 180.degree. C., preferably between about 120.degree. C. and
160.degree. C. The temperature of the mix increases at a rate that
is mainly affected by the contact time of the material and the
barrel and exchange of material by the screws. The contact time is
a function of rpm and throughput rate, which determine the degree
of fill. The material exchange is affected by the screw
configuration.
[0071] In barrel 4, mixing elements alternate with medium pitch
conveying elements and ensure sufficient material exchange and a
high degree of fill. Staggering kneading disks at an angle of 90
degrees to each other allows additional leakage flow and prevents
high shear. As long as the energy dissipation into the material is
low, which is the case at a relative low material viscosity,
resulting from relatively high moisture contents, the mass is
heated via the barrel wall and its temperature is normally a few
degrees lower than the actual barrel temperature. The mass forms a
dough, that may have a temperature of about 5.degree. C. to
30.degree. C. lower than the barrel temperature, in this case
90.degree. C. to 155.degree. C. With an extruder set up as
described in FIG. 2, gelatinization of starch occurs within the
first 4 barrel sections. Optional steam injection may be applied in
this gelatinization or heating section to increase the thermal
energy input and further decrease the mechanical energy input.
[0072] Before the vent opening in barrel 5, a kneading disc element
increases the degree of fill and increases pressure of the mass in
barrel 4. This pressure is needed to further enhance the cooking of
the starch. If the starch is high in amylose, temperatures of about
120.degree. C. may be reached under this pressure, which may be
between about 5 and 30 bars, for example 10 bars. After this
element, high pitch conveying elements follow, that decrease the
degree of fill by their function of higher conveying capacity. One
open barrel section 5, optionally connected to a vacuum pump,
allows the pressure to decrease substantially, for example from
about 10 bar to about less than 1 bar. This pressure drop results
in water evaporation and subsequent moisture loss of the cooked
mass. The amount of moisture evaporated to the atmosphere or to the
vacuum, additionally depends upon the temperature of the product
and residence time of the product in this open barrel section 5.
Residence time is affected by the rpm of the screw, pitch of the
screw elements, and available open area for water evaporation,
which may vary from one, two or more vent ports. High barrel
temperatures, above for example 150.degree. C., force more steam to
escape from the cooked mass than low barrel temperatures, for
example 80.degree. C. Exemplary temperatures in the vented heating
zone of barrel 5 may be between about 80.degree. C. and 160.degree.
C., preferably about 100.degree. C. to 140.degree. C.
[0073] The subsequent barrels 6 and 7 may be cooled down with water
to reduce mass temperature further. Temperatures in this section
may be between about 20.degree. C. and 90.degree. C. Low pitch
conveying elements that are staggered increase degree of fill to
enhance heat transfer from product to barrel in barrels 6 and 7.
Low rpm are critical for optimum processing. Exemplary ranges which
may be utilized are between about 20 and about 200 rpm. Higher rpm
tend to introduce more shear, dextrinize and destructurize starch
to a larger extent. Additionally higher screw speeds tend to
severely reduce capability for water removal because the residence
time in the open vent section is greatly reduced. Low screw speeds
(rpm's) also increase the degree of fill and thus heat transfer
capability, i.e. heating and cooling.
[0074] Barrel 7 may be open to the atmosphere to enable addition of
encapsulant. Optionally, a side feeder (not shown) may be used that
is directly connected to the side of the extruder to feed a solid
encapsulant into the extruder. In addition, liquid encapsulants can
be introduced into the blend via one or more injection nozzles into
the same extruder barrel. The side feeder may be a conventional
twin screw feeder. The temperature of the barrel is adjusted
depending upon the heat sensitivity of the encapsulant and can, for
example, be adjusted to temperatures between about 20 and 90 degree
C.
[0075] The product temperature at the encapsulant input location in
barrel 7 is sufficiently low so as to not thermally destroy or
disintegrate the encapsulant. In case the encapsulant is oxygen
sensitive, the hopper (not shown) of the side feeder (not shown)
may be optionally flooded with CO.sub.2 or nitrogen. After the mix
has been introduced into the barrel section, it is conveyed into a
barrel section 8 and then barrel section 9, both of which may
contain screw elements with forward pitch and staggered position,
that mix the added ingredients into the matrix while minimizing the
introduction of shear energy. Simultaneously, the temperature of
the barrels 8 and 9 may be maintained low enough so as to not
thermally destroy the encapsulant and to ensure that the viscous
properties of the dough are sufficiently high to allow extrusion
and forming of ropes that can be cut into pellets. Temperatures may
range between 25.degree. C. and 95.degree. C., preferably around
40.degree. C. to 80.degree. C.
[0076] After exiting the barrel section 9 of the extruder, the mass
enters into the die area, where it is distributed into a multitude
of openings. Critical is the rate of extrudate per die area, which
should be less than about 5 kg/h per mm.sup.2, preferably less than
3 kg/h per mm.sup.2 and most preferably less than about 0.5 kg/h
per mm.sup.2. High rates will result in higher shear rates inside
the die that will cause increased viscous dissipation, pressure and
temperature which may adversely affect the encapsulant and may lead
to unwanted product expansion.
[0077] FIG. 3 shows an alternative execution of the invention,
whereby the fed solid ingredients may be either pregelatinized
starch or flour with specific properties, such as flour from durum
wheat that is normally used to produce pasta, such as semolina. As
shown in FIG. 3, the dry feed and at least one additional component
for affecting the release properties may be fed to barrel 1 without
cooking. The dry feed solids and the at least one more component to
affect the release properties of the matrix may then be mixed with
water in barrel 2 to hydrate the dry feed ingredients. In this
case, the moisture needs to be sufficiently high so as to provide
sufficiently low viscosity without destructurizing or dextrinizing
the pregelatinized starch. For example, the added moisture content
may be between about 20% and 45% by weight, preferably between
about 25% and 35% by weight, for example about 30% by weight. As
shown by the barrel temperature profile in FIG. 3, the temperature
of the extruder barrel 1 is kept at about room temperature, but
barrels 2 and 3 need to be about between 40.degree. C. and
100.degree. C. to maintain low viscosity and low specific
mechanical energy input. The encapsulants may be added in barrel 4
and/or barrel 5 with continued mixing and conveying. The product
may be cooled in barrels 4, 5, and 6 at the end of the extruder in
similar manner as described for FIG. 2. Thus, the temperature of
the barrels 4, 5, and 6 may be maintained low enough so as to not
thermally destroy the encapsulant and to ensure that the viscous
properties of the dough are sufficiently high to allow extrusion
and forming of ropes that can be cut into pellets. Temperatures may
range between 20.degree. C. and 95.degree. C. After exiting the
barrel section 6 of the extruder, the mass enters into the die
area, where it is distributed into a multitude of openings.
[0078] FIG. 4 shows a spherical product which may be produced in
accordance with the present invention. The pellet shown in FIG. 4
has a primary coating of a film-forming ingredient which enrobes or
coals the underlying matrix material. An encapsulant, which has
been pre-coated with a secondary coating of a film-forming
ingredient, is encapsulated or surrounded by the matrix material.
The primary coating and the secondary coating may be the same or
different compositions.
[0079] FIG. 5 shows as an example of four basic release properties
of the encapsulated products of the present invention which are
dependent upon the presence and thickness and material of a coating
for the discrete extrudate particles or for the encapsulant.
According to the present invention, a primary factor that
determines the release properties of the encapsulant from the
matrix, is the matrix material, and particularly its diffusivity or
solubility (against aqueous or digestive liquids). The diffusivity
or solubility may be controlled by the hydrophobicity of at least
one additional matrix component next to the starch. Also, as shown
in FIG. 5, a fast and early release of encapsulant from the matrix
may be achieved with a relatively thin primary coating and a
relatively thin secondary coating. A slow but early release of
encapsulant may be obtained with a relatively thin primary coating
and relatively thick secondary coating. A fast but late release of
encapsulant may be achieved with a relatively thick primary coating
and a relatively thin secondary coating. A slow and late release
may be achieved with a relatively thick primary coating and a
relatively thick secondary coating.
[0080] The encapsulated products of the present invention may be
incorporated with or without grinding into foods intended for human
or animal consumption such as baked goods, for example, bread,
wafers, cookies, crackers, pretzels, pizza, and rolls, ready-to-eat
breakfast cereals, hot cereals, pasta products, snacks such as
fruit snacks, salty snacks, grain snacks, and microwave popcorn,
dairy products such as yoghurt, cheese, and ice cream, sweet goods
such as hard candy, soft candy, and chocolate, beverages, animal
feed, pet foods such as dog food and cat food, aqua-culture foods
such as fish food and shrimp feed, and special purpose foods such
as baby food, infant formulas, hospital food, medical food, sports
food, performance food or nutritional bars, or fortified foods,
food preblends or mixes for home or food service use, such as
preblends for soups or gravy, dessert mixes, dinner mixes, baking
mixes such as bread mixes, and cake mixes, and baking flour.
[0081] The present invention is further illustrated by the
following non-limiting examples where all parts, percentages,
proportions, and ratios are by weight, and all temperatures are in
.degree. C. unless otherwise indicated:
Example 1
Encapsulation of a Water Soluble, Sensitive Pharmaceutical
Component
[0082] Acetylcysteine may be encapsulated by feeding a prepared
blend of 96.3% corn starch, 3% low density polyethylene (LDPE) and
0.7% glycerin-mono-stearate (GMS) at a rate of 4.0 kg/h into a
first feed barrel of a co-rotating twin screw extruder. In addition
to the corn starch/GMS/LDPE mix, vegetable oil was fed into barrel
#1 via a piston pump at a rate of 0.17 kg/h. Water was added to the
mix at a rate of 1.1 kg/h via a piston pump through a liquid
injection port of barrel #2. The extruder used was a Werner and
Pfleiderer ZSK 25 with a screw diameter of 25 mm. The screw
configuration and barrel temperature profile used was as described
in FIG. 2. The extruder used had nine barrel sections. Each barrel
section was equipped with bores to either heat or cool the
individual barrels. Barrels 1 and 2 were cooled with tap water,
barrel 3 was heated at 100.degree. C. and barrels 4 and 5 were
heated at 120.degree. C. using heat stable thermo-oil, that was
temperature controlled via two separate control units (SINGLE,
GERMANY). Barrels 6, 7, 8 and 9 were tap water cooled at a constant
temperature of 15.degree. C.
[0083] Screw elements are arranged in a way to first convey the
material from the feed barrel into subsequent closed barrels to
allow addition and mixing of additional ingredients, while
increasing the degree of fill to effectively heat the product
through conductive heat transfer with the barrel walls. Barrels 3,
4 and the first part of barrel 5 are dedicated for heating the
product. The screw configuration in these barrels is designed to
maintain sufficient residence time so as to at least partially
gelatinize the starch while simultaneously admixing the additional
ingredients at sufficiently low viscosity so as to prevent
substantial dextrinization of the starch. This is accomplished
through the high moisture content (30.9%) and addition of oil
(3.2%) and emulsifier (0.7%) in the added amounts, combined with
sufficiently low screw rpm, which was held constant at 150 rpm.
[0084] High temperature in Barrel #5 may also allow sufficient
moisture to be removed in order to obtain sufficiently low moisture
to enable sufficient forming and cutting of the extrudate after
exiting the extruder. It has been experienced, that relatively high
moisture contents in the extrudate, for example values greater than
about 30% tend to cause the material to be difficult to shape at
the die into stable ropes. Furthermore, it has been found that
softer and moister ropes are extremely difficult to cut after
exiting the extruder, particularly at the die face using high speed
rotating cutters. Therefore, it has been found advantageous to cook
the starch at relatively high moisture contents to prevent
dextrinization and over shearing, but reduce the moisture level
prior to extruding to prevent the extrudate from collapsing and to
ensure adequate forming.
[0085] It has been observed that dextrinization during extrusion
will result in dextrin formation during the cooking process and
cause the mass to be sticky at the extruder exit and may severely
reduce the ability to cut the mass into discrete particles. It has
been therefore an additional objective of this invention to
minimize dextrinization and reduce moisture after cooking to enable
the forming and cutting of discrete particles that after cooling
and drying exhibit specific release properties of the
encapsulant.
[0086] After reducing the moisture content of the plastizized mass,
the mass is cooled down to a sufficiently low temperature in barrel
6. The screw elements are conveying elements, that may be staggered
and thus provide extended residence time to increase the degree of
fill and thus enable effective cooling.
[0087] Barrel 7 was held open for the addition of the encapsulant
and was kept at a temperature of 15 degrees C. The product
temperature at this barrel was 25.degree. C. The screw elements
were high pitch elements to allow sufficient intake of the
material. An additional supporting barrel insert may be used to
prevent product build up while it is being conveyed through this
open barrel section. Acetylcysteine was fed into barrel 7 a rate of
0.4 kg/h, conveyed into the subsequent barrel and mixed into the
matrix material using distributive low shear mixing elements. The
encapsulant was fed at about room temperature into the extruder.
The choice of screw elements and their configuration in this
section is such that the elements must not introduce high
mechanical energy, but still mix the encapsulant into the matrix.
This can be accomplished, for example, through the use of so-called
distributive mixing elements that provide axial leakage flow in
combination with a chopping action and a minimum of kneading
action.
[0088] The last 2 to 3 l/d screw length may be used to generate
sufficient pressure to extrude the material through the die
openings. The die used comprised 20 openings, arranged in two
circles of ten bores, each having a cylindrical bore of 2 mm over a
length of 4 mm and a subsequent narrow opening of 1 mm over a land
length of 2 mm. The larger opening of the first part of the dies is
critical to prevent substantial energy dissipation within the die
through overshearing that would result in an increase of the
product temperature and thus cause a thermal destruction of the
encapsulant. Additionally, too narrow die channels cause higher
pressures before the die and may result in overheating of the
product in the last barrel despite the cooling. The product
temperature of the matrix at the encapsulant feeding point was
about 25.degree. C. The product temperature at the exit die was
52.degree. C. The pressure at the die was 80 bar. The mean
residence time of the encapsulant from the feed location to the die
exit was about 35 seconds.
[0089] Immediately after the extrudate exited the extruder, it was
cut into distinct pellets of approximately 1 mm length, allowing
the pellets to have approximately spherical dimensions. The
extrudate may be optionally sprayed with oil or other film-building
substances while being cut. After extrusion, the extruded pellets
were dried at 30.degree. C. for about 12 hours to a final moisture
content of approximately 8% by weight.
[0090] The dried pellets were stable in water for 16 hours and the
acetylcysteine may be sufficiently encapsulated within the matrix
to allow controlled release under appropriate conditions.
Appropriate release conditions may be a release in an aqueous or
gastric juice environment that allows a release of the encapsulant
of no more than from about 10% in about 1 hour to no less than
about 90% in about 24 hours.
Example 2 and Comparative Example 1
Encapsulation of a Heat Sensitive Component Prior and after Heat
Treatment
[0091] In this example, the effect of addition of the encapsulant
prior to and after heat treatment was evaluated. The extruder used
was the same as used in Example 1 and screw rpm was 150. A blend of
99.7% by weight starch with 0.3% GMS was fed at 4.0 kg/hr into
barrel #1. Vegetable oil was fed at a rate of 0.39 kg/h into barrel
#1. Ascorbic acid was fed at a rate of 1.15 kg/h into barrel 1
(Comparative Example 1) and was exposed to the following barrel
temperature profile: Barrel 1 (15.degree. C.), Barrel 2 (15.degree.
C.), Barrel 3 (120.degree. C.), Barrel 4 (140.degree. C.), Barrel 5
(140.degree. C.), Barrel 6 (15.degree. C.), Barrel 7 (15.degree.
C.), Barrel 8 (15.degree. C.), Barrel 9 (15.degree. C.). Analysis
of ascorbic acid after extrusion resulted in a 72.3% loss.
[0092] The same extrusion conditions were used in Example 2, except
that ascorbic acid was fed into barrel #7 at a product temperature
of about 20.degree. C. and subsequent analysis resulted in only a
12.2% loss of ascorbic acid. After extrusion, the extruded pellets
were dried at 30.degree. C. for about 12 hours and had a final
moisture content of approximately 8%. The dried pellets were stable
in water for 16 hours and the ascorbic Acid may be sufficiently
encapsulated within the matrix to allow controlled release under
appropriate release conditions.
Example 3
Encapsulation of a Heat Sensitive Fat Soluble Component
[0093] In this example, a heat-sensitive fat soluble component was
encapsulated. The extruder used was the same as used in Example 1
and the screw rpm was 150. A blend of 96.7% by weight starch, 3% by
weight LDPE and 0.3% by weight GMS was fed at 4.0 kg/hr into barrel
#1. Vegetable oil was fed at a rate of 0.16 kg/h into barrel #1.
Following barrel temperature profile was used: Barrel 1 (15.degree.
C.), Barrel 2 (15.degree. C.), Barrel 3 (120.degree. C.), Barrel 4
(140.degree. C.), Barrel 5 (140.degree. C.), Barrel 6 (15.degree.
C.), Barrel 7 (15.degree. C.), Barrel 8 (15.degree. C.), Barrel 9
(15.degree. C.). The encapsulant salicylic acid may be fed at a
rate of 1.15 kg/h into barrel 7 at a temperature of 20.degree. C.
The encapsulant was mixed into the matrix and extruded into ropes
that were cut at the die into distinct spherical pellets having a
diameter of about 1 mm. After extrusion, the extruded pellets were
dried at 30.degree. C. for about 12 hours to a final moisture
content of approximately 8% by weight. The dried pellets were
stable in water for 16 hours and the salicylic acid may be
sufficiently encapsulated within the matrix to allow controlled
release under appropriate conditions.
Examples 4 to 8 and Comparative Example 2
Encapsulation of a Water Soluble and Heat Sensitive Substance into
Various Matrices
[0094] In Examples 4 through 8 and Comparative Example 2, the
extruder of Example 1 was used to encapsulate a water soluble, heat
sensitive substance, ascorbic acid, in various matrices using
various extrusion conditions. A release-rate controlling component
was employed in Examples 4 to 8 but not in Comparative Example 2.
The rate of release of the ascorbic acid from the matrices into
meta-phosphoric acid was evaluated. The matrix compositions,
extrusion conditions, and release results are presented in Table
1:
TABLE-US-00001 TABLE 1 Matrix Compositions, Extrusion Conditions,
and Release Results Example Comparative Units Example 2 4 5 6 7 8
Ingredient (Preblend) kg M1 M3 M4 M6 M6 M9 (AA/oil) (Hydroph.) Corn
Starch 4.00 3.00 3.00 3.00 3.00 0.00 Wheat Gluten 0.00 1.00 1.00
1.00 1.00 0.00 Gelatin 0.00 0.00 0.00 0.50 0.50 0.00 Wax 0.00 0.50
1.00 0.50 0.50 0.00 GMS 0.00 0.04 0.04 0.04 0.04 0.00 Hydrophilic
Corn Starch 0.00 0.00 0.00 0.00 0.00 4.00 Total 4.00 4.54 5.04 5.04
5.04 4.00 Extrusion Conditions Matrix Preblend Feed Rate kg/hr 4.00
3.50 3.50 3.50 3.50 3.50 Oil Feed Rate kg/hr 0.00 0.00 0.16 0.00
0.00 0.00 Water Feed Rate kg/hr 1.05 1.82 1.32 2.38 1.15 1.15
Ascorbic Acid/oil premix Oil kg/hr 0.00 0.00 0.00 0.00 1.12 0.00
Ascorbic acid kg/hr 0.00 0.00 0.00 0.00 2.00 0.00 Screw rpm
min.sup.-1 150 150 160 150 150 150 Temp. Barrel 1 .degree. C. 15 15
15 15 15 15 Temp. Barrel 2 .degree. C. 15 15 15 15 15 15 Temp.
Barrel 3 .degree. C. 120 120 150 140 140 140 Temp. Barrel 4
.degree. C. 150 150 165 165 165 165 Temp. Barrel 5 .degree. C. 150
150 165 165 165 165 Temp. Barrel 6 .degree. C. 15 15 15 15 15 15
Temp. Barrel 7 .degree. C. 15 15 15 15 15 15 Temp. Barrel 8
.degree. C. 15 15 15 15 15 15 Temp. Barrel 9 .degree. C. 15 15 15
15 15 15 Pressure bar 90 40 45 15 -- 50 Die Temperature .degree. C.
62 57 86 66 -- 71 Other Data % added Ascorbic Acid Wt. % 7.1 3.9
7.1 8.57 31.8 3.74 (Dry Basis) Weight % Ascorbic Acid Released in
Meta Phosphoric Acid 0 minutes Wt. % 0.00 0.00 0.00 0.00 0.00 0.00
30 minutes 56.00 73.28 3.37 15.85 45.02 41.91 60 minutes 80.21
86.39 5.11 26.29 -- -- 90 minutes 91.72 -- 5.52 32.34 73.08 -- 120
minutes 94.96 -- 6.49 33.49 77.40 82.63 240 minutes 107.42 94.61
7.27 34.77 92.67 97.39
[0095] The ascorbic release data in meta-phosphoric acid has been
corrected for destruction of ascorbic acid by the meta-phosphoric
acid over time by dividing the analytical value by a correction
factor ranging from 1.0 (at 0 minutes) to 0.906 (at 240
minutes).
[0096] The release data is also presented in graphical form in FIG.
6 where the percentage of encapsulant released in meta-phosphoric
acid is plotted as a function of lime. As demonstrated by the data
shown in Table 1 and FIG. 6, in Comparative Example 2 (M1) pure
starch does not present a sufficient matrix for encapsulation,
because the time to release 100% of the encapsulant is too short.
Therefore, at least one additional component is added to control
the hydrophobicity and control the release of the encapsulant. As
shown in Examples 4-8, the addition of matrix components such as
lipids and/or proteins, shifts the encapsulant retention properties
substantially towards longer retention times.
Example 9
Encapsulation of Heat Sensitive Substances into Various
Matrices
[0097] Heat sensitive encapsulants or components may be
encapsulated into various matrices using the extruder, screw
configuration, barrel configuration, screw speed (150 rpm), and die
configuration of Example 1. The barrel temperature profile which
may be used is: Barrel 1 (15.degree. C.), Barrel 2 (15.degree. C.),
Barrel 3 (120.degree. C.), Barrel 4 (140.degree. C.), Barrel 5
(140.degree. C.), Barrel 6 (35.degree. C.), Barrel 7 (35.degree.
C.), Barrel 8 (35.degree. C.), Barrel 9 (35.degree. C.). In another
embodiment, the barrel temperature in barrels 4 and 5 may be
150.degree. C.
[0098] The ingredients and their concentrations which may be used
in matrices to vary the release rate of the encapsulant are
presented in Table 2:
TABLE-US-00002 TABLE 2 Matrix Components and Concentrations from to
to Matrix Component low mid max Function Carbohydrates Plant Starch
1 40 99 base matrix material Cyclodextrin 0 10 60 affects molecular
encapsulation Hydrophobic starch 0 20 40 affects hydrophobicity of
matrix Protein sources Wheat Gluten 0 10 50 affects tolerable
oil/fat addition Soy Protein Conc. 0 10 50 affects tolerable
oil/fat addition Casein 0 10 50 affects tolerable oil/fat addition
Gelatin 0 10 30 affects water binding properties and affects oil
addition Hydrocolloid sources Guar 0 5 30 increases water binding
capacity Pectin 0 5 30 increases water binding capacity Gum Arabic
0 5 30 increases water binding capacity Lipids and Lipoids veg. Oil
3 10 20 affects hydrophobicity of matrix Paraffin 0 5 20 affects
hydrophobicity of matrix GMS 1 5 10 affects hydrophobicity of
matrix Shellac 0 5 20 affects hydrophobicity of matrix Synthetic
Polymers LDPE 0 2 6 affects hydrophobicity of matrix Polyvinyl- 20
40 60 plasticizer, allows molecular pyrollidone dispersion
[0099] A blend of starch and/or plasticizer, and one or more of the
listed components may be fed at 4.0 kg/hr into barrel #1. Vegetable
oil or any other hydrophobic substance may be fed at a rate of 0.1
to about 3 kg/h into barrel #1. The encapsulant may be fed at a
rate of 0.1 to 3 kg/h into barrel 7 at a temperature of about
20.degree. C. The encapsulant may be mixed into the matrix and
extruded into ropes that are cut at the die into distinct spherical
pellets having a diameter of about 1 mm. After extrusion, the
extruded pellets may be dried at 30.degree. C. for sufficient time,
such as about 12 hrs to a final moisture content of approximately
8% by weight. The dried pellets may be stable in aqueous solution
for sufficient time, for example, 16 hrs and the encapsulant may be
sufficiently encapsulated within the matrix to allow controlled
release under appropriate conditions.
[0100] The encapsulant may be pretreated before the encapsulation
using a sprayable material, such as an alcoholic solution of zein,
a chitin-based material, shellac, paraffin or a similar coating
material. For this purpose, the encapsulant may be placed into a
rotating coating drum, commonly used in the candy industry. The
coating composition, for example zein at a concentration of, for
example 10% zein may be applied as a coating onto the surface of
the encapsulant. The drum may be treated with warm air to
facilitate drying of the solvent. After drying the coated
encapsulant, it may be added to the extruder as described in
Example 1. The additional coating may additionally control the rate
of release of the encapsulant after the matrix has been dissolved
and the encapsulant is dispersed in the environment for its
expected action.
[0101] After extrusion under the described process conditions, the
obtained pellets may be coated with a film of variable thickness to
delay the access of either aqueous or digestive liquids to the
matrix and thus delay solution of the matrix. For this purpose, a
sprayable material may be used, such as an alcoholic solution of
zein, a chitin-based material, shellac, paraffin or similar
film-forming or coating substance. The extruded pellets may be
placed into a rotating coating drum, a device commonly used in the
candy and confectionery industry and a solution of about 10% by
weight zein and about 90% by weight isopropyl alcohol or other
solvent may be applied as a coating onto the surface of the
encapsulant. The drum may be treated with warm air to facilitate
drying and removal of the solvent. The additional coating may
additionally control the rate and time of release of the
encapsulant and may provide complete control over the release
properties of the encapsulant. It is expected, that the release
properties follow the schematic diagram in FIG. 5.
* * * * *