U.S. patent application number 10/820147 was filed with the patent office on 2005-02-24 for natamycin dosage form, method for preparing same and use thereof.
Invention is credited to Gouin, Sebastien, Hansen, Carsten Bjorn, Thomas, Linda Valerie, Tse, Kathryn Louise.
Application Number | 20050042341 10/820147 |
Document ID | / |
Family ID | 28460172 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050042341 |
Kind Code |
A1 |
Thomas, Linda Valerie ; et
al. |
February 24, 2005 |
Natamycin dosage form, method for preparing same and use
thereof
Abstract
The present invention relates to a novel natamycin dosage form
for the food industry, and more particularly to microcapsules where
natamycin is encapsulated within a physiologically acceptable shell
to provide a protected natamycin product. The present invention
relates also to novel processes for preparing the capsules
according to the invention, as well as to the use of the capsules
of the present invention. The invention further relates to food
products containing natamycin in encapsulated form.
Inventors: |
Thomas, Linda Valerie;
(Dorchester, GB) ; Gouin, Sebastien; (Arhus,
DK) ; Tse, Kathryn Louise; (Arhus, DK) ;
Hansen, Carsten Bjorn; (Knebel, DK) |
Correspondence
Address: |
STEPTOE & JOHNSON LLP
Attn: Docket Administrator - Box USPTO
1330 Connecticut Avenue, NW
Washington
DC
20036
US
|
Family ID: |
28460172 |
Appl. No.: |
10/820147 |
Filed: |
April 8, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60497409 |
Aug 22, 2003 |
|
|
|
Current U.S.
Class: |
426/321 |
Current CPC
Class: |
A21D 2/00 20130101; A23L
3/34635 20130101; A23L 3/3544 20130101; B01J 13/043 20130101; A23L
3/3571 20130101; A23B 4/10 20130101; A23V 2002/00 20130101; A23B
4/22 20130101; A23L 33/127 20160801; Y02A 40/90 20180101; A23L 2/52
20130101; Y02A 40/946 20180101; A23C 19/11 20130101; A23L 3/3472
20130101; A23B 4/20 20130101; A23B 5/16 20130101; A23L 33/135
20160801; A23B 5/06 20130101; B01J 13/22 20130101; A23P 10/30
20160801; A23B 4/12 20130101; A23C 19/084 20130101; A23P 10/35
20160801; B01J 13/08 20130101; A23L 13/72 20160801; A23B 5/14
20130101; A23V 2002/00 20130101; A23V 2200/224 20130101; A23V
2200/10 20130101 |
Class at
Publication: |
426/321 |
International
Class: |
C12H 001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 22, 2003 |
GB |
0319817.3 |
Claims
1. A natamycin dosage form comprising microcapsules where natamycin
is encapsulated within a physiologically acceptable shell to
provide a protected food preservative natamycin product.
2. A natamycin dosage form according to claim 1, wherein said shell
is effective in substantially retaining said natamycin within said
shell during processing of said food product.
3. A natamycin dosage form according to claim 1, wherein said shell
is effective in providing slow or delayed release of said
encapsulated natamycin into said food product.
4. A natamycin dosage form according to claim 1, wherein said shell
is effective in protecting said encapsulated natamycin from
degradation by conditions prevailing in the production of a product
whereto said encapsulated natamycin is added and in providing
release of natamycin in said finished product.
5. A natamycin dosage form according to claim 1, wherein said
encapsulation is provided by a process selected from a fluidized
bed process, liposome encapsulation, spray drying, spray cooling,
extrusion, co-extrusion, coacervation and combinations thereof.
6. A natamycin dosage form according to claim 1 wherein said shell
is made of a material selected from the group consisting of
hydrophobic materials, hydrocolloid materials and mixtures or
combinations thereof.
7. A natamycin dosage form according to claim 6 wherein said
hydrophobic material is chosen from lipids and resins including
fatty acids, fats, oils, emulsifiers, fatty alcohols, waxes and
mixtures or combinations thereof.
8. A natamycin dosage form according to claim 7, wherein said
hydrophobic material is selected from the group consisting of food
grade animal oils and fats, fully hydrogenated vegetable or animal
oils, partially hydrogenated vegetable or animal oils, unsaturated,
hydrogenated or fully hydrogenated fatty acids, unsaturated,
partially hydrogenated or fully hydrogenated fatty acid
monoglycerides and diglycerides, unsaturated, partially
hydrogenated or fully hydrogenated esterified fatty acids of
monoglycerides or diglycerides, unsaturated, partially hydrogenated
or fully hydrogenated free fatty acids, other emulsifiers, animal
waxes, vegetable waxes, mineral waxes, synthetic waxes, natural and
synthetic resins and mixtures thereof.
9. A natamycin dosage form according to claim 6 wherein said
hydrocolloid comprises a soluble or dispersible coating material
selected from food grade gums, polysaccharides, proteins, shellac
and mixtures or combinations thereof.
10. A natamycin dosage form according to claim 9, wherein said
hydrocolloid is selected from cellulosic derivatives including
hydroxy propyl methyl cellulose, cellulose acetate phthalate,
carboxy methyl cellulose, methyl cellulose and microcrystalline
cellulose, sodium alginate, gum arabic, gellan gum, guar gum, agar
gum, pectin, amidified pectin, carrageenan, gelatine, chitosan,
mesquite gum, hyaluronic acid, methyl acrylic copolymers, such as
Eudragit.RTM., psyllium, tamarind, xanthan, locust bean gum, wellan
gum, zein, shellac, whey protein, soy protein, sodium caseinate,
synthetic or natural water-soluble polysaccharides, proteins and
other hydrocolloids, with or without fatty acids, fatty alcohol,
plasticizers including glycerol, polyethyleneglycol and other low
molecular weight hydrophilic alcohols, or combinations of any of
said hydrocolloids.
11. A natamycin dosage form according to claim 1 wherein said shell
is provided by co-processing natamycin with an encapsulating
material, which is in an aqueous or lipidic solution or suspension
or in a molten state.
12. A natamycin dosage form according to claim 11, wherein said
natamycin is in aqueous suspension or comprises a dry powder.
13. A natamycin dosage form according to claim 1, which comprises
microcapsules having a solidified hydrophobic shell matrix,
encapsulated aqueous beads which are further encapsulated in the
solidified hydrophobic shell matrix, and natamycin incorporated in
the encapsulated aqueous beads.
14. A natamycin dosage form according to claim 1, wherein the
percentage of active natamycin in said protected natamycin product
is from 1 to 80% by weight.
15. A natamycin dosage form according to claim 14, wherein said
percentage is between 15 and 50% by weight.
16. A natamycin dosage form according to claim 15, wherein said
percentage is between 30 and 40% by weight.
17. A process for preparing a natamycin dosage form comprising
co-processing natamycin with a physiologically acceptable
encapsulating material to cause said material to encapsulate said
natamycin within a shell, and recovering a protected food
preservative natamycin product.
18. A process according to claim 17, wherein said encapsulation
process is selected from a fluidized bed process, liposome
encapsulation, spray drying, spray cooling, extrusion,
co-extrusion, coacervation and mixtures thereof.
19. A process according to claim 17 wherein said encapsulating
material comprises a material selected from the group consisting of
hydrophobic materials, hydrocolloid materials and mixtures or
combinations thereof.
20. A process according to claim 17, wherein said encapsulation
process comprises fluidized bed encapsulation of natamycin with an
encapsulating material in an aqueous solution or suspension or in a
molten state.
21. A process according to claim 17, wherein said encapsulation
process comprises coacervation of natamycin with an encapsulating
material.
22. A process according to claim 19, wherein said encapsulating
material comprises a hydrocolloid or a mixture of
hydrocolloids.
23. A process according to claim 17, which includes the steps of a)
providing an aqueous phase and natamycin incorporated in the
aqueous phase, b) providing a hydrophobic phase in a molten form,
c) incorporating or dissolving an encapsulating material or mixture
of encapsulating materials in the aqueous phase or in the
hydrophobic phase d) combining the aqueous phase with the
hydrophobic phase and homogenizing or mixing the combined phases to
form a water-in-oil emulsion, e) encapsulating the aqueous phase in
the emulsion, whereby a dispersion comprising encapsulated aqueous
beads is formed and the natamycin is encapsulated in the aqueous
beads, and f) processing the dispersion obtained in step e) to form
microcapsules where the encapsulated aqueous beads are further
encapsulated in solidified hydrophobic shell material.
24. A method for the preservation of a food product comprising
adding to said food product an effective food-preserving amount of
natamycin which is encapsulated within a physiologically acceptable
shell.
25. A method according to claim 24, wherein said encapsulated
natamycin is added to said food product prior to or in connection
with the production of said food product and said shell is
effective in protecting said encapsulated natamycin from
degradation by conditions used in the production or storage of said
food product said shell providing release of natamycin in said food
product.
26. A method according to claim 25, wherein said conditions are
selected from natamycin-degrading heat and high or low pH.
27. A method according to claim 24 wherein said food product is
selected from a salad dressing, a condiment, a ketchup, puree, a
salsa sauce, a pickle, a dip, an acidic dairy product including
natural cheese, cottage cheese, acidified cheese, cream cheese,
yoghurt, sour cream and processed cheese, a fruit juice, an acidic
drink, an alcoholic drink including wine and beer, a chilled dough,
a cooked or uncooked bakery product, a dairy filling or topping, a
surface glaze or coating a marinade, marinated or breaded meat or
poultry, a pizza topping or base, a fast food product, a kit for
making a snack or a meal, a kit for making a bakery product,
combinations thereof, pet food and broiler feed.
28. A method according to claim 24 wherein said encapsulated
natamycin is included in a dough for a yeast-leavened or
non-yeast-leavened bakery product.
29. A method according to claim 28, wherein said dough is baked
into bread and subsequently sliced.
30. A preserved food product which comprises as a preservative an
effective food preserving amount of natamycin which is encapsulated
within a physiologically acceptable shell.
31. A food product according to claim 30 wherein said food product
is selected from a salad dressing, a condiment, a ketchup, a puree,
a salsa sauce, a pickle, a dip, an acidic dairy product including
natural cheese, cottage cheese, acidified cheese, cream cheese,
yoghurt, sour cream and processed cheese, a fruit juice, an acidic
drink, an alcoholic drink, a chilled dough, a cooked or uncooked
bakery product, a dairy filling or topping, a surface glaze or
coating, a marinade, marinated meat or poultry, breaded meat or
poultry, a pizza topping or base, a fast food product, a kit for
making a snack or meal, a kit for making a bakery product,
combinations thereof, pet food and broiler feed.
32. A food product according to claim 31 wherein said bakery
product is sliced or cut bread.
Description
CLAIM OF PRIORITY
[0001] This application claims priority under 35 U.S.C. .sctn. 119
to GB application no. 0319817.3, filed Aug. 22, 2003, the entire
contents of which have been incorporated by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to natamycin dosage forms for
the food industry, and more particularly to microcapsules where
natamycin as the active food preservative ingredient is
encapsulated within a shell. The present invention relates also to
novel methods for preparing the microcapsules according to the
invention, to the use of the microcapsules of the present invention
in the food industry, as well as to food products containing the
same. Preferred food products include acidic food products and
sliced bread.
BACKGROUND OF THE INVENTION
[0003] Natamycin is a polyene macrolide natural antifungal agent
produced by fermentation of the bacterium Streptomyces natalensis.
Natamycin (previously known as pimaricin) has an extremely
effective and selective mode of action against a very broad
spectrum of common food spoilage yeasts and moulds with most
strains being inhibited by concentrations of 1-15 ppm of
natamycin.
[0004] Natamycin is accepted as a food preservative and used world
wide, particularly for surface treatment of cheese and dried
fermented sausages. It has several advantages as a food
preservative, including broad activity spectrum, efficacy at low
concentrations, lack of resistance, and activity over a wide pH
range. Neutral aqueous suspensions of natamycin are quite stable,
but natamycin has poor stability in acid or alkaline conditions, in
the presence of light, oxidants and heavy metals. For example,
natamycin can be used in pasteurised fruit juice to prevent
spoilage by heat-resistant moulds such as Byssochlamys. The acid pH
of the juice, however, promotes degradation of natamycin during
pasteurisation as well as during storage if the juice is not
refrigerated. Natamycin is also degraded by high temperature heat
processing, such as occurs during cooking of bakery items in an
oven.
[0005] At extreme pH conditions, such as pH less than 4 and greater
than 10, natamycin is rapidly inactivated with formation of various
kinds of decomposition products. Acid hydrolysis of natamycin
liberates the inactive aminosugar mycosamine. Further degradation
reactions result in formation of dimers with a triene rather than a
tetraene group. Heating at low pH may also result in
decarboxylation of the aglycone. Alkaline hydrolysis results in
saponification of the lactone. Both acid degradation products
(aponatamycin, the aglycone dimer, and mycosamine), and alkaline or
UV degradation products proved even safer than natamycin in
toxicology tests, but are inactive biologically.
[0006] Natamycin is generally dosed into or onto food as a powder
or as an aqueous natamycin suspension. This kind of dosage form
leaves the natamycin unprotected under the conditions of processing
and use. The natamycin powder, although mixed with excipients such
as lactose, may also be sticky to handle and cause dust problems
within the food processing plants. Furthermore, natamycin is so
highly effective as an antifungal compound that it may adversely
affect the processing of the products that it is intended to
preserve if this is dependent on desired fungal activity. There is
thus a need for a protected dosage form of natamycin.
[0007] A general description of natamycin and its current uses may
be found in Thomas, L. V. and Delves-Broughton, J. 2003. Natamycin.
In: Encyclopedia of Food Sciences and Nutrition. Eds. B. Caballero,
L. Trugo and P. Finglas, pp 4109-4115. Elsevier Science Ltd.
[0008] Encapsulation technology has been applied to a number of
food ingredients, usually to mask flavour or activity. The present
invention is based on the realization that unexpected benefits are
derivable from the encapsulation of natamycin.
[0009] Koontz & Marcey, 2003, J Agric Food Chemistry 51:
7106-7110 describes the formation of a natamycin/cyclodextrin
inclusion product. The cyclodextrin acts as host molecules to
protect mainly against light, but also low pH, heat and oxidation.
However, this natamycin/cyclodextrin complex is not a true
encapsulation. A molecule of natamycin will not `fit` into the
cavity of gamma-cyclodextrin, thus it can only be considered a
partial encapsulation. Acidic conditions tend to destabilise this
kind of complex, releasing the contents of the cyclodextrin
molecule and the natamycin molecule is not completely enclosed and
protected by the cyclodextrin molecules. Koontz et al. 2003. J
Agric Food Chemistry 51: 7111-7114 has also described the stability
of natamycin and its cyclodextrin inclusion complexes in aqueous
solution.
[0010] EP115618 describes an anti-caking antimycotic food
ingredient wherein the anti-caking agent is encapsulated and then
treated with natamycin to provide antimycotic activity.
[0011] U.S. Pat. No. 5,445,949 describes a process for recovery of
natamycin by separation of a hydrophobic fermentation product such
as natamycin. The process involves a step including encapsulation
of a protein but there is no mention of encapsulating the
natamycin.
[0012] EP-A1-1382261 describes the use of microbial inhibitors such
as natamycin for baked bread products, including shelf stable kits
for making snacks or meals. The microbial inhibitor is not
protected by encapsulation.
[0013] Copending patent application U.S. Ser. No. 10/765,210, filed
Jan. 28, 2004 relates to the protection of fine bakery goods by
spraying the surface of the goods with a natamycin suspension and
thus to increase the shelf life of the products.
[0014] WO 89/033208 describes a polyene macrolide powder for
liposome preparation. The polyene macrolide is encapsulated in
liposomes in order to modify the pharmokinetics of the antifungal
in systemic diseases. The liposome is intended for pharmaceutical
use only.
[0015] U.S. Pat. No. 5,821,233 concerns an antifungal composition
wherein natamycin is incorporated in porous silica to provide
delayed release of natamycin in an aqueous medium.
[0016] General descriptions of encapsulation processes may be found
in Shahidi, F., and X.-Q., Han. 1993. Encapsulation of food
ingredient. Critical Reviews in Food Science and Nutrition 33 (6):
501-547.
[0017] The encapsulation of mold inhibitors is described by Ranum,
P., 1999. Encapsulated mold inhibitors--the greatest thing since
sliced bread in Cereal Foods World, Vol 44, No 5, p. 370-371.
[0018] U.S. Pat. No. 5,204,029 discloses a process for preparing
edible microcapsules which contain a multiplicity of liquid cores.
In the process, a water-in-oil emulsion, with the active ingredient
dissolved in an inner aqueous phase, is spray cooled, which causes
the solidification of the fat phase and the entrapment of the
aqueous phase as minute droplets dispersed in a microcapsule. This
process, however, leads to very unstable microcapsules from which
the water phase migrates from the inner part of the microcapsule to
an outer part. This further results in the condensation of the
water on the wall of a container.
[0019] Kirk-Othmer Encyclopedia of Chemical Technology, 3.sup.rd
ed. Vol. 15, pp. 473 to 474, discloses a process in which liquids
are encapsulated using a rotating extrusion head containing
concentric nozzles. The process is only suitable for liquids or
slurries, and the products of the process are large beads having
meltable coatings, such as fats or waxes. However, the
microcapsules containing a single liquid droplet as a core are very
susceptible to rupture.
[0020] In their article "Mass preparation and characterization of
alginate microspheres" in Process Biochemistry 35 (2000) 885 to 888
Mofidi, N. et al. describe a method for mass preparation of
microspheres, in which method a sterilized alginate solution is
prepared and the solution is then poured into a reactor containing
a non-aqueous phase, while being stirred. An emulsion of alginate
microdroplets is formed and an appropriate amount of the
cross-linker is added. Microspheric alginate-gel particles fell to
the bottom and they were collected by filtration.
[0021] Similarly, Wong, T. W. et al in J. Microencapsulation, 2002
Vol. 19, no 4, 511 to 522, describe release characteristics from
pectin microsphperes and the method for preparing these
microspheres. In this method, pectin microspheres are prepared by a
water-in-oil emulsion technique, in which minute droplets of pectin
containing an active ingredient dispersed in a liquid hydrophobic
continuous phase are hardened and collected by filtration.
[0022] Microencapsulation by a coacervation-phase separation
process is known from an article by Joseph A. Bakan in Controlled
Release Technologies, 1980 by Agis F. Kydonieus. The process
consists of a series of three steps carried out under continuous
agitation: (1) formation of three immiscible chemical phases; (2)
deposition of the coating; and (3) rigidization of the coating.
[0023] Sanghvi, S. P. and Nairn J. G. have studied the effect of
viscosity and interfacial tension on the particle size of cellulose
acetate trimellitate microspheres. The results are presented in
their article in J. Microencapsulation, 1992, Vol. 9, no 2, 215 to
227.
[0024] In their article in Lebensm. -Wiss. u. -Technol., 33, 80 to
88 (2000) Lee, S. J. and Rosenberg, M. describe a double
emulsification and heat gelation process for preparing whey
protein-based microcapsules. The microcapsules prepared according
to the described process are whey protein-based microcapsules
containing an apolar core material.
[0025] In their article in Science Vol. 298, 1 Nov. 2002, Dinsmore
et al. describe selectively permeable capsules composed of
colloidal particles. The capsules are fabricated by the
self-assembly of colloidal particles onto the interface of emulsion
droplets. After the particles are locked together to form elastic
shells, the emulsion droplets are transferred to a fresh
continuous-phase fluid that is the same as that inside the
droplets.
[0026] The documents mentioned in this specification should be
considered incorporated herein by reference.
[0027] A problem associated with the prior art natamycin dosage
forms is that they leave the natamycin unprotected. The efficacy
and application of natamycin is compromised by the lability of the
preservative to conditions of heat, high and low pH, light and
oxidation. There is a need to protect the natamycin and also to
provide release of the active natamycin in a controlled manner from
the dosage form.
[0028] The present invention seeks to overcome the problems of the
known natamycin dosage forms, as described above, by providing
capsules which are stable against processing conditions and which
provide a controlled and/or sustained release of the natamycin.
BRIEF DESCRIPTIONS OF THE INVENTION
[0029] The present invention is based on the use of encapsulation
to protect the natamycin molecule from degradation during adverse
conditions and/or to protect process ingredients from exposure to
natamycin during processing. The present invention comprises the
encapsulation of natamycin by various processes in order to protect
it from such degradation or in order to protect the ingredients
from such exposure, and the encapsulated natamycin food product
itself and its use as a food preservative.
[0030] An object of the present invention is thus to provide a
natamycin dosage form comprising microcapsules, where natamycin is
encapsulated within a physiologically acceptable shell to provide a
protected food preservative natamycin product.
[0031] An object of the invention is also a process for producing a
natamycin dosage form comprising co-processing natamycin with a
physiologically acceptable encapsulating material to cause said
material to encapsulate said natamycin within a shell, and
recovering a protected food preservative natamycin product.
[0032] A further object of the invention is a method for the
preservation of a food product comprising adding to the food
product an effective food-preserving amount of natamycin which is
encapsulated within a physiologically acceptable shell.
[0033] A further object of the invention is a preserved food
product which comprises as a preservative an effective food
preserving amount of natamycin which is encapsulated within a
shell. The food product is preferably selected from salad
dressings, acidic dairy products (including natural cheese, cottage
cheese, acidified cheese, cream cheese, yoghurt, sour cream,
processed cheese), fruit juices, acidic drinks, alcoholic drinks
(including wine and beer), chilled dough and cooked or uncooked
bakery products, dairy fillings and toppings for baked goods,
surface glazes and coatings for bakery items and other
heat-processed items, condiments, dips, purees, pickles, marinades,
marinated meat or poultry, breaded meat or poultry, pizza toppings
and bases, fast food products, kits for making snacks or meals,
kits for making bakery products, pet food, broiler feed and any
other acidic, heat-processed and/or fungal fermented food
products.
[0034] An especially preferred preserved food product is a sliced
or cut bakery product, especially sliced bread, wherein
encapsulated natamycin has been incorporated into the dough before
cooking and provides preservation of the bakery product after
baking.
[0035] Another preferred preserved food product comprises an acidic
food product, into which pH-protected natamycin of the present
invention has been incorporated.
[0036] The objects of the invention are achieved by the
microcapsules, processes, methods and products defined in the
independent claims. Preferred embodiments of the invention are
disclosed in the dependent claims.
[0037] The invention is based on the concept of protecting the
active natamycin ingredient by encapsulating it within a
physiologically acceptable shell material, for example a
hydrophobic material or a hydrocolloid or any other suitable
encapsulating material or a mixture or combination thereof.
[0038] The encapsulation of the natamycin is performed by processes
which are novel in combination with natamycin and which provide
unexpected benefits to the food industry. The encapsulation
processes and encapsulating materials or shell materials are
selected depending on the nature of the continuous phase in the
food application. The shell material must be water-insoluble if the
continuous phase of the food application is water-based, and
vice-versa in order to provide slow and/or delayed release as well
as protection/segregation.
[0039] Suitable encapsulating processes comprise fluidized bed
processes, liposome encapsulation processes, spray drying
processes, spray cooling processes, extrusion processes,
co-extrusion processes (such as centrifugal co-extrusion),
coacervation processes and combinations thereof.
[0040] In a special double encapsulation process, the present
invention provides a microcapsule which comprises a solidified
hydrophobic shell matrix, an encapsulated aqueous bead or beads
encapsulated in the solidified hydrophobic shell matrix, and
natamycin as an active ingredient incorporated in the encapsulated
aqueous bead or beads.
[0041] This natamycin dosage form is provided by a double
encapsulation method for preparing microcapsules, which method
comprises the steps of
[0042] a) providing an aqueous phase and natamycin incorporated in
the aqueous phase,
[0043] b) providing a hydrophobic phase in melted form,
[0044] c) incorporating or dissolving an encapsulating material or
mixture of encapsulating materials in the aqueous phase or in the
hydrophobic phase,
[0045] d) combining the aqueous phase with the hydrophobic phase
and homogenizing or mixing the combined phases to form a
water-in-oil emulsion,
[0046] e) encapsulating the aqueous phase in the emulsion, thus
converting the liquid aqueous phase into encapsulated aqueous
beads, whereby a dispersion comprising aqueous beads is formed and
the natamycin is incorporated in the aqueous beads, and
[0047] f) processing the dispersion obtained in step e) to form
microcapsules where the encapsulated aqueous beads are further
encapsulated in the solidified hydrophobic shell matrix.
[0048] The encapsulation process of the present invention may also
include gelling, cross-linking, coacervation, sintering or any
other suitable means. In the above double encapsulation this
results in a dispersion where encapsulated aqueous beads comprising
the active natamycin ingredient are dispersed in the hydrophobic
phase. The dispersion is cooled below the melting or dropping point
of the hydrophobic phase by any suitable process, which results in
the formation of microcapsules. The cooling process can be
performed, for example by spray cooling or fluidized bed cooling.
The microcapsules comprise a number of encapsulated aqueous beads,
which further contain the natamycin, and the encapsulated aqueous
beads are further encapsulated in a solidified hydrophobic shell
matrix.
[0049] An advantage of the present invention is that the natamycin
is protected by the shell and that the release of the natamycin
from the capsules can be controlled. The release rate may be
controlled, for instance, by the choice and the amount of the shell
material. Thus, the release rate may be controlled by the melting
of the hydrophobic shell or by the diffusion of water into the
capsule and subsequent migration of natamycin outside the capsule.
The release rate of natamycin from the capsules may be selected
according to the intended use by selecting a suitable encapsulating
material. The release of the natamycin from the capsules of the
present invention can be controlled and the release can be
initiated in various ways, for example by heat treatment, e.g. by
heating, such as in a microwave oven or baking oven, or by
freezing, by stress treatment or by any other suitable process. The
release of the active ingredients from the capsules of the present
invention can also be sustained or it can happen very slowly.
[0050] Based on the present disclosure, the person skilled in the
art is able to select a suitable encapsulation process as well as
the right type and amount of shell material to be used in any one
specific food application based on the conditions required to
protect and to release the natamycin in accordance with the present
invention.
[0051] The new improved natamycin dosage form of the present
invention enables the use of natamycin in a wide variety of
applications, for example in various new applications in the
food/feed or pharmaceutical fields.
[0052] Yet another advantage of the method of the invention is that
it enables a high production capacity to be achieved while the
costs are still low.
[0053] In the following, the invention will be described in greater
detail by means of preferred embodiments and with reference to the
examples.
DETAILED DESCRIPTION OF THE INVENTION
[0054] The present invention relates to a natamycin dosage form
comprising natamycin which is encapsulated within a physiologically
acceptable shell to provide a protected natamycin product. The
preferred dosage form comprises natamycin encapsulated in
microcapsules.
[0055] The main object of the invention is to improve the use of
natamycin in the food industry and, consequently, the shell of the
natamycin dosage form of the present invention should be made of a
physiologically acceptable material suitable for addition to a food
product. The shell provides protection for the natamycin and it
should be effective in substantially retaining said natamycin
within said shell during processing of food products. Once
introduced into a food product, the shell should be effective in
providing slow or delayed release of the encapsulated natamycin
into the food product.
[0056] Most preferably, the natamycin dosage form of the present
invention has a shell which is effective in protecting the
encapsulated natamycin from degradation by conditions prevailing in
the production of a product whereto the encapsulated natamycin is
added, and/or in protecting food ingredients from unwanted attack
by natamycin at the wrong time, as well as in providing release of
natamycin in said finished product.
[0057] The term "food" as used in the present specification and
claims refers generally to edible products and beverages of the
food and feed industry. The edible products in question are mainly
nutritive and/or enjoyable products requiring preservation for
their storage between the time of production and eventual use.
[0058] The term "physiologically acceptable" likewise refers to
materials acceptable and intended for ingestion in connection with
food and feed products.
[0059] Any suitable food grade coating material may be used as the
physiologically acceptable shell material. However, preferred
materials are selected from the group consisting of hydrophobic
materials, hydrocolloid materials and mixtures or combinations
thereof.
[0060] The preferred hydrophobic material is chosen from resins and
lipids and combinations thereof. The lipids include fatty acids,
fats, oils, emulsifiers, fatty alcohols, waxes and mixtures or
combinations thereof. The preferred hydrocolloids comprise soluble
or dispersible coating materials selected from food grade gums,
polysaccharides, proteins, shellac and mixtures or combinations
thereof.
[0061] Typical hydrocolloid shell materials are selected from
cellulosic derivatives (including hydroxy propyl methyl cellulose,
carboxy methyl cellulose, methyl cellulose, microcrystalline
cellulose and mixtures thereof) with or without stearic acid, zein,
shellac and mixtures or combinations thereof.
[0062] Generally, the shell on the natamycin dosage form of the
invention is provided by co-processing natamycin with an
encapsulating material, which is in an aqueous or lipidic solution
or suspension or in a molten state.
[0063] The natamycin which is to be encapsulated may be in liquid
form such as in an aqueous suspension or it may be encapsulated as
a dry powder. In a preferred process the shell is provided by
co-processing the natamycin with a molten encapsulating
material.
[0064] A special form of encapsulated natamycin is provided by a
doubly encapsulated natamycin dosage form, which comprises
microcapsules having a solidified hydrophobic shell matrix,
encapsulated aqueous beads which are further encapsulated in the
solidified hydrophobic shell matrix, and natamycin incorporated in
the encapsulated aqueous beads.
[0065] The percentage of active natamycin in the protected
natamycin product of the present invention is from 1 to 80% by
weight. A preferred amount of natamycin is between 15 and 50% and
the most preferred amount is between 30 and 40% by weight.
[0066] The process according to the present invention for producing
the natamycin dosage form of the invention comprises co-processing
natamycin with an encapsulating material to cause said material to
encapsulate said natamycin within a shell, and recovering a
protected natamycin product.
[0067] The encapsulating process is preferably selected from a
fluidized bed process, liposome encapsulation, spray drying, spray
cooling, extrusion, centrifugal co-extrusion, coacervation and
mixtures thereof. Fluidized bed encapsulation and coacervation are
the most preferred processes for providing the natamycin dosage
form of the present invention.
[0068] In a preferred fluidized bed encapsulation natamycin is
co-processed with an encapsulating material in an aqueous solution
or suspension or in a molten state to provide a shell around the
natamycin.
[0069] In a preferred coacervation process, an encapsulating
material comprising a hydrocolloid or a mixture of hydrocolloids is
used to provide the shell.
[0070] A special coacervation process of the invention comprises a
double encapsulation including the steps of providing an aqueous
phase and natamycin incorporated in the aqueous phase, providing a
hydrophobic phase in a molten form, incorporating or dissolving an
encapsulating material or mixture of encapsulating materials in the
aqueous phase or in the hydrophobic phase, combining the aqueous
phase with the hydrophobic phase and homogenizing or mixing the
combined phases to form a water-in-oil emulsion, encapsulating the
aqueous phase in the emulsion, whereby a dispersion comprising
encapsulated aqueous beads is formed and the natamycin is
encapsulated in the aqueous beads, and processing the dispersion
obtained to form microcapsules where the encapsulated aqueous beads
are further encapsulated in solidified hydrophobic shell
material.
[0071] The novel natamycin dosage form of the present invention
provides a novel method for the preservation of food products,
which comprises adding to a food product an effective
food-preserving amount of natamycin which is encapsulated within a
shell. The encapsulated natamycin may be added to the food product
prior to or in connection with the production of the food product.
The shell is effective in protecting the encapsulated natamycin
from degradation by conditions used in the production or storage of
the food product and/or in protecting the ingredients of the food
product from the antifungal effect of the natamycin, and it
provides release of natamycin in the food product.
[0072] The encapsulation protects the natamycin from degradation by
conditions such as heat, light, oxidation and high or low pH.
[0073] A special benefit is provided by a preferred embodiment of
the invention when the encapsulated natamycin is included in a
dough prior to the cooking of a yeast-leavened bakery product since
the yeast is protected by the encapsulating shell from direct
contact with the natamycin during the leavening.
[0074] Furthermore, the encapsulated natamycin is preferably
protected against the heat of the baking by the shell. Natamycin is
degraded by exposure to heat. During baking, which is typically
performed at temperatures ranging from 180 to 300.degree. C.,
natamycin degradation would significantly reduce the level of
active natamycin in the finished baked product. By selecting an
encapsulating material having a sufficient heat stability, the heat
degradation of natamycin can be substantially reduced. During
baking and/or after baking, the shell releases the natamycin so
that the finished product is effectively protected against fungal
attack.
[0075] A preferred use of the present invention comprises use of
the novel natamycin dosage form in dough for bread, which is to be
sliced for sale. The natamycin released from within the capsule
shell in the finished product protects the individual cut bread
slices from fungal attack.
[0076] Sliced bread is a very convenient food product for
consumers. However, the slicing provides an additional process step
in the production, and one which is typically performed after the
bread has cooled after baking when the product is very susceptible
to fungal attack. When the slicing is performed, contamination may
take place and as a result, the sliced product will show fungal
growth between the slices during storage. The bread slicing exposes
a much greater surface area of the bread to contamination
particularly by molds.
[0077] The copending patent application U.S. Ser. No. 10/765,210,
filed Jan. 28, 2004 and included herein by reference, discloses the
protection of fine bakery goods by spraying the surface of the
goods with natamycin and thus to increase the shelf life of the
product. However, it is impossible to apply natamycin between the
slices of sliced bread. The present invention provides a solution
to the problem of protecting sliced bread by natamycin.
[0078] The present invention provides a preserved food product
which comprises as a preservative an effective food preserving
amount of natamycin which is encapsulated within a shell. Such food
products are preferably selected from salad dressings, dips, salsa
sauce, ketchup, purees, pickles, acidic dairy products (including
natural cheese, cottage cheese, acidified cheese, cream cheese,
yoghurt, sour cream, processed cheese), fruit juices, acidic
drinks, alcoholic drinks (including wine), cooked and uncooked
bakery products, chilled dough and similar bakery items, dairy
fillings and toppings for baked goods, surface glazes and coatings
for bakery items and other heat-processed items, marinades,
marinated meat or poultry, breaded meat or poultry, fast food
products, kits for making snacks or meals, kits for making bakery
products, and combinations thereof. The present invention also
provides preserved heat processed pet foods and other feed products
such as dog or cat food and broiler feed.
[0079] In a preferred embodiment of the invention natamycin is
protected against pH attack by a process comprising encapsulating
natamycin within a shell material to provide an encapsulated
natamycin which is protected against degradation caused by low or
high pH, the shell material being sufficiently resistant to protect
the encapsulated natamycin from degradation by pH and said shell
material providing a slow and/or delayed release of natamycin.
[0080] Natamycin in solution is fairly stable at neutral pH but is
easily degraded, especially at room temperature when the pH rises
above pH 10 or sinks below pH 4.5, and especially below pH 4. Thus,
for instance natamycin included in acidic products will gradually
degrade and will consequently leave the product unprotected at
storage and use. The rate of natamycin degradation increases as the
temperature is increased.
[0081] Many acidic products, such as salad dressings and condiments
are stored at ambient temperature and used during a prolonged space
of time even after opening of the package. Acidic beverages such as
fruit juices can be stored at ambient temperature and may be open
to fungal attack. Marinades and marinated meat and poultry are
typically stored for a prolonged time at ambient temperature. Many
acidic dairy products are stored at ambient or chilled temperatures
and may be spoiled by fungal growth. When encapsulated natamycin is
added to such products, the encapsulation protects the enclosed
natamycin and slowly allows it to diffuse into the product to
replace any degraded natamycin thus keeping the amount of active
natamycin at a suitable antifungal level in the product.
[0082] The encapsulated natamycin of the present invention provides
similar benefits in other acidic products, especially those that
are stored at ambient temperature.
[0083] The encapsulating shell may also be designed to protect the
natamycin against any heat during processing of the acidic food
product, such as pasteurization at temperatures of typically 60 to
120.degree. C. and more often 60 to 95.degree. C.
[0084] The processes used for the encapsulation are briefly
outlined below.
[0085] Coacervation is a process which works for both water- and
fat-based applications since the shell is crosslinked and not
soluble in either water or fat.
[0086] Fluidized bed coating is suitable for food applications
where the continuous phase is water, the possible coating materials
include lipids (mono-, di-, triglycerides, fatty acids, waxes and
mixtures) applied from the melted form, water-insoluble polymers
applied from an ethanolic solution (such as zein and shellac). For
applications where the continuous phase is fat, the coating
materials include natural, modified or synthetic hydrocolloids
(carrageenan, alginate, pectin, locust bean gum (LBG),
hydroxypropyl methylcellulose (HPMC), methycellulose) with or
without additives (such as film forming agents) applied from a
water solution or suspension. The particle size of the natamycin
should be over 100 .mu.m, preferably over 150 .mu.m.
[0087] A double encapsulation according to the present invention is
suitable for fat-based food applications. The inner phase might be
composed of water containing a dissolved natamycin/b-cyclodextrin
complex and any gelled/crosslinked hydrocolloids or might be
composed of glycols (such as ethylene glycol) containing dissolved
natamycin and gelled/crosslinked zein.
[0088] In a liposome encapsulation natamycin could be incorporated
in the lipidic bilayer of the liposome phase.
[0089] Spray cooling is a process suitable for water-based food
applications. Natamycin is typically incorporated and suspended in
melted lipid (mono-, di-, triglycerides, fatty acids, waxes and
mixtures) and atomized in cool air to form solid particles
containing encapsulated natamycin.
[0090] Spray drying is suitable for fat-based food applications.
Natamycin is typically incorporated and suspended in aqueous
solution of hydrocolloids (gum arabic, modified starch,
maltodextrins, whey proteins, caseinate, or the like) with or
without additives (such as emulsifiers) and the mixture is atomized
in hot air to evaporate the water and form a solid particles
containing encapsulated natamycin.
[0091] Extrusion is a process which is mainly suitable for
fat-based food applications and centrifugal coextrusion is suitable
for water-based food applications.
[0092] Encapsulation in crosslinked hydrocolloid beads is suitable
for both water- and fat-based food applications. A suspension of
natamycin (alone or in combination with a suitable solvent) is
typically prepared in aqueous alginate, low ester pectin or any
other "crosslinkable" hydrocolloids and added dropwise or sprayed
into a bath of aqueous calcium ions. The crosslinked beads or
particles containing the encapsulated natamycin are collected by
filtration and used as is (wet) or dried by fluidized bed or any
other suitable means.
[0093] Food products, which are especially suitable for being
preserved by the novel natamycin dosage form of the present
invention include fat-containing acidic products such as salad
dressings and acidic dairy products (natural cheese, cottage
cheese, acidified cheese, cream cheese, yoghurt, sour cream). Many
of these products can be preserved with natamycin in
non-encapsulated form and they will generally keep well, if chill
stored. However, if they are stored at ambient temperature,
degradation of the natamycin is a problem. This problem is solved
by the encapsulated natamycin of the present invention.
[0094] In USA salad dressings are usually cold-processed, in which
case contaminant yeasts and moulds are potential spoilage
contaminants. The combination of ambient temperature storage and
low pH causes rapid natamycin degradation. If non-encapsulated
natamycin, which is added when the dressings are first made fails
to rapidly kill all the contaminant yeasts, and if any mould spores
are present (these are not normally killed by natamycin), there is
potential for fungal growth/spoilage once natamycin levels
drop.
[0095] By use of the encapsulated natamycin of the present
invention the acidic food products may be stored at ambient
temperature for up to 12 months.
[0096] The preferred processes for encapsulation for the acidic
food products comprise coacervation and fluidized bed
encapsulation.
[0097] The coacervation process typically involves 1) preparing a
suspension of natamycin in an aqueous solution of hydrolloids, 2)
decreasing the solubility of the hydrocolloids, to cause a phase
separation and the formation of a hydrocolloid-rich third phase by
use of additives or by adjusting the temperature, 3) processing the
tri-phasic system in such as way as to deposit the newly formed
coacervate phase onto the suspended natamycin particles and finally
4) hardening the hydrocolloid shell around the natamycin by
adjusting the temperature, adding chemical or enzymatic crosslinker
or otherwise followed by the isolation of the microcapsules by
freeze-drying, spray-drying, filtration or any other means.
[0098] In the fluidized bed encapsulation the appropriate shell
material is typically applied from aqueous solutions or suspensions
include HPMC, methylcellulose, microcrystalline cellulose and other
cellulosic derivatives with or without stearic acid, other fatty
acids, or other hydrophobic additives. Appropriate shell material
applied from the molten state include lipids, mono-, di- or
tro-glycerides, fatty acids, fatty alcohols, waxes, or mixture
thereof or any other meltable hydrophobic material.
[0099] Another type of food product which derives great benefits
from the present invention is fruit juice and acidic drinks.
Benefits are also derived for processed fruit, low pH sauces, such
as ketchups and purees, salsa sauces, condiments, dips, pickles,
etc, alcoholic drinks such as wine or beer and the like. These
liquid products may contain fat (acidified fruit milk drinks, etc).
They may be pasteurised. The combination of pasteurisation at low
pH, but more importantly acid pH and ambient temperature storage
results in degradation of non-protected natamycin. If
post-processing contamination with yeasts or moulds has occurred,
or heat-resistant mould spores (e.g. Byssochlamys, Talaryomyces) or
yeast ascospores survive the processing, fungal growth will occur
once natamycin levels are degraded.
[0100] Animal feed products such as dog and cat food or broiler
feed is often heat processed during the production thereof and then
stored at ambient temperature. The encapsulated heat-stable
natamycin of the present invention can conveniently be used to
protect such feed products.
[0101] In liquid products such as juices or wines, the shell
material should be made of a material which does not disturb the
clarity of the liquid.
[0102] When the natamycin is added in the form of the novel
capsules of the present invention, the shell will slowly dose out
small amounts of natamycin and keep the liquid products free of
fungal growth for extended periods (3-9 months) of storage at
ambient temperature. The encapsulation provides a special benefit
for heat-treated acidic liquids since the shell protects the
natamycin both from heat and acid attack.
[0103] Natamycin is a preservative which may also be used to
advantage in bakery products. Most baked goods are susceptible to
mould spoilage due to aerial contamination with mould spores after
baking. Propionate is commonly incorporated into bread and other
yeast-leavened doughs as an anti-mould agent. The anti-yeast
activity of propionate is much weaker compared to its anti-mould
activity in these doughs. Although propionate has a slight
inhibitory effect against the bakers' yeast, this is
acceptable.
[0104] Natamycin cannot be used in this way because it is strongly
active against both yeasts and moulds. Encapsulation of the
natamycin prevents the natamycin activity against the bakers' yeast
until after the leavening is complete. It also protects the
natamycin during the baking process. This is particularly useful
for products such as sliced breads that have a large surface area
exposed to air contamination.
[0105] The encapsulation processes of the present invention are
described in some detail below:
[0106] 1. Fluidized Bed Encapsulation
[0107] The natamycin is preferably used in dry powder form. If the
raw natamycin particle size is too fine, the powder can be
agglomerated in an suitable equipment using a binder solution
(solution of sticky hydrocolloids such as alginate or
maltodextrine) in order to obtain a dense powder of particle size
between 100-500.mu.. The appropriate powder is then introduced into
the coating chamber of a fluidized-bed microencapsulation unit and
fluidized at inlet air flow rate of 20-135 cm/s at the bottom plate
and temperature between 5 to 75.degree. C. are used to fluidized
the particles. A coating material is then sprayed onto the
fluidized bed of antimicrobial using a double fluid nozzle and high
pressure atomization air.
[0108] In one example, a melted mixture of triglyceride and
additives is sprayed onto the antimicrobial powder to form a
continuous layer of fat around each individual particle as the
melted fat spread and solidifies on the particles. The amount of
fat applied can be up to 60%, but no usually no lower than 15%
w/w.
[0109] In another example, a dispersion or solution of coating
material in water and/or ethanol is sprayed onto the fluidized
particles and the fluidization air is used to evaporate the solvent
or the water, which leaves behind a continuous film of coating
material on the antimicrobial particles.
[0110] Examples of coating material in this case include any
hydrocolloids (polysaccharides, proteins, shellac, zein or any
other soluble or dispersible coating materials).
[0111] 2. Liposome Encapsulation.
[0112] Typically, liposomes are prepared using a
dehydration-hydration method involving organisc solvent, such as
the one described below. However, solvent-free methods, more
suitable for food ingredients, are also available using
microfluidization or homogenization devices or by repeated
freeze-thaw cycles.
[0113] A typical procedure for the preparation of
liposome-encapsulated natamycin involves the preparation of a
solution of 1 g of a bilayer-forming lipid and 100 mg of
cholesterol or alpha-tocopherol in a suitable organic solvent and
evaporating the solvent so as to form a thin dry lipid film on the
bottom of the container.
[0114] After thorough drying of the lipid film, 1 L of water
containing natamycin at or over the saturation concentration
(natamycin solubility can be increased if desired by the formation
of alkaline salts) is added to the container and the mixture is
thoroughly mixed or homogenized.
[0115] The resulting suspension of multilamellar vesicle (MLV) can
be further processed by microfluidization and or sonication to form
smaller more homogenous small unilamellar vesicle (SUV). The
suspension of liposome-encapsulated natamycin can be added directly
to the application or dried by lyophilization or any other
appropriate drying procedures.
[0116] 3. Spray Drying
[0117] Natamycin can be encapsulated in a matrix of hydrocolloids
by means of spray drying. In a typical procedure, an aqueous
natamycin suspension in which a hydrocolloid or a mixture of
hydrocolloids is dissolved (water-soluble polysaccharides,
proteins, modified polysaccharides with or without film forming
agents such as oligosaccharides, plasticizers, emulsifiers or other
additives) is prepared at near-neutral pH (to minimize degradation
of natamycin). Then, the mixture is pumped through an atomizer
(rotary atomizer, pressure nozzle, double fluid nozzle or any other
atomization device) into a drying chamber co- or counter-currently
with heated air.
[0118] The temperature of the heated air is typically between 160
and 200.degree. C., can be as high as 300.degree. C., but is
preferably in the range of 100-160.degree. C. Evaporation of water
yields a free flowing powder of microcapsules containing dispersed
natamycin in the dry hydrocolloid(s) matrix.
[0119] 4. Spray Cooling
[0120] In spray cooling/chilling/congealing of natamycin, the
powdered natamycin is dispersed in a molten lipid or mixture of
lipids (mono-, di-, tri-glycerides, esterified glycerides, animal,
vegetable or mineral waxes, any other meltable material at
temperature between 45 and 125.degree. C.) with or without the aid
of surface-active additives. The dispersion is then pumped through
an atomizer (rotary atomizer, pressure nozzle, double fluid nozzle,
spinning disk or any other atomization device) into a cooling
chamber co- or counter-currently with cooled air.
[0121] The temperature of the cooled air is typically between -10
and 30.degree. C., but can be as low as -40.degree. C.
solidification of the lipid yields a free flowing powder of
microcapsules containing dispersed natamycin in the crystallized
lipidic matrix.
[0122] 5. Extrusion
[0123] Encapsulation of natamycin by extrusion can be achieved by
processing the powdered natamycin (preferably of small particle
size) together with a melted or plasticized polymeric shell
material in a double- or single-screw extruder under pressure,
followed by the cooling or the drying of the mass coming out of the
extruder die and milling or crimpling to the appropriate particle
size. The polymeric mass is melted in the extruder at relatively
high temperatures in the presence of small amount of water, which
causes the mass to become flowable. The mass, in which the
natamycin is incorporated, is extruded and cooling results in the
transformation of the mass into a glassy state which is highly
impermeable to oxygen and other hydrobobic external agents. Shell
materials suitable for extrusion of natamycin include
oligosaccharides, polysaccharides, modified polysaccharide,
proteins or mixtures thereof with or without the use of
plasticizing, emulsifying or stabilizing additives.
[0124] 6. Centrifugal Co-Extrusion
[0125] Encapsulation of natamycin by centrifugal co-extrusion is a
variation of the spray cooling process. In centrifugal coextrusion
of natamycin, the powdered antimicrobial is first dispersed in a
molten lipid or mixture of lipids (mono-, di-, tri-glycerides,
esterified glycerides, animal, vegetable or mineral waxes, any
other meltable material at temperature between 45 and 125.degree.
C.) with or without the aid of surface-active additives. The
dispersion is then pumped through the inner part of a double fluid
nozzle while another stream of molten lipid or mixture of lipids
(same as above) is pumped through the outer part of the double
fluid nozzle. The nozzle is rotated around its axis so as to break
up the stream of melted fat in discrete globules, which are
solidified by cooled air. The resulting microcapsules are composed
of an outer layer of solidified fat encapsulating a core of
solidified fat containing dispersed natamycin.
[0126] 7. Coacervation
[0127] The natamycin dosage form of the present invention can be
formed by coacervation. The coacervation of the shell material,
such as hydrocolloid, is carried out by using any suitable
coacervation process. The coacervation can be performed for example
by adding salt(s), sugar(s), or other additives, which cause the
phase separation of the hydrocolloid(s). The coacervation can also
be performed by subjecting the emulsion to heating, cooling, pH
change by adding acid or base, which cause the phase separation of
the hydrocolloid(s). The deposition of the coacervated phase around
the aqueous phase is spontaneous and driven by surface tension
forces. The coacervate layer can afterwards be subjected to
cross-linking or hardening by any suitable means, which are known
to persons skilled in coacervation.
[0128] The shell materials suitable for coacervation are selected
form the group comprising any mixture of one or many ionic
hydrocolloids and one or many amphoteric hjydrocolloids, such as
any mixture of polysaccharides and proteins, gelatine/arabic gum,
gelatine/CMC, any proteins/ionic hydrocolloids, any combination of
hydrocolloids and a solubility-reducing agent such as salts,
sugars, acids or bases.
[0129] 8. Double Encapsulation
[0130] According to a special aspect of the present invention, the
natamycin suspension is double encapsulated in microcapsules. In
that case, the natamycin is first incorporated (suspended) in an
aqueous phase containing encapsulating material, such as
hydrocolloid or any other suitable encapsulating material or
mixture thereof, and the aqueous phase is encapsulated, for example
by gelling, cross-linking, coacervation, sintering or by any other
suitable means, and the resulting encapsulated aqueous bead or
beads is/are further encapsulated in a solidified hydrophobic shell
material.
[0131] A hydrophobic shell material is selected based on desired
properties of the capsules, for example based on the intended use
of the capsules, storage temperature, etc. The hydrophobic shell
material should have a melting point above 45.degree. C. so that it
can be stored at room temperature, in general any hydrophobic
material can be used if the capsules are stored below the melting
temperature of the hydrophobic material.
[0132] In this application, melted form means that the hydrophobic
phase is at the lowest temperature at which the hydrophobic phase
is sufficiently fluid to drip, as determined by test method ASTM D
566 or D 265.
[0133] The hydrophobic shell material useful in the various
processes of the invention is selected from the group comprising
fats, oils, waxes, resins, emulsifiers or mixtures thereof, which
are preferably food-grade. Preferably the hydrophobic shell
material is selected from the group comprising animal oils and
fats, fully hydrogenated vegetable or animal oils, partially
hydrogenated vegetable or animal oils, unsaturated, hydrogenated or
fully hydrogenated fatty acids, unsaturated, partially hydrogenated
or fully hydrogenated fatty acid monoglycerides and diglycerides,
unsaturated, partially hydrogenated or fully hydrogenated
esterified fatty acids of monoglycerides or diglycerides,
unsaturated, partially hydrogenated or fully hydrogenated free
fatty acids, other emulsifiers, animal waxes, vegetable waxes,
mineral waxes, synthetic waxes, natural and synthetic resins and
mixtures thereof.
[0134] Animal oils and fats are such as, but not restricted to,
beef tallow, mutton tallow, lamb tallow, lard or pork fat, sperm
oil. Hydrogenated or partially hydrogenated vegetable oils are such
as, but not restricted to, canola oil, cottonseed oil, peanut oil,
corn oil, olive oil, soybean oil, sunflower oil, safflower oil,
coconut oil, palm oil, linseed oil, tung oil and castor oil. Free
fatty acids are such as, but not restricted to, stearic acid,
palmitic acid and oleic acid. Other emulsifiers are such as, but
not restricted to, polyglycerol esters, sorbitan esters of fatty
acids. Animal waxes are such as, but not restricted to, beeswax,
lanolin, shell wax or Chinese insect wax. Vegetable waxes are such
as, but not restricted to, carnauba, candelilla, bayberry or
sugarcane waxes. Mineral waxes are such as, but not restricted to,
paraffin, microcrysalline petroleum, ozocerite, ceresin or montan.
Synthetic waxes are such as, but not restricted to, low molecular
weight polyolefin, polyol ether-esters and Fisher-Tropsch process
synthetic waxes. Natural resins are such as rosin, balsam, shellac
and zein.
[0135] The hydrocolloid shell material of the invention is any
food-grade hydrocolloid which is susceptible to encapsulation by
the processes of the invention.
[0136] The material is selected from the group comprising
hydrocolloids, sodium alginate, gum arabic, gellan gum, starch,
modified starch, guar gum, agar gum, pectin, amidified pectin,
carrageenan, xanthan, gelatine, chitosan, mesquite gum, hyaluronic
acid, cellulose derivatives such as cellulose acetate phtalate,
hydroxy propyl methylcellulose (HPMC), methyl cellulose, ethyl
cellulose and carboxy methyl cellulose (CMC), methyl acrylic
copolymers, such as Eudragit.RTM., psyllium, tamarind, xanthan,
locust bean gum, whey protein, soy protein, sodium caseinate, any
food-grade protein, shellac, zein, any synthetic or natural
water-soluble polymers, and mixtures thereof.
[0137] According to a special double encapsulation embodiment of
the present invention, the microcapsule comprises a solidified
hydrophobic shell matrix, a gelled or cross-linked aqueous
hydrocolloid bead or beads encapsulated in the solidified
hydrophobic shell matrix, and natamycin suspended in the gelled or
cross-linked aqueous hydrocolloid bead or beads.
[0138] The gelled hydrocolloids have a gelling temperature above
room temperature. Examples of gelled hydrocolloids include
carrageenan, gelatine, guar gum, agar gum, starch, modified starch
and mixture of xanthan and locust bean gum, mixture of carrageenan
and locust bean gum and mixture of any gelling hydrocolloids and
other non-gelling hydrocolloids.
[0139] The cross-linking of the hydrocolloids is carried out by
using cross-linking agents or by a variety of mechanisms. If the
hydrocolloid is a protein or polysaccharide bearing amino groups,
it can be cross-linked by using dialdehydes, such as
glutaraldehyde. If the hydrocolloid is a polysaccharide, such as
sodium alginate, gellan gum or pectin, it can be cross-linked with
multivalent ions, such as calcium or magnesium. The cross-linking
can also be carried out by other mechanisms, such as heating, pH
adjustment, applying pressure or by enzymatic cross-linking.
Proteins, for example, can be cross-linked by subjecting a protein
to a high pressure, preferably from 5 to 200 bar, and/or by
subjecting a protein to a temperature which is above the
denaturation temperature of the protein. The enzymatic
cross-linking of proteins can be carried out for example with
transglutamidase. Based on the hydrocolloid used, a person skilled
in the art is able to decide which method of gelling or
cross-linking is used.
[0140] The capsules of the present invention are preferably
microcapsules and comprise 1 to 80%, preferably 15 to 50%, most
preferably 30 to 40% natamycin encapsulated in the hydrophobic or
hydrocolloid shell. The size of a microcapsule is approximately
between 40 to 800 microns, preferably 100 to 150 microns. The
amount of natamycin encapsulated within the shell of a microcapsule
may vary, depending on the intended use of the microcapsules. The
size of the microcapsules of the present invention may also vary
depending on the intended use.
[0141] The aqueous phase mentioned in the present specification
means water or a mixture of water and any other water-miscible
solvents, such as ethanol, ethylene glycol or glycerol. The aqueous
phase may also contain additives, such as carbohydrates, such as
monosaccharides or oligosaccharides to modify the properties of the
hydrocolloid gel, inorganic salts to modify the properties of
protein gels, preservatives to avoid deterioration of the
microcapsules by bacteria or fungus or emulsifiers as processing
aids, sorbitan tristearate or other emulsifiers as crystal form
modifier, hydrophobic natural or synthetic polymers to modify
mechanical properties of the capsule, plastizisers, preservatives
to avoid deterioration of the capsules.
[0142] The encapsulated natamycin described above can be used in a
wide variety of applications in food industry and in pharmaceutical
applications.
[0143] The capsules of the present invention can be used in a great
variety of applications, depending for example on the properties of
the capsules, the hydrocolloid, the hydrophobic material or the
size of the capsules. A controlled release of the active
ingredients from the capsules can be achieved by the present
invention. The release of the active ingredients from the capsules
can be controlled by initiating the release in various ways, for
example by heat treatment, by heating in a microwave oven or baking
oven, by pH, by light, or by any other suitable process. The
release of the active ingredients from the capsules of the present
invention can also happen very slowly. The release of the natamycin
may also take place upon freezing of the capsules. Freezing causes
any water phase inside the capsule to expand, which causes the
external shell material to crack. Upon thawing, the natamycin is
quickly released from the microcapsule.
[0144] In bakery, for example, delayed release of natamycin can be
achieved with the capsules of the present invention. This is very
important in order to avoid inhibition of the required activity of
the baker's yeast. Increased heat stability of the natamycin is
achieved for example in pasteurised or heat-processed foods.
Delayed release of natamycin is also very important for other yeast
fermented foods.
[0145] The present invention relates to the use of encapsulated
natamycin as preservative agent providing slow, controlled and/or
sustained release of the natamycin.
[0146] Controlled release of natamycin in food products, such as
baked goods, pizza, is achieved with the capsules of the present
invention. The encapsulated natamycin is retained in the product
until heat, pH, light and/or stress treatment is applied to release
the natamycin. Heat can be provided for example by a
micro-wave-oven, conventional oven or hot water. Stress can be
provided for example by processing conditions or mastication.
[0147] Slow release of natamycin for example in processed meat
products or in beverages, such as orange juice, is achieved with
the encapsulated natamycin of the present invention. The natamycin
preservative agent in the capsules of the present invention is
slowly released in the product as it is naturally degraded. This
effectively prevents growth of fungi or other undesirable micro
organisms for a longer period of time than non-encapsulated
natamycin, thus ensuring a longer shelf life for the food product.
The shell can also provide thermal stability to natamycin so as to
survive heat treatment and harsh processing conditions, but to
remain active during storage of the processed product.
[0148] Delayed release of natamycin in bakery applications is
achieved by the capsules of the present invention. Natamycin is
useful for extending the shelf life of breads and other bakery
products, but at the expense of detrimentally affecting the
effectiveness of the yeast. The delayed release allows a more
efficient use of the yeast, while also providing the preservative
properties after the natamycin is released during baking.
[0149] The encapsulated natamycin is also useful in many
ready-to-use food products, in snacks and in kits for producing
snacks and meals. The encapsulated natamycin ensures the slow and
continuous release of natamycin into the product so as to keep the
level of active (non-degraded) natamycin high enough to prevent
spoilage of the product.
[0150] The following examples serve to illustrate the invention
EXAMPLES
Example 1
[0151] Production of Encapsulated Natamycin by a Coacervation
Process
[0152] First, a solution of gelatine (219 g, isoelectric point=8)
in 6 liters of water at 50.degree. C. was prepared. Secondly, a
solution of 219 g of gum acacia was dissolved in 6 L of water at
50.degree. C. The two solutions were mixed together and kept at
45.degree. C. under vigorous stirring. 700 g of Natamax.TM. SF
(Danisco) was added to the aqueous solutions and the pH was rapidly
lowered to 4.0 using 1M HCl, after which the temperature was
lowered to 5.degree. C. at the rate of approximately 1.degree.
C./min, maintaining the stirring throughout. 36 ml of an 1:1
aqueous solution of glutaraldehyde was added, the pH was
re-adjusted to 8.5 using aqueous 1M NaOH and then the temperature
was increased back to 45.degree. C. at a rate of approx 2.degree.
C./min. Finally, the whole mixture was spray dried in a spray tower
using a double-fluid nozzle mounted in the fountain configuration,
air inlet temperature of 180.degree. C. and a spray rate to
maintain the outlet air temperature of about 100.degree. C.
[0153] In an alternatively process, 1 kg each of gum arabic and
maltodextrin (DE 12) are dissolved in the aqueous mixture just
prior to spray drying.
Example 2
[0154] Fluid Bed Encapsulation of Natamycin Preprocessing.
[0155] If the natamycin particle size is too fine (below 100
micrometers average), the powder is agglomerated to a larger
average particle size for easier processing by fluidized bed.
Larger average particle size not only makes the process easier, but
also allow the use of less coating material while achieving the
same protection as with more shell material. Natamycin is
agglomerated in an suitable equipment such as a high shear mixer
(such as a Lodige mixer using a binder solution (solution of sticky
hydrocolloids such as alginate or maltodextrine) in order to obtain
a dense powder of particle size above 150, preferably between
200-350 .mu.m and bulk density above 0.4, preferably above 0.7
g/cm.sup.3.
[0156] Hotmelt Fluid Bed Encapsulation
[0157] 3 kg of agglomerated natamycin is introduced into the
coating chamber of a Aeromatic-Fielder MP1 fluidized-bed
microencapsulation unit and fluidized using inlet air flow rate of
80 cm/s and temperature of 43.degree. C. A melted hydrogenated
triglyceride kept at 85.degree. C. is then sprayed onto the
fluidized bed of antimicrobial using a peristaltic pump and a
double fluid nozzle set a 2 bar and 2 m.sup.3 of air/h. The fat is
applied at around 1 kg/h, in such a way to form a continuous layer
of fat around each individual particles as the melted fat spread
and solidifies on the particles. Enough fat is applied to reach a
final product containing 30% fat and 70% natamycin.
Example 3
[0158] Extrusion Encapsulation of Natamycin
[0159] A mixture of 60 parts of corn starch, 25 parts of natamycin
and 10 parts of polyethyleneglycol and 5 parts of water is mixed
together and introduced in a clextral double-screw extruder, the
first barrel heated to 40.degree. C. The mass is treated at
100.degree. C. for just a few seconds in barrels 2 and 3 then
cooled down to 45.degree. C. in barrels up to the die.
Alternatively, a vacuum pump is installed on the last barrel so as
to get rid of the water. The exiting rope is cut into pieces
between 250 and 500 .mu.m.
Example 4
[0160] Use of Encapsulated Natamycin in Orange Juice
[0161] Natamycin was encapsulated by a coacervation method as
described in Example 1, using either gelatine and acacia as a shell
material (NAP03015), or gelatine, acacia and maltodextrin
(NAP03023).
[0162] The samples, together with natamycin as Natamax.TM.
(Danisco) were added to orange juice (pH 3.85) and heated at
100.degree. C. for 10 minutes. The residual natamycin levels in the
juice before and after treatment were tested by HPLC. Samples were
diluted in methanol for this assay.
[0163] The results are shown in Table 1.
[0164] The experiment shows that the microcapsule prevented release
of natamycin, so that not all the estimated natamycin present could
be detected before the heating step. After heating, the
encapsulated natamycin showed recovery levels higher than with the
unprotected natamycin.
1TABLE 1 Heat protection of encapsulated natamycin in orange juice
Theoretical Detectable Detectable payload Actual natamycin in
natamycin in based on natamycin juice before juice after pure added
heating/ppm heating/ppm natamycin Addition (based on estimated (%
of natamycin (% of natamycin Sample W/w level payload) added)
added) Natamax .TM. 50% 40 ppm 20 ppm 19.7 (98.5%) 5.2 (26%)
NAP03015 80% 80 ppm 64 ppm 33.0 (52%) 21.1 (33%) NAP03023 36% 140
ppm 50 ppm 14.1 (28%) 14.8 (30%)
Example 5
[0165] Use of Encapsulated Natamycin in Vinaigrette
[0166] A vinaigrette dressing was prepared containing water (494.6
ml), 10% vinegar (220 ml), sugar (90 g) and salt (10 g), pH 2.6.
Additions of encapsulated and unencapsulated natamycin were made as
shown in Table 2. Sample NAP03015 was encapsulated by coacervation
as described in Example 1. Sample NAP03007 was encapsulated by
spray-cooling with a shell material of triglyceride.
2TABLE 2 Theoretical Actual natamycin payload of pure Addition
added (based on Sample natamycin level estimated payload) Natamax
.TM. 50% 40 ppm 20 ppm NAP03007 40% 100 ppm 40 ppm NAP03015 80% 50
ppm 40 ppm
[0167] The vinaigrette was incubated at 25.degree. C., and samples
assayed for residual natamycin content at regular intervals. The
vinaigrette was shaken before each sampling, and a sample taken for
HPLC analysis, which was diluted 1:1 in methanol. The natamycin
levels found in the mixed vinaigrette and in the water layer only
are shown in Table 3 and 4. The results show that encapsulation
protects the natamycin from acid degradation in the vinaigrette,
allowing a slow release of the preservative with time. Sample
NAP03007 contained only a small amount of unencapsulated natamycin
at the beginning of the experiment.
3TABLE 3 Detectable natamycin in a vinaigrette dressing at
25.degree. C. (Sample taken from homogenised dressing) Natamycin
percentage of estimated addition level (based on estimated addition
level) Days at 25.degree. C. Natamax NAPO3007 NAPO3015 0 70.5% 1.8%
70% 1 38% 4.5% 50.5% 6 22.5% 19.3% 23.8% 9 13% 29.5% 36.5% 14 10%
40.8% 29% 21 4.5% 17.5% 10.2%
[0168]
4TABLE 4 Detectable natamycin from the water phase of a vinaigrette
dressing at 25.degree. C. Natamycin % of estimated addition level.
(based on estimated addition level) Days at 25.degree. C. Natamax
NAPO3007 NAPO3015 0 48% 1.5% 13% 1 25% 2.25% 15.3% 6 8% 2.75% 7.8%
9 8% 13% 5% 14 6% 13.5% 5.3% 21 2.5% 11.8% 4.3%
Example 6
[0169] Use of Encapsulated Natamycin in Bread
[0170] A bread is made by preparing a dough containing flour,
water, yeast, salt and a dough conditioner. Included in the dough
mix is either natamycin or encapsulated natamycin or neither. Both
natamycin preparations are added at a potency dosage of 12 ppm
(0.0012%) on flour weight and these are added together with the
other dry ingredients. All ingredients are mixed together
thoroughly for between 3 and 10 minutes.
[0171] The dough is then given a short resting period after mixing
(approx. 5 to 10 minutes) followed by scaling at the required
weight. A second rest period is then applied following a second
moulding in shape the dough as desired. The dough is then placed
into a tin or tray. A leavening period for about 50 minutes at 85%
relative humidity at 40.degree. C. then follows.
[0172] The fully proved dough is then baked at between 190 and
230.degree. C. for approximately 15 to 30 minutes.
[0173] Bread containing unencapsulated natamycin shows poor
leavening, whereas leavening of the encapsulated natamycin proceeds
in a similar fashion to the control bread not containing any
natamycin. This demonstrates the benefit of encapsulation, which
prevents the natamycin from inhibiting the yeast fermentation
reaction.
[0174] When the bread is cool, the natamycin content in the bread
is assayed. The natamycin content from bread containing
encapsulated natamycin is higher than that in the bread containing
unencapsulated natamycin, indicating the heat protective benefit of
encapsulated natamycin. The bread is then sliced and observed over
the normal shelf life period for growth of moulds. Delay of mould
spoilage is observed for bread containing natamycin. This extension
of shelf life is greater for bread containing encapsulated
natamycin, which is a reflection of the higher natamycin levels
surviving the baking process.
Example 7
[0175] Encapsulation of Natamycin in a Double Shell
[0176] First, a solution of 15 g kappa-carrageenan in 1000 ml of
phosphate buffer at pH 7.0 is prepared at 85.degree. C. To this is
added 300 g of commercial natamycin (Natamax.TM. SF, Danisco). The
resulting mixture is thoroughly mixed. At the same time, a mixture
of 1333 g of a vegetable triglyceride (GRINDSTED.RTM. PS 101, m.p.
58.degree. C.) and 73 g of acetylated emulsifier (Acetem 50 00) is
melted at 85.degree. C. in a water bath. The melted fat mixture is
kept under homogenization (Silverson mixer, 8000 rpm) as the
aqueous mixture is slowly incorporated. The homogenization is
maintained for 5 minutes after the whole aqueous mixture is added
and then a solution of 3 g of polysorbate 80 in 40 ml of water is
added under constant mixing. The resulting low-viscosity
water-in-oil emulsion is then immediately spray cooled in a Niro
spray tower using the following parameters: inlet air temperature
10.degree. C., outlet air temperature 28.degree. C., rotating
atomization wheel speed 10 000 rpm. A free flowing powder is
obtained. The incorporation of encapsulated natamycin in an orange
juice results in a much more stable natamycin formulation compared
to when unencapsulated natamycin is used in the liquid, thus
dramatically improving survival rate of the natamycinin the
beverage. The encapsulated natamycin, as presented in this example,
is released at a rate of only 7% after three days.
[0177] It will be obvious to a person skilled in the art that as
technology advances, the inventive concept can be implemented in
various ways. The invention and its embodiments are not limited to
the examples described above but may vary within the scope of the
claims.
* * * * *