U.S. patent application number 10/921895 was filed with the patent office on 2005-04-14 for powder of amino acids and method for producing the same.
This patent application is currently assigned to AJINOMOTO CO., INC.. Invention is credited to Katouno, Junichi, Tsujimoto, Susumu, Watanabe, Aiji, Yoshida, Teruo.
Application Number | 20050080136 10/921895 |
Document ID | / |
Family ID | 27759684 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050080136 |
Kind Code |
A1 |
Watanabe, Aiji ; et
al. |
April 14, 2005 |
Powder of amino acids and method for producing the same
Abstract
Dry powders of amino acids which exhibit great oral meltability
and solubility, may be produced by spray drying a hydrous liquid of
amino acids to produce a powder of amino acids, where the hydrous
liquid of amino acids is prepared into the form of microfine liquid
droplets in the presence of trehalose for spray drying, to obtain a
powder having a mean particle size of 0.1 .mu.m to 15 .mu.m, as
well as granulating and drying during the spray drying or after the
spray drying, to obtain a granulated powder having a mean particle
size of 20 .mu.m to 1,000 .mu.m.
Inventors: |
Watanabe, Aiji;
(Kawasaki-shi, JP) ; Katouno, Junichi;
(Kawasaki-shi, JP) ; Yoshida, Teruo;
(Kawasaki-shi, JP) ; Tsujimoto, Susumu;
(Kawasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
AJINOMOTO CO., INC.
Tokyo
JP
|
Family ID: |
27759684 |
Appl. No.: |
10/921895 |
Filed: |
August 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10921895 |
Aug 20, 2004 |
|
|
|
PCT/JP03/01198 |
Feb 5, 2003 |
|
|
|
Current U.S.
Class: |
514/561 ; 34/130;
514/53 |
Current CPC
Class: |
A23V 2250/0626 20130101;
A23V 2200/254 20130101; A23V 2250/0628 20130101; A23V 2250/06
20130101; A23V 2250/0654 20130101; A23V 2200/254 20130101; A23V
2250/636 20130101; A61P 1/16 20180101; A23V 2250/636 20130101; A23L
33/175 20160801; A23V 2002/00 20130101; A23V 2002/00 20130101; A61P
3/02 20180101; A61P 3/04 20180101; A23V 2002/00 20130101; A61K
9/1652 20130101; A61K 31/198 20130101; A61P 13/12 20180101; A23P
10/40 20160801; A61K 9/1623 20130101; A61P 43/00 20180101 |
Class at
Publication: |
514/561 ;
034/130; 514/053 |
International
Class: |
A61K 031/7012; A61K
031/198; F26B 011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2002 |
JP |
046580/2002 |
Jul 10, 2002 |
JP |
201848/2002 |
Claims
1. A method for producing a powder of one or more amino acids,
comprising: (1) spray drying a hydrous liquid comprising at least
one amino acid to obtain a powder of said at least one amino acid,
wherein said hydrous liquid comprising said at least one amino
acids is prepared into the form of microfine liquid droplets in the
presence of trehalose for spray drying to obtain a powder having a
mean particle size of 0.1 .mu.m to 15 .mu.m.
2. The method of claim 1, wherein said trehalose is added to said
hydrous liquid comprising said at least one amino acid.
3. The method of claim 1, wherein said trehalose is prepared into
the form of a trehalose solution existing as microfine liquid
droplets and is spray dried with said hydrous liquid comprising
said at least one amino acid.
4. The method of claim 1, wherein said spray drying is carried out
under a condition of an exhaust gas temperature during spray drying
of less than 97.degree. C.
5. The method of claim 1, wherein said at least one amino acid is
one or more slightly soluble amino acids.
6. The method of claim 1, wherein said at least one amino acid is
one or more branched amino acids.
7. The method of claim 1, wherein said hydrous liquid comprising at
least one amino acid is a solution.
8. The method of claim 1, wherein said hydrous liquid comprising at
least one amino acid is a suspension.
9. The method of claim 1, wherein said hydrous liquid comprising at
least one amino acid is an emulsion.
10. A powder of one or more amino acids, wherein said powder is
prepared by a process according to claim 1.
11. A method for producing a powder of one or more amino acids,
comprising: (1) spray drying a hydrous liquid comprising at least
one amino acid to obtain a powder of said at least one amino acid,
wherein said hydrous liquid comprising at least one amino acid is
prepared into the form of microfine liquid droplets in the presence
of trehalose for spray drying, and said powder of said at least one
amino acid is then granulated and dried, during spray drying or
after spray drying, to obtain a granulated powder having a mean
particle size of 20 .mu.m to 1,000 .mu.m.
12. The method of claim 11, wherein said trehalose is added to said
hydrous liquid comprising at least one amino acid.
13. The method of claim 11, wherein said trehalose is prepared into
the form of a trehalose solution existing as microfine liquid
droplets and is spray dried and/or a granulated with said hydrous
liquid comprising said at least one amino acid.
14. The method of claim 11, wherein said spray drying or
granulation is carried out under a condition of an exhaust gas
temperature during spray drying of less than 97.degree. C.
15. The method of claim 11, wherein said at least one amino acid is
a slightly soluble amino acid.
16. The method of claim 11, wherein said at least one amino acid is
a branched amino acid.
17. The method of claim 11, wherein said hydrous liquid comprising
at least one amino acid is a solution.
18. The method of claim 11, wherein said hydrous liquid comprising
at least one amino acid is a suspension.
19. The method of claim 11, wherein said hydrous liquid comprising
at least one amino acid is an emulsion.
20. A powder of one or more amino acids, wherein said powder is
prepared by a process according to claim 11.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of International Patent
Application No. PCT/JPO3/01198, filed on Feb. 5, 2003, and claims
priority to Japanese Patent Application No.046580/2002, filed on
Feb. 22, 2002, and Japanese Patent Application No. 201848/2002,
filed on Jul. 10, 2002, all of which are incorporated herein by
reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to powders of amino acids,
which is a microfine or granulated amino acid powder containing
trehalose. The present invention further relates to methods for
producing such powders.
[0004] 2. Discussion of the Background
[0005] Amino acids, amino acid salts, and amino acid derivatives
(simply referred to as amino acids hereinafter) are widely used in
medical diets for nutrition supplements, disease-specific amino
acid preparations for oral administration and infusion for subject
patients with renal impairment and liver disorders, infantile
nutritious compositions, diet food materials, health foods, and
functional foods. Further, amino acids are used in cosmetics and in
veterinary preparations for dosing to animals, after being mixed in
feeds and the like.
[0006] Trehalose, when contained in amino acids, not only serves as
a saccharide nutrient but also suppresses the bittern taste of
amino acids, advantageously, without any occurrence of the Maillard
reaction (browning reaction). Therefore, the presence of trehalose
therein is recommended. Specifically, those formulations described
below are known.
[0007] For example, trehalose-coated (film) powders of amino acids
are known, and may be prepared by one of the following methods. In
a first method, a binder is added to a powder of amino acids in
mixture to prepare granules by an extrusion granulation process,
and the granules surfaces are then coated with trehalose as a
coating material by fluid granulation. In a second method,
trehalose and a binder are added to a powder of amino acids in
mixture for coating by fluid granulation, and spraying an aqueous
ethanol solution over the resulting coated powder for granulation
(see, JP-A-6-227975).
[0008] Furthermore, an amino acid infusion containing trehalose and
having the same effects as described above is also known (see,
JP-A-6-70718).
[0009] Also known are amino acid food products containing
trehalose, which are adjusted to a pH 3.0 to 6.0 by the addition of
sour agents such as citric acid so as to prevent flavor
deterioration due to heating of the amino acid, or flavor
modification or color modification of the amino acid during
long-term storage. The test results of heating the hydrous amino
acid-containing solution are disclosed (see, JP-A-2000-4836).
[0010] As compositions for use in the suppression of blood amino
acid variation following vigorous athletic motion, a hydrous
solution of a composition of amino acids and sugar is disclosed,
which contains at least 13 types of amino acids and trehalose. The
hydrous solution is said to be effective for the improvement of
athletic potential and the amelioration of fatigue (see,
JP-A-2000-72669).
[0011] As described above, various findings exist about amino acid
compositions containing trehalose, but only JP-A-6-227975 describes
such a powder. Further, no amino acid powder with a high oral
meltability, high solubility, and masked taste is known. In
particularly, there remains a need for a dry power of a branched
amino acid and a slightly soluble amino acid, which has improved
oral meltability and solubility and suppressed bitterness.
[0012] As production methods of dry powders, meanwhile, the spray
drying method, hot-air drying method, and freeze-drying method are
known. Among them, the spray drying method is capable of producing
microfine particles, and is a dry method for recovering a dry
powder of spherical and spherical shell-shaped powder, by
dispersing a solution or a particle slurry into the form of
microfine particles in hot air, where the spray method uses
pressure nozzle, rotating disk, and two-fluid nozzle and the like.
In many cases, the mean particle size of the dry powder is about 20
.mu.m to 500 .mu.m (see, Handbook of Chemistry and Engineering,
revised sixth edition, p. 770, p. 780 (1999), issued by Maruzen),
while in the pharmaceutical field, a production example of
microfine particles of 10 .mu.m or less is introduced (see,
JP-A-9-235238, JP-T-10-500672, and JP-A-11-114027). In recent
years, a four-fluid nozzle has been developed, which has enabled
mass-scale spray drying with a liquid droplet having a mean
particle size of several micrometers (see, Chemical Apparatus,
pp.60-65 (June, 2000), and U.S. Pat. No. 2,797,080, and
JP-A-2002-17337, etc.).
[0013] Similar to the powders containing microfine amino acids, an
inhalation dry composition containing the pharmacologically active
component, interferon, as the essential component and containing a
hydrophobic amino acid selected from leucine, isoleucine, and
valine at 60% or more to less than 100% (mean particle size
(volume-based distribution) of 0.1 .mu.m or more to 10 .mu.m or
less) is disclosed for the purpose of avoiding the deliquescence of
the inhalation dry composition, when left at a high humidity (see,
JP-A-9-235238). In Example 2 of JP-A-9-235238, a dry particle
powder is obtained as a control, by preparing a solution containing
3.5 g of isoleucine, 0.7 g of serum albumin, 695.8 g of deionized
water, and 300 g of ethanol for spray drying, and then spraying the
resulting solution with a spray dryer (aerodynamic mean particle
size of 0.9897 .mu.m). However, this Example does not include any
description of oral meltability, solubility, and taste masking.
[0014] Moreover, it is also desired that the production of powders
of amino acids by spray drying in such manner can be done on a mass
scale; that the quality can be maintained; and that the oral
meltability and solubility of the resulting powders are great.
Accordingly, there remains a need for any improved process so as to
satisfy these properties.
SUMMARY OF THE INVENTION
[0015] Accordingly, it is one object of the present invention to
provide novel dry powders (meaning microfine powder or granulated
powder) of amino acids, which have great oral meltability and
solubility and a high masking effect of the taste.
[0016] It is another object of the present invention to provide
novel methods for preparing such powders.
[0017] It is another object of the present invention to provide
novel spray drying methods for preparing such powders.
[0018] These and other objects, which will become apparent during
the following detailed description, have been achieved by the
inventors' discovery that a dry powder of amino acids with great
oral meltability and solubility can be produced by a spray dryer
capable of preparing an amino acid solution containing trehalose
into the form of liquid droplets of several micrometers (particle).
Thus, the invention has been achieved and provides the following
embodiments:
[0019] (1) A method for producing a powder of amino acids,
comprising spray drying a hydrous liquid of amino acids to produce
a powder of amino acids, where the hydrous liquid of amino acids is
prepared into the form of microfine liquid droplets in the presence
of trehalose for spray drying to prepare a powder having a mean
particle size (Mean Volume Diameter) of 0.1 .mu.m to 15 .mu.m.
[0020] (2) A method for producing a powder of amino acids,
comprising spray drying a hydrous liquid of amino acids to produce
a powder of amino acids, where the hydrous liquid of amino acids is
prepared into the form of microfine liquid droplets in the presence
of trehalose for spray drying, and the resulting powder is then
granulated and dried during spray drying or after spray drying, to
prepare a granulated powder having a mean particle size (Mean
Volume Diameter) of 20 .mu.m to 1,000 .mu.m.
[0021] (3) A method for producing a powder of amino acids as
described in (1) or (2), where the trehalose is added to the
hydrous liquid of amino acids or the trehalose is prepared in the
form of a trehalose solution at a microfine liquid droplet state to
be fed into a spray dryer and/or a granulation dryer.
[0022] (4) A method for producing a powder of amino acids as
described in (1) through (3), where the exhaust gas temperature
during spray drying or granulation drying is less than 97.degree.
C.
[0023] (5) A method for producing a powder of amino acids as
described in (1) through (4), where the amino acids are slightly
soluble amino acids.
[0024] (6) A method for producing a powder of amino acids as
described in (5), where the amino acids are branched amino
acids.
[0025] (7) A powder of amino acids, as obtained in a manner
described in (1) through (6).
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same become better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0027] FIG. 1 depicts two X-ray diffraction charts, in which the
upper line is the X-ray powder diffraction pattern of the spray dry
granulated powder of Example 1 and the lower line is the X-ray
powder diffraction pattern of the mixed powder before drying of
Comparative Example 2; and
[0028] FIG. 2 depicts three X-ray diffraction charts, in which the
upper line is the X-ray diffraction pattern of trehalose; the
middle line is the X-ray diffraction pattern of "the mix powder of
amino acids" used as the raw materials of Comparative Example 2;
and the lower line is the X-ray diffraction pattern of
hydroxypropyl cellulose.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Thus, in a first embodiment, the present invention provides
novel powders comprising amino acids and methods of producing such
powders. The various aspects of the present invention are
specifically described below.
[0030] Amino Acids:
[0031] The amino acids to be used in accordance with the present
invention include amino acids, salts of amino acid, and amino acid
derivatives, for example branched amino acids such as leucine,
isoleucine, and valine, sulfur-containing amino acids such as
cystine and methionine, aromatic amino acids such as phenylalanine
and tyrosine, heterocyclic amino acids such as tryptophan and
histidine, acidic amino acids such as aspartic acid and glutamic
acid, and various amino acid derivatives such as sulfur-containing
amino acid derivatives including taurine. These amino acids may be
used singly or in combination of two or more thereof.
[0032] The subject hydrous solution of the amino acid(s) is in the
solution state or a particle slurry solution state (for example, a
slurry containing particles having a mean particle size (Mean
Volume Diameter) of 0.1 .mu.m to 15 .mu.m), and the solvent may
contain ethyl alcohol and the like.
[0033] The amino acids to which the present invention is
effectively applied include amino acids relatively slightly soluble
in water, such as amino acids with a solubility of 9 g or less in
10 g of water at 20.degree. C. Particularly, the amino acids
preferable for the application of the present invention are
slightly soluble amino acids. The present invention is preferably
applied to amino acids with a solubility of 5 g or less in 100 g of
water at 20.degree. C. The present invention is applicable to
leucine, isoleucine, cystine, phenylalanine, tyrosine, tryptophan,
and aspartic acid, and salts thereof and derivatives thereof, in
particular.
[0034] The amount of the amino acid(s) to be used generally
includes but is not specifically limited to 20% by weight to 95% by
weight in the dry powder. If necessary, the amount may be at 50% by
weight to 95% by weight, 60% by weight to 95% by weight, or 70% by
weight to 95% by weight. The amount to be used may satisfactorily
be determined, taking account of the conditions of product design,
namely the balance between the amount of amino acid(s) required as
effective ingredients and the specific volume of the dry powder of
amino acids.
[0035] Trehalose:
[0036] The raw material trehalose for use in accordance with the
invention includes .alpha.,.alpha.-trehalose, .alpha.,
.beta.-trehalose, and .beta.,.beta.-trehalose.
.alpha.,.alpha.-Trehalose is preferable, because
.alpha.,.alpha.-trehalose is a naturally occurring substance and is
now not costly. If necessary, the dihydrate thereof with almost no
hygroscopicity over time may be used, satisfactorily. For example,
a commercially available "Treha" (Hayashibara, Co., Ltd.) is listed
and may be used.
[0037] The amount of trehalose (on an anhydride basis) is 5% by
weight to 80% by weight in the dry powder, satisfactorily. If
necessary, the content can be 5% by weight to 50% by weight, 5% by
weight to 40% by weight and 5% by weight to 30% by weight. The
amount of trehalose to be used may be adjusted to the conditions
for product design, as described above.
[0038] The trehalose and the amino acid(s) may be mixed together to
prepare a mixture solution prior to spray drying. Otherwise, a
hydrous solution containing the amino acid(s) as the main
components and a hydrous solution containing trehalose as the main
component may be simultaneously sprayed together during spray
drying. Alternatively, after a hydrous solution containing the
amino acid(s) as the main component(s) has been spray dried, a
hydrous solution containing trehalose as the main component may be
sprayed and/or granulated as a coating agent and a binder,
satisfactorily. If necessary, further additives, other than
trehalose, may be added satisfactorily as a matter of course.
[0039] Apparatus in Relation With Spray Drying:
[0040] As the spray drying apparatus for use in accordance with the
present invention, commercially available apparatus can be used.
For example, a spray drying apparatus which has a vertical parallel
flow function is preferable. In particular, when a system with a
dehumidifying and drying function is used, the productivity can be
maintained, even under drying conditions with dehumidification at
low temperature, and the quality of the resulting dry powder can be
maintained at a high level, preferably. As described below, for
example, an apparatus capable of blowing a high volume of dry
dehumidified gas at 1% RH or less is particularly preferable as the
dehumidifying apparatus, which is for example a dry dehumidifier BX
series manufactured by Munsters K. K., and HCS series and HCP
series manufactured by Nichias Corporation. Other suitable spray
drying apparatus include the micromist dryer MD series and the
hybrid granulator series manufactured by Fujisaki Electric Co.,
Ltd., the FSD spray dryer with internal fluid layer as manufactured
by Niro Corporation, the fluid granulation spray dryer and L-8 type
spray dryer manufactured by O-gawara Chemical Engineering Machine
Corporation, and the DL-21 type and GB-21 type manufactured by
Yamato Scientific Co., Ltd.
[0041] In accordance with the present invention, it is important to
carry out the spray drying, using a spray nozzle capable of
generating a liquid droplet (microfine particle, single particle)
having a mean particle size (Mean Volume Diameter) of 0.1 .mu.m or
more to less than 20 .mu.m. Specifically, it is important to carry
out the drying using a spray dryer or a spray dry granulation
apparatus with a spray nozzle capable of generating a large volume
of liquid droplets having a mean particle size (Mean Volume
Diameter) of 0.1 .mu.m or more to less than 20 .mu.m, preferably
0.1 .mu.m to 10 .mu.m, and more preferably 1 .mu.m to 8 .mu.m. When
the liquid droplet is dried, a dry powder having a mean particle
size (Mean Volume Diameter) of 0.1 .mu.m to 15 .mu.m, preferably
0.1 .mu.m to 7 .mu.m, and more preferably 0.7 .mu.m to 6 .mu.m is
obtained. This is preferable with the respect to the control of the
product quality and productivity, because such liquid droplets can
be dried under low-temperature conditions within a short time. For
example, the four-fluid nozzle manufactured by Fujisaki Electric
Co., Ltd., which can spray a large volume (for example, 1 kg/min)
of liquid droplets of several micrometers (see, U.S. Pat. No.
2,797,080; Chemical Apparatus, 2000, No. 6, pp. .sub.60-.sub.65)
and the three-fluid nozzle manufactured by Fukusen Production
Corporation, which can spray a large volume (for example, 150
g/min) of liquid droplets of 1 .mu.m to 10 .mu.m (see, Japanese
Patent Publication Sho 63-5146) are included. The four-fluid nozzle
is particularly preferable because a large volume can be sprayed
from the nozzle.
[0042] Granulation:
[0043] Furthermore, the spray dryer is preferably an apparatus with
a granulation function or is additionally mounted with a
granulation dryer if the spray dryer does not have such granulation
function (referred to as "spray dry granulation apparatus"). Then,
importantly, the resulting apparatus is of a specification to
enable the granulated powder (aggregate particle powder) to be
finally dried to the desired moisture. In the case of particles
with such a small specific gravity such as those of amino acids for
use in accordance with the present invention, particles (Mean
Volume Diameter) of 0.1 .mu.m to 15 .mu.m disadvantageously involve
difficulty in handling. Therefore, preferably, a granulation dryer
is additionally mounted in the inside of the spray dryer or in a
state in communication with the spray dryer.
[0044] Appropriate conditions for the granulation size may
satisfactorily be selected, depending on the need. For example, the
granulation size is 20 .mu.m to 1,000 .mu.m, and preferably 20
.mu.m to 500 .mu.m (Mean Volume Diameter). Satisfactorily,
granulation is sometimes effected almost simultaneously with spray
drying or in other cases, fluid granulation is effected after spray
drying or both fluid granulation and spray drying are effected
simultaneously.
[0045] Then, preferably, the apparatus can carry out the final
drying during granulation or immediately after granulation. As to
the conditions prior to or after granulation, the conditions such
as the outlet temperature (also referred to as "drying temperature"
or "exhaust gas temperature") of the spray dry granulation
apparatus, the inlet temperature thereof, the outlet relative
humidity thereof and the inlet relative humidity thereof are almost
identical to those of spray drying conditions described below. In
other words, the outlet temperature of the spray dry granulation
apparatus is 20.degree. C. to less than 97.degree. C., preferably
20 to 80.degree. C., and more preferably 20 to 60.degree. C.
Additionally, the outlet relative humidity of the spray dry
granulation apparatus is 1% RH to 50% RH, preferably 3% RH to 35%
RH, and more preferably 6% RH to 30% RH. Further, the inlet
temperature of the spray dry granulation apparatus is 60 to
300.degree. C., and preferably 70 to 180.degree. C. Under
conditions lower than 60.degree. C., the productivity is
undesirably lowered. Under conditions above 300.degree. C., the
quality of the resulting dry powder is undesirably deteriorated.
Furthermore, the inlet relative humidity of the spray dry
granulation apparatus of the invention is 35% RH or less,
preferably 15% RH or less, more preferably 7% RH or less, and most
preferably 1% RH or less. These preferable conditions are selected
with the respect to the control of product quality such as the
suppression of the Maillard reaction and with the respect to
productivity improvement. Spray drying granulation apparatus with
such granulation function include for example the "Hybrid
Granulator Series as granulation apparatus on filter cloth with
spray drying function equipped" manufactured by Fujisaki Electric
Co., Ltd.
[0046] Operation Conditions of the Spray Dryer:
[0047] Among the operation conditions of the spray dryer, the
outlet temperature (also referred to as "drying temperature" or
"exhaust gas temperature") of the spray dryer is 20.degree. C. to
less than 97.degree. C., preferably 20 to 80.degree. C., and more
preferably 20 to 60.degree. C. At temperatures lower than
20.degree. C., the productivity is undesirably lowered. Furthermore
because the melting point of trehalose in the dihydrate form is
97.degree. C., the outlet temperature is preferably set within a
range not exceeding the melting point, with respect to quality
control.
[0048] Meanwhile, the outlet relative humidity of the spray dryer
set in the present invention is 1% RH to 50% RH, preferably 1% RH
to 35% RH, and more preferably 1% RH to 30% RH. The outlet relative
humidity of the spray dryer as referred to in accordance with the
present invention means the relative humidity in the vicinity of
the powder collection part of the spray dryer. For the spray dryer
of the vertical parallel flow type, the outlet relative humidity
(exhaust gas humidity) means the relative humidity at the exhaust
part thereof. For the "Hybrid Granulator Series HGL-130 as
granulation apparatus on filter cloth with spray drying function
equipped" manufactured by Fujisaki Electric Co., Ltd., for example,
the outlet relative humidity means the relative humidity (exhaust
gas humidity) in the vicinity of the filter cloth at the powder
collection part of the apparatus.
[0049] Herein, the inlet temperature of the spray dryer is 60 to
300.degree. C., and preferably 70 to 180.degree. C. Under
conditions lower than 60.degree. C., the productivity is
undesirably lowered. Under conditions above 300.degree. C., the
quality of the resulting dry powder is undesirably deteriorated.
Furthermore, the inlet relative humidity of the spray dryer of the
present invention is 35% RH or less, preferably 15% RH or less,
more preferably 7% RH or less, and most preferably 1% RH or less.
These preferable conditions for the inlet temperature, the outlet
temperature, the inlet relative humidity, and the outlet relative
humidity are selected with the respect to the control of product
quality such as the suppression of the Maillard reaction, and with
respect to productivity improvement.
[0050] The volume of dry gas, for example dry air for use in
accordance with the present invention is preferably 0.5 m/min or
more, more preferably 1 m/min to 5 m/min, and still more preferably
1 m/min to 3.5 m/min, with respect to the improvement of the
productivity of the dry powder. Herein, the volume of dry air means
the air rate (m/min) in the spray dryer or at the cylinder part
(the trunk part) of the body of the spray dry granulation
apparatus. For the "Hybrid Granulator HGL-130 as granulation
apparatus on filter cloth with spray drying function equipped"
manufactured by Fujisaki Electric Co., Ltd., for example, the
volume means the filtration rate. Further, the liquid transfer rate
of the raw material solutions such as the hydrous solution of amino
acids and the hydrous trehalose solution can be preset
appropriately, in relation with the inlet temperature, the outlet
temperature, the exhaust gas humidity, the types of the raw
material solutions, the desired particle size and the like.
Additionally, the spraying pressure is preferably 0.5 kg/cm.sup.2
or more, more preferably 1 kg/cm.sup.2 to 5 kg/cm.sup.2, and still
more preferably 1 kg/cm.sup.2 to 3 kg/cm.sup.2.
[0051] Furthermore, the gas to be used in accordance with the
invention is preferably air, but may be a gas other than air,
depending on the case. Inert gases, for example nitrogen gas and
carbonate gas, can be used. In the case of addition of readily
oxidizable substances or readily modifiable substances, the use of
an inert gas is effective and may be preferred.
[0052] The moisture content (loss on drying) of the dry powder thus
produced is preferably 5 wt. % or less when dried at 60.degree. C.
for 5 hours. By spray drying the hydrous solution containing
trehalose and amino acids or the hydrous solution containing amino
acids and the hydrous solution containing trehalose in the form of
liquid droplets having a mean particle size of 0.1 .mu.m or more to
less than 20 .mu.m, and preferably 0.1 .mu.m to 10 .mu.m, the
liquid droplet is instantly dried. By instant drying at a
temperature lower than 97.degree. C., and preferably at a
temperature of 20 to 60.degree. C., the trehalose in the dry powder
exists in a structure of an almost amorphous state. The existence
in the amorphous state may possibly generate excellent effects such
as oral meltability of the dry powder, the solubility thereof, and
the taste-masking effect thereof. Furthermore, some of amino acids
are observed to have low crystallinity, according to the method of
the present invention, which suggests an increase of amorphous
materials.
[0053] The dry powder thus produced can be used as it is or as an
intermediate material, in the pharmaceutical field of, for example,
oral or infusion amino acid preparations specific to individual
diseases for subject patients with renal impairment or liver
disorders, and the cosmetic field, and the like. For example, the
dry powder can be used in the form of powders, tablets, and
capsules, as individual materials for foods such as sport drinks,
diet food materials, health foods and functional foods, and amino
acid-series cosmetics.
[0054] Other features of the invention will become apparent in the
course of the following descriptions of exemplary embodiments which
are given for illustration of the invention and are not intended to
be limiting thereof.
EXAMPLES
[0055] Herein, the mean particle size of the microfine powders
(single particle powder generated from liquid droplet) were
measured visually with a microscope, while the mean particle size
(Mean Volume Diameter) of the granulated powders were measured with
a dry particle size distribution measurement system of laser
diffraction & scattering microtruck, 9320 HRA manufactured by
Honeywell Co., Ltd.).
Example 1
[0056] Water was added to 4.98% by weight of a mixture of branched
amino acids having a mean particle size (Mean Volume Diameter) of
20 .mu.m (leucine:isoleucine:valine=47% by weight:24% by weight:29%
by weight; manufactured by Ajinomoto Co.); 4.98% by weight
trehalose dihydrate ("Treha" manufactured by Hayashibara, Co.,
Ltd.); 0.45% by weight of hydroxypropyl cellulose; and others, to
prepare an aqueous solution of amino acids at a solid concentration
of 10.4% by weight.
[0057] The flow of dehumidified hot air having a relative humidity
of 1% RH at 25.degree. C. (produced by the dry dehumidifier BX-600
type manufactured by Munsters, K. K.) was preset to 5.5 m.sup.3/min
(filtration rate of about 3 m/min), and spray drying and
granulation were carried out with a "HGL-130 type as granulation
apparatus on filter cloth with spray drying function equipped"
manufactured by Fujisaki Electric Co., Ltd. using the conditions of
the inlet temperature of the spray dry granulation apparatus
described below as set to 131 to 139.degree. C. and the feed rate
of the aqueous solution of amino acids as set to 6.7 to 7.3 kg/hr.
With the exhaust gas temperature (outlet temperature) at 49 to
58.degree. C. and the exhaust gas humidity (outlet relative
humidity) at 20% RH to 30% RH, the mean particle size of the
microfine powder (single particle powder generated from the liquid
droplets) was about 2 .mu.m to 3 .mu.m (diameter), as observed with
a microscope. Then, the microfine powder was densified under
pressure into granules on the filter membrane for particle
collection, so that the dry powder granulated as the final product
was a powder of amino acids, which had a mean particle size (Mean
Volume Diameter) of 40 .mu.m (moisture content of 4 wt. %).
Comparative Example 1
[0058] An aqueous solution of amino acids (a solid concentration of
5.85% by weight) was prepared at ratios of 4.95% by weight of a
powder of branched amino acids of a mean particle size (Mean Volume
Diameter) of 20 .mu.m (leucine:isoleucine:valine=47% by weight:24%
by weight:29% by weight; manufactured by Ajinomoto Co.); 0.45% by
weight of sucrose powder; 0.45% by weight of hydroxypropyl
cellulose; and 94.15% by weight of water.
[0059] The flow of dehumidified hot air having a relative humidity
of 1% RH at 25.degree. C. (produced by the dry dehumidifier BX-600
type manufactured by Munsters K.K.) was preset to 5.5 m.sup.3/min
(filtration rate of about 3 m/min), and spray drying and
granulation were carried out with a "HGL-130 type as granulation
apparatus on filter cloth with spray drying function equipped"
manufactured by Fujisaki Electric Co., Ltd., using the conditions
of the inlet temperature of the spray dry granulation apparatus
described below set to 130 to 137.degree. C., and the supply rate
of aqueous amino acids solution set to 6.1 to 7.7 kg/hr. With the
exhaust gas temperature (outlet temperature) at 49 to 61.degree. C.
and the exhaust gas humidity (outlet relative humidity) at 18% RH
to 30% RH, the mean particle size (diameter) of the microfine
powder (single particle powder generated from the liquid droplets)
was about 2 .mu.m to 3 .mu.m, as observed with a microscope. Then,
the microfine powder was densified under pressure into granules on
the filter membrane for particle collection, so that the dry powder
granulated as the final product was a powder of amino acids, which
had a mean particle size (Mean Volume Diameter) of 32 .mu.m
(moisture content of 1 wt. %).
Comparative Example 2
[0060] Leucine, isoleucine, and valine. (manufactured by Ajinomoto
Co.) were individually pulverized to a mean particle size (Mean
Volume Diameter) of 20 .mu.m, and were then mixed together
uniformly at 47% by weight, 24% by weight and 29% by weight,
respectively. Then, 47.8% by weight of the powder of the amino acid
mixture, 47.8% by weight of trehalose.circle-solid.dihydrate
("Treha" manufactured by Hayashibara, Co., Ltd.), and 4.4% by
weight of hydroxypropyl cellulose powder were uniformly mixed
together.
Test Example 1
[0061] The granulated powder samples or powder mixture samples as
recovered in Example 1, and Comparative Examples 1 and 2 were
evaluated for their oral meltability, solubility, the degree of
bitterness, and solidification property. The results are shown in
Table 1.
1TABLE 1 Evaluation results Comparative Comparative Items Example 1
Example 1 Example 2 Oral meltability 5 2 3 Bitterness masking 5 2 3
Solubility 5.5 min 6.00 min 14 min Solidification no problem no
problem no problem Notes: The oral meltability and the degree of
bitterness masking were evaluated, while the scores of those of
Comparative Example 2 were ranked as 3. 1. Oral meltability (5:
very good; 4: relatively good; 3: normal; 2: slightly poor; 1:
poor) 2. Degree of bitterness masking (5: very good; 4: relatively
good; 3: normal; 2: slightly poor; 1: poor) 3. Solubility: 250 ml
off water at 16.degree. C. was placed in a 300-ml beaker; an amount
of a sample was measured to an amino acid content of 50 mg, and was
then placed in the beaker under agitation at 300 rpm with a
magnetic stirrer, F-616 Type (Tokyo Glass Kikai, Co., Ltd.), the
time until the sample was completely dissolved was determined and
is reported. 4. Solidification property: After individual samples
were prepared, the samples were pouched and sealed, and were then
left to stand for 2 weeks, to observe the solidified state.
[0062] As described above, the granulated powder containing
trehalose (Example 1) had great oral meltability, great solubility,
and a great effect on bitterness masking. The granulated powder
containing sugar (Comparative Example 1) had good solubility but
poor oral meltability without any masking effect of bitterness.
Additionally, the granulated powder tasted very powdery and had bad
aftertaste.
[0063] Herein, the spray dry granulated powder containing trehalose
(Example 1) is compared with the mixed powder of the powders and of
the same composition (Comparative Example 2). The solubility of the
mixed powder of the powders of Comparative Example 2 was similar to
the solubility (13.5 minutes) of the "mix powder of amino acids"
(leucine:isoleucine:valine=47% by weight:24% by weight:29% by
weight) as the raw material of Comparative Example 2 but was
apparently poorer than the solubility of the spray dry granulated
powder containing trehalose (Example 1). Furthermore, the oral
meltability and the bitterness-masking effect of the mix powder of
the powders of Comparative Example 2 were more or less worse than
those of the spray dry granulated powder (Example 1).
Test Example 2
[0064] The spray dry granulated powder containing trehalose
(Example 1), the mixed powder of the powders (Comparative Example
2) and the individual raw material powders such as trehalose were
analyzed by powder X ray diffraction. The results are shown in
FIGS. 1 and 2. It was clearly verified that trehalose in the spray
dry granulated powder of Example 1 was in an amorphous state, which
apparently makes contributions to the oral meltability and the
bitterness-masking effect. Additionally, the spray dry granulated
powder (Example 1) lost the crystallinity essential to amino acids.
The spray dry granulated powder (Example 1) exhibits partial
crystallinity, but contains an amorphous fraction at a high
content, when compared with Comparative Example 2.
[0065] In accordance with the present invention, a dry powder of
amino acids of high quality, such as improved oral meltability,
solubility, and a taste-masking effect, can be obtained.
[0066] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that, within the scope of the
appended claims, the invention may be practiced otherwise than as
specifically described herein.
[0067] All patents and other references mentioned above are
incorporated in full herein by this reference, the same as if set
forth at length.
* * * * *