U.S. patent application number 12/289489 was filed with the patent office on 2009-05-28 for modified gum arabic.
Invention is credited to Saphwan Al-Assaf, Tsuyoshi Katayama, Glyn Owen Phillips, Yasushl Sasaki.
Application Number | 20090137689 12/289489 |
Document ID | / |
Family ID | 33156824 |
Filed Date | 2009-05-28 |
United States Patent
Application |
20090137689 |
Kind Code |
A1 |
Al-Assaf; Saphwan ; et
al. |
May 28, 2009 |
Modified gum arabic
Abstract
The present invention provides a water-soluble modified gum
arabic with a weight average molecular weight not less than 0.9
million and arabinogalactan protein not less than 17% by weight
obtained by heating Acacia senegal gum arabic and modified
water-soluble gum arabic with a weight average molecular weight not
less than 2.5 million and with protein containing high molecular
weight components of not less than 25% by weight. Moreover, the
present invention provides modified gum arabic with standardized
and predictable molecular properties and methods for providing the
modified gum arabic endowed with high emulsification efficiency and
stability and for uniforming natural variations in unmodified gum
arabic. The present invention changes the natural protein
distribution of gum arabic, and increases AGP content.
Inventors: |
Al-Assaf; Saphwan; (Wrexham,
GB) ; Phillips; Glyn Owen; (London, GB) ;
Sasaki; Yasushl; (Osaka, JP) ; Katayama;
Tsuyoshi; (Osaka, JP) |
Correspondence
Address: |
Sheldon Palmer;c/o Galvin & Palmer
630 Third Avenue - 23rd Floor
New York
NY
10017
US
|
Family ID: |
33156824 |
Appl. No.: |
12/289489 |
Filed: |
October 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10498988 |
Feb 10, 2005 |
7462710 |
|
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PCT/JP04/05050 |
Apr 7, 2004 |
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12289489 |
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Current U.S.
Class: |
516/54 ; 516/53;
516/9; 536/114; 536/128 |
Current CPC
Class: |
B01J 13/02 20130101;
A23L 27/13 20160801; A61Q 19/04 20130101; C08B 37/0087 20130101;
A23L 29/25 20160801; B01F 17/005 20130101; A23P 20/105 20160801;
C09B 67/009 20130101; A23L 33/12 20160801; A23L 5/44 20160801; A61K
8/73 20130101; A23L 27/80 20160801; A23P 10/30 20160801; A23L 27/70
20160801; A23V 2002/00 20130101; A23V 2002/00 20130101; A23V
2250/5028 20130101; A23V 2200/222 20130101; A23V 2250/1868
20130101; A23V 2250/1944 20130101; A23V 2002/00 20130101; A23V
2250/5028 20130101; A23V 2200/222 20130101; A23V 2250/211 20130101;
A23V 2250/1944 20130101; A23V 2002/00 20130101; A23V 2250/5028
20130101; A23V 2200/222 20130101; A23V 2250/5114 20130101; A23V
2002/00 20130101; A23V 2200/222 20130101; A23V 2250/5028 20130101;
A23V 2002/00 20130101; A23V 2250/211 20130101; A23V 2250/192
20130101; A23V 2250/5028 20130101; A23V 2200/222 20130101; A23V
2002/00 20130101; A23V 2200/15 20130101; A23V 2250/192 20130101;
A23V 2250/5028 20130101; A23V 2200/222 20130101 |
Class at
Publication: |
516/54 ; 536/114;
536/128; 516/9; 516/53 |
International
Class: |
C08B 37/00 20060101
C08B037/00; C07H 1/08 20060101 C07H001/08; B01F 3/08 20060101
B01F003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2003 |
JP |
2003-103495 |
Claims
1. Water-soluble modified gum arabic having a weight average
molecular weight of not less than 2.5 million obtained by heating
gum arabic from Acacia seyal.
2. Water-soluble modified gum arabic having a protein-containing a
high molecular weight component content of not less than 25 weight
% obtained by heating gum arabic from Acacia seyal.
3. Water-soluble modified gum arabic having a weight average
molecular weight of not less than 1.5 million and a
protein-containing high molecular weight component content of not
less than 22 weight % obtained by heating gum arabic from Acacia
seyal.
4. Water-soluble modified gum arabic according to any one of claims
1 to 3, wherein the difference in the degree of immunological
inhibition is within +0.10% between the water soluble modified gum
arabic and the unmodified gum arabic from Acacia seyal as measured
by indirect competitive ELISA using a quantifiable antibody for gum
arabic.
5. Water-soluble modified gum arabic according to any one of claims
1 to 3, obtained by heating gum arabic from Acacia seyal at
110.degree. C. for not less than 10 hours or under conditions
capable of obtaining substantially same effect.
6. A method for manufacturing the modified gum arabic of any one of
claims 1 to 3, comprising heating gum arabic from Acacia seyal at
110.degree. C. for not less than 10 hours or under conditions
capable of obtaining substantially the same effect.
7. An emulsifier comprising the modified gum arabic of any one of
claims 1, 2 and 3 as an active component.
8. An emulsifier comprising the modified gum arabic as an active
component and having a protein distribution different from that of
natural gum arabic from Acacia seyal and a higher arabinogalactan
protein content than that of natural gum arabic from Acacia
seyal.
9. An emulsion, obtained by dispersing and stabilizing a
hydrophobic substance in a hydrophilic solvent using the emulsifier
of claim 7.
10. The emulsion according to claim 9, which is an O/W emulsion or
a W/O/W emulsion.
11. The emulsion according to claim 9, wherein the hydrophobic
substance is an edible hydrophobic substance.
12. The emulsion according to claim 9, wherein the hydrophobic
substance is at least one member selected from the group consisting
of essential oils, oleoresins, absolutes, oil-based flavorings,
oil-based colorants, oil-soluble vitamins, C.sub.18-C.sub.22
polybasic unsaturated fatty acids, animal and vegetable fats and
oils, SAIB and C.sub.6-C.sub.12 fatty acid triglycerides.
13. A method for preparing an emulsion comprising dispersing a
hydrophobic substance in a hydrophilic solvent using an emulsifier
according to claim 7.
14. A thickener, coating agent, binder and material for capsules
comprising the modified gum arabic according to any one of claims
1, 2 and 3 as an active component.
15. A method of preparing an emulsifier using the modified gum
arabic according to any one of claims 1, 2 and 3.
16. A method of preparing an emulsion using the modified gum arabic
according to any one of claims 1, 2 and 3.
17. A method of preparing a thickener, coating agent, binder and
material for capsules using the modified gum arabic according to
any one of claims 1, 2 and 3.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of copending application
Ser. No. 10/498,988 filed Feb. 10, 2005
TECHNICAL FIELD
[0002] The present invention relates to modified gum arabic. In
particular, the invention relates to modified gum arabic wherein
the properties such as emulsifiability, emulsion stability,
encapsulation ability, adhesiveness, protective colloid property
and film forming ability have been improved or enhanced compared to
natural gum arabic. Specifically, the invention relates to the
modified gum arabic obtained from gum arabic belonging to the
Acacia senegal species, the modified gum arabic comprising
components with specific molecular weight and having a protein
distribution that are suitable for uniformly providing superior
emulsifiability.
BACKGROUND ART
[0003] Gum arabic is a natural exudate from the trunks and branches
of the plants that belong to the genus Acacia (especially, Acacia
senegal and Acacia seyal) of the Leguminasae family. Gum arabic is
highly soluble in water and its aqueous solution provides high
emulsifiability, emulsion stability, encapsulation ability,
adhesiveness, protective colloid property and film forming ability
even at low concentration, so that it has been widely used as an
emulsifier, thickener, stabilizer, binder, and coating agent.
[0004] Gum arabic is collected in various countries in the Sahara
region of Africa and has a wide variation in molecular weight and
composition of constituent components due to differences in the
soil and climate in each habitat and age of the original tree. For
this reason, functions of gum arabic in its original state
delivered from the habitat are nonuniformity, and thereby
properties of preparation using the gum arabic are not consistent
(Williams, P. A. and Phillips, G. O., (2000) in Handbook, of
Hydrocolloids, pp. 155-168, Editors: Williams, P. A. and Phillips,
G. O., Woodhead, London and New York). In the present
specification, such gum arabic is referred to as simply "gum
arabic" or "natural gum arabic" or "unmodified gum arabic", as
distinguished from "modified gum arabic" of the present
invention.
[0005] As mentioned above, emulsifiability is one of the useful
properties that gum arabic exhibits in a wide variety of products.
Several methods have been proposed and studied to reduce as much as
possible the variation of emulsifiability between samples
attributable to the variation of the properties of natural gum
arabic and to enhance emulsifiability. For instance, one method
comprises removing metal ions from gum arabic to obtain arabic acid
and subjecting it to thermal modification to improve its
emulsifiability (Japanese Unexamined Patent Publication No.
1990-49001), and another method comprises modifying gum arabic
having a loss-on-drying of not more than 50 weight % by heating it
at 60-140.degree. C. for not less than 30 minutes to thereby
enhance its emulsifiability (Japanese Unexamined Patent Publication
No. 2000-166489).
[0006] However, these methods do not satisfactorily modify gum
arabic so as to obtain the expected emulsifiability. Therefore,
effective methods for manufacturing a modifying gum arabic having
uniform quality and improved emulsifiability are still required.
Furthermore, it is necessary to develop a method for manufacturing
modified gum arabic, which has improved properties, such as
emulsion stability, encapsulation ability, adhesiveness, protective
colloid property, or film forming ability, as well as the
above-mentioned emulsifiability, and has a uniform quality by being
reduced variation between natural gum arabic samples.
[0007] Documents relating to gum arabic include the following
Documents 1-4 can be listed, in addition to the aforesaid
documents.
Document 1: Mikio Nakamura, Pharmaceutics, Vol. 42, No. 1 (1982)
pp. 25-29.
Document 2: Carbohydrate Research, 246 (1993) pp. 303-318
Document 3: WO02/072862
Document 4: Japanese Unexamined Patent Publication No.
1983-18370
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1 (A) and (B) show chromatograms of Sample 1 and
Sample 1/36 prepared in Experimental Example 1 obtained when these
were subjected to GPC-MALLS mentioned in Experimental Example 1.
FIG. 1 (A) shows the chromatogram of Sample 1 (untreated: natural
gum arabic). FIG. 1(B) shows the chromatogram of Sample 1/36
(heat-treated: modified gum arabic).
[0009] FIG. 2 shows chromatograms of gum arabic sample (untreated:
natural gum arabic) from the A. seyal species obtained when it was
subjected to GPC-MALLS mentioned in Experimental Example 1.
[0010] FIG. 3 shows the UV absorption profile (wavelength: 214 nm)
of Samples 2, 2/24 and 2/48 prepared in Experimental Example 2
obtained on the basis of GPC-MALLS, which indicate the protein
distribution thereof.
[0011] FIG. 4 shows the molecular weight distribution of Samples 2,
2/24 and 2/48 prepared in Experimental Example 2, which is obtained
on the basis of GPC-MALLS.
[0012] FIG. 5 shows the immunological inhibition ratio (%) obtained
by conducting indirect competitive ELISA using quantifiable
antibodies (SYCC7) for Sample 3, Sample 3/24, and Sample 3/48 in
Experimental Example 8.
DISCLOSURE OF THE INVENTION
[0013] The first object of the present invention is providing
modified gum arabic having a high emulsifiability, especially
modified gum arabic having substantially uniform quality in
emulsifiability. Furthermore, the invention aims to provide an
emulsifier using such modified gum arabic.
[0014] The second object of the present invention is providing
modified gum arabic wherein any one or more of the properties such
as emulsifiability, emulsion stability, encapsulation ability,
adhesiveness, protective colloid property and film forming ability
has been improved or enhanced compared to natural (unmodified) gum
arabic.
[0015] The third object of the present invention is providing
someone with safe modified gum arabic exhibiting the immunological
reactivity the same as or similar to natural (unmodified) gum
arabic.
[0016] The inventors of the present invention conducted extensive
research to reach the above-mentioned objectives, and found that
emulsifiability is improved by heating natural gum arabic (Acacia
senegal or Acacia seyal) under specific conditions and that such
modified gum arabic with improved emulsifiability is significantly
different from natural gum arabic in at least one of weight average
molecular weight and a protein distribution. The present invention
has been accomplished based on the above findings, and comprises
the following aspects.
[0017] Item 1. Water-soluble modified gum arabic having a weight
average molecular weight of not less than 0.9 million that is
obtained by heating gum arabic from Acacia saenegal.
[0018] Item 2. Water-soluble modified gum arabic having the weight
average molecular weight of not less than 1.5 million that is
obtained by heating gum arabic from Acacia senegal.
[0019] Item 3. Water-soluble modified gum arabic having the weight
average molecular weight of not less than 2 million that is
obtained by heating gum arabic from Acacia senegal.
[0020] Item 4. Water-soluble modified gum arabic having an
arabinogalactan protein content of not less than 17 weight % that
is obtained by heating gum arabic from Acacia senegal.
[0021] Item 5. Water-soluble modified gum arabic having the weight
average molecular weight of not less than 0.9 million and an
arabinogalactan protein content of not less than 10 weight % that
is obtained by heating gum arabic from Acacia senegal.
[0022] Item 6. Water-soluble modified gum arabic according to Items
1 to 5, wherein a difference in degree of immunological inhibition
is within .+-.10% between the water-soluble modified gum arabic and
unmodified gum arabic from Acacia senegal as measured by indirect
competitive ELISA using a quantifiable antibody for gum arabic.
[0023] Item 7. Water-soluble modified gum arabic having a weight
average molecular weight of not less than 2.5 million that is
obtained by heating gum arabic from Acacia seyal.
[0024] Item 8. Water-soluble modified gum arabic having a
protein-containing high molecular weight component content of not
less than 25 weight % that is obtained by heating gum arabic from
Acacia seyal.
[0025] Item 9. Water-soluble modified gum arabic having a weight
average molecular weight of not less than 1.5 million and a
protein-containing high molecular weight component content of not
less than 22 weight % that is obtained by heating gum arabic from
Acacia seyal.
[0026] Item 10. Water-soluble modified gum arabic according to any
one of Items 7 to 9, wherein a difference in degree of
immunological inhibition is within .+-.10% between the
water-soluble modified gum arabic and unmodified gum arabic from
Acacia seyal as measured by indirect competitive ELISA using a
quantifiable antibody for gum arabic.
[0027] Item 11. Water-soluble modified gum arabic according to any
one of Items 1 to 6, which is obtained by heating gum arabic from
Acacia senegal at 110.degree. C. for not less than 10 hours or
under conditions capable of obtaining substantially same
effect.
[0028] Item 12. Water-soluble modified gum arabic according to any
one of Items 7 to 10, which is obtained by heating gum arabic from
Acacia seyal at 110.degree. C. for not less than 10 hours or under
conditions capable of obtaining substantially same effect.
[0029] Item 13. A method for manufacturing the modified gum arabic
of any one of Items 1 to 6, comprising a step of heating gum arabic
from Acacia senegal at 110.degree. C. for not less than 10 hours or
under conditions capable of obtaining substantially same
effect.
[0030] Item 14. A method for manufacturing the modified gum arabic
of any one of Items 7 to 10, comprising a step of heating gum
arabic from Acacia seyal at 110.degree. C. for not less than 10
hours or under conditions capable of obtaining substantially same
effect.
[0031] Item 15. An emulsifier comprising the modified gum arabic of
any one of Items 1 to 10 as an active component.
[0032] Item 16. An emulsifier according to Item 15, comprising the
modified gum arabic of any one of claims 1 and 4 as an active
component.
[0033] Item 17. A novel emulsifier comprising the modified gum
arabic as an active component that has a protein distribution
different from that of natural gum arabic from Acacia senegal or
Acacia seyal and a higher arabinogalactan protein content than that
of natural gum arabic from Acacia senegal or Acacia seyal.
[0034] Item 18. An emulsion, which is obtained by dispersing and
stabilizing a hydrophobic substance in a hydrophilic solvent using
the emulsifier of Items 15 or 16.
[0035] Item 19. The emulsion according to Item 18, which is an O/W
emulsion or a W/O/W emulsion.
[0036] Item 20. The emulsion according to Item 18, wherein the
hydrophobic substance is an edible hydrophobic substance.
[0037] Item 21. The emulsion according to any one of Items 18 to
20, wherein the hydrophobic substance is at least one selected from
the group consisting of essential oils, oleoresins, absolutes,
oil-based flavorings, oil-based colorants, oil-soluble vitamins,
C.sub.18-C.sub.22 polybasic unsaturated fatty acids, animal and
vegetable fats and oils, SAIB and C.sub.6-C.sub.12 fatty-acid
triglycerides.
[0038] Item 22. A method for preparing an emulsion comprising a
step of dispersing a hydrophobic substance in a hydrophilic solvent
using any emulsifier of Item 15.
[0039] Item 23. A thickener, coating agent, binder and material for
capsules comprising the modified gum arabic according to any one of
Items 1 to 10 as an active component.
[0040] Item 24. A use of the modified gum arabic according to any
one of Items 1 to 10 for preparation of emulsifier.
[0041] Item 25. A use of the modified gum arabic according to any
one of Items 1 to 10 for preparation of emulsion.
[0042] Item 25. A use of the modified gum arabic according to any
one of Items 1 to 10 for preparation of a thickener, coating agent,
binder and material for capsules.
[0043] As mentioned above, the present invention provides a
modified gum arabic from the species Acacia senegal or Acacia seyal
which is obtained by treating a natural gum arabic from the species
Acacia senegal or Acacia seyal, respectively. These natural gum
arabic from these species have different molecular weights,
different protein distributions and have different properties, due
to their structural differences. For instance, the natural gum
arabic from A. senegal is laevorotatory and has the specific
optical rotation of approximately -30 degrees. On the other hand,
the natural gum arabic from A. seyal is dextrorotatory and has the
specific optical rotation of approximately +50 degrees.
Additionally, compared to the gum arabic from A. senegal, it is
known that gum arabic from A. seyal has a lower protein nitrogen
content (nitrogen content), a lower viscosity, and a different
sugar composition.
BEST MODE FOR CARRYING OUT THE INVENTION
[0044] (1) Modified Gum Arabic Derived from A. senegal
[0045] (1-1) The present invention provides water-soluble modified
gum arabic having a weight average molecular weight of not less
than 0.9 million, preferably not less than 1.5 million, and more
preferably not less than 2 million that is obtained by heating gum
arabic from Acacia Senegal.
[0046] The weight average molecular weight is determined by the use
of a gel permeation chromatography wherein three detectors, i.e., a
multi angle laser light scattering (MALLS) detector, a refractive
index (RI) detector and an ultraviolet (UV) detector are coupled by
on-line. In the present specification, a technique of such gel
permeation chromatography is referred to as "GPC-MALLS". According
to the GPC-MALLS, the molecular weight is measured by the MALLS
detector, the weight of each component (composition ratio) is
measured by the RI detector, and protein content is measured by the
UV detector. Therefore, it is possible to obtain the molecular
weight and the composition of the analyzed components without
reference to a standard gum arabic of known molecular weight. For
detailed principals and characteristics of the GPC-MALLS, see
Idris, O. H. M., Williams, P. A. Phillips, G. O.; Food
Hydrocolloids, 12, (1998) pp. 375-388".
[0047] Conditions for GPC-MALLS employed in the present invention
are as below:
[0048] Column: Superose (6HR) 10/30 (Pharmacia Biotech, Sweden)
[0049] Flow rate: 0.5 ml/minute
[0050] Elution solvent: 0.2 M NaCl
[0051] Preparation of Sample: the Sample to be Analyzed is diluted
with the elution solvent (0.2 M NaCl).
[0052] Sample concentration: 0.4% (W/V)
[0053] Injection volume of sample solution: 100 .mu.l
[0054] dn/dc: 0.141
[0055] Temperature: Room temperature
[0056] Detector: 1. MALLS (multi angle laser light scattering)
detector: DAWN DSP (manufactured by Wyatt Technology Inc., USA), 2.
RI detector, 3. UV detector (absorption at 214 nm)
[0057] By processing the data obtained by the GPC-MALLS conducted
under the above-described conditions using software, i.e., ASTRA
Version 4.5 (Wyatt Technology), each parameter of the components of
the gum arabic such as the weight average molecular weight,
recovery rate (% mass), polydispersity value (P) and root mean
square radius of gyration (Rg) can be obtained. When the data is
processed considering the whole peaks on the chromatogram obtained
using an RI detector as one peak, the obtained molecular weight is
identified as the weight average molecular weight (M.sub.wt) of the
present invention (specifically, "M.sub.wt processed as one peak").
When the point where the RI chart begins to rise from the baseline
of the chromatogram is defined as the "starting point", and the
point where the RI chart falls and intersects the baseline is
defined as the "ending point", the aforementioned one peak on the
chromatogram means the area from the starting point to the ending
point.
[0058] There is no limitation to the weight average molecular
weight of the modified gum arabic of the present invention as long
as it is not less than 0.9 million, but preferably it is not less
than 1.2 million, more preferably not less than 1.5 million, and
still more preferably not less than 2 million. There is no specific
upper limit to the weight average molecular weight as long as the
modified gum arabic is soluble in water; however, it is preferably
2.5 million or less.
[0059] Furthermore, the modified gum arabic of the present
invention is characterized in that it has the foresaid weight
average molecular weight and is water-soluble. "Water-soluble" in
this specification means that a sample is almost completely
dissolved in an excess of water, regardless of the type of water,
e.g., ion-exchanged water or ion-containing water, or water
temperature as long as the gum arabic is soluble.
[0060] Hydrogelatinous gum arabic cannot be dissolved in water even
if a large amount of water is added or by heating, and therefore
the term "water-soluble" is used in the present specification to
distinguish the modified gum arabic of the invention from
hydrogelatinous gum arabic, which is insoluble in water. In other
words, the modified gum arabic of the invention does not include
modified polymeric gum arabic that are insoluble in water, such as
hydrogels, etc.
[0061] Moreover, it is preferable that the modified gum arabic of
the present invention has the foresaid weight average molecular
weight, be water-soluble, and be the same as or similar to
unmodified gum arabic in terms of immunological reactivity. The
phrase "the same as or similar to unmodified gum arabic in terms of
immunological reactivity" means that difference between the degree
of immunological inhibition of the modified gum arabic and that of
unmodified gum arabic from Acacia senegal is within .+-.10%, as
measured by indirect competitive ELISA using a quantifiable
antibody for gum arabic, for example "SYCC7" [Thurston, M. I. et
al., Detection of gum from Acacia seyal and species of combreturn
in mixtures with A. senegal using monoclonal antibodies, Food &
Agric. Immunol., 10 : 237-241 (1998); Thurston, M. I. et al.,
Effect of heat and pH on carbohydrate epitopes from Acacia senegal
by specific monoclonal antibodies, Food & Agric. Immunol., 11 :
145-153 (1999)].
[0062] The form of the modified gum arabic of the present invention
is not limited and it can take any form including blocks, beads,
coarse pulverizates, granules, pellets and powders.
[0063] The modified gum arabic of the present invention can be
prepared by heating gum arabic from Acacia senegal using a
thermostat or a heater, such as an oven, for example, at
110.degree. C. for not less than 10 hours.
[0064] The unmodified gum arabic (A. senegal) used as a raw
material in this embodiment is a natural exudate obtained from the
trunks and branches of Acacia senegal of the genus Acacia, family
Leguminasae or any other tree belonging to the same genus. It is
also possible to use unmodified gum arabic that has been subjected
to a treatment, such as purification treatment, desalting
treatment, pulverization, or spray drying, etc.
[0065] The unmodified gum arabic (A. senegal) is produced in
countries of North and West Africa from Ethiopia to Senegal
(Ethiopia, Sudan, Senegal, Nigeria, Niger, and Ghana), countries of
East Africa such as Kenya and Uganda, the Sahara region of Africa
and the basins of the tributaries of the Nile. The unmodified gum
arabic (A. Senegal) produced in any of the above areas can be used
in the present invention regardless of its origin.
[0066] Furthermore, unmodified gum arabic (A. senegal) is not
particularly restricted in its water content. Commercially
available unmodified gum arabic (A. senegal) undergoes a reduction
in water content when dried by heating at 105.degree. C. for 6
hours (loss on drying), generally not more than 40 weight %,
preferably not more than 30 weight %, and more preferably not more
than 20 weight %. In the present invention, unmodified gum arabic
(A. senegal) having such water contents or showing a reduction in
water content (loss-on-drying) can be used without limitation.
[0067] Unmodified gum arabic (A. senegal) can usually be procured
in the forms of blocks, beads, coarse pulverizates, granules,
pellets, and powders (including spray dried powder). However, in
the present invention, unmodified gum arabic (A. senegal) of any
form can be used without limitation as a raw material to be
processed. It is possible to use spray dried gum arabic powder
having an average particle diameter of several tens .mu.m to
several hundred .mu.m. There is no particular upper limit to the
average particle diameter but from the point of view of
modification efficiency, the average particle diameter is
preferably not more than 100 mm. The average particle diameter is
preferably in the range from 1 mm to 100 mm and more preferably in
the range from 2 mm to 50 mm.
[0068] Examples of the methods for heating unmodified gum arabic
(A. senegal) include heating unmodified gum arabic at 110.degree.
C. for more than 10 hours using an oven (thermostat) as mentioned
above. The preferable heat treatment is such that unmodified gum
arabic (A. senegal) is heated at 110.degree. C. for not less than
15 hours, more preferably for not less than 24 hours, and still
more preferably for not less than 48 hours. While depending on the
type of the unmodified gum arabic (A. senegal) to be subjected to
heat treatment, the upper limit to the duration of heating when
heated at 110.degree. C. may be about 72 hours. As long as it is
possible to obtain modified gum arabic that has the molecular
weight specified in the present specification and that is soluble
in water, the heating method is not limited to the above examples
and heating temperature, duration of heating, heating means, and
heating conditions (relative humidity, an opened or a closed
system) can be optionally selected. The effects of the present
invention achieved by the heat treatment conducted under the
conditions described above can also be obtained by a method wherein
unmodified gum arabic is heated at a temperature lower than
110.degree. C. for more than 10 hours or at a temperature higher
than 110.degree. C. for a shorter time. Specifically, a method
wherein the unmodified gum arabic is heated at 80.degree. C. for 3
days to 1 week or longer may be mentioned as one example of the
former case. When the unmodified gum arabic is heated using
microwave radiation instead of an oven, the same effects can be
achieved in less time. In addition, a heat treatment in the absence
of oxygen, such as under nitrogen displacement conditions, is
desirable because it can prevent discoloration of the gum
arabic.
[0069] (1-2) The present invention also provides water-soluble
modified gum arabic that contains not less than 17 weight %
arabinogalactan protein that is obtained by heating gum arabic from
Acacia senegal.
[0070] Arabinogalactan protein (hereinafter, simply described as
"AGP") is one of three major components contained in gum arabic
along with arabinogalactan (AG) and glycoprotein (GP). Unmodified
gum arabic (A. senegal) generally contains AGP in a proportion of
5-15 weight %.
[0071] The content of AGP in gum arabic (unmodified gum arabic and
modified gum arabic) can be determined by the GPC-MALLS mentioned
above. Specifically, when the RI Chart of a chromatogram obtained
using an RI detector is divided into two parts, i.e., Peak 1 (high
molecular weight fraction) which traces the first eluted portion,
and Peak 2 (low molecular weight fraction) which traces the later
eluted portion, and the data are then processed with ASTRA Version
4.5 (Wyatt Technology) software, the obtained recovery ratio of
Peak 1 (% Mass) corresponds to the AGP content (weight %) of the
gum arabic. This is explained in detail with reference to the
chromatogram (FIG. 1(A)) showing the results wherein unmodified gum
arabic (A. senegal) was analyzed using the GPC-MALLS. In the RI
chromatogram, the point where the RI chart begins to rise from the
baseline of the chromatogram is defined as the "starting point" and
the point where the RI chart falls and intercepts the base line is
defined as the "ending point". Between the starting point and the
ending point, the point where the RI value shows a minimum is
defined as the boundary, with the area between the starting point
and the boundary being defined as Peak 1 and the area between the
boundary and the ending point being defined as Peak 2.
[0072] The content of AGP in modified gum arabic of the present
invention is not specifically restricted as long as it is not less
than 17 weight %, but preferably it is not less than 20 weight %.
Its upper limit is not particularly restricted as long as the
modified gum arabic is soluble in water but it is generally about
30 weight %.
[0073] The modified gum arabic obtained by the present invention is
characterized in that is has an AGP content in the above-mentioned
range and is soluble in water. Furthermore, it is preferable that
the modified gum arabic of the present invention contains AGP in
the ratio mentioned above, be water-soluble, and has properties the
same as or similar to those of unmodified gum arabic in terms of
immunological reactivity. "Water-soluble" and "properties the same
as or similar to those of unmodified gum arabic in terms of
immunological reactivity" described here have the same meanings as
stated in (1-1).
[0074] The form of the modified gum arabic of the present invention
is not particularly restricted, and it can take any form including
blocks, beads, coarse pulverizates, granules, pellets, and powders
(including spray dried powder).
[0075] As described above, the modified gum arabic of the present
invention can be prepared by heating unmodified gum arabic (A.
senegal) using a thermostat or heater such as an oven, for example,
at 110.degree. C. for not less than 10 hours. As examples of the
unmodified gum arabic (A. senegal) as a raw material to be
processed, the aforementioned ones may be used, and as specific
heating methods, the above-described methods can be employed as
well.
[0076] (1-3) The present invention provides water-soluble modified
gum arabic that has a weight average molecular weight of not less
than 9.0.times.10.sup.5 (0.9 million) and AGP at the ratio of not
less than 10 weight % that is obtained by heating unmodified gum
arabic from Acacia senegal.
[0077] The weight average molecular weight is preferably at least
10.0.times.10.sup.5 (1.0 million), more preferably at least
12.0.times.10.sup.5 (1.2 million), still more preferably at least
15.0.times.10.sup.5 (1.5 million), and yet more preferably at least
20.0.times.10.sup.5 (2.0 million). Its upper limit is not
particularly restricted as long as the modified gum arabic is
soluble in water but is preferably approximately
25.0.times.10.sup.5 (2.5 million) or less.
[0078] The content of AGP in the modified gum arabic is preferably
not less than 15 weight %, more preferably not less than 17 weight
%, and still more preferably not less than 20 weight %. Its upper
limit is not particularly limited as long as the modified gum
arabic is soluble in water but is preferably approximately 30
weight % or less.
[0079] The modified gum arabic provided by the present invention is
characterized in that it has the above-mentioned properties and is
soluble in water. Furthermore, it is preferable that the modified
gum arabic of the present invention has the aforementioned weight
average molecular weight and AGP content, be water-soluble, and has
properties the same as or similar to unmodified gum arabic in terms
of immunological reactivity. "Water-soluble" and "properties the
same as or similar to unmodified gum arabic in terms of
immunological reactivity" described here have the same meanings as
stated in (1-1).
[0080] The form of modified gum arabic of the present invention is
not particularly limited, and it can take any form including
blocks, beads, coarse pulverizates, granules, pellets, and powders
(including spray dried powder).
[0081] As described above, the modified gum arabic of the present
invention can be prepared by heating unmodified gum arabic (A.
senegal) using a thermostat or a heater such as an oven, for
example at 110.degree. C. for not less than 10 hours. As examples
of the unmodified gum arabic (A. senegal) to be processed, the
aforementioned ones may be used, and as specific heating methods,
the above-described methods can be employed as well.
(2) Modified Gum Arabic Derived from Acacia seyal
[0082] (2-1) The present invention provides water-soluble modified
gum arabic having a weight average molecular weight of not less
than 25.0.times.10.sup.5 (2.5 million) that is obtained by heating
unmodified gum arabic from Acacia seyal.
[0083] In the present invention, the weight average molecular
weight of the modified gum is not particularly restricted as long
as it falls in the range described above, and is preferably not
less than 26.0.times.10.sup.5 (2.6 million), and even more
preferably not less than 30.0.times.10.sup.5 (3.0 million). The
upper limit of the weight average molecular weight thereof is not
restricted as long as the modified gum arabic is soluble in water
but is preferably about 40.0.times.10.sup.5 (4.0 million).
[0084] The modified gum arabic obtained by the present invention is
characterized in that it has the above-mentioned weight average
molecular weight and is soluble in water. Furthermore, it is
preferable that modified gum arabic of the present invention has
the above-mentioned weight average molecular weight, be
water-soluble, and has properties the same as or similar to those
of unmodified gum arabic in terms of immunological reactivity.
"Water-soluble" and "properties the same as or similar to those of
unmodified gum arabic in terms of immunological reactivity"
described here have the same meanings as stated in (1-1).
[0085] The form of modified gum arabic of the present invention is
not particularly limited, and it can take any form including
blocks, beads, coarse pulverizates, granules, pellets, and powders
(including spray dried powder).
[0086] The modified gum arabic of the present invention can be
prepared by heating unmodified gum arabic (A. seyal) using a
thermostat or a heater such as an oven, for example at 110.degree.
C. for not less than 10 hours.
[0087] The unmodified gum arabic (A. seyal) used as a raw material
in this embodiment is a natural exudate from the trunks and
branches of Acacia seyal of the genus Acacia, family Leguminasae or
any other plant belonging to the same genus. It is also possible to
use unmodified gum arabic that has been subjected to a treatment,
such as purification treatment, desalting treatment, pulverization,
or spray drying, etc.
[0088] The unmodified gum arabic (A. seyal) is generally produced
in countries of North and West Africa from Ethiopia to Senegal
(Ethiopia, Sudan, Senegal, Nigeria, Niger, and Ghana), countries of
East Africa such as Kenya and Uganda, the Sahara region of Africa
and the basins of tributaries of the Nile. The unmodified gum
arabic (A. seyal) produced in any of the above areas can be
employed as a raw material to be modified in the present invention
regardless of its origin.
[0089] Furthermore, unmodified gum arabic (A. seyal) is not
particularly restricted in its water content. Any commercially
available unmodified gum arabic (A. seyal) can be used regardless
of its water content.
[0090] The unmodified gum arabic (A. seyal) can usually be procured
in such forms as blocks, beads, coarse pulverizates, granules,
pellets, and powders (including spray dried powder). The unmodified
gum arabic (A. seyal) of any form can be used without limitation as
a raw material to be subjected the heat treatment of the present
invention. It is possible to use spray dried gum arabic having an
average particle diameter of several tens .mu.m to several hundred
.mu.m. There is no particular upper limit to the average particle
diameter but from the point of view of modification efficiency, the
average particle diameter is preferably not more than 100 mm. The
average particle diameter is preferably in the range from 1 mm to
100 mm and more preferably in the range from 2 mm to 50 mm.
[0091] Examples of the methods for heating unmodified gum arabic
(A. seyal) include heating the unmodified gum arabic at 110.degree.
C. for not less than 10 hours using a thermostat or a heater as
mentioned above. The preferable heat treatment is such that
unmodified gum arabic (A. seyal) is heated at 110.degree. C. for
not less than 15 hours, more preferably for not less than 24 hours,
and still more preferably for not less than 48 hours. While
depending on the type of the unmodified gum arabic (A. seyal) to be
subjected to heat treatment, the upper limit to the duration of
heating when heated at 110.degree. C. may be, for example, about 72
hours. As long as it is possible to obtain modified gum arabic that
has the specific molecular weight defined in the present invention
and that is soluble in water, the heating method is not limited to
the above examples and heating temperature, duration of heating,
heating means, and heating conditions (relative humidity, opened or
closed system) can be optionally selected. The effects of the
present invention achieved by the heat treatment conducted under
the conditions described above can also be obtained by a method
wherein the unmodified gum arabic is heated at a temperature lower
than 110.degree. C. for more than 10 hours or at a temperature
higher than 110.degree. C. for a shorter time. Specifically, the
method for heating the unmodified gum arabic at 80.degree. C. for 3
days to 1 week or longer may be mentioned as one example of the
former case. When the unmodified gum arabic is heated using
microwave radiation instead of an oven, the same effects can be
achieved in less time. In addition, a heat treatment in the absence
of oxygen, such as under nitrogen displacement conditions, is
desirable because it can prevent discoloration of the gum
arabic.
[0092] (2-2) The present invention also provides water-soluble
modified gum arabic that contains more than 25 weight % of the
protein-containing high molecular weight component that is obtained
by heating gum arabic from Acacia seyal.
[0093] The content of the protein-containing high molecular weight
component in the unmodified gum arabic from Acacia seyal and the
modified gum arabic thereof can be determined by the GPC-MALLS
mentioned above. Specifically, when RI chart of a chromatogram
obtained using an RI detector is divided into two parts, i.e., Peak
1 (high molecular weight fraction) which traces the first eluted
portion, and Peak 2 (low molecular weight fraction) which traces
the later eluted portion, and the data are then processed with
ASTRA Version 4.5 (Wyatt Technology) software, the recovery ratio
of Peak 1 (% Mass) corresponds to the content (weight %) of the
protein-containing high molecular weight component in the gum
arabic. This is explained in detail with reference to the
chromatogram (FIG. 2) showing the results wherein unmodified gum
arabic (A. seyal) is analyzed using the GPC-MALLS. In the RI
chromatogram, the point where the RI chart begins to rise from the
baseline of the chromatogram is defined as the "starting point" and
the point where the RI chart falls and intercepts the baseline is
defined as the "ending point". Between the starting point and the
ending point, the point where the RI value shows a minimum is
defined as the boundary, with the area between the starting point
and the boundary being defined as the Peak 1 and the area between
the boundary and the ending point being defined as the Peak 2.
[0094] As with the Acacia senegal, the protein-containing high
molecular weight component (peak 1) is one of the major components
contained in the unmodified gum arabic (A. seyal). The unmodified
gum arabic (A. seyal) generally contains this component at a ratio
from 10 to 24 weight %.
[0095] The content of the protein-containing high molecular weight
component (peak 1) in the modified gum arabic (A. seyal) of the
present invention is not particularly limited as long as it falls
within the above-mentioned range. However, it is preferably not
less than 26 weight % and more preferably not less than 30 weight
%. Its upper limit is not particularly restricted as long as the
modified gum arabic is soluble in water; however, it is preferable
that the content of the protein-containing high molecular weight
component be about 45 weight % or less.
[0096] The modified gum arabic (A. seyal) obtained in the present
invention is characterized in that it has the protein-containing
high molecular weight component content in the above-mentioned
range and is soluble in water. Furthermore, it is preferable that
the modified gum arabic of the present invention contains the
protein-containing high molecular weight component in the ratio
mentioned above, be water-soluble, and has the properties the same
as or similar to those of unmodified gum arabic (A. seyal) in terms
of immunological reactivity. "Water-soluble" and "properties the
same as or similar to those of unmodified gum arabic (A. seyal) in
terms of immunological reactivity" described here have the same
meanings as stated in (1-1).
[0097] There is no limitation to the form of modified gum arabic
(A. seyal) of the present invention, and it can take any form
including blocks, beads, coarse pulverizates, granules, pellets,
and powders (including spray dried powder).
[0098] As described above, the modified gum arabic of the present
invention can be prepared by heating unmodified gum arabic (A.
seyal) using a thermostat or a heater such as an oven, for example
at 110.degree. C. for more than 10 hours. As examples of the
unmodified gum arabic (A. seyal) to be modified, the aforementioned
ones may be used, and as specific heating methods, the
above-described methods can be employed as well (see (2-1)).
[0099] (2-3) The present invention also provides water-soluble
modified gum arabic that has a weight average molecular weight of
15.0.times.10.sup.5 (1.5 million) or greater and a content of the
protein-containing high molecular weight component of not less than
22 weight % that is obtained by heating unmodified gum arabic from
Acacia seyal.
[0100] The weight average molecular weight of the water-soluble
modified gum arabic (A. seyal) is preferably at least
20.0.times.10.sup.5 (2.0 million) and more preferably at least
25.0.times.10.sup.5 (2.5 million). There is no particular upper
limit thereof as long as the modified gum arabic (A. seyal) is
water-soluble but generally it is, for example, about
40.0.times.10.sup.5 (4.0 million) or less.
[0101] The content of the protein-containing high molecular weight
component (peak 1) in the modified gum arabic (A. seyal) is
preferably not less than 25 weight % and more preferably not less
than 30 weight %. There is no particular upper limit thereof as
long as the modified gum arabic is water-soluble but generally it
is, for example, about 45 weight % or less.
[0102] The modified gum arabic (A. seyal) obtained by the present
invention is characterized in that it has the above-mentioned
properties and is soluble in water. Furthermore, it is preferable
that the modified gum arabic of the present invention has the
above-described weight average molecular weight and content of the
protein-containing high molecular weight component, be
water-soluble, and has properties the same as or similar to
unmodified gum arabic in terms of immunological reactivity.
"Water-soluble" and "properties the same as or similar to
unmodified gum arabic (A. seyal) in terms of immunological
reactivity" as described here have the same meanings as stated in
(1-1).
[0103] The form of the modified gum arabic (A. seyal) of the
present invention is not particularly restricted, and it can take
any form including blocks, beads, coarse pulverizates, granules,
pellets, and powders (including spray dried powder).
[0104] As described above, the modified gum arabic of the present
invention can be prepared by heating unmodified gum arabic (A.
seyal) using a thermostat or a heater, such as an oven, for example
at 110.degree. C. for not less than 10 hours. As examples of
unmodified gum arabic (A. seyal) to be modified, the aforementioned
ones may be used, and as specific heating methods, the
above-described methods can be employed as well (see (2-1)).
[0105] The modified gum arabic of the present invention, especially
the modified gum arabic derived from the species A. senegal
provided at any one of the above (1-1) to (1-3), can be clearly
distinguished from the unmodified gum arabic in terms of
emulsifiability. The modified gum arabic, especially the modified
gum arabic derived from the species A. senegal, has higher
emulsifiability than the unmodified gum arabic.
[0106] The modified gum arabic of the present invention, especially
the modified gum arabic derived from the species A. seyal provided
at any one of the above (2-1) to (2-3), can also be clearly
distinguished from the unmodified gum arabic in terms of
emulsifiability, emulsion stability, encapsulation ability,
adhesiveness, protective colloid property or film forming ability.
The modified gum has an improved emulsifiability, emulsion
stability, encapsulation ability, adhesiveness, protective colloid
property or film forming ability relative to that of the unmodified
gum arabic.
[0107] The emulsifiability of the modified gum arabic, especially
the modified gum arabic derived from the species A. senegal, can be
evaluated by measuring the average particle diameter of droplets in
an emulsion (dispersed phase), when the emulsion is prepared using
it. It is preferable that the average particle diameter of droplets
in the emulsion prepared using the modified gum arabic is generally
not greater than 1 .mu.m, preferably not greater than 0.8 .mu.m,
more preferably not greater than 0.7 .mu.m, and still more
preferably not greater than 0.6 .mu.m. The emulsion for use in this
evaluation can be prepared according to a method described in
Experimental Example 1 (2).
[0108] Furthermore, it is preferable that the obtained emulsion be
stable over time. This emulsion stability over time can be
evaluated by measuring the average particle diameter of emulsion
immediately after preparation [average particle diameter (a)] and
the average particle diameter of emulsion at several days (2-7
days) after storing at 60.degree. C. [average particle diameter
(b)], respectively, and obtaining the difference between the two
values [(b)-(a)]. Although it is not restricted, in the case of an
emulsion has been stored for 7 days at 60.degree. C., it is
preferable that such difference be 1 .mu.m or less, more preferably
0.3 .mu.m or less, and still more preferably 0.1 .mu.m or less.
[0109] (3) The modified gum arabic according to the invention,
especially the modified gum arabic derived from the species A.
senegal, is suitable as an emulsifier for preparing varied
emulsions, especially oil-in-water (O/W) or W/O/W emulsions in
foods, pharmaceuticals, Medicine, quasi-drugs, perfume, cosmetics
and other fields. The modified gum arabic is extremely suitable as
an emulsifier for preparing products which are taken orally, such
as foods, pharmaceuticals, and quasi-drugs. The present invention
provides an emulsifier comprising the above-mentioned modified gum
arabic as an active component.
[0110] To be more specific, the modified gum arabic of the present
invention can be suitably used as an emulsifier to emulsify; foods
or constituents thereof, such as confectionery (for example, candy,
chewing gums, cough drops, candy lozenges, gum drops, jujubes,
pastille, tablet confections, dry snacks, etc.), dairy products or
frozen products (for example, ice cream, ice and sherbets,
package-able milk and cream, etc.), bakery products, beverages (for
example, drinks, powdered drinks), desserts, processed fish
products, processed stock farm products, retort foods, etc.;
coatings for foods or pharmaceuticals such as a tablet, etc.;
oil-based flavorings or cosmetics; or oil-based colorants, etc.
[0111] The above-described modified gum arabic per se can be used
without additives as an emulsifier when formed into a solution, a
granular, or powder; however, it is also possible to prepare it as
an emulsifier by adding other carriers and/or additives according
to the usual manner in the above-mentioned fields, if necessary. In
this case, the carriers and additives can be suitably selected
according to the usual manner using natural gum arabic as an
emulsifier in the above-mentioned fields, depending on the type and
usage of the product to be emulsified. For example, modified gum
arabic can be added with dextrin, maltose, lactose and like
saccharide, or glycerol, propylene glycol and like polyhydric
alcohols. In this embodiment, Document 1 (Roy L. Whistlerand James
N. BeMiller, "INDUSTRIAL GUMS--Polysaccharides and Their
Derivatives", SECOND EDITION, ACADEMIC PRESS, New York and London,
1973, pp, 197-263) and Document 2 (Martin Glicksman, "Gum
Technology in the Food Industry" ACADEMIC PRESS, New York and
London, 1969, pp, 94-124) can be used as reference.
[0112] (4) The present invention further provides a method for
preparing an emulsion using the above-mentioned modified gum arabic
as an emulsifier, especially the above-mentioned modified gum
arabic derived from A. senegal. This emulsion can be prepared by
dispersing and stabilizing a hydrophobic substance, which is a
dispersoid, in a hydrophilic solvent using the above-mentioned
modified gum arabic as an emulsifier. Examples of emulsion shown in
the present invention include an oil-in-water (O/W) emulsion or a
W/O/W emulsion.
[0113] The hydrophobic substance to be emulsified in this invention
is not particularly restricted as long as it is a substance which
can be generally formed into an emulsion or must be processed into
an emulsion; however, hydrophobic substances which are used in the
field of foods, pharmaceuticals, quasi-drugs or fragrances and
cosmetics are preferable, and hydrophobic substances that can be
taken orally, i.e., edible hydrophobic substances are especially
preferable.
[0114] Specific examples include essential oils derived from plant
sources, for example, citrus plants such as orange, lime, lemon,
grapefruit, etc.; oleoresins derived from plant sources such as
pepper, cinnamon, ginger, etc.; absolutes derived from plant
sources such as jasmine, rose, etc.; oil-based flavorings such as
oil-based synthetic flavorings and oil-based blending flavorings,
etc.; oil-based colorants such as .beta.-carotene, paprika color,
lycopene, palm oil carotene, Donalliella carotene, carrot carotene,
etc.; oil-soluble vitamins such as vitamin A, D, E, and K;
polybasic unsaturated fatty acids such as C.sub.18-C.sub.22
polybasic unsaturated fatty acids including n-6 type polybasic
unsaturated fatty acids (linoleic acid, .gamma.-linolenic acid, and
arachidonic acid, etc.) and n-3 type polybasic unsaturated fatty
acids (.alpha.-linolenic acid, docosahexaenoic acid, and
eicosapentanoic acid, etc.); animal and vegetable fats and oils
such as soybean oil, rapeseed oil, corn oil and fish oil; SAIB
(sucrose acetate isobutyrate), food processing oils such as
C.sub.6-C.sub.12 medium-chain triglycerides, and optionally
mixtures of such edible oil-based materials.
[0115] The method for preparing an emulsion using the
above-described modified gum arabic is not particularly restricted
and may comprise a step of mixing a hydrophobic substance and a
hydrophilic solvent in the presence of the modified gum arabic
according to standard method for preparing oil-in-water (O/W)
emulsions or W/O/W emulsions, preferably by mechanical agitation,
for example using a homogenizer or a high-pressure injection
system. In particular, the following process can be mentioned as an
example.
[0116] First, the modified gum arabic is dissolved in a hydrophilic
solvent such as water, and, if necessary, contaminants are removed
by a suitable solid-liquid separation means such as centrifugation
or filtration with a filter press or the like, giving an aqueous
gum arabic solution. An objective hydrophobic substance (for
example, an oil or fat or a mixture obtained by dissolving a
flavoring or a color in such an oil or fat) is admixed with the
obtained aqueous gum arabic solution using a stirrer for
preliminary emulsification. During this process, its specific
gravity may be adjusted using a specific gravity control agent such
as SAIB. The preliminary emulsion thus obtained is then emulsified
using emulsifying equipment.
[0117] Examples of usable hydrophobic substances include the
substances mentioned above. However, when an emulsified flavoring
or an emulsified color is to be prepared using oil-based flavoring
or color, it is preferable to use a solution mixture wherein an
oil-based flavoring or color is dissolved beforehand in oil or fat
as the hydrophobic substance; This makes it possible to stabilize
the emulsion and prevent the evaporation of components. The oils
and fats in which such an oil-based flavoring or color is to be
dissolved are not particularly restricted but usually medium-chain
triglycerides (C.sub.6-12 fatty acid triglycerides) and vegetable
oils such as corn oil, safflower oil and soybean oil can be
employed.
[0118] There is no limitation to the emulsifying equipment used and
it can be suitably selected according to the droplet size of the
objective emulsion and the viscosity of the material. For example,
a homogenizer, a pressurized homogenizer and other emulsifying
equipment, such as a Disper Mill, a colloid mill, etc., can be
employed.
[0119] The emulsification can be conducted by adding a hydrophobic
substance to a hydrophilic solvent while stirring, performing
preliminary emulsification to prepare an emulsion having a particle
diameter of 2-5 .mu.m, and treating it with an emulsifying
equipment such as a homogenizer to give an emulsion having fine and
uniform particles (for example, average particle diameter of not
greater than 1 .mu.m).
[0120] Many colorants including .beta.-carotene exist in the form
of crystal suspensions. Therefore, to process such colorants into
emulsions (emulsified colorants), it is preferable to mix and
dissolve crystals of color in a suitable oil or fat at an elevated
temperature beforehand, and then add the resulting solution into a
hydrophilic solvent.
[0121] Compared with an emulsion prepared using natural
(unmodified) gum arabic, an emulsion prepared using the modified
gum arabic of the invention has a uniform particle diameter and is
very stable, so that emulsified particles are significantly
prevented from coagulation or unification of the emulsified
particles caused by hard dealing or under severe conditions such as
heating, long-term storage, etc.
[0122] (5) The modified gum arabic of the present invention
especially that derived from the species A. seyal, can be suitably
used as a thickener, binder, coating agents, suspending agents,
sizing and finishing agents, material for capsules (encapsulant)
and the other, in the foods, pharmaceuticals, quasi-drugs,
flavor/cosmetic, inks, paints, adhesives, lithography, textiles
industries due to its improved and enhanced emulsifiability,
emulsion stability, encapsulation ability, adhesiveness, protective
colloid property and film forming ability. Therefore, the present
invention provides a thickener, binder, coating agent and material
for capsules (encapsulant) wherein the aforementioned modified gum
arabic, especially the modified gum (A. seyal), serves as an active
component. The thickener, binder, coating agent or material for
capsules (encapsulant) is prepared according to the usual manner in
the field, except for using the modified gum arabic of the present
invention as an active component.
[0123] In this embodiment, Document 1 (Roy L. Whistlerand James N.
BeMiller, "INDUSTRIAL GUMS--Polysaccharides and Their Derivatives",
SECOND EDITION, ACADEMIC PRESS, New York and London, 1973, pp,
197-263) and Document 2 (Martin Glicksman, "Gum Technology in the
Food Industry" ACADEMIC PRESS, New York and London, 1969, pp,
94-124) can be used as reference.
EXAMPLES
[0124] The present invention will be described below in detail with
reference to the following Experimental Examples and Examples, but
is not limited to these Examples. In each Example, unless otherwise
specified, "part" means "part by weight" and "%" means "% by
weight". In each formulation, a substance marked by "*" means the
product of San-Ei Gen F.F.I. Inc.
Experimental Example 1
Modification of Gum Arabic and Evaluation of the Obtained Modified
Gum Arabic
[0125] 70 kg of cracked gum arabic (A. senegal: Sample 1) (5 mm
particle size) was charged into a 100 L volume stainless steel drum
and was then heated at 110.degree. C. for 36 hours to give `sample
1/36`. These gum arabic samples (Sample 1 and Sample 1/36) were
subjected to GPC-MALLS under the following conditions to obtain
chromatographs.
<Conditions of GPC-MALLS>
[0126] Column: Superose (6HR) 10/30 (Pharmacia Biotech)
[0127] Flow rate: 0.5 ml/min.
[0128] Elution solvent: 0.2 M NaCl
[0129] Preparation of a sample: the assay samples were dissolved
with the elution solvent (0.2 M NaCl)
[0130] Sample concentration: 0.4% (W/V)
[0131] Sample charge volume: 100 .mu.l
[0132] dn/dc: 0.141
[0133] Temperature: room temperature
[0134] Detector: [0135] (1) MALLS (multi angle laser light
scattering) detector: DAWN DSP (Wyatt Technology), [0136] (2) RI
(refractive index) detector, [0137] (3) UV detector (absorption at
214 nm)
[0138] The chromatograms obtained from the Sample 1 and Sample 1/36
are shown in FIGS. 1 (A) and (B), respectively. "Volume (ml)"
corresponding to the abscissa shows the cumulative volume of the
elution solvent passing through the column and `AUX, 90.degree.
Detector` corresponding to the ordinate shows the relative
intensity of each detector (MALLS detector, RI detector, and UV
detector). The chromatogram (MALLS chart) obtained by the MALLS
detector indicates the light scattering intensity at 900, which
correlates with the molecular weight distribution. The RI
chromatogram (RI chart) obtained with the RI detector indicates the
refractive index intensity, which correlates with the weight of
component containing in each eluate. The UV chromatogram (UV chart)
shows the UV absorption at 214 nm, which correlates with the
protein distribution.
[0139] Based on the RI chart obtained with the RI detector, the
eluted components can be classified into two fractions; an eluted
fraction of high molecular weight components which eluted first
(Peak 1 area shown in FIG. 1), and an eluted fraction of low
molecular weight components which eluted at a later time (Peak 2
area shown in FIG. 1). More specifically, the point at which the RI
chart (RI curve) begins to rise from the baseline of the
chromatogram is defined as the `starting point`, and the point at
which the RI chart (RI curve) falls and intersects the baseline is
defined as the `ending point`. The point at which the RI intensity
shows a minimum between the starting point and the ending point is
defined as a boundary. The peak area between the starting point and
the boundary is the aforesaid eluted fraction of high molecular
weight components (Peak 1 area), and the peak area between the
boundary and the ending point is the aforesaid eluted fraction of
low molecular weight components (Peak 2 area).
[0140] The eluted fraction of high molecular weight components
(Peak 1 area) is the fraction containing the highest protein
content and the recovery ratio (% mass) thereof is corresponding to
the arabinogalactan protein (AGP) content of the gum arabic.
Comparison between FIG. 1 (A) showing the elution profiles of gum
arabic (A. senegal) (Sample 1) and FIG. 1 (B) showing the elution
profiles of the heated gum arabic (A. senegal) (sample 1/36) shows
the following.
[0141] The eluted fraction of the highest molecular weight protein
component (AGP) (Peak 1 area) in Sample 1 (unmodified gum arabic)
exhibited a low measured value with the light scattering detector
(MALLS detector) monitored at 90.degree. (peak height: about 1.3),
low RI measured value (small amount) and a broadened UV absorption.
In contrast, the eluted fraction of the highest molecular weight
protein component (AGP) (Peak 1 area) in Sample 1/36 (heated gum
arabic) shows a high measured value with the MALLS detector (peak
height: about 8), a high RI intensity (large amount) and a sharp UV
absorbance peak.
[0142] A weight average molecular weight, recovery ratio (% mass),
polydispersity value (P), and root mean square (RMS) radius of
gyration (Rg) were obtained by processing the data obtained under
the above-described conditions using ASTRA Version 4.5 (Wyatt
Technology) software.
[0143] `Weight average molecular weight (M.sub.wt)` (in more
detail, M.sub.wt processed as one peak) used in the present
invention is defined as the molecular weight obtained when the
whole peaks in the chromatogram obtained with the RI detector was
data-processed as one peak. The said whole peaks mean one presented
in the area from a starting point to an ending point, when the
point at which the RI chart (RI curve) begins to rise from the
baseline of RI chromatogram is defined as the `starting point`, and
the point at which the RI chart (RI curve) falls and intersects the
baseline is defined as the `ending point`. Recovery ratio (t mass)
of the Peak 1 area shows the AGP content of gum arabic (natural gum
arabic (A. senegal), modified gum arabic (A. senegal)). RMS-radius
of gyration (Rg) is used as an indicator of molecular size. The Rg
value corresponds to the molecular weight, and thus an increased
molecular weight corresponds to an increased Rg value.
Polydispersity (P) value is defined as the ratio of weight average
molecular weight (M.sub.w) to the number average molecular weight
(M.sub.n) [i.e. (M.sub.w/M.sub.n)]. When P value is high, peaks in
the RI chromatogram become broad, which indicates that the
molecular weight has highly variable (polydispersity) (peaks of
various molecular weight exist intermixed). When P value is low,
peaks in the RI chromatogram become sharp, which indicates that the
polydispersity is low.
[0144] These parameters were determined by two kinds of
data-processing: by data-processing as one peak the whole peaks in
the chromatogram obtained with the RI detector, and by
data-processing as two peaks with the chart divided into the eluted
fraction of high molecular weight components which eluted first
(Peak 1 area) and the eluted fraction of low molecular weight
components which eluted a later time (Peak 2 area) as shown in
FIGS. 1 (A) and (B). The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Parameters processed Parameters processed as
one peak as two peaks % % Sample M.sub.wt.sup.1) Mass P Rg M.sub.wt
Mass P Rg 1 5.36 .+-. 0.02 .times. 10.sup.5 101 2.01 20.4 2.30 .+-.
0.01 .times. 10.sup.6 8.1.sup.2) 1.19 34.0 3.74 .+-. 0.01 .times.
10.sup.5 92.9 1.56 18.9 1/36 1.97 .+-. 0.04 .times. 10.sup.6 101
4.62 33.6 9.44 .+-. 0.25 .times. 10.sup.6 16.1.sup.2) 1.79 54.5
5.16 .+-. 0.03 .times. 10.sup.5 84.9 1.44 27.7 .sup.1)Weight
average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
[0145] These results show that, by heat treatment the gum arabic,
the weight average molecular weight thereof increased from about
5.36.times.10.sup.5 (Sample 1) to about 1.97.times.10.sup.6 (Sample
1/36) and the AGP thereof was increased from about 8.1% (Sample 1)
to 16.1% (Sample 1/36).
(2) Evaluation of Emulsifying Ability
[0146] Emulsions were prepared using the above gum arabic samples
(Sample 1 and Sample 1/36) according to the method given below, and
emulsifiability of each sample was evaluated by determining the
average particle diameter and the storage stability of the
emulsions.
[0147] More specifically, the obtained samples (Sample 1 and Sample
1/36) were each dissolved in water, centrifuged to remove
insolubles and prepared into 7.5%, 10%, 15% and 20% aqueous
solutions of gum arabic. To 800 g of each of these aqueous
solutions was added 200 g of medium-chain triglyceride
(octanoic/decanoic acid triglyceride O.D.O. (trade name, product of
Nisshin Oil Mills, Ltd.)) while stirring, and the mixtures were
emulsified using a homogenizer (manufactured by APV Gaulin)
(homogenized 4 times at a pressure of 44 MPa (450 kg/cm.sup.2)),
giving emulsions. The average particle diameter of the resulting
emulsions was measured immediately after emulsification and after 2
days of storage at 60.degree. C. using a particle size distribution
analyzer (SALD-1100 Laser Diffraction Particle Size Analyzer,
manufactured by Shimadzu).
[0148] Generally, the emulsifiability of an emulsifier is superior
as the average particle diameter of the emulsion prepared using the
emulsifier is smaller and the particle diameter is held more stably
over time ("the Study by the turbidimetric assay method of O/W
emulsion emulsified with gum arabic", Yakugaku Zasshi (Pharmacology
Journal), 112(12)906-913, (1992)).
[0149] The average particle diameter and the storage stability of
the emulsions prepared using each gum arabic sample (Sample 1 and
Sample 1/36) are shown in Table 2. The storage stability can be
determined based on the difference [(b)-(a)] between the average
particle diameter of the emulsions immediately after emulsification
(a) and the average particle diameter of the emulsions after an
accelerated test (2 days of storage at 60.degree. C.) (b).
TABLE-US-00002 TABLE2 Average particle diameter of emulsions
(.mu.m) Sample 1 Sample 1/36 After After accelerated accelerated
Aqueous Immediately test (2 days Immediately test (2 days solution
of after storage at after storage at gum arabic emulsification
60.degree. C. Change emulsification 60.degree. C. Change 7.5 0.98
3.73 2.75 0.82 0.83 0.01 10 0.88 2.95 2.07 0.72 0.73 0.01 15 0.74
2.10 1.36 0.65 0.66 0.01 20 0.68 1.54 0.86 0.63 0.64 0.01
[0150] The smaller is the change in the average emulsion particle
diameter, the better is the storage stability of the emulsion.
Conclusions can be drawn considering the average emulsion particle
diameter as follows:
[0151] `Excellent emulsifiability`: when the change in the average
emulsion particle diameter is less than 0.1 pin;
[0152] `Moderately good emulsifiability`: when the change in the
average emulsion particle diameter ranges from 0.1 .mu.m to 1
.mu.m; and
[0153] `Bad emulsifiability`: when the change in the average
emulsion particle diameter is 1 .mu.m or more.
[0154] As can be seen from Table 2, in terms of emulsifiability,
the unmodified gum arabic (Sample 1) was bad, whereas the heated
gum arabic (Sample 1/36) was superior since the average particle
diameter change was less than 0.1 .mu.m.
Experimental Example 2
Modification of Gum Arabic and Evaluation of the Obtained Modified
Gum Arabic
[0155] 1 kg of cracked gum arabic belonging to Acasia senegal
species (natural gum arabic from A. senegal: `Sample 2`) (5 mm
particle size) was placed in an unsealed stainless steel container,
exposed to the air and heated at 110.degree. C. for 24 hours and 48
hours using an oven (gum arabic samples heated for 24 hours and 48
hours are referred to as `Sample 2/24` and `Sample 2/48`,
respectively). These gum arabic samples (Sample 2, Sample 2/24 and
Sample 2/48) were subjected to GPC-MALLS and the chromatogram was
obtained in the same manner as in Experimental Example 1. A weight
average molecular weight, recovery ratio (% mass), polydispersity
(P) value and RMS-radius of gyration (Rg) were obtained by
processing the obtained data using ASTRA Version 4.5 (Wyatt
Technology) software. These parameters were determined by two kinds
of data-processing: by data-processing as one peak the whole peaks
in the chromatogram obtained with the RI detector, and by
data-processing as two peaks with the chart divided into an eluted
fraction of high molecular weight components which eluted first
(Peak 1 area) and an eluted fraction of low molecular weight
components which eluted a later time (Peak 2 area). The results are
shown in Table 3.
TABLE-US-00003 TABLE 3 Parameters processed Parameters processed as
one peak as two peaks % % Sample M.sub.wt.sup.1) Mass P Rg M.sub.wt
Mass P Rg 2 4.13 .+-. 0.15 .times. 10.sup.5 106 2.14 28.1 1.87 .+-.
0.19 .times. 10.sup.6 7.38.sup.2) 1.23 34.4 3.04 .+-. 0.11 .times.
10.sup.5 98 1.67 24.7 2/24 8.62 .+-. 0.36 .times. 10.sup.5 116 2.99
36.4 3.52 .+-. 0.14 .times. 10.sup.6 17.3.sup.2) 1.56 42.3 3.97
.+-. 0.16 .times. 10.sup.5 97 1.58 24.7 2/48 1.43 .+-. 0.06 .times.
10.sup.6 102 3.68 42.5 5.29 .+-. 0.23 .times. 10.sup.6 20.2.sup.2)
1.76 46.3 4.79 .+-. 0.18 .times. 10.sup.5 82 1.49 29.6
.sup.1)Weight average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
[0156] A UV absorption profile (wavelength: 214 nm) indicating the
protein distribution of each sample is shown in FIG. 3 and a
profile indicating the molecular weight distribution of each sample
is shown in FIG. 4. In FIG. 3, the X axis plots the cumulative
amount of eluate from the column (mL) (Volume (mL)) and the Y axis
plots the relative intensity of the UV response at a wavelength of
214 nm (LS, AUX (volts)).
[0157] The molecular weight of each of the gum arabic samples
(Sample 2, Sample 2/24 and Sample 2/48) at the maximum point of the
RI curve (Mp/RI.sub.max) and the maximum point of the UV curve
(Mp/UV.sub.max) is shown in Table 4.
TABLE-US-00004 TABLE 4 Sam- Vol. Vol. ple Mp/RI.sub.max (ml) Rg
Mp/UV.sub.max (ml) Rg 2 1.74 .+-. 0.06 .times. 10.sup.6 6.008 33.4
1.06 .+-. 0.03 .times. 10.sup.6 6.667 29.9 2/24 3.01 .+-. 0.06
.times. 10.sup.6 5.842 37.9 4.38 .+-. 0.01 .times. 10.sup.6 5.608
40.4 2/48 3.97 .+-. 0.12 .times. 10.sup.6 5.817 40.9 9.86 .+-. 0.33
.times. 10.sup.6 5.517 44.5
[0158] The results showed that, by heat treatment the gum arabic,
the weight average molecular weight thereof was increased from
about 4.13.times.10.sup.5 (Sample 2) to about 8.62.times.10.sup.5
(Sample 2/24) or about 1.43.times.10.sup.6 (Sample 2/48) and the
AGP content thereof was increased from about 7.38% (Sample 2) to
17.3% (Sample 2/24) or 20.2% (Sample 2/48).
(2) Evaluation of Emulsifying Ability
[0159] Emulsions were prepared using the above gum arabic samples
(Sample 2, Sample 2/24 and Sample 2/48), according to the method
given below, and the average particle diameter and the storage
stability of the emulsions were determined to evaluate
emulsifiability of each sample.
[0160] More specifically, 1 kg of each of the obtained samples
(Sample 2, Sample 2/24 and Sample 2/48) was dissolved in 4 kg of
water, centrifuged to remove insolubles, and prepared into 20%
aqueous solution of each gum arabic sample. To 850 g of 20% aqueous
solution of each sample was added 150 g of medium-chain
triglyceride (octanoic/decanoic acid triglyceride O.D.O. (trade
name, product of Nisshin Oil Mills. Ltd.) while stirring, and each
mixture was emulsified using a homogenizer (manufactured by APV
Gaulin) (homogenized 4 times at a pressure of 44 MPa (450
kg/cm.sup.2)), giving emulsions. The average particle diameter of
the obtained emulsions was measured immediately after
emulsification and after 7 days of storage at 60.degree. C. using a
particle size distribution analyzer (SALD-1100 Laser Diffraction
Particle Size Analyzer, manufactured by Shimadzu).
[0161] The average particle diameter and the storage stability of
the emulsions prepared using each gum arabic sample (Sample 2,
Sample 2/24 and Sample 2/48) are shown in Table 5. The storage
stability was determined based on the difference [(b)-(a)] between
the average particle diameter immediately after emulsification (a)
and the average particle diameter of the emulsion after an
accelerated test (7 days of storage at 60.degree. C.) (b).
TABLE-US-00005 TABLE 5 Average particle diameter of Average
particle Particle emulsion diameter of diameter immediately
emulsion after change after accelerated test (7 (.mu.m) Group of
emulsification days at 60.degree. C.) ([b] - Sample emulsifiability
(.mu.m) [a] (.mu.m) [b] [a]) 2 C 0.63 2.12 1.49 2/24 A 0.51 0.51 0
2/48 A 0.51 0.51 0
[0162] The above table shows that the smaller the change of the
emulsion droplet size (average particle diameter), the better the
storage stability. Emulsifying ability of each Sample was
classified 3 groups based on the change of the average particle
diameter (the emulsion droplet size) as follows:
[0163] `Excellent emulsifiability (Group A)`: when the change of
the average particle diameter is less than 0.1 .mu.m,
[0164] `Moderately good emulsifiability (Group B)`: when the change
of the average particle diameter ranges from 0.1 .mu.m to 1 .mu.m,
and
[0165] `Bad emulsifiability (Group C)`: when the change of the
average particle diameter is 1 .mu.m or more.
[0166] Consequently, as shown in Table 5, the unmodified gum arabic
(Sample 2) is classified as Group C, showing bad emulsifying
ability, whereas the heat-treated gum arabic samples of both Sample
2/24 and Sample 2/48 are classified as Group A, showing superior
emulsifying abilities. There are relationships between properties
and emulsifiability of gum arabic as listed in the followings (1)
to (4), based on FIG. 3 shown the UV absorption profile, FIG. 4
shown the molecular weight profile and Tables 3 and 4 shown the
various parameters, which are indicated by contrasting the
heat-treated Samples 2/24 and 2/48 in Group A (superior emulsifying
ability) with Sample 2 in Group C (bad emulsifying ability).
[0167] (1) As the weight average molecular weight increases, the
emulsifiability improves. Specifically, the weight average
molecular weight of the modified gum arabic should be preferably
0.9 million or more, more preferably 1.2 million or more, still
more preferably 1.5 million or more, and further more preferably 2
million or more, in terms of emulsifiability.
[0168] (2) As the AGP content increases, the emulsifiability
improves. Specifically, the AGP content should be preferably 12% or
more, more preferably 17% or more, and still more preferably 20% or
more, in terms of emulsifiability.
[0169] (3) As the molecular weight at the maximum point of the RI
curve (Mp/RI.sub.max) and the molecular weight at the maximum point
of the UV curve (Mp/UV.sub.max) become higher, the emulsifiability
improves. In particular, the molecular weight is preferably
4,000,000 or more at the maximum point of the UV trace
(Mp/UV.sub.max), in terms of emulsifiability.
[0170] (4) As the shape of the first peak in the UV chart becomes
sharper, the emulsifiability become better.
[0171] This process (heat-treatment) allows the re-distribution of
proteins of the natural gum arabic (in other words, this process
(heat-treatment) allows the protein distribution of gum arabic to
be changed) to increase the AGP content which enhances the
emulsified ability.
Experimental Example 3
[0172] 1 kg of cracked gum arabic (A. senegal: `Sample 3`) (5 mm
particle size) was heated at 110.degree. C. for 24 hours and 48
hours using an oven in the same manner as in Experimental Example
2. The gum arabic samples heated for 24 hours and 48 hours are
referred to as `Sample 3/24` and `Sample 3/48`, respectively. These
gum arabic samples (Sample 3, Sample 3/24 and Sample 3/48) were
subjected to GPC-MALLS and the chromatograms were obtained in the
same manner as in Experimental Example 1. Various parameters
(weight average molecular weight, recovery ratio (% mass),
polydispersity (P) value, and RMS-radius of gyration (Rg)) were
obtained by processing the obtained data in the same manner as in
Experimental Example 1. The weight average molecular weight
(M.sub.wt processed as one peak) of the gum arabic samples (Sample
3, Sample 3/24 and Sample 3/48) is shown in Table 6.
TABLE-US-00006 TABLE 6 Sample M.sub.wt processed as one peak.sup.1)
% by mass 3 5.15 .+-. 0.18 .times. 10.sup.5 101 Control 3/24 1.15
.+-. 0.21 .times. 10.sup.6 105 Heated at 110.degree. C. for 24
hours 3/48 1.91 .+-. 0.17 .times. 10.sup.6 103 Heated at
110.degree. C. for 48 hours .sup.1)Weight average molecular weight
of the gum arabic sample
Experimental Example 4
[0173] 1 kg of spray-dried gum arabic (A. senegal: `Sample 4`)
(powder form) was heated at 110.degree. C. for 24 hours using an
oven (gum arabic heated for 24 hours is referred to as `Sample
4/24`) in the same manner as in Experimental Example 2. These gum
arabic samples (Sample 4 and Sample 4/24) were subjected to
GPC-MALLS and chromatograms were obtained in the same manner as in
Experimental Example 1. Various parameters (weight average
molecular weight, recovery ratio (% mass), polydispersity (P)
value, and RMS-radius of gyration (Rg)) were obtained by processing
the obtained data in the same manner as in Experimental Example 1.
The results are shown in Table 7.
TABLE-US-00007 TABLE 7 Parameters processed Parameters processed as
one peak as two peaks % by % by Sample M.sub.wt.sup.1) Mass P Rg
M.sub.wt Mass P Rg 4 5.99 .+-. 0.2 .times. 10.sup.5 107 2.24 25
2.34 .+-. 0.09 .times. 10.sup.6 14.55.sup.2) 1.49 35.2 3.19 .+-.
0.08 .times. 10.sup.5 93.1 1.34 -- 4/24 1.43 .+-. 0.26 .times.
10.sup.6 102 4.66 97.6 6.38 .+-. 0.91 .times. 10.sup.6 18.sup.2)
2.78 109 3.82 .+-. 0.08 .times. 10.sup.5 83.3 1.45 19 .sup.1)Weight
average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
Experimental Example 5
[0174] 1 kg of spherical cluster of gum arabic (A. senegal: `Sample
5`) (cluster size of 20 mm.times.30 mm or less) was heated at
110.degree. C. for 24 hours using an oven (gum arabic heated for 24
hours is referred to as `Sample 5/24`) in the same manner as in
Experimental Example 2. These gum arabic samples (Sample 5 and
Sample 5/24) were subjected to GPC-MALLS and chromatograms were
obtained in the same manner as in Experimental Example 1. Various
parameters (weight average molecular weight, recovery ratio (%
mass), polydispersity (P) value, and RMS-radius of gyration (Rg))
were obtained by processing the obtained data in the same manner as
in Experimental Example 1. The results are shown in Table 8.
TABLE-US-00008 TABLE 8 Parameters processed Parameters processed as
one peak as two peaks % by % by Sample M.sub.wt.sup.1) Mass P Rg
M.sub.wt Mass P Rg 5 8.05 .+-. 0.44 .times. 10.sup.5 99 2.48 34.1
3.20 .+-. 0.18 .times. 10.sup.6 13.6.sup.2) 1.55 49.7 3.95 .+-.
0.04 .times. 10.sup.5 85.5 1.39 -- 5/24 1.63 .+-. 0.28 .times.
10.sup.6 107 4.73 124 5.88 .+-. 1.1 .times. 10.sup.6 23.4.sup.2)
2.43 138 4.06 .+-. 0.32 .times. 10.sup.5 84.5 1.48 21 .sup.1)Weight
average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
Experimental Example 6
[0175] cracked gum arabic (A. seyal: `Sample 6`) (5 mm particle
size) was heated at 110.degree. C. for 15 hours using an oven (gum
arabic heated for 15 hours is referred to as `Sample 6/15`) in the
same manner as in Experimental Example 2. These gum arabic samples
(Sample 6 and Sample 6/15) were subjected to GPC-MALLS and
chromatograms were obtained in the same manner as Experimental
Example 1. Various parameters (weight average molecular weight,
recovery ratio (% mass), polydispersity (P) value, and RMS-radius
of gyration (Rg)) were obtained by processing the obtained data in
the same manner as in Experimental Example 1. The results are shown
in Table 9.
TABLE-US-00009 TABLE 9 Parameters processed Parameters processed as
one peak as two peaks % by % by Sample M.sub.wt.sup.1) Mass P Rg
M.sub.wt Mass P Rg 6 1.65 .+-. 0.66 .times. 10.sup.6 105 1.77 27.1
4.82 .+-. 0.19 .times. 10.sup.6 15.77.sup.2) 1.20 30.5 1.10 .+-.
0.10 .times. 10.sup.6 89.7 1.33 24.1 6/15 3.65 .+-. 0.17 .times.
10.sup.6 110 2.75 40.2 8.38 .+-. 0.44 .times. 10.sup.6 37.2.sup.2)
1.53 42.5 1.21 .+-. 0.04 .times. 10.sup.5 73.2 1.26 30.7
.sup.1)Weight average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
Experimental Example 7
[0176] Spray-dried gum arabic (A. seyal: `Sample 7`) (powdered
form: 2 mm or less) was heated at 110.degree. C. for 24 hours using
an oven (gum arabic heated for 24 hours is referred to as `Sample
7/24`) in the same manner as in Experimental Example 2. These gum
arabic samples (Sample 7 and Sample 7/24) were subjected to
GPC-MALLS and the chromatograms were obtained in the same manner as
in Experimental Example 1. Various parameters (weight average
molecular weight, recovery ratio (% mass), polydispersity (P)
value, and RMS-radius of gyration (Rg)) were obtained by processing
the obtained data in the same manner as in Experimental Example 1.
The results are shown in Table 10.
TABLE-US-00010 TABLE 10 Parameters processed Parameters processed
as one peak as two peaks % by % by Sample M.sub.wt.sup.1) Mass P Rg
M.sub.wt Mass P Rg 7 1.15 .+-. 0.04 .times. 10.sup.6 107 2.80 36.4
4.72 .+-. 0.33 .times. 10.sup.6 10.9.sup.2) 1.73 47.8 5.85 .+-.
0.14 .times. 10.sup.5 96.7 1.56 13.2 7/24 1.46 .+-. 0.26 .times.
10.sup.6 104 3.13 51.5 6.15 .+-. 0.57 .times. 10.sup.6 22.9.sup.2)
1.81 60.3 3.82 .+-. 0.08 .times. 10.sup.5 82 1.47 18.5
.sup.1)Weight average molecular weight of the gum arabic sample
.sup.2)Arabinogalactan protein content of the gum arabic sample (%
by weight)
Experimental Example 8
Immune Reaction of Modified Gum Arabic
[0177] Immune-reactivity of each of gum arabic samples from A.
Senegal (Sample 3, Sample 3/24, and Sample 3/48) obtained in
Experimental Example 3 were evaluated. More specifically,
immune-reactivity of each of gum arabic samples was measured using
plates immobilized with the each gum arabic (concentrations: 0.005,
0.01, 0.05, 0.1, 0.5, 1, 5 mg/ml) by indirect competitive ELISA
according to Thurston, M. I. et al. [Thurston, M. I., et al.,
Detection of gum from Acacia seyal and species of combretum in
mixtures with A. senegal using monoclonal antibodies, Food &
Agric. Immunol., 10:237-241 (1998); Thurston, M. I., et al., Effect
of heat and pH on carbohydrate epitopes from Acacia senegal by
specific monoclonal antibodies, Food & Agric. Immunol.,
11:145-153 (1999)]. The ELISA method is described below.
[0178] Monoclonal antibodies having no specificity to any species
of gum arabic and showing quantitative cross-reactivity were
prepared. More specifically, adjuvant was added to saline solution
containing 1 mg/ml of gum arabic from Acasia seyal to prepare the
immunogen. Balb/c mice were given intraperitoneal injections of the
immunogen three times at 2-week intervals. The splenocytes of the
mice with highly raised antibody titers were taken and fused with
the myeloma cells in polyethylene glycol. After incubating the
obtained cells on an incubation plate for 10 days, the hybridoma
cells were selected based on specificity of antibodies produced in
the supernatant of the proliferated hybridoma cells. The selected
hybridoma cells were incubated for another 10 days on the
incubation plate and specific hybridoma cells were selected by the
same procedure. The hybridoma cells producing only SYCC7 antibodies
having no specificity to any species of gum arabic and showing
quantitative cross-reactivity were finally selected.
[0179] Each of 1 mg/ml and 5 mg/ml solutions of the three samples
(Sample 3, Sample 3/24, and Sample 3/48) was diluted at 10-fold,
100-fold and 1000-fold. 200 .mu.l of each solution was added into
wells of a plastic plate, and immobilized at 4.degree. C. for 1
hour. The wells were washed with saline solution, blocked with 0.3%
casein-containing saline solution and washed with 0.05% Tween
20-containing saline solution. Culture supernatant of the prepared
hybridoma cells was added and immobilized for 1 hour. After washing
as in the above-mentioned procedure, the wells were subsequently
immobilized with peroxidase-labeled goat anti-mouse antibodies
(SIGMA, diluted 1.000-fold with saline solution) for 1 hour. After
washing, tetramethylbenzidine was added as a substrate to the wells
and the color intensity was measured as UV absorption at 450 nm
(UV.sub.450nm). The inhibition ratio (%) for each sample at various
concentrations was indicated by comparison with the UV absorption
at 450 nm (UV.sub.450nm) of natural gum arabic from A. seyal, which
is 100% inhibition.
[0180] The results are shown in FIG. 5. The abscissa represents the
concentration (mg/ml) of each gum arabic sample used for coating
the plates, and ordinate represents the inhibition ratio (%). Test
results show that the modified gum arabic of the present invention
and natural gum arabic have the same or similar immunological
reactivity since differences in the immunological inhibition ratio
therebetween are within the range of +10% over the tested
concentrations, and therefore negligible.
Example 1
.beta.-Carotene Emulsion
An Emulsified Colorant Preparation
[0181] Using the heat-treated gum arabic samples (Acacia senegal)
obtained in Experimental Examples 1 through 6 as modified gum
arabic samples, .beta.-Carotene emulsions were prepared according
to the formulation given below.
TABLE-US-00011 <Formulation> .beta.-Carotene 30% suspension 5
Medium-chain triglyceride 10 Modified gum arabic (Acacia senegal)
17 Water 68 Total 100 (% by weight)
[0182] More specifically, 170 g of modified gum arabic (Acasia
senegal) was dissolved in 680 g of water, and the solution was
centrifuged to remove insoluble substances, thus giving a 20%
aqueous solution of modified gum arabic. The gum arabic solution
was used as an emulsifier, and to the solution was added a mixed
solution prepared by dissolving 100 g of medium-chain triglyceride
(octanoic/decanoic acid triglyceride O.D.O (trade name, product of
Nisshin Oil Mills, Ltd.)) in 50 g of a 30% suspension of
.beta.-carotene with heating at 150.degree. C., followed by mixing
under stirring. The mixture was emulsified with a homogenizer
(manufactured by APV Gaulin) (homogenized 4 times at the pressure
of 44 MPa (450 kg/cm.sup.2)) to give a .beta.-Carotene emulsion
serving as an emulsified colorant preparation.
Example 2
Orange Flavoring Emulsion
An Emulsified Flavoring
[0183] Using the heat-treated gum arabic samples (Acacia senegal)
obtained in Experimental Examples 1 through 6 as modified gum
arabic samples, orange flavoring emulsions were prepared according
to the formulation given below.
TABLE-US-00012 <Formulation> Orange flavoring 2 (% by weight)
Medium-chain triglyceride 13 Modified gum arabic (Acacia senegal)
17 Water 68 Total 100 (% by weight)
[0184] More specifically, 170 g of modified gum arabic (Acasia
senegal) was dissolved in 680 g of water, and the solution was
centrifuged to remove insoluble substances, thus giving a 20%
aqueous solution of modified gum arabic. The gum arabic solution
was used as an emulsifier, and to the solution was added a mixed
solution prepared by sufficiently mixing 20 g of orange flavoring
and 130 g of medium-chain triglyceride (octanoic/decanoic acid
triglyceride O.D.O (trade name, product of Nisshin Oil Mills,
Ltd.)) at room temperature, followed by mixing by stirring. The
mixture was emulsified with a homogenizer (manufactured by APV
Gaulin) (homogenized 4 times at the pressure of 44 MPa (450
kg/cm.sup.2)) to give an orange flavoring emulsion serving as an
emulsified flavoring.
Example 3
Docosahexaeoic Acid (DRA) Emulsion
An Emulsified DHA Preparation
[0185] Using the heat-treated gum arabic samples (Acacia senegal)
obtained in Experimental Examples 1 through 6 as modified gum
arabic samples, DHA emulsions were prepared according to the
formulation given below.
TABLE-US-00013 <Formulation> 20% DHA containing fish oil 5 (%
by weight) Medium-chain triglyceride 10 Modified gum arabic (Acacia
senegal) 17 Water 68 Total 100 (% by weight)
[0186] More specifically, 170 g of modified gum arabic (Acasia
senegal) was dissolved in 680 g of water, and the solution was
centrifuged to remove insoluble substances, thus giving a 20%
aqueous solution of modified gum arabic. The gum arabic solution
was used as an emulsifier, and to the solution was added a mixed
solution prepared by mixing 50 g of 20% DHA containing fish oil and
100 g of medium-chain triglyceride (octanoic/decanoic acid
triglyceride O.D.O (trade name, product of Nisshin Oil Mills,
Ltd.)) and heating the mixture at 80.degree. C., followed by mixing
by stirring. The mixture was emulsified with a homogenizer
(manufactured by APV Gaulin) (homogenized 4 times at the pressure
of 44 MPa (450 kg/cm.sup.2)) to give a DHA emulsion.
Example 4
Lemon Powder Flavoring
[0187] Using the heat-treated gum arabic sample (Acacia seyal)
obtained in Experimental Example 7 as a modified gum arabic sample,
a lemon powder flavoring was prepared according to the formulation
given below.
TABLE-US-00014 <Formulation> Lemon oil 20 (% by weight)
Modified gum arabic (Acacia seyal) 20 Dextrin 60 Water 150 Total
250 (% by weight)
[0188] More specifically, 200 g of the modified gum arabic (Acasia
seyal) and 600 g of dextrin was dissolved in 1,500 g of water to
prepare an aqueous solution of modified gum arabic. The gum arabic
solution was used as an emulsifier. Lemon oil (200 g) was added to
the gum arabic solution, followed by mixing by stirring. The
obtained mixture was emulsified with a homogenizer (manufactured by
APV Gaulin) (homogenized once at the pressure of 19.6 MPa (200
kg/cm.sup.2)). Subsequently, the solution was spray-dried with a
spray dryer (manufactured by Anhydro) (inlet temperature
140.degree. C., outlet temperature 80.degree. C.), to prepare a
lemon powder flavoring (950 g).
INDUSTRIAL APPLICABILITY
[0189] The present invention can provide a modified gum arabic,
especially a modified gum arabic from the species A. senegal, with
improved emulsifiability. Moreover, the present invention can
provide a modified gum arabic, especially a modified gum arabic
from the species A. senegal, which exhibits stable and improved
emulsifiability by uniformly adjusting and standardizing,
especially in terms of emulsifiability, variations in quality and
properties of natural gum arabic ascribable to different harvesting
areas, times and climates. Such a modified gum arabic of the
invention, especially a modified gum arabic from the species A.
senegal, can be suitably used for emulsifying various hydrophobes
such as essential oils, oil-based colorants, oil-based flavorings,
oil-soluble vitamins, etc. The emulsions prepared using the
modified gum arabic of the invention are more stable in quality as
compared with those prepared using natural (unmodified) gum arabic
since particle distribution is uniform and qualitative
deterioration caused by agglomeration or integration of the
emulsion particles under conditions such as heating or long-time
storage can be significantly suppressed.
[0190] The present invention can provide a modified gum arabic,
especially a modified gum arabic from the species A. seyal, with
improved and enhanced emulsifiability, emulsion stability,
encapsulation ability, adhesiveness, protective colloid property,
and film forming ability as compared with natural (unmodified) gum
arabic. Moreover, the invention can provide a modified gum arabic,
especially a modified gum arabic from the species from A. seyal,
which exhibits stable emulsifiability by uniformly adjusting and
standardizing variations in quality and properties of gum arabic
ascribable to different harvesting areas, times climates,
especially in terms of emulsifiability, encapsulation ability,
adhesiveness, protective colloid property, film forming ability,
etc. Such a modified gum arabic of the invention can be suitably
used for a thickener, binder, material for capsules (encapsulant),
coating agent and emulsifier.
* * * * *