CA2020742C

CA2020742C - Process for preparing a layered hydrogel product

Info

Publication number: CA2020742C
Application number: CA002020742A
Authority: CA
Inventors: Saburo Kohara; Naoko Fujimoto; Shiro Oohashi; Hiroki Iida
Original assignee: San Ei Kagaku Co Ltd
Current assignee: San Ei Kagaku Co Ltd
Priority date: 1990-07-09
Filing date: 1990-07-09
Publication date: 2000-02-29
Anticipated expiration: 2010-07-09
Also published as: CA2020742A1

Abstract

An industrially advantageous process for preparing a layered hydrogel product, which comprises pouring into a mold of a desired shape an aqueous solution (I) containing at least one gelling agent, and an aqueous solution (II) containing xanthan gum and at least one thickening agent selected from a group of locust bean gum, tara gum, cassia gum and glucomannan, separately or simultaneously;
and cooling the resultant to dive a layered hydrogel product.

Description

~~~~w SPECIFICATION
TIT~.E OF THE INVENTION
PROCESS FOR PREPARING A LAYERED HYDROGEL pROIaUCT
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a prooess for prepar-ing a layered hydrogel product, which i$ industrially advan-tageous and utilizable for confectionery industry.

2. Prior Art Conventionally, a layered hydrogel product has been prepared in the following manners:
(i) A gelling agent which is gelled by cooling such as agar, gelatin or the like (hereinafter called as known gelling agent) is dissolved in water, then the aqueous solution is cooled to a temperature below its gelation temperature: On the gelled solution, laminated is an aqueous solution of the same or another gelling agent such as carra-geenan, pectin, gellan gum or the like which is maintained at a temperature higher than its gelation temperature, then cooled to give a layered hydrogel product.
(ii) Specific gravities of the above two solutions are made different by increasing or decreasing their water-soluble solid contEnts, then the two solutions in sol state are Laminated and cooled to give a layered hydrogel product.

~~2~r~~~
Neither of these processes are industrially advanta-geous. Namely, the method (i) needs to gelatinize the first aqueous solution of a gelling agent by cooling to a tempera-ture below its gelation temperature, to laminate the second solution an the first solution and to cool them, with the result that energy loss in the cooling steps becomes consid-erably high and also the preparing process becomes compli-cated. Further, the two layers tend to be detached from each other at the interface. In the method (ii), although the specific gravities of the two solutions are made different, tastes, colors, fragrances and the like contained in each of the solutions are mixEd when the two solutions arc poured into a mold, so that the value of the product degrades significantly. Further, the pouring operation must be care-fully and slowly conducted, resulting in disadvantage in ~.ndustrial application.
SUhIMARY OF' xFIE INVENTION
Accordingly, an object of the invention is to solve the abovementioned problems of the prior art methods.
Further object of the invention is to provide an indus-trially advantageous process for preparing a layered hydro-gel product.
Thus, the present invention provides a p~cocess for preparing a layered hydrogel product, which comprises pour Q ~ ~~ N
ing into a mold of a desired shape an aqueous solution (I) containing at least one gelling agent, or its whipping solution and an aqueous solution (IZ) containing xanthan gum and at least one thickening agent selected from a group of locust bean gum, tare gum, cassia gum and glucamannan, or its whipping solutions and cooling the resultant to give a layered hydrogel product.
In the present invention, a mold of a desired shape is meant by a mold, cup or vessel of any shape for confection-ery such as truncated cone, circular cylinder, rectangular parallelopiped, elliptic cylinder or the like, and its volume is not specifically limited.
The term "pouring" as used above is meant by an opera-tion of pouring either one of the aqueous solution (I) or its whipping solution and the solution (II) or its whipping solution into the mold, followed by pouring the remaining one. Even if both of the solutions (I) and (II) or their whipping solutions are simultaneously poured into the mold, they unexpectedly become a clearly separated and layered hydrogel product when cooled. Therefore, the solutions form a layered hydrogel product provided that they are not stixred by farce.
DETAILED DESCRIPTION OF THE PREFERRED EMB~bIMEHT
Acoordirig to the invention, an aqueous solution of a

3 11~
known gelling agent such as carrageenan, agar, gelatin, low methoxyl pectin, gellan gum, alginic acid or the like is heated and maintained at a temperature higher than its gelation temperature (usually higher than 50 °G). Tv the above solution added is an aqueous solution of a blend of xanthan gum and at least one thickening agent such as locust bean gum, taro gum, cassia gum and glucomannan which is heated and maintained at a temperature higher than its gelation temp~rature (usua~.ly higher than 60 °C). Each of the above solutions can be used in whipped state before pouring. The above step can be carried out in reverse order, namely, the solution of a known gelling agent can be added to the solution containing xarithan gum. The two solutions or their whipping solutions may be simultaneously poured. They are then coated to form a layered hydrogel product. The two layers of the resulting layered gel product are clearly cut and separated without mixing thQir tastes, colors, fragrance and the like, and will not be detached from each other even if they are cut with knife or mechanically given a shock.
The above two solutions may be the same or different in specific gravity ar brix, acidity or alkalinity and so forth. Eithor or both of the solutions may contain fruit juices (e. g., orange, apple, grape, pear, strawberry, peach or the l~.ke) or their essence, coffee, tea extract, wine, milk or its processed product, flavors, sweetening agents

4 te.g., sugar, fructose or the like) and so forth.
The gelling agent can be used in an amount sufficient to gave a gelation, o.g., 0.2 to 2 % (w/w). The total amount of xanthan gum and the thickening agent is used in an amount sufficient to cause gelation, e.g., 0.2 to 2 (w/w). A ratio of xanthan gum to the thickening agent is net specifically limited but preferably 2 . 1 to i : 2. A ratio of at least one of tare gum, cassia gum and glucomannan to the blend of xanthan gum and locust bean gum may be any desired ratio, far exempla, 1 . 1 to 0.1 : 1. As well, a ratio of at least one of tars gum, cassia gum and glucomannan to xanthan gum is not specifically limited.
An amount of the above thickening agent may~vary de-pending an the target gelation degree of the product and texture thereof. Generally, however, it may be within the range from 0.2 to 2 wt% with respect to the total weight of the raw materials to be used. Resides, when the solution contains 0.25 % (w/w) ar mare of the blend of xanthan gum and e.g., locust bean gum in 1 : 1 ratio, it may also con-tain a gelling agent in order to improve a taste of the layered product.
The gelling agents used in the invention may decrease in their gelatian degree in the acid side, therefore, addi-tion of a buffering agent such as sodium citrate, sodium phosphate, polyphosphate ar the like can prevent decrease in gelation degree. An amount of the buffering agent to be used is desirably 0.05 to 0.3 wt%.
The layered hydrogel praduats of the invention may be two, three, four ox more layered products.
Hereinafter, the present invention will be more fully described with reference~to Test ExamplQS and Examples which are merely examples and not limitative to the invention.
Test Example 1 Xanthan gum (5 g) and locust bean gum (5 g) were added to water (990 g) under stirring. Tha gums were dissolved in a hot water bath under stirring until a temperature of the mixture was raised to 80 °C to give an aqueous solution tA) which was maintained at 70 °C.
Xanthan gum (5 g) and tare gum (3 g) were added to water (992 g) under stirring. The gums were dissolved in a hot watex bath under stirring until a temperature of the mixture was raisQd to 80 °C to give an aqueous solution (B) which was maintained at 70 °C.
Agar (6 g) was added to water (994 g) under stirring, then the mixture was stirred in a hot water bath until its temperature was raised to 95 °C to give an aqueous solution (C) which was maintained at 40 °C.
Gelatin (20 g) was added to water (980 g) under stir-ring, then the mixture was stirred in a hat bath until its temp~sraturo was raised to 80 °C to give an aqueous solution l~.r~~~ B~°~~N
(D) which was maintained at 30 °C.
Carragcenan (12 g) was added to water (988 g) under stirring, then the mixture was stirred in a hot bath until its temperature was raised to 80 °C to give an aqueous solution (E) which was maintained at 50 °C.
Carrageenan (6 g) and locust bean gum (9 g) were added to water (990 g) under stirring, then the mixture was stirred in a hot water bath until its temperature was raised to 80 °C to give an aqueous solution (F) which was main-tained at 70 °C.
Low methoxyl pectin (10 g) was added to water (984 g) under stirring, then the mixture was stirred in a hot bath until its temperature wag raised to 80 °C. To the mixture further added were citric acid (3 g) and calcium lactate (3 g) to give an aqueous solution (G) which was maintained at 80 °C.
Kelco-gel (Z g, manufactured by Relco Co.) was added to water (997 g) under stirring, then the mixture was stirred in a hot bath until its temperature was xaised to 90 °C. To the mixture further added was calcium lactate (1 g) to give an aqueous solution (~i) which was maintained at BO °C.
Xanthan gum (6 g), locust bQan gum (4 g) and cassia gum (2 q) were added to water (988 g) under stirring. They were dissolved in the water in a hot bath under stirring until a temperature of the mixture was raised tp 80 °C to give an aqueous solution (I) which was then maintained at 70 °C, Next, combinations of two, three and four of the above solutions respectively maintained at their proper tempera-tures werQ each (50 ml) poured into a cylindrical cup (diamQter: 6.3 cm, height: 5.3 cm, internal volume: 115 ml), These were cooled for 6 hours at 5 °C in a refrigerator. The results thereof are shown in the following Table 1.

2~~~'~~~
Table 1 TestSample Resulting Layered Gel Product A + A mixed, irregular layers A + B mixed, irregular layers A + C not mixed, clearly separatedlayers A + D not mixed, clearly separatedlayers A + E not mixed, clearly separatedlayers A + P not mixed, clearly separatedlayers A + G not mixed, clearly separatedlayers A + H not mixed, alaarly separatedlayers A + Z mixed, irregular layers A+C+A not mixed, clearly separatedlayers A+C+A+D net mixed, clearly separatedlayers a + B mixod, irregular layers 8 + C not mixed, clearly separatedlayers H + D not m~.xed, clearlyseparatedlayers B + E not mixed, clearly separatedlayers ~g + F not mixed, clearly separatedlayers B + G not m~.xed, clearlyseparatedlayers g + H not mixed, clearly separatedlayers H + I mixed, irregular layers H+E+B not mixed, clearly separatedlayers H+G+B+F not mixed, clearly separatedlayers C + C mixed, ~.rregular layers C + D mixed, irregular layers ~~/<~~rf '~,' Tables 1 (continued) C + E mixed, irregularlayers C + F mixed, irregularlayers C + G mixed, irregularlayers G * rtr mixed, irregularlayers G + I not mixed, layers clearly separated D + D mixed, irregularlayers D + E mixed, irregularlayers D + F mixed, irregularlayers D + G mixed, irregularlayers D + 1H mixed, irregularlayers D +~I not mixed, layers clearly separated E + E mixed, irregularlayers E + F mixed,. irregularlayers E + G mixed, irregularlayers E + H mixed, ~.rregularlayers E -~r not mixed, layers clearly separated F + F mixed, irregularlayers F + G mixed, irregularlayers F + I not mixed, layers clearly separated G + G mixed, irregularlayers G + I not mixed, layers clearly separated H + H mixed, irregularlayers H + I not mixed, layers clearly separated I + I mixed, irregularlayers ~~~~ 8~~~~
Example 1 Carrageenan (10 g) was added to water (890 g) under stirring with 2000 revolutions per minute. The mixture was then stirred in a hot bath until its temperature was raised to 80 °C and added with orange juice (100 g). The resulting mixture (60 ml) was poured into a cylindrical cup (diameter:
6.3 cm, height: 5.3 cm, internal volume: 11.5 ml) and main-tained at a temperature higher than its gelation tempera-ture. On the other side, xanthan gum (7 g) and cassia gum (3 g) were added to water (790 g) under stirring with 1500 revolutions per minute. The mixture was then stirred i.n a hot bath until its temperature was raised to 80 °C and added with apple juice (200 g). The resulting mixture was main-tained at a temperature higher than its gelation tempera-ture, 40 ml of which was poured onto the previ.ausly poured mixture. The combination of the two mixtures in the cylin-drical cup was cooled at ? °C foz 10 hours in a refrigera~
tor. The resulting hydrogel product had two layers which wexe not mixed and wexe clearly separated.
Example 2 Gelatin (20 g) and grape juice (50 g) were added to water (930 g) under stirring with 1000 revolutions per minute. The mixture was then stirred in a hot bath until its temperature was raised to 70 °C, 50 ml of which was poured ~~~~;~~~~
into a cylindrical cup (diameter: 6.3 cm, height: 5.3 cm, internal volume: 115 ml) and maintained at a temperature higher than its gelation temperature. On the other side, xanthan gum (4 g), tars gum (S g) and orange juice (80 g) were added to water (911 g) under stirring with 1500 revolu-tions per minute, which was then stirred in a hot bath until a temperature of the mixture was raised to ~0 °C. The re-sulting mixture was then maintained at a temperature higher than its gelation temperature, 50 ml of which was poured onto the previously poured mixture. The combination of the two mixtures in the cylindrical sup Was cooled at 7 °C for hours in a refrigerator. The resulting hydrogel product had twa layers which were not mixed and were clearly sepa-rated.
EX~Jtlple 3 Agar (7 g1 was added to water (933 g) under stirring with 1500 revolutions per minute. The mixture was then

5~tirred in a hot bath unt~.l its temperature was raised to 95 °C and added with apple juice (60 g), 60 ml of which was poured into a cylindrical cup (diameter: 6.3 cm, height: 5,3 cm, internal volume: 115 ml) and maintained at a temperature higher than its gelation temperature. On the other side, xanthan gum (5 g), locust bean gum (3 g) were added to water (892 g) under stirring with 1000 revolutions per minute. The mixture was then stirrod in a hot bath until its temperature 2~~~~~2 was raised tp 85 °C and added with grape fruit juice (1~0 g). The resulting mixture was then maintained at a tempera-ture higher than its gclation temperature, ~0 ml of which was poured onto the previously poured mixture. The combina-tion of the two mixtures in the cylindrical cup was cooled at 5 °C for 8 hours in a refrigerator. The resulting hydro-gel product had two layers which were not mixed and were clearly separated. The aup containing the layered hydrogel product is sealed and stationarily sterilized at 85 °C for 30 minutes.
As seen above, according to the invention, an ideal layered hydragel product can be advantageously prepared without complex operations.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing a layered hydrogel product, which comprises:
pouring into a mold of a desired shape, (I) an aqueous solution containing at least one gelling agent, and (II) an aqueous solution containing xanthan gum and at least one thickening agent selected from the group consisting of locust bean gum, tara gum, cassia gum and glucomannan, wherein the solution (I) is maintained at a temperature higher than its gelation temperature, and the solution (II) is maintained at a temperature higher than its gelation temperature, prior to pouring; and cooling the resultant to give a layered hydrogel product.

2. The process as set forth in claim 1, wherein the gelling agent is selected from the group consisting of carrageenan, agar, gelatin, low methoxyl pectin, gellan gum and alginic acid.

3. The process as set forth in claim 1 or 2, wherein the solution (I) and the solution (II) have substantially the same specific gravity.

4. The process as set forth in claim 1, 2 or 3, wherein either one or both of the solutions (I) and (II) contain a fruit juice or an essence thereof, coffee or tea extract.

5. The process as set forth in any one of claims 1 to 4, wherein one kind of the solution (I) is combined with two same or different kinds of the solution (II), or two same or different kinds of the solution (I) are combined with one kind of the solution (II) to form a multilayered hydrogel product.

6. The process as set forth in any one of claims 1 to 5, wherein the gelling agent is used in an amount sufficient to give a gelation and the total amount of xanthan gum and the thickening agent is used in an amount sufficient to cause a gelation.

7. The process as set forth in any one of claims 1 to 6, wherein xanthan gum and the thickening agent are employed at a weight ratio of 2:1 to 1:2.

8. The process of any one of claims 1 to 7, wherein the gelation temperature of solution (I) is 50°C.

9. The process of any one of claims 1 to 8, wherein the gelation temperature of solution (II) is 60°C.

10. The process as set forth in any one of claims 1 to 9, wherein the gelling agent is present at a concentration from 0.2 to 2% (w/w).

11. The process as set forth in any one of claims 1 to 10, wherein the xanthan gum and the at least one thickening agent are present at a total amount of from 0.2 to 2% (w/w).

12. A process for preparing a layered hydrogel product, which comprises:
(a) providing a first aqueous solution (I) containing at least one gelling agent, each maintained at a temperature higher than its gelation temperature, (b) providing a second aqueous solution (II) of a blend of xanthan gum and at least one thickening agent selected from the group consisting of locus bean gum, tara gum, cassia gum and glucomannan, each maintained at a temperature higher than its gelation temperature, (c) pouring into a mold of a desired shape the solution provided in step (a) and the solution provided in step (b) simultaneously or consecutively in any order, and (d) cooling the solutions poured in the mold to lower the temperature below the gelation temperatures of the solutions provided in steps (a) and (b), thereby forming the layered hydrogel product.

13. The process as set forth in claim 12, wherein the gelling agent contained in the solution provided in step (a) is at least one member selected from the group consisting of carrageenan, agar, gelatin, low methoxyl pectin, gellan gum and alginic acid.

14. The process as set forth in claim 13, wherein the solution provided in step (a) also contains locust bean gum.