CA1087018A - Shelf stable food gel - Google Patents

Abstract

TITLE: FOOD PRODUCTS

ABSTRACT OF THE DISCLOSURE
The invention relates to food products and provides novel foods for animals, especially pets. In particular the invention relates to coherent elastic semi-moist food products which are stabilized against bacterial growth by the inclusion of humectants at reduced water activity. The products include subdivided protein material bound together with a gel formed by a polysaccharide gelling agent containing monosaccharide units other than (including in addition to) glucose residues and preferably having free or esterified acidic substituent groups, A preferred example of such a gelling agent is a mixture of xanthan and carob gums. Quantities of gelling agent in the range 0.2 to 5% are preferred and the moisture content should be from 30 to 70%, the humectant concentration 5 to 40%, the pH from 3.5 to 7.5, and the water activity (Aw) below 0.95 or below 0.85 depending on the acidity of the product. The invention allows for the preparation of meat-like products for animals having an elastic coherent structure with a high gel strength from the less attractive varieties or cuts of meats or offals.

Description

~IL087~8 This inVention relates to food products and more especially it relates to food products ~or animals. In certain of its aspects it provides products having the texture, taste and appearance of meat.
There i~ an increasing interest in the preparation of meat-like products from what are generally unacceptable protein sources such as the les~ attractive varieties or cuts of meat or offals, as for example tripe, or from vegetable proteins.
The preparation of meat-like products for animals is complicated b~ the frequent desire to formulate products which are microbiologically stable without the need for elaborate packaging or storage.
One recent approach to the preparation of meat-like products for animals has been that of semi-moist products stabilizèd by humectants at reduced water activity (~). Semi-moist products are u~ually plastic de~ormable materials, but it is- possible to obta~n eLastic coherent mafises of improved chewing properties by the inclusion of relatively high levels of a heat coagulable protein such as gluten. These proteins however re~uire~extraction from a natural source and are reIatively expensive.
It has now been found that it is pos~sible to obtain an elastic coherent structure using an alternative approach.
According to this invention there is provided a solid, bacteriologically stabilized food product having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling, said product comprising: edible solids containing sub-divided edible los7a~s protein material which constitutes at least 10% by weight of said product; 0-25~ fat; 0-3~ antimycotic; 5-40~ humectant; and a matrix bonding said edible material together consisting of a thermo-reversible gelling agent prepared from a polysaccharide containing monosaccharide units at least some of which are other than glucose residues, and being selected from the group consist-ing of xanthan and carob gums, carrageenan, furcellaran, agar-agar, pectin having a degree of methoxyl esterification of less than 40% and mixtures thereof, said gelling agent constituting 0.2-5% of said product; said food product having a pH between about 3.5 and about 4.5 and a bacteriostatic water activity of from about 0.75 to about 0.95, and containin~ from about 3~%
to 70% by weight total moisture, the total concentration of said humectant plus said moisture being greater than about 40% by weight.
As will be apparent, the water activity of the product can be adjusted by altering either or both of the moisture content and the humectant content of the formulation used.
Indeed, it is the relationship between the concentration of the humectant and the moisture content which mainly determines the water activit~. A given wate~ activity may be achieved by having a low level of both humectant and moisture, or a high level of both. It is to be noted, however, that if the combined level of humectant plus moisture becomes too low the gel structure will not form and a plastic product of greater or less stiffness will result.

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~ he actual strength of the product depends, among other things, upon the type o~ protein material used~ ~he protein material ma~ b~ naturally moist, as in the case o~
~resh or cooked meat, of~al or fish, or relativel~ dr~
as i~ the case of meat meal. It may be subdivided as by cutti~g into pieces of desired size or by mirLcing, or by comminution to ~iner particle siæes, as with meals~ Meats with a marked ~ibrous structure 3uch as muscle meat produce ;~
~er~ strong firm gels, whereas tripe which has less fibrosity gives a weaker structure~ Meat meals ~ive a ~uch weaker structure, i~ which it is ~ecessary to increase the gellin~
agent concentration to maintain an acceptable product.
~he preferred protein material is therefore meat having some fibrosity, though meat meals, fish meal~t and vegetable proteins can be employed~ ~he preferred amo~unt of protein material is from 10 to 8~/o by weight of ~he product, and in the case of ~atural meats or fish of normal moisture content from 30 to 8~o~ ' The humectant can be any of a ~ariety of water soluble substances, includi~g those conventionally used in the formu-; lation of food products. Exa~ples include pxopyle~e glycol, sucrose, glucose, glucose syrups, sorbitol, low molecular weight polypeptides (for example fish solubles), glycerol i and ~alt.
While a huméctant will preve~t bacterial growth it will not necessarily prevent mould or yeast ~rowth.
Accordingl~ iO is preferred to incorporate an anti~ycotic _4_ ;
`' ' , ~ILiD8~ 8 additive in a concentration not exceeding 3%, for example up to 0.5% by weight of potassium sorbate or up to 1% by weight of propionic acid. Other suitable additives include benzoic acid, p-hydroxyben~oic acid esters and sorbic acid. When a humectant having antimycotic properties, for example propylene glycol, is used it may not be necessary to add a separate antimycotic.
The pH of the product can be adjusted to a desired value within the range 3.5 to 4.5 by the inclusion where necessary of up to 5% by weight of a food grade acid such as citric, propionic, malic, fumaric, hydrochloric, phosphoric or lactic acid, 1~ The preferred polysaccharide gelling agents, as well as containing non~glucosidic monosaccharide units alone or together with glucose residues, also have acidic substituent groups, for example carboxyl or sulphate groups, which may be free or esterified. The present most preferred gelling system is a mixture of xanthan and carob gums. Other polysaccharide gelling agents can, however, be used, selected from carrageenan, furcellaran, agar-agar or a ;

pectin which has a degree of methoxyl esterification of less than 40%.
Xanthan gum is a relatively low cost gum obtained from the microbial fermentation of sugars and mineral salts by a bacteria of the genus Xanthomonas.
The gum obtained from the preferred bacterium Xanthomonas com~estris has been cleared for food use by the U.S. Food Drug Administration. Xanthan gum is relatively stable to the humectants which are ~i used in semi-moist products and is generally applicable in other types o~ products~ e.g. those including acidulants. It is, however, not able to form gels. The addition of carob gUm7 a non-gelling polysaccharide obtained from the seeds of the leguminous carob gum tree Ceratonia siliqua, to ~anthan gum produces an agent capable of forming a thermoreversible gel which appears to be relatively unaf~ected by, among other things, low pH and high water activity conditions.
A significant advantage which stems from the use of the polysaccharide gelling agents used in this invention is that the quantity needed to obtain the required textural effect is a low percentage of the composition of the product and this allows relatively high moisture contents in the formulations with eonsequent aceeptanee and price advantages. A further advantage to be gained from the use of these gelling agents is the ease with which the final product can be manufactured.
Besides the protein material, humectant, gel, and optional antimycotic additive and acid~ other ingredients can be included, such as are commonly included in meat-like products. Among these ingredients can be fats, oils, flavour-ings, nutritional supplements, and colourings. It is preferred that the fats and oils constitute O to 25% of the product. Well-refined fats and oils with a low free fatty acid concentration give a weaker product in which the fat or oil is poorly emulsified as the fat or oil coalesces, inter-fering with both structure and appearance. On the other . :..~ . . :

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hand, high free fatty acid fats or oils readily emulsify and cause no loss of strength in the gel. Preferred oils are vegetable oils such as arachis, soya, sunflower and rape.
A process for preparing a food product of edible solids held together in a gel matrix, said edible solids including edible protein material, said process comprising the steps of: preparing a mix of edible protein material in amounts such that the eventual product will contain at least 10%
by weight of said edible protein material, and about 30 and 70% total moisture `
providing an aqueous phase; heating said mix to pasteurize it; homogenizing said mix; dissolving in said aqueous phase of said mix either before or after said pasteurizing or homogenizing, a polysaccharide gelling agent containing monosaccharide units at least some of which are other than glucose residues and acidic substituent groups (free or esterified), said gelling agent being capable of forming wi.th water a thermoreversible gel having a melting point above ambient temperature and selected from the group consisting of xanthan and carob gums, carrageenan, furcellaran, agar-aqar,pectin having a degree of methoxyl esterification of less than 40% and mixtures thereof, whereby to form a solution gellable on cooling; incorporating in said mix at any time prior tc gel formation on cooling at least one humectant in an amount such that the eventual product will contain 5-40~ in total of humectant, the total concentration oF said humectant plus said moisture in the eventual product being greater than about 40% by weight; and cooling said mix below said melting point and thereby causing the polysaccharide gelling agent to gel and provide said matrix of said product; said product having a pH between about 3.5 and about 4.5 and a bacteriostatic water activity of from about 0.95 to about 0.75.
The mixture may be formed in a variety of other ways. One preferred process involves pasteurizing the protein material at 100C with water if , .:

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needed ana the other ingred~ents and hom~genizing ~he mixture. Ihis is then followed by th~3 addition of the ~ll~ng age~t and hunectant. The method o oooling may be varied according to the desired texture and product form re~uired.

~ 7a -7(1~3 A simple process is to deposit the mixture onto a tray and cool under an air flow prior to cutting. Alternatively the mixture can be extruded through a simple extrusion plate and cut off into suitably sized pieces.
If required the mixture can be extruded at elevated temperature and pressure so as to create an expanded product. Such a technique produces an aerated spongy appearance in the product simulating certain offal meats such as lung. However, if a meat-coloured mixture is extruded and expanded together with a fat-coloured mixture and the co-extruded product is allowed to set under controlled temperature conditions ~he product has a desirable variegated appear-ance closely approarhing the appearance of fibrous meat with fatty tissue.
The invention will now be illustrated by way of six examples, in which all percentages are by weight unless the context otherwise requires, Examples 2 and 4 being for reference purposes.
Example 1 Tripe 59.55%
Beef dripping 15%
Glycerol 20%
Potassium sorbate0.1%
Carob gum 1.0%
Xanthan gum 1.0%
Dyestuff soln. 0.35%
Citric acid 3.0%
The meat and beef dripping were heated together with stirring at 100C. After 20 minutes the gums and citric acid were mixed in and heated for a further 5 minutes. The heated mix was then made up to the original weight with boiling water, transferred to a high speed homogeniser and the remaining ingredients added. The mlx was poured into a tray, allowed to cool and cut into suitably sized pieces before packing. The product had a tough and firm structure similar !~ . 8 , . ; '. . ~ .,!,' , : i " ~ '. ' , ' ' 11 ! '~ ' ' ' , ' ~LOF~37~

to that of ~eat, with a pH value o~ 3.6 and Aw f 0.88.
Alternatively, the hot mix can be ext~d0d through a mincer plate on to a cool conveyor belt.
~x~
-- ~ibrous meat ~.5~/o Bee~ drippi~ 15%
Glycerol 2~o Sugar 18/~
Potassium sorbate0.1%
Carob gum 1.~o Xanthan gum 1.~/o Dyestuff soln.o.350/O
~he meat, bee~ dripping and su~ar were heated together with stirring at 100C. After 20 minutes the gums, sorbate and dyes were added, with su~ficient water to compensate f`ox the water lost on heating. ~he mixture was transferred to a high speed homogeniser and the glycerol added. ~he mix was poured into a tray and allowed to cool and the solidified product cut into suitably sized pieces iand packed.
~he product had a similar appeara~ce to meat although iti~ texture was softer than that o~ Example 1. ~he water activity was 0.84 and the pH 6~5.
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Pig maws 59.23~
Beef dripping 15%
Glycerol 2C)%
Potassium sorbate0.1~
Carob gum 1.0Yo ~arrageenan 1.~h ~yestuff ~olnØ6~o Citric acid 30~o ~he product was prepared ir. the manner described in Example 1 and was ~ound to have a less elastic, more brittle :.
taxtureO ~he water acti~ity ~as 0.90 and the pE 3.6.
~èS~
j Bee~ dripping 10%
~ripe 60.5%
Propylene glycol ~%
Glycerol 6%
Sucrose 10%
~anthan 1%
. 20 Carob gum ~ 1%
Potassium sorbateØ5%
Dyestuff solnØ01%
Greaves 204~/o Salt 2.5% . :.
~, . 25 ~he tripe, beef dripping a~d grea~es were heated together with stirring at 100C. A~ter 10 minutes the re-Z ~aining ingredients were added and the mixture heated for -~:` . -10~
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a further 5 minutes. The mixture was made up to 95% of the original wei~ht with boiling water, then transferred to a high speed homo~eniser and mixed. ~he final mix was poured o~to a tray and allowed to cool before packi~g~ The Aw was 0.82 and pX 6.5.

Beef dripping 5%
~rip~ 79.3%
Propylene glycol 5%
qo Gl~cerol 5%
Xanthan 1%
Carob gum 1%
Potassiu~ sorbate 0.5%
Citric acid1 . ~o Salt ~
. This product was made up in a similar way to the above product. ~he Aw was 0.93 and pH 4.2.

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~eef dripping 5%
Maw~ 6~/o ` ~iver ~
~i~h solubles5.5%
Propylene glycol5%
Glycerol 5%
Carob gum 1%
Xanthan 1%
Potassium sorbate 0.~/o Salt ~%
Citric acid ~o Fish meal 5~ .
~eef dripping, maws, liver, fish solubles and ~ish meal were heated together for 10 ~inutes at 100C. he re-maining ingredients were added and heated for a ~urther 5 mi~utes. ~he mix was transferred to a high speed mixer and mixed ~or 2 mi~utes. ~he ~inal mix wa~ transferred to a tray, allowed to cool, and then minced through a 5 mm plate prior to packing. ~he Aw was 0.90 and pH 4.2.

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Claims (11)

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

1. A process for preparing a solid, bacteriologically stabilized food product having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling, said process comprising the steps of: preparing a mix of edible protein material in amounts such that the eventual product will contain at least 10% by weight of said edible protein material, 0 to 25% fat and between about 30 and 70% total moisture providing an aqueous phase; heating said mix to pasteurize it; homogenizing said mix; dissolving in said aqueous phase of said mix, either before or after said pasteurizing or homogenizing, a polysaccharide gelling agent containing monosaccharide units at least some of which are other than glucose residues and acidic substituent groups (free or esterified), said gelling agent being capable of forming with water a thermoreversible gel having a melting point above ambient temperature and selected from the group consisting of xanthan and carob gums, carrageenan, furcellaran, agar-agar,pectin having a degree of methoxyl esterification of less than 40% and mixtures thereof, whereby to form a solution gellable on cooling; incorporating in said mix at any time prior to gel formation on cooling at least one humectant in an amount such that the eventual product will contain 5-40% in total of humectant, the total concentration of said humectant plus said moisture in the eventual product being greater than about 40% by weight;
and cooling said mix below said melting point and thereby causing the polysaccharide gelling agent to gel and provide said matrix of said product;
said product having a pH between about 3.5 and about 4.5 and a bacterio-static water activity of from about 0.95 to about 0.75.

2. The process of claim 1 wherein said polysaccharide gelling agent is a mixture of xanthan and carob gums.

3. The process of claim 1 wherein the solid, bacteriologically stabilized food product contains about 10 to 80% edible protein materials said materials having a moisture content consistent with an overall moisture content of the product of about 30 to 70% moisture.

4. The process of claim 1 wherein the solid bacteriologically stabilized food product contains about 30 to 80% edible protein materials and a gelling agent selected from the group consisting of xanthan, carrageenan, furcellaran gums and mixtures thereof with carob gum.

5. The process according to claim 1 wherein said mixture is deposited onto a tray and cooled under an air flow.

6. The process according to claim 1 wherein said mixture is extruded.

7. The process according to claim 1 wherein said mixture is extruded at elevated temperature and pressure so as to create an expanded product.

8. A solid, bacteriologically stabilized food product having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling, said product comprising:
edible solids containing edible protein material which constitutes at least 10% by weight of said product; 0-25% fat; 0-3% antimycotic;
5-40% humectant; and a matrix bonding said edible material together consisting of a thermo-reversible gelling agent prepared from a polysaccharide containing monosaccharide units at least some of which are other than glucose residues, and being selected from the group consisting of xanthan and carob gums, carrageenan, furcellaran, agar-agar, pectin having a degree of methoxyl esterification of less than 40% and mixtures thereof, said gelling agent constituting 0.2-5% of said product; said food product having a pH between about 3.5 and about 4.5 and a bacteriostatic water activity of from about 0.75 to about 0.95 and containing from about 30% to 70% by weight total moisture, the total concentration of said humectant plus said moisture being greater than about 40% by weight whenever prepared by a process according to claim l or equivalent thereof.

9. A food product according to claim 8 having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling, wherein the polysaccaride gelling agent is a mixture of xanthan and carob gums whenever prepared by a process according to claim 2 or equivalent thereof.

10. A food product according to claim 8 having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling, comprising 10-80% sub-divided edible protein materials having a moisture content consistent with an overall moisture content of the product of about 30 to 70% whenever prepared by a process according to claim 3, or equivalent thereof.

11. A food product according to claim 8 having elastic chewing properties and being fluidizable with heat and reversibly setting to a gelatinous solid upon cooling wherein said edible material contains from about 30 to about 80% by weight of natural edible protein material and the gelling agent is selected from the group consisting of xanthan, carrageenan, and furcellaran gums and mixtures thereof with carob gum whenever prepared by a process according to claim 4 or equivalent thereof.