CA1068537A - Preserved proteinaceous food product - Google Patents

Abstract

A B S T R A C T

A shelf stable food product, which can be used for domestic animals comprises solid protein pieces in an aqueous gel or gravy and contains 6 - 20% protein, 3 - 12 %
fat and 65 - 95 % moisture and is stablized by a pH of 4.5 or below achieved with acid-producing micro-organisms. The preferred method of preparation employs a gelling agent which is caused to gel at a pH value above 4.5, and the pH
is reduced by fermentation to a value below 4.5 to give a relatively acid product. Gelling or thickening agents may be polysaccharides, including pectin substances, or thermoreversible gelling systems such as gelatine.

Description

The present invention relates to gelled or thickened food products and in particular to microbiologically stable products containing edible proteinaceous solids in aqueous medium.
Compositions comprising particles or pieces of meat or other edible protein solids in a gelled or thickened aqueous medium are ~ell known, in both human and animal food contexts, for example as brawns and meat-in-jelly or meat-in-gravy products. Such products, however, are not ordinarily shelf-stable and can only be stored by special measures, usually by sterilization within sealed containers, as by canning.
According to the present invention there is provided a food product comprising solid foodstuff, including particles or pieces of proteinaceous tissue, in an aqueous medium, such as a gel or thickened gravy, surrounding said foodstuff, the product having a moisture content of 65-95%, a protein content of 6-20% and a fat content of 3-12%, and being maintained under antimycotic conditions and microbiologically stable by virtue of an acidic pH value not exceeding 4.5 achieved or maintained by acid-producing micro-organisms.
The product preferably has a pH in the range 3.5-4.5 and should be maintained under antimycotic conditions usually by the inclusion of an antimycotic, for example sorbic acid compounds such as potassium sorbate, benzoates such as p-hydroxy benzoate or a mixture of the two.

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--- - 10t;853'7 I~ the past~ difficulties ha~-e been encountered in forming stable gel co~figuration~ with co~entio~al gelling age~ts at the low pH values employed in this i~vention for securing stabilit~.

In accorda~ce with a further important aspect of this i~ve~tion, a gel structure i9 formed by a gelling agent in a mix containing a solid foodstuff including protei~aceous tiss~ue, ferme~table substance a~d moisture at a pH value above 4.5 a~d the compositio~ is thereafter subjected to acid-produci~g fermentatio~
u~til its p~ value is 4.5 or below, especially in the ra~ge 3.5-4-5. -.
~his.tèc~ique of forming a~ aqueous mIx co~tai~ing ed.ible protei~ tissue at a pH above 4.5 aDd subsequently a¢hisvi~g micro-biological stability by fermentatio~ with a¢id-producing orga~isms is ~ot, however, confined to products having a rigid gel matrix. It ca~ also be employed more generally to obtain products of the type, for example, of meat i~ gravy. I~ these cases, a gelling age~t or thic~e~er may be prese~t to provide a thicke~ed gravy or ~uch age~ts ma~ be 20 : completel~ absent. ~his procedure has the adva~tage that it ca~ be carried out, without adaptation, in the same pla~t as is employed i~ the production of gel products as described above.
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~ 0~,8537 Accordingl~, the method of this invention ca~ be broadly defined a~ formi.ng a mix containi~g particles or pieces of edible proteinaceous tissue, a~d preferably also fa~ and . -:
moisture in the abo~e defined proportions, including fermentable ~ubstance and having a pH value above 4.5; and thereafter . subjecti~g the mix to acid-producing fermentation until its pH
~alue is 4.5~ or below and a microbiblogicPlly stable compositi~n i~ produced.

I~ most cases where a gel i8 required, the freæhly prepared m~x and the de.sired acid-producing microorganisms .are filled into packaging containers and subsequentl~ incubated in the contai~erY. When a gravy product is being made, howe~er, or when a low temperature thermoreversible gel system i8 emplo~ed, --- the mix can be ferme~ted in bulk and held at the incubation .temperature until it is packaged.

~ uitable gelling agents include polysaccharide gelling age~ts such as pectic substances, alginates, guar gum,carrageenan and carob ~m, alæo starches and gelling agentæ of microbial ~ origin, such as microbial alginates and xanthan gum.
Proteinaceous gelling agents such as gelatin can also be used, bub preferably not solel~ protein~ of the casein group.
~he mix may contain a source of calcium or other acceptable div~lent metal ions, more especially for nutritional .rea~ons or where such io~s are nseded to as~ist i~ the formation of a good gel structure. The necessity for a~ exogenous source of calcium-ions will depend on the gelling agent or agents used, , - . - . . ..

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1~537 the ~ature of the ingredie~ts and nutritio~al requirements.

Pectic substances employed i~ this invention are preferably pectates or pecti~s having a degree of esterification (D.E.) below 2~/o. Crude natural sources of pectins can be employed, especially when their D.E. has been reduced, chemically or ` enzymatically, to below 20/o.

Citrus peel is a readly available source of pectins and in this specification the expression 'treated citrus peel' refe~s to citrus peel that has been comminuted and its D.E.
reduced below 2c~h by treatment with alkali or enzymes or by promoti~g the action o~ en~ymes naturally contained within th peel. Where a rigid gel is desired it is preferable to include a source of calcium io~s and sequestrant such as sodium tripolyphosphate, tetrasodium pyrophosphate or citric acid.

As proteinaceous ti~sue in the product of this invention may be used, and by thi~ term is thus meant to be ` iucluded, an~ edible, solid, ordinarily insoluble protein sue9 notably traditional meats, i~cluding fish or poultry, offals, other animal protei~ sources such as dried greaves, vegetable protei~ materials and structured or textured proteins, ~eaty materials may be pasteurized or sterilized, as may be required by current food regulations or a~ demanded in achieving .

' desirable microbiological safety ~tandards.

~part from the proteinaceous material, or other solid foodstuff, fat moiæture and ~elling agent, the product will usually contain residual ferme~table carbohydrate, a~d may also contain vitamins or other nutritional supplements, -¢olouring agents, antioxidants, antimycotics, preser~atives or other additives.
In putting the invention into practice, a solution may be prepared with desired amount of water and containing the gelling agent, any necessary calcium or other metal ion, ~equestrant and fermentable substances additional to aI~y already present in the other ingredients such as fermentable carboh~drate, e.g. glucose or lactose, and optionally a~ organic nitrogen source, and preferably also a~ a~timycotic. ~he solution may be hea~ed to dissolve the soluble substances, but should the~
be cooled before a c~lture of an acid producing micro-organism i8 added. Preferred micro-organisms are homo-fermentative la¢tic acid-producing bacteria such as ~actobacillus Casei, ~. ~ul~aricus~ Stre~tococcus lactis and S. thermoPhilus, either singly or in any combination.It has bee~ found most convenient to add the micro-organisms in the form of a~
i~oculum, in a quantity depending on the time necessary for fermentation to the final pH and on the strain of micro-organisms used. The quantity will most usually be in the ran~e .

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of 1-10% b7 weight of the total composition as packed.
Other forms of cultu~for example freeze-dried starter cultures, ca~ also be used.
~he solution, which will ordinarly have a pH in the regio~ of 6, is then mixed with the solid ~oodstuffs~
which may be a previously prepared a~d pasteurized mix of meats or meat by-products, but may also include or consist of vegetable protein i~ a suitably prepared from. ~he latter need not be pasteurized in the manner necessary in the case of meats. ~he protein materials may be finely divided into particles, for example by grinding, b~t more usually will be in the form of minced or chopped pieces which, at least in the case of pasteurized meat chunks, are preferably not larger tha~ ~.0 cm3. This limit is less significant in the case of sterilized materials or vegetable protein materials such as textured vegetable protein, but the pieces should not be larger than is convenient for filling t-he containers to be employed or for acceptance by the consumer.
When the solution of gelling agent and the inoculum have been mixed with the solid proteinaceous materials, the composition is subJected to m cubation conditions. ~he gelling agent will form a gel structure throughout the product under the relatively neutral pH conditions prevailing in the earl~

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-- 10~8S37 of incubation, but as incubation proceedq the micro-organisms will bring about a reduction in p~I ~alue until st~bility is reached at a pH value of 4.5 or less without loss of the gel structure. ~he product may be packed into sealable containers before incubation or, when a thermo-reversible gel is pro~uced, it may be incubated in bulk at a temperature above the gel point and packed before cooling. Gravy type products can also be fermented in bulk. The resulting product will usu~lly contain, and indeed preferably contains, viable acid-producing organisms, and can be stored for long periods at ordi~ary temperatures.

I~ the preferred embodiments of the prese~t process, a sequestering agent, antimycotic, colouring agent a~d glucose ma~ be added to cold water and dissolved while being heated to, for example, 70 - 90C whereupo~ gelling agents such as treated citrus peel a~d guar gum are added with vigorous agitation.
~he mixture is then cooled to ~5 - 4~C before the acid-producing fermentation inoculum is added.
Alternatively, the sequestering agent may be dissolvèd in water and glucose and, if desired, a~ organic nitrogen source added and-dissolved. ~he temperature of the liquid i9 raised, for example to 70 - 90C a~d the gelling agents such as treated citrus peel and guar gum are added with vigorous agitation.
~he mixture is then partially cooled before the addition of pot~s~ium sorbateg colouring agents as desired, and a~ acidic , .
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, fermentation i~oculum Or lactic acid-producing bacteria, e.g.
. casei or S. lactis.

~he gravy mix prepared by either of these alternative procedures is added to a previously prepared and pasteurized or sterilized meat mix. ~he resultant mixture may be packaged in tra~sparent plastic re-sealable containers before being i~cubated, for example at 30C for 12-24 hours.

A further alternative is for the inoculum to be added bo the mixed meats after they have been mixed with the gravy.
When proceeding in this way, on may be able to make use of the temperature difference betwee~ the meats and the gravy to effect so~e of the necessary cooling.

~he products prepared in this way ~ay be found to possess a good meat-in-jelly appearance with a fresh meaty aroma. ~he food is highly acceptable to pet anlmals.
~he following examples illustrate the practice of this inve~tio~. All perce~tages are b~ weight unless the context otherwise requires.
Example 1 ~his example illustrates the preparation of a stable low pE7 high Awohunky ~eat in aelly food product.

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~06~353'7 ~ ripe, luns and musclè meats were comminuted by passage through a mincer fittèd with a 1.0 cm plate and four-bladed cutter. ~he meats were mixed in the xatio 44:40:16 of tripe:lung:muscle meats and the muxture was boiled for 20 min at 100C
A gravy was prepared to the following formulation:
Water ~Z-54 Sodium tripolyphosphate 0.5 Glucose 2.8 Potassium sorbate 0-4 D~estuff As desired Guar B
~reated citrus peel 0.93 Inoculum 1.90 ~he sodum tripolyphosphate, glucose, potassuim sorbate and dyestuff were added to the water, and the mixture was heated to 70C with agitation. ~he guar B and treated peel were added with ~igorous agitation and the temperature was increased to 80C. ~he resultant mixture was cooled to 35a before the addition of the inoculum which was a 20IH
culture of ~. casei.
- ~he gravy was added to the meat mix in a meat:
~ravy ratio of 70:30 and mixed well before being packaged in tran~pare~t plastic pots with resealable lids. ~he pH of the mix~ure was 6.4.

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:i: . ., . , ,, ,, . -- . -~68537 ~he pots were placed in an incubator at 30C for ~4 hours.
During the initial part of this period, i.e. 1-2 hours, the io~ic gel structure formed. Only subse~uently did the viable inoculum reduce the pH of the system ~o 3.8 - 4.2 by conversio~ of the added sugars to lactic acid. ~he gel system was stabilized against sy~eresis b~ the guar gum.

~ he inoculum was prepared b~ growing a pure c~ture of I~acto-bacillus casei in MRS broth for a period of 12-20 hours.
~ he product possessed a very attractiv~ appearance with discrete chunks of meat in the jelly matri~. It appeare~
very similar to traditional c~nned aelly meat pet food products.
Exa~ple 2 ~ hi5 example demonstrate~ the production of a microbiologically stable brawn-like product.
~ meat mix was prepared as in Example 1 except that (a) the meats were put through a 4.0 mm plate, (b) equal ratios of lung a~d muscle meats were used, and (c) the meats were boiled in the presence of 0.4% potassium sorbate.
` A grav~ was prepared to the following formulation:
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- Water ~ 90.64 Sodium tripolyphosphate 0.50 - Glucose 2.80 ~reated citrus peel 0.93 Guar gum 0.9 Po~assium sorbate 0.4 Dyestuff ~s desired Inoculum ~.80 .. , ;. . , .. ............. . - .- ~ ~ -., . . . . . , . - .

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~068537 The gravy was prepared as degcribed i~ Example l.
~he inoculum was a culture of ~. bul~aricus prepared as described for I~ casei in Examplel.
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~he meat and gravy mixes were combined in the ratio 52:48 and the resultant mix packaged in plastic tubs of the t~pe conve~tionally used to hold margarine. ~he tubs were incubated for 24 hours at 30C.
~he product exhibited a pH of 4.0 and a brawn-like appearance. It waR stable at ambient temperature against any microbial attack.

~ he contal~er can serve either as a re-sealable supply vessel of the food ar as a disposable food dish.

~ his Example demonstrates the use of anothex gel system normally unstable during formation at acid pH values.
A ~olution of 20/o spray dried skimmed milk solids in water was prepared. To 3000 ml. of this solution at 80C
were added 6.0 g of carrageena~, 3.0 g of potassium -~orbate, ~ 27.0 g of ~otassium chloride and colouring agents. These components were dissolved and then 600 g of cooked meat chunks were added. ~he whole mixture was cooled to 68C
before the addition of 5.0 ml of a viable suspen~ion of ~.
ca~ei i~ MRS broth. The inoculum was mixed in and the mixture poured into suitable tran~parént containers.
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106853~7 ~he containers were then rapidly cooled to about 40C before bein~ put into an incubator at 3C for 12-15 hours.
The product had the appearance of meat chunis in a cloudy opa~ue gel system. The pH of the product was 4.0 and it possessed a meaty and milky aroma. It was highly acceptable to pet animals especially cats.
Exæmple 4 ~his Example shows the use of an alternative ionic gel system.
10` A high ~iscosity alginate (grade IH7) was used as in Example l in place of the treated peel at 5CP~ of the level of treated peel, i.e. 0.5%. ~he product has the same appearance as that described in Example 1.
~x~nple 5 ~his Example demonstrates the use of a thermal setting gelling agent in the process of this invention.
Calcium and phosphorus are included at desirable additional levels. ~he calcium doe~ not here play any part in the gel system.

Meats were prepared a~d cooked as described i~
Example 2.

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A gra~y was prepared to the following formulation:
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Calcium Phosphate (Ca3(P04)2) 0~8 Gelatine 7-5 Glucose 6.0 Potassium sorbate 0.4 Erythrosine solution . 0 5 Caramel 0.75 Inoculum (~ Casei) 2.0 (of total composition as - packed) Water to l00%
The gravy w~s prepared by dissolving all the - in~redients in water, heating gently to dissolve the gelatine, and cooling the mixture to 40 - 45G before addi~g the inoculu~.
~he grav~ ~as added to the meats in a 70 : 30 meat/gravy ratio~
well mixed and the composition was packaged i~ reseqlable containers prior to incubation at 30C for 24 hours.
~he product had a pH of 4.3 a~d the ~ollowing analy~
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- - Mixture 8~.0 Protei~ ll.5 ~at 2-5 Ash -9 % acidity - 1.77 ~he gelatine gel was tough and rubbery and the product Dxhibited a ~ery pleasing apperance .
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Example 6 1~8S37 ~y using an inoculum e.g. of ~. buI~aricus with a highergrowth temperature, i.e. 42C~the above Example ~ can be adapted to fermentation in bulk prior to packaging, the gel being allowed to set on cooling in the individual containers.
Example 7.
~ his example illustrates the use of dry ingredients in the formulation.

A grav~ is prepared according to the following formulation:
` ~ of total Product Sodum tripolyphosphate 0.25 ~reated peel 0.5 Guar gum ~5 Caramel 1.5 Erythrosine solution 0.5 Potassium sorbate 0.4 Glucose (e.g. ~rudex) ~.0 Org~nic nitrogen source 0.5 (e.g. Corn Steep Liquor) Water ~ to 75.0 only half of the water is used i~ gravy preparation.

After preparation of the gravy as described previously the remaining cold water is added, ~ollowed by the required amount of dried greaves i.e. 25% of the total product. ~he additional of cold ingredie~ts at this stage lowers the temperature of the mixture to 30 - 40~ and he~ce avoids the necessity.

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Of an additional cooling step prior to additional o~ the inoculum (3%). All ingredients are then throughly mixed prior to packaging and incubation at 30C ~or 24 hours.

After 24 hours the pH of the mixture had falle~
to PH 4.2.
Example 8 The following is an e~ample o$ a meat`and cereal product.
Conditioned sheep lung which had been minced through a 1.0 cm plate was mixed with~
Maize Grits 15% ( based on the wèigh~ of lung) Wheat`Feed 5% ( based on the weight of lu~g) ~ e meat and cereals were cooXed at 121C for 50 minutes to produce a firm 'loaf~ structure.
A gra~y was prepared according to the formulation:-- -` h of Grav~
,' Treated citrus peel 1.0 Guar gum 1.0 ` ~ Glucose 7.0 ~otasslum sorbate 0.4 Sodium tripolyphosphate 0.5 Caramel 1.5 Erythrosine solution 0.5 Water Bala~oe.
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` --` 11)68537 ~ he meat and cereal~ were formulated with gravy in a 60:40 ratio and the mixture cooled to 35C before inoculation with ~. bul~aricus suspension (3.CP/c of total pack). After packaging a~d incubation, the product had a p~ of 3.9 and a firm 'loaf' type structure with a cereal aroma.
Example 9 ~ his example demonstrates the preparation of a greav,y product.
3.5 kg of conditin~ed sheep lung was minced through a 3.0 mm plate using a Hobart mincer fitted with a four bladed : cutter. ~he minced meat was cooked at 121C fo~ 50 mi~s.
A gravy was prepared accor~ing the following for~ulatio~:-- . . ~ of ~ravY
,, ' G~uax gum ' ' 1.0 , . .
`~ Glucose (Trudex) 8.0 Caramel . 1.5 Erythrosi~e 801ution 0. 5 potassium sorbate 0.4 ,~ Emulsif~ing age~t (Tween 80) 1.0 . Artificial flavour 10.2 Water Balance .
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106~537 ~ he gra~ was prepared as descrlbed pre~iou~ly.
Meats a~d gravy were mixed together in a 70;30 ratio and cooled to 35C prior to inoculation with a 20 IE old ~S both suspension of ~. Casei (3% of the total mix). The inoculum was mixed in well a~d the mixture packaged in 'Saran' (Trade Mark) pouches, sealed and incubated at ~0O for 24 hours.
~ he final pH of the product was 4.2 and it possessed a mince meat in thick, rich gravy, type of appearance.
Example 10 ~his example demonstrates the use of a starch gravy.
A ~ravy Sheep lu~g was prepared as described above. A gravy was prepared to the followin~ formulation:-/0 of Grav~
: aa3 (P04)2 0.8 Glucose 6.0 *P - OE ~enzoates 0.5 Erythrosine æol. 0.5 Caramel 1.5 `, Modified St~rch (Col-~lo) 5.0 Water. Balance I~ this context the calcium phosphate was added as a ~utritio~al supplement.
* P - OH ~enzoates = a 3:1 o~ methyl and propyl substituted benzoate~.
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1068~37 ~ he grav~ was added to the cooked meats in~eratio of 30:70 and the mixture cooled to 35C. The i~oculum at a level of 2% of the total pack was added a~d lnixed well ~ ne resultant mixture was packed into plastic tubs ar~d 5 i~cubated at ~0C for 20 hours.
~ he product had a pH of 4.1 and a meat in gra~
appearance.

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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A food product comprising:
solid foodstuff, including particles or pieces of edible proteinaceous tissue;
and an aqueous medium surrounding said foodstuff said product having a protein content of 6 - 20%, a fat content of 3 - 12%, a moisture content of 65 - 95% and being maintained under antimycotic conditions and at a pH
value not exceeding 4.5 by acid-producing micro-organisms.

2. A food product according to Claim 1, wherein said aqueous medium contains acid-producing micro-organisms in viable form.

3. A food product according to Claim 1 wherein said aqueous medium contains a gelling agent and is thereby maintained as a stable gel.

4. A food product according to Claim 3, wherein said gelling agent is a polysaccharide gelling agent.

5. A food product according to Claim 4, wherein said gelling agent is a crude pectin source the degree of esterification whereof has been reduced to below 20%.

6. A food product according to Claim 3, wherein said gelling agent is gelatine.

7. A food product according to Claim 1 wherein said proteinaceous tissue comprises animal tissue in pieces not exceeding 3.0 cm3 in size.

8. A method of making a food product comprising solid proteinaceous foodstuff in an aqueous medium, which comprises forming a mix containing particles or pieces or edble proteinaceous tissue, including fermentable substance and having a protein content of 6 - 20%, a fat content of 3 - 12%
and 65 - 95 % moisture at a pH value above 4.5;
and thereafter subjecting said mix to acid-producing ferm-entation until its pH value is 4.5 or below and a microbiologic-ally stable composition is produced.

9. A method of making a food product comprising solid proteinaceous foodstuff in an aqueous gel, which method comprises:
forming a mix containing particles or pieces of edible proteinaceous tissue, including fermentable substance and a gelling agent and having a protein content of 6 - 20 %, a fat content of 3 - 12 % and a moisture content of 65 - 95%

at a pH above 4.5;
initiating the formation of a gel at a pH above 4.5;
and subjecting the mix to acid-producing fermentation until its pH is 4.5 or below and a microbiologically stable composition including an aqueous gel is produced.

10. A method according to Claim 9, wherein a culture of acid-producing micro-organisms is incorporated in said mix, and after formation of the gel at a pH above 4.5 the mix is incubated to promote fermentation.

11. A method according to Claim 10, wherein the micro-organisms comprise Lactobacillus casei, L. bulgaricus, Streptococcus thermophilus or S. lactis, or a mixture thereof.

12. A method according to Claim 10 wherein said gelling agent and fermentable substance are dissolved in water and the solution and the culture of micro-organisms together with an antimycotic are mixed with said proteinaceous tissue.