IE42863B1 - Food product and process - Google Patents

Abstract

A foodstuff or animal feed containing pieces of edible protein in a gelled aqueous medium with a total moisture content of 65 to 95% is prepared. A mixture containing 6 to 10% of protein, 3 to 12% of fat, fermentable carbohydrates, thermally reversible gelling agent, an antimycotic and moisture is formed at a pH of greater than 4.5. The mixture is inoculated with an acid-producing microorganism and fermented until it reaches a pH of at most 4.5. Stable foodstuffs or animals feeds are obtained by this process.

Description

The present invention relates to gelled or thickened food products and in .particular to the preparation of microbiologically stable products containing edible proteinaceous solids in an aqueous medium.

Compositions comprising particles or pieces of meat or other edible protein solids in a gelled or thickened aqueous medium are well 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 shelfstable 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 method of making a microbiologically stable food product comprising solid proteinaceous foodstuff in a gelled or thickened aqueous medium, which method comprises: forming a mix containing particles or pieces of edible proteinaceous tissue suspended in an aqueous medium fermentable substance, gelling agent and antimycotic, the mix having a protein content of 6-20%, a fat content of 3-12% and a pH value above 4-5 5 incorporating a culture of acid-producing micro-organisms in the mix, and thereafter promoting acid-producing fermentation of the said organisms until the pll value of the mix is below 4-5 and a microbiologically stable composition is produced having a moisture content of 65-95% all percenCages being by weight.

The product preferably has a pH between 3-5 and 4-5 to inhibit the growth of bacteria, and mould growth is prevented - 2 4 2 8 6 3 by the inclusion of the antimycotic, for example sorbic acid compounds such as potassium sorbate, benzoates such as p-hydroxy benzoate, or a mixture of the two.

In the past, difficulties have been encountered in 5 forming stable gel configurations with conventional gelling agents at the low pH values employed in this invention for securing stability.

In accordance with a further important aspect of this invention, a gel structure is formed by a gelling agent in the mix at a pH value above 4-5 and the composition is thereafter subjected to acid-producing fermentation until its pH value is below 4·5 This technique of forming an aqueous mix containing edible protein tissue and other ingredients at a pH above 4-5 and subsequently achieving micro-biological stability by fermentation with acid-producing organisms is not, however, confined to products having a rigid gel matrix. It can also be employed more generally to obtain products of the type, for example, of meat in gravy, in which the gelling agent serves as thickener.

This procedure has the advantage that il. can be carried out, without, adaptation, in the same plant as is employed in t.he production of' gel products as described above. - 3 63 In most cases where a gel is required, the freshly epared mix and the desired acid-producing micro-orgaiams are lied into packaging containers and subsequently incubated in e containers. When a gravy product is being made, however, when a low temperature thermoreversible gel system is employed, ie mix can be fermented in bulk and held at the incubation imperature until it is packaged.

Suitable gelling agents include polysaccharide gelling agents such as pectic substances, alginates, guar gum, carrageenan id carob gum, also starches and gelling agents of microbial rigin, such as microbial alginates and xanthan gum. roteinaceous gelling agents such as gelatin can also be used, ut preferably not solely proteins of the casein group.

The mix may contain a source of calcium or other cceptable divalent metal ions, more especially for nutritional easons or where such ions are needed to assist in the formation f a good gel structure. The necessity for an exogenous source f calcium ions will depend on the gelling agent or agents used, - 4 42863 the nature of the ingredients and nutritional requirements.

Poetic substances employed in this invention are preferably pectates or pectins having a degree of esterification (D.E.) below 20%. Crude natural sources of pectins can be employed, especially when their D.E. has been reduced, chemically or enzymatically, to below 20%.

„· Citrus peel is a readly available source of pectins and in this specification the expression 'treated citrus peel' refers to citrus peel that has been comminuted and its D.E. reduced below 20% by treatment with alkali or enzymes or by promoting the action of engymes naturally contained within the peel. Where a rigid gel is desired it is preferable to include a source of calcium ions and sequestrant 3uch as sodium tripolyphosphate, tetrasodium pyrophosphate or citric acid.

As proteinaceous tissue in the product of this invention may be used, and by this term is thus meant to be included, any edible, solid, ordinarily insoluble protein tissue, notably traditional meats, including fish or poultry, offals, other animal protein sources such as dried greaves, vegetable protein materials and structured or textured proteins, Meaty materials may be pasteurized or sterilized, as may be required by current food regulations or as demanded in achieving -5563 dosirablo microbiological safety standards.

Apart from the proteinaceous material, or other solid foodstuff, fat moisture and gelling agent, the product will usually contain residual fermentable carbohydrate, and may also contain vitamins or other nutritional supplements, colouring agents, antioxidants, preservatives or other additives.

In putting the invention into practice, a solution may be prepared with a desired amount of water and containing the gelling agent, any necessary calcium or other metal ion, sequestrant and fermentable substances additional to any already present in the other ingredients such as fermentable carbohydrate, e.g. glucose or lactose, and optionally an organic nitrogen source, and preferably also the antimycotic. The solution may be heated to dissolve the soluble substances, but should then, be cooled before a culture of an acid producing micro-organism is added. Preferred micro-organisms are homo-fermentative lactic acid-producing bacteria such as lactobacillus Casei, 1. Bulgaricus, Streptococcus lactis and S. thermophilus, either singly or in any combination.lt has been found most convenient to add the micro-organisms in the form of an inoculum, in a quantity depending on the time necessary for fermentation to the final pH and on the strain of microorganisms used. The quantity will most usually be in the range -642863 of 1-10% by weight of the total composition as packed.

Other forms of culture,for example freeze-dried starter cultures, can also be used.

The solution, which will ordinarly have a pH in 5 the region of 6, is then mixed with the solid foodstuffs, which may be a previously prepared and pasteurized mix of meats oi' meat by-products, but may also include or consist of vegetable protein in a suitably prepared from. The latter need not be pasteurized in the manner necessary in the case of meats. The protein materials may be finely divided into particles, for example by grinding, but 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 than 3.0 cm2. This limit is less significant in the case of ^•5 sterilized materials or vegetable protein materials such as textured vegetable protein, but the pieces should not be larger than is convenient for filling the 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 incubation conditions. The gelling agent will form a gel structure throughout the product under the relatively neutral pH conditions prevailing in the early •7383 stages of incubation, but as incubation proceeds the micro-organisms will bring about a reduction in pH value until stability.is reached at a pH value below 4-5 without loss of the gel structure. The product may be packed into sealable containers before incubation or, when a thermo-reversible gel is produced, 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 usually contain viable acid-producing organisms, and can be stored for long periods at ordinary temperatures.

Ih the preferred embodiments of the present process, a sequestering agent, antimycotic, colouring agent and glucose may be added to cold water and dissolved while being heated to, for example,’ 70 - 90% whereupon gelling agents such as treated citrus peel and guar gum are added with vigorous agitation.

The mixture is then cooled to 35 - 45% before the acid-producing fermentation inoculum is added.

. Alternatively, the sequestering agent may he dissolved in water and glucose and, if desired, an organic nitrogen source added and dissolved. The temperature of the liquid is raised, for exanple to 70 - 90°C and the gelling agents such as treated citrus peel and guar gum are added with vigorous agitation.

The mixture is then partially cooled before the addition of · potassium sorbate, colouring agents as desired, and an acidic 842863 fermentation inoculum of lactic acid-producing bacteria, e.g.

L. casei or S. lactis.

The gravy mix prepared by either of these alternative procedures is added to a previously prepared and pasteurized or sterilized meat mix. The resultant mixture may be packaged in transparent plastic re-sealable containers before being incubated, for example at 50°C for 12-24 hours.

A further alternative is for the inoculum to be added to the mixed meats after they have been mixed with the gravy.

When proceeding in this way,one may be able to make use of the temperature difference between the meats and the gravy to effect some of the necessary cooling.

The products prepared in this way may be found to possess a good meat-in-jelly appearance with a fresh meaty aroma. The food is highly acceptable to pet animals.

The following examples illustrate the practice of this invention. All percentages are by weight unless the context otherwise requires.

Example 1 This example illustrates the preparation of a stable low pH, high water activity (A)w chunky meat in jelly food product. -92803 Tripe, lung and muscle meats were comminuted by passage through a mincer fitted with a 1.0 cm plate and fourbladed' cutter. The meats were mixed in the ratio 44:40:16 of tripe:lung:muscle meats and the mixture was boiled for 20 min at 100°C A gravy was prepared to the following formulation % Hater 92.54 Sodium tripolyphosphate 0.5 Glucose 2.8 Potassium sorbate 0.4 Dyestuff As desired Guar gum 0.93 Treated citrus peel 0.93 Inoculum 1.90 ’ The sodum tripolyphosphate, glucose, potassuim sorbate and dyestuff were added to the water, and the mixture was heated to 70°C with agitation. The guar gum and treated peel were added with vigorous agitation and the temperature was increased to 80°C. The resultant mixture was cooled to 35°0 before the addition of the inoculum which was a 20LH culture of L. oasei.

The gravy was added to the meat mix in a meat: gravy ratio of 70:30 and mixed well before being packaged in transparent plastic pots with resealable lids. The pH of the mixture was 6.4. -1042S63 The pots were placed in an incubator at 30°C for 24 hours.

During the initial part of this period, i.e. 1-2 hours, the ionic gel structure formed. Only subsequently did the viable inoculum reduce the pH of the system to 3.8 - 4.2 by conversion of the added sugars to lactic acid. The gel system was stabilized against syneresis by the guar gum.

The inoculum was prepared, by growing a pure culture of Lacto-bacillus casei in M.R.S. (de Mann, Rogosa and Sharp) broth for a period of 12-20 hours.

The product possessed a very attractive appearance with discrete chunks of meat in the jelly matrix. It appeared very similar to traditional canned jelly meat pet food products.

Example 2 This example demonstrates the production of a microbiologically stable brawn-like product.

A 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 and muscle meats were used, and (c) the meats were boiled in the presence of 0.4% potassium sorbate.

A gravy was prepared to the following formulations % Water 90.64 Sodium tripolyphosphate 0.50 Glucose 2.80 Treated citrus peel 0.93 Guar gum 0.93 Potassium sorbate 0.4 Dyestuff As desired Inoculum 3.80 *1 T She gravy was prepared, as described in Example 1.

She inoculum was a culture of 1. bulgaricus prepared as described for L. casei in Example :i.

She meat and gravy mixes were combined in the ratio 52:48 and the resultant mix packaged in plastic tubs of the type conventionally used to hold margarine. She tubs were incubated for 24 hours at 30°C.

She product exhibited a pH of 4.0 and a brawn-like appearance. It was stable at ambient temperature against any microbial attack.

She container can serve either as a re-sealable supply vessel of the food or as a disposable food dish.

Example 5 Shis Example demonstrates the use of another gel system normally unstable during formation at acid pH values.

A solution of 20% spray dried skimmed milk solids in water was prepared. So 3000 ml. of this solution at 80°C were added 6.0 g of carrageenan, J.O g of potassium sorbate, 27.0 g of potassium chloride and colouring agents. Shese components were dissolved and then 600 g of cooked meat chunks were added. She whole mixture was cooled to 68°0 before the addition of 5·θ ml of a viable suspension of L. casei in MRS broth. She inoculum was mixed in and the mixture poured into suitable transparent containers. -12The containers were then rapidly cooled to about 40°C before being put into an incubator at JO°c for 12-15 hours.

The product had the appearance of meat chunks in a cloudy opaque 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.

Example 4 This Example shows the use of an alternative ionic gel system.

A high viscosity alginate (grade LH7) was used as in Example 1 in place of the treated peel at 50% of the level of treated peel, i.e. 0.5%· The product has the same appearance as that described in Example 1.

Example 5 · This 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. The calcium does not here play any part in the gel system.

Meats were prepared and cooked as described in Example 2. 13833 A gravy was prepared to the following formulation? % Calcium Phosphate (Ca^OPO^) Gelatine Glucose Potassium sorbate Erythrosine solution Caramel Inoculum (E Casei) Uater 0;8 7-5 6.0 0.4 0.5 0.75 2.0 (of total composition as packed) to 100% The gravy was prepared by dissolving all the ingredients in water, heating gently to dissolve the gelatine, and cooling the mixture to 40 - 45°C- before adding the inoculum. The gravy was added to the meats in a 70 : 3θ meat/gravy ratio, well mixed and the composition was packaged in resealable containers prior to incubation at 30°C for 24 hours.

The product had a pH of 4.3 and the following analysis: % Mixture 84.0 Protein 11.5 Pat 2.5 Ash 0.9 % acidity 1·77 The gelatine gel was tough and rubbery and the product exhibited a very pleasing appearance. -1442S63 Example 6 Sy using an inoculum e.g. of L. bulgaricus with, a higher growth temperature, i.e. 42°C, the above Example 5 can be adapted to fermentation in bulk prior to packaging, the gel being allowed to set on cooling in the individual containers.

Example 7.

This example illustrates the use of dry ingredients in the formulation.

A gravy is prepared according to the following formulation: % of total product Sodum tripolyphosphate 0.25 Treated peel 0.5 Guar gum 0.5 .Caramel 1.5 Erythr osin e s oluti on 0.5 Potassium sorbate 0.4 Glucose (e.g. Trudex-Trade Mark) 5·0 Organic nitrogen source 0.5 (e.g. Corn Steep Liquor) Water * to 75·0 ♦ only half of the water is used in gravy preparation.

After preparation of the gravy as described previously the remaining cold water is added, followed by the required amount of dried greaves i.e. 25% of the total product. The addition of cold ingredients at this stage lowers the temperature of the mixture to JO - 40°C and hence avoids the necessity -15363 of an additional cooling step prior to addition of the inoculum (5%)· All ingredients are then throughly mixed prior to packaging and incubation at 50°C for 24 hours.

After 24 hours the pH of the mixture had fallen to EH 4.2.

Example 8 The following is an example of a meat and cereal product.

Conditioned sheep lung which had been minced through a 1.0 cm plate was mixed withsMaize Grits 15% ( based on the ‘weight of lung) Wheat Feed 5% C based on the weight of lung) The meat and cereals were cooked at 121°C for 50 minutes to produce a firm ’loaf’ structure. Ά gravy was prepared according to the formulation:% of Gravy Treated citrus peel 1.0 Guar gum 1.0 Glucose . 7.0 Potassium sorbate 0.4 Sodium tripolyphosphate 0.5 Caramel 1.5 Erythrosine solution 0.5 Water Balance. -16The meat and cereals were formulated with gravy in a 60:40 ratio and the mixture cooled to 35°C before inoculation with L. bulgaricus suspension (3.0% of total pock). After packaging und incubation, the product had a pH of 3-9 and a firm 'loaf' type structure with a cereal aroma.

Example 9 This example demonstrates the preparation of a greavy product. 3.5 kg of conditioned sheep lung was minced through a 3.0 mm plate using a Hobart(Trade Mark) mincer fitted with a four bladed cutter. The minced meat was cooked at 121°C for 50 mins.

A gravy was prepared according to the following formulation:% of gravy Guar gum 1.0 Glucose (Trudex-*Trade Mark) 8.0 Caramel 1,5 Erythrosine solution 0.5 potassium sorbate 0.4 Emulsifying agent (Tween 80-Trade Mark) 1.0 Artificial flavour 10.2 Water Balance -178S3 The gravy was prepared as described previously.

Meats and gravy were mixed together in a.70!30 ratio and cooled to 35°O prior to inoculation with a 20 IB old MRS both suspension of L. Oasei (j% of the total mix). The inoculum was mixed in well and the mixture packaged in 'Saran' (Trade Mark) pouches, ( sealed and incubated at 30°C for 24 hours.

The final pH of the product was 4.2 and it possessed a mince meat in thick, rich gravy, type of appearance.

Example 10 This example demonstrates the use of a starch gravy.

Sheep lung was prepared as described above. A gravy was prepared to the following formulation:- % of Gravy Ca3 (P04)2 0.8 . Glucose 6.0 T - OH Benzoates 0.05 Erythrosine sol. 0.5 Caramel 1.5 Modified Starch (Col-Elo-Trade Mark ) 5.0 Water. Balance In this context the calcium phosphate was added as a nutritional supplement.

* P - OH Benzoates = a 3:1 of methyl and propyl substituted benzoates. -1842863 The gravy was added to the cooked meats inlhe ratio of 30:70 and the mixture cooled to 35°0· The inoculum at a level of 2% of the total pack was added and mixed well in. The resultant mixture was packed into plastic tubs and incubated at 3θ°0 for 20 hours.

The product had a pH of 4.1 and a meat in gravy appearance.

Claims (12)

1. CLAIMS:1. A method of making a microbiologically stable food product comprising solid proteinaceous foodstuff in a gelled or thickened aqueous medium, which method comprises: forming a mix containing particles or pieces of edible proteinaceous tissue suspended in an aqueous medium fermentable .substance, gelling agents and antimycotic, the mix having a protein content of 6-20%, a fat content of 3-12% and a-pH value above 4-5; incorporating a culture of acid-producing micro-organisms in the mix; and thereafter promoting acid-producing fermentation of the said organisms until the pH value of the mix is below 4»5 and a'microbiologically stable composition is produced having a moisture content of 65-95%, all percentages being by weight.

2. A method according to Claim 1 wherein the formation of a gel in the mix is initiated at a pH above 4-5, prior to reduction of the pH value by fermentation.

3. A method according to Claim I or 2, wherein the gelling agent and fermentable substance are dissolved in water, and the resulting solution together with the culture of micro-organisms and the antimycotic are mixed with the proteinaceous tissue prior to fermentation .

4. A method according to Claim 3 wherein the fermentable substance, antimycotic and gelling agent are dissolved in water, the resulting solution is cooled if previously heated, and the culture is added to the cool solution prior to mixing of the solution with the proteinaceous tissue. 428 63

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

6. A method according to any of claims 1 to 5, wherein the 5 gelling agent is a polysaccharide gelling agent.

7. · A methodj according to Claim 6, wherein the gelling agent is a crude pectin source the degree of esterification whereof has been reduced to below 20% and the mix contains sufficient acceptable divalent metal ions to form a gel structure 10 therewith.

8. A method according to any of Claims 1 to 5, wherein the gelling agent is gelatine.

9. A method according to any of Claims 1 to 8, wherein the proteinaceous tissue comprises animal tissue in pieces not 15 exceeding 3.0 cm in size.

10. A method of making a food product substantially as described in any one of Examples 1 to 7 herein.

11. A method of making a food product substantially as described in any one of Examples 8 to 10 herein. 20

12. A food product made by a method according to any preceding claim.