CA2090333A1 - Shelf-stable proteinaceous products and processes for their production - Google Patents

Abstract

Proteinaceous, and in particular meat, products are made shelf-stable by acid heat-treatment in the presence of a polymeric acid such as alginic acid.

Description

WO 92t03938 - 2 0 9 0 3 3 3 Pcr/GB9l/0l469 ~HXLF-S5'AE~LE: PR~'rEI~AÇgQ~lS P~!l;~ D PP~OCESSES EoR ~LEIR
~B5~2~ION
Thi~ invention relates to shelf-stable, acid heat-treated s proteinaceous products and to processes for their production.

In the context o~ this descript~on, by proteinaceous product is generally meant 8 product containing meat. However, ~
proteinaceous product i8 not li~ited to meat-containing products but also encompasses products containing such ani~al-derived proteins as milk proteins, egg proteins, whey powder, blood plasma and collagen. It also includes products containing fish, such as crab meat and tuna meat.
It further includes products containing vegetable-based proteins such as soya protein, faba bean protein, gluten (~or instance derived from w~eat) and pea protein. It y~t further includes products containing mycoprotein materials such ~s that sold under the name Quorn0 (Quorn is a mycoprotein produced by the fungus F. ~raminearu~). The products ~ay also contain mixtures of proteins fro~ these various sources.
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By shel~-stable is meant that the product can be stored at room temperature for long periods of time without being sub~ect to spoilage by microbial action, without its organoleptic propertie~ deteriorating and without it acquiring any undesirable flavour. Typically, ~ood products are considered to be shelf-stable i~ ~ey meet these require~ents after several months, pre~erably at least nine and most preferably twelve to fourteen ~onths, of storage at room temperature.

The ~ajor reason that ~any food products are not 6helf-stable i~ that the growth of spoilage microorganisms i~ notinh$bited. ~herefore, an essential reguiremert of a ohelf-stable product is t~at it should not be susceptible to the growth of spoilage ~icroorganis~s.

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`' '' ' '' ` " ' ' ' .. : ' W092/03938 2 ~ 9 o 3 3 ~ PCT/GB9~/01469 2 t' ,;

Acid-heat treatment with nor~aliy-used rood acids is one well known proce~s which h~s been used in connection with a variety of shelf-~table products for some long time. Acid-heat treatment was developed in order to enable a product to be processed ~t a much lower temperature th~n is possible if heat treatment ifi carried out ~t neutral pH. It is generally recognised th~t lf the p~ of a product is reduced to about 4.5 or below, it i8 possible to produce a safe product without needing to heat it a~ove the boiling point of w~ter. This ~s advantageous because the ~ilder heating can avo~d overcooking the product. It al50 means that heating can be carried out by steaming at atmospheric pres6ure or fioaking in hot water. Thus, there is no requirement for pressurized ~ystems to accomplish the heating.

It i5 believed that acid-heat treatment is effective because the pH destroys or prevents from multiplying ma~y of the microorganisms which could spoil the product. Any microorganisms which are resistant to the ~cid pH are destroyed or inactivated by the relat~vely mild heat treatment.

When acid-heat treatment is attempted on proteinaceous products, such ns meat product~, with the normally-used food acids, problams often encountered are fiubstantial water 108s~ a granular, d~stinctly crumbly texture, and/or a pronounced, unacceptable sour taste to the product. It has not been possibl~ up to now to produce shelf-stable proteinaceous products using known methods of ~cid heat-treatment with normally-used food ~cids without them having t~ese unacceptable propert~es.

We have now di~covered that shelf-stability can be imparted 35 to proteinaceous products, in particular meat products, by .
heat treat~ent in ~he prssence of particular food-acceptable acids. It i~ believed that heat treatment with these particular acid~ has nsver before ~een employed on proteinaceous product~ to improve ~helf life.
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W092/0393~ 2 0 9 ~ 3 3 3 PCT/GBgl/0l469 - . ~
According to the present invention there is provided a shelf~stable, acid heat-treated proteinaceous product wherein the acidifying agent is a polymeric ~ood-acceptable acid.

Preferably, the proteinaceous prod~ct is a ~eat based product. Alternatively the product ~ay ~e based on other animal protein, ~ish proteins, vegetable protein or lo mycoprotein. Suitable protein materials are referred to in the ~econd paragraph of this description.

The proteinaceous product of the present invention ~ay be, -~
~or example, a sausage, a ~eat loaf, a hamburger, ooked ~ince meat or a meat 6auce for human consumption. The proteinaceous product may alternatively comprise ~ moist or inter~ediate-moisture pet food, for instance in the form of a meat bar or pat~. The proteinaceous product may in a further alternative co~pri~e p~rt of a larger package, for -~
20 instance a shelf-~table ready meal or a shelf~stable snack -~
product.
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According to a further aspect of the present invention, there is provided ~ process for preparing a shelf-stable proteinaceous product which comprises~
~a) bringing a proteinaceous product into contact with a polymeric ~ood-~cceptAble acid, and ~b) sub~ecting thu proteinaceous product/polymeric acid combination to ~ heat treatment ~uf~icient to achieve ~helf~
stability o~ the product.

Preferably the polymeric acid has a cellulosic or ,;
saccharide-derived backbone having pendant carboxyl groups. ~ -- Examples of ~uch polymeric acids are ~lginic ncid, pectic acid, ~ara~eenic ~cid and carboxycethylcellulose acid. The most preferred ~cid at present i8 alginic acid.
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W092/03938 2 0 9 0 3 3 3 ~ PCT/GB91/01469 The heat treatment ~ay be a pastaurisation process wherein a cooked or semicooked proteinaceou~ product i8 given - further expo~ure to heat to arrest ~utura miorob~al growth.
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Alternatively, the heat treatment ~ay be ~he coo~ing process itself.
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The heating ~y be carried out by pan-~rying, deep-fryi~g, oven-heating, immer~ion in hot or boiling water, microwave heating, RF heat~ng, ohmic heating or ~tea~-treat~ent, depending on the product to ~e produced and on the téxture qu~lities desired for the product.

In addition to the proteinaceous ~aterial, the product may contain vegetable, cereal, spice, ~erb or fruit ~omponents in order to improve the taste, texture or mouthfeel of the product.

~mong the vegetable component~ which can be used are onions and rad and grQen peppers. Under ~cid conditions, green and red peppers behave differently. While green peppers maintain their vegetable and sweet-bitter taste, red peppers also maintain their fiweetness but develop a fruity pickling note. Thus, red peppers ~re only recommended if such a ;
fruity pic~ling note is required.

~here the product is ~ meat product! the protein can be the product of ~ single animal, either a ~ingle particular cut of meat or a ~ixtur~ of cuts from the same ~nimal! or it can be a composite product based on the products o~ several ~nimals t~or exa~ple some sausages, meat loave~, hamburgers and pet foods). Pr~or to its acid heat-treatment, the meat can be, for exa~ple, fresh, precooked or preserved. If desired, the me t protein may be extended by use of any of the vegetable proteins or mycoprotein~ re~err~d to above.

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WQ92/03938 ~ 2 0 9 0 3 3 3 PCT/GBgl/01469 Sufficient of the polymeric food-acceptable acid 6hould be added to redu-~ the pH as low ~ possible, typically to a target R~ nbout 4.0 - 5.0, without ~poiling the taste qualities of the product. The actual pH used will depend, a~ong other thin~s, on the type of prote~n contained ~n the product and the type and severity of the heat treatment. ~e have discovered that the extent to which the p~ can be rsduced without i~poiling taste is very dependent on the particul r type of proteinaceoui product concernsd. Best results have been obta~ned with products containing pork, chicken, veal, beef, turkey or rabbit meat or mixtures thereof.

The polymeric food-acceptable ac~d may be provided as such.
Alternatively, it may be generated ~n situ by reaction between a salt or other derivative of the poly~eric acid and ~n inorganic or low molecular weight organic acid. For instance, alginic acid ~ay be generated by reacting sodium alginate with hydrochloric acid. This will be particularly advantageous in that the other product of the reaction w~ll ~ei sodium chloride, which can reduce the amount of salt which may need to be added to the product.

The polymeric food-acceptable acid can be brought into contact with the proteinaceous product in a number o~ ways.
For exAmplel with a co~posite product such as a sausage, it can be included in the s~usage recipe. For a preserved meat product (such as cured ham) it can be incorporated ~n the prsserving ~olution. For cuts of ~eat to be cooked, it can be ~ncluded in the cooking isolution or in a heat treatment 301ution in contact with the ~eat sub6equent to eithier full or parti~l roo~ing. The actual a~ount will be dictated in part by thei pH/~as~e relationship m~ntioned abo~e. Other factor~, such ai~ the size of the proteinaceous product (e.g.
~e~t) particles and t~e ~ntended type of produc~ will al~o a~fect the a~ount used. Preferably, ~rom 0.~ to 5 % by waig~t polymeric acid (based on tha weight of the product) w~ll b~ ~mployed. However, it ~hould be appreci~ted that SUBSTITUTE SHEET

W092/03938 ~ 0 9 0 3 3 3 PCT/GB9l/01~9 proportion sultable for incorpor~tion into, Sor lnst~nce, a - sausage mixture will not nece~sarily be suitable for incorporation lnto a cooking or heat treatment solution.

Th~ product ~ay, ~ desired, contain one or more conventlonal acidulants in order to potentiate the action of the polymeric acid. The amount of oonve~tional ~cidulant used should not be ~o qrsat as to introduce acid flavour notes to the product. Even lf a potentiating acidulant i~
used, it ia st$11 the polymeric ~cid ~hich ~nable~ the product to be acid heat-treated without the introduction of acid flavour note~.

~ he potentiating acidulants will be used to ~ssist in controlling the pH of tha product at the desired level, but will not generally be present in sufficient quantity to bring the pH to the desired level themselves. In particular, it should be ensured that the amount of potentiating acidulant used i8 not 50 large n~ to impart acid flavour notes to the product.

Suitable potentiating acidulants incluqe inorganic acids, such as hydrochloric, ~ulphuric and phosphoric acids, and low molecular weig~t organic Acids, such as malic, lactic, gluconic, citric, tartaric, adipic, fumaric, acetic, ascorbic, isoascorbic and succinic acids.
,~, I~ ~ potenti~ting acidulant i8 usQd, it will be possible to reduce the a~ount of polymeric food-acceptable acid which i6 used. However, the amount used should not ~e reduced to such nn extent that the addition of the potentiating acidulant leads to the introduction of ~cid flavour notes into the produc~. ~
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Additional ncids may be added along with the polyueric acid to i~prove the quality of the protein aqeous product. A~ino ~cids, ~uch ~s glutamic ~cid or ~spartic acid, can b~ used ~oth ~s potentiating acidulants and in order to improve the SUBSTITUTE SHEFr W0~2/03938 2 ~ 9 0 3 3 37 - PCT/GB91/01~9 taste of the product. Acids or ac~d derivatives, such as ~orbic acid ~nd glucono-~elta-lactone (~ cyclic aster of gluconic acid, which partially ~orms the acid when hydrolysed) can be u~ed both as preservatives and as potentlating ~cidulant6.

It has been found that the ~cidifying effect of the polymeric ~ood-acc~ptable acid in combination with a potentiating acidulant is improved ~f the two ~cidifying lo components are heat treated for between 1 and 2 hour6 in an aqueous solution or suspension at a temperature between 40C
and 60C, before being added to the proteinaceous product.
It is therefore preferred that, if used, a combination of the polymeric food-acceptable acid and a potentiating acidulant are subjected to such a heat-pretreatment.

With composite meat products (such as sausages), thickeners or gelling age~ts (such as hydrocolloids) can be e~ployed to reduce the amount of water and fat which ~ay ~eparate during the heat treat~ent. Examples of such compounds are agar, locust bean gum, gelatin, gum ~rabic, carrageenan, alginates and pectin. Locust bean gum has proved to be particularly suitable in sausage-type products, especially in co~bination with agar, carrageenan, xanthan or guar gum.
The proteinaceous product is preferably contained for ~torage in a miaroorganism-impermeable container to preserve shelf stability. Adv~ntageously the container is al~o gas-imper~eable, particularly to pre~ent oxygen ingres~ which can accelerate microbial growth or cause discolouration, rancidity and development of off-flavours through ox~dation.
Such containers are well Xnown and $nclude c~ns, jars, bottles, foil trays, pouches and certain types of sau~age c~sings.
The ~eat product nay be packed under vacuu~ or a ~odlfied atmo~phere to improve shelf-life.

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W092/03938 2 9 3 3 3 8 PCT/GB91/01469 ,_ The invention will now be ~urther described in the ~ollowing Examples, given by way of illu~tration only. All chem~cal6 were analytical or ~ood grada. All parts and percentages are ~y weight unless otherwise ~tated.
E~a~kE l~t~ANCHED SAUS~GXL

Meat emulsion~ to provide ~ausages of the ~yon variety were prepared to the following basic reeipe:
: - Parts lean pork 24.43 beef 19.55 - ~-fat pork 14.66 - bacon l9.5S
ice 19.55 curing ~alt* i.72 pepper . 0.15 ~C2 0.04 : :
nutmeg 0.04 ~ . :
coriander 0.08 sodiu~ dipho~phate 0.23 .
100. 00 ~* conventional - sodiu~ nitrite:sodium chloride :: 5:995) The meat components were all cooled to 2 to 4C. The lean pork and beef were then cut together at high speed in a :
30 butcher's cutter to ~ temperature of 14 - 16C with the ::
curing ~lt and 80diu~ diphosph~te addad. The fat pork, : :
bacon, ~nd ice were then ~dded and cutting continued until _ tha te~perature reached 4C. The re~aining spice ingr~dients and additional ingredients (see below) were ..
added and cutting continued until the temperature reached 11 - 12C.
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.. . .... ... .. . . .. . .. .. . . . .. . . ~ . . j.. ..... ... i wo~ 2090333 2/03938 PCT/GB93/Ot~9 A reference, non-acidified sau~agé emul~ion WaD pr~pared to the above basic zecipe. Vario~s other emulsion~ wers . prepared with a variety o~ ~ddit~onal ingredients, which are listed below. . .... . . . .-S - . . .
A. a~d~
1. Algin~c acid:
(1) Xelacid alginic acid ~elco Division of Merck, USA); and . (ii) alginic acid type Protacid F 120 or F
120~ (Protan A/S, Norway~.
2. Pectic acid (Herbstreith, Germany) 3. Amino acids~
gluta~ic acid; and ~ : :
aspartic acid.

4. Preservative acid: :
sorbic acid. . :

5. Inorganic ~cid: .~ `:
hydrochloric acid.

6. Low molecular weight organic acids:
adipic acid; and lactic acid. : ~.
B. ~hickeners Yarious gelling agents were tested singly or ;~
2S in mixtures: ~
agar; ~:
carageenan; ~ : .
locust bean gum;
Xon~ac flour;
gelatin; and pectin.
C. Additional chemicals : :
Sodium al~inate was u~ed to replace ~lginic ~cid :.
in ~o~e tests (thi8 relea~es alginic acid on aci~ification).
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Neat e~ulsions were packed into cups made fro~ a laminate of two lay~rs of polypropylene sandwiching between them a protect~ve layer o~ ethylene/~inyl alcohol (EVOH) poly~er. ``
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W092/039~ 2 0 9 0 3 3 3 PCT/GB91/01~9 .,, ~he -cups were sealed with ~luminium lids under normal pressure. H~at trsa~menl was carried out for 40 minutes at 105-C under a pressure of 2.4 ba~. With these conditions, an F value o~ fro~ 1.7 to 2.5 was achieved. Oxygen can be excluded from tha product to prevent discolouratlon.

Alternati~ely, ~eat emulsions were cubed and, without the addition of f~t, fried in a cao~ iron pan. Frying was halted when the centre temperature of the pieces of meat had lo reached 98 DC. After cooling, they were then packed in biaxially-stretched polyester pouches, which were evacuatsd and stored under ambient conditions.

~esu~ts Taste Out of ~ series of acid combinations in di~ferent concentrations, best results were achieved with the basic recipe ~iven above, but Additionally containing:

0.29 parts Protacid F 120 alginic acid;
0.38 parts glutamic ac~d;
0.05 parts sorbic acid;
0.097 parts hydrochlor$c acid; ~nd O.99 parts locust bean gum.

In this sausage e~ulsion, the pH value w~s decreased to 4.8 without giving a ~our tasta. In comparison, the non-acldified re~erence sausage had a pH value about 6.4.

Fried sample~ dev~loped a salt ta~te due to water loss -during this procass step. Thi~ wa~ easily a~oided by r~duc~ng t~e cNring ~alt concentration (this was not necessary for the samples heat-treated at 105C).

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W092/039~ PCT/GB91/01469 11' ~ex~ure The texture of the non-acidified re~erence ~ausage can be described a~ homogeneously ela~tic. After acidification ~elow a p~ value of about 5, but without the addition of any ot~er components, the texture changed. The ~tructure became crumbly and the mass contained particles with rubber-like elastic~ty. In addition, separation of so~e fat and large amount of water occurred, causing a firm texture. The addition of thickeners helped to retain the water and fat.
The best single thickener was locust bean gum. Sa~ples con.taining this ~ubstance had an elastic, fine and creamy texture similar to that of the non-acidi~ied reference.
Only a little water and almost no fat separated out on heat treatment at 105C. Fried samples show similar weight loss behaviour. During frying the non-acidified reference meat emulsion lost about 25% liquid, whereas the other acidified meat emulsions lost Srom 40% up to more than 50S liquid.
The exception was the locust bean gum-containing sample, which only lo~t the ~ame water and fat quantities as the reference aample. The re~aining fat has a positive effect on texture.
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Agar waa the second beat single thickener tested in terms of minimising ~luid 1085- The addition of 0.99% by weight led to a product with a relatively small liquid loss. The water and ~at retention wa~ paralleled by a retention of the smoother texture. In terms of taste, however, agar had a less positive influence than locust bean gum. Compared with an acidified sauaage containing no hydrocolloid, it had le~s sourness t but was ~ore 80ur th~n the locust bean gum-Fontaining ~ample-~p~e~nce Parallel with water and fat loss during heat treatment at105C, the ~urf~ce o~ the me~t product took on a porous appear~nce. When fried, the non-acidif~ed reference ~ausage SUBSTITUTE Sl IEET

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: . -W092/039~ 2 0 9 0 3 3 3 12 PCT/GB91/01469 developed a bright brown colour; The same behaviour was observed with the ac~dified locust ~ean qum-containing sample. Most o~ the other acidified sausages tended to become dark brown under these conditions.
Bene~its o~ frvinq . _ . ..
The average water activity (a~) ~measured a~ 25C~ of the sausage heat-treated at 105C was 0.98. ~y frying the samples the aw was reduced to 0096 in the re~erence and in the acidified samples co~taining hydrocolloids. (Reduction in water activity is highly desirable to be able to obtain acceptable shelf-life for t~ese products at the pH values obtainable using the acidification system described herein.) Microbioloqical Safetv . :
The sa~ples heat-treated at 105C were stored for 11 ~onths ~ -at ambient temperature. The best acidi~ied samples showed no microbiological growth, and the total standard plate count remained below 10 colonies per gram. ~Although the ~amples in this Example were heat-treated at 105^C, we ~elieve similar results will be obtained with a ~ilder heat treatment.) ' ~, ':".
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W092/03938 2 0 9 o 3 3 3 13 PCT/GB91/01469 Lean pork (hind leg) was pickl~d in a curing solution to provide cured ham. The basic curing solution was produced by boiling and cooling 900 g water and diæsolving 100 g conventional curing salt (as described in Example 1) therein. 0.2% sucrose was al80 added. To this basic solution varlous additional inqredients were added (see below).
' ' ' ' ~ :' ~ " ' Lean pork samples were placed in a dish and covered with the curing solution. The dishe~ were packed in polypropylene/polyamide pouches and evacuatedO The evacuation loosens up the meat cells and increases their s~ze and permeability. This allows the curing solutlon ~ora easily to enter the particles, thereby speeding up thi~ ~
process. They were then stored at 4 - 8C for 2 days. The --meat was then removed ~rom the curing ~olution, cut into pieces of approximately 80 - lS0 g, pac~ed in polyester bags, evacuated and cooked for 45 minutes at 85C in an open water bath.
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The addition o~ 4% Protaicid 120 and ~S glutamic acid, ~oth with and without 0.2% hydrochloric acid ~concentrations are with r~erenae to the weight o~ th~ basic curing solution) led to products with a pH value of 5.3. In comparison to this, a ham, marinated in a curing solutio~ without acid~
added, had a pH of 6Ø

Tast~ `
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These samples had ~ typical cooked note. No ~our taste-could be detected. Compared to the reference sample, the - addition of Protacid F 120 and glutamic acld to the curing solution led to a ham that had a more aromati~ ~nd ~ore savoury taste.

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~extur~

The structure of the acid~fizd ha~ did not differ ~rom that of the non-acidi~ied reference. They maintained their fibrou~ texture and were ~uicy and moist.

App~arançe , lo The ham surfaee was covered by ~ shiny film and had a bright pink colour.
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Alternative additives :-':-. 15 A pH value o~ 4.5 was achieved by adding to the curing solution: ~
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5S Protacid F 120;
2% glutamic acid; :.
0.5 % hydrochloric acid; and : ~:
0.1% lact~c acid. . :

The finished product had a fibrous structure. In terms cftaste it was comparable to a German ~Sauerbraten~, which has a sli~ht, but accept~ble, sour note.

During curing, it i8 de~irable continuously to ~gitate the ~`
material gently, for instance by rocking, in order to prevent any alginic ~c$d which i6 present in solid form from ;~
settling out.
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Experiments were carried out using a sinilar curing ~olution but wit~ meat which had been ground through a 13m~ plate. ~; :
The curing solution in ~ddition contained 0.2% dextrose 35 .~onohydrate, 3.0~ alginic ac~d, 2.0S gluta~ic acid and 0.4% :~ :
hydrochlori~ acid. This gave a product with a pH of about 3.0, which ~ far too low to be acceptable. It can therefore b~ seen that the amount of acldulating agents used SUBSTITUTE SHEET
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WO 92/03938 . 2 0 9 0 3 3 3 PCl`tGB9ltO1469 in a curing ~olution must be controlled in relation to the size of the meat partlcles.
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I~ wa~ also found that a heat pretreatment of the acidulating agents W~8 advantageous. The algin~c acid and the hydrochloric acid were ~dded to 50~ of the water : -required to produce the curing solution. This ~ixture was kept at 80C for one hour and then allowed to cool. The remaining 50S of the water w~s mixed with the remaining component~ o~ the curing 801ution- The cooled ~lginic acid solution and the other solution were then mixed to produce the curing ~olution. Using this procedure led to a final product having ~ pH approximately 0.3 pH units lower than ~ -that which was obtained using a curing solution which had ~ ~
15 not been pretreated. ~ :
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W092/03938 PcT/GB9l/ol~9 _ 209~333` 15 - E~P~E ~ tCOOKED MEAT) The inventlon was tested by cosking ~eats with th~ ac$ds present in the cookin~ liquor. Three different ~eats were tested:
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lean pork Sshoulder);
beef (fro~ which the residual fat had been ~ -removed); and chicken (breast).

Coskina ~rocedure ~ -A. Cookin~ in an_~Den water ~th 1 kg snall meat pieces, each weighing about 150 g, were put into 3 1 boiling water, which was slightly flavoured with salt and pepper and acidified with alginic and other acids in Yarious co~binations and concentrations. The meat wa~
cooked for 30 minute~. (Due to the small size of the ~eat piaces, one can be assured that their centre was heated up to the boiling point o~ water.) The meat was then drained and packed into polyester bags under vacuum. The products were stored under ambient conditions. ~;~
B. In-pouch-~okin~ ~chicken~ ~ ~

Blaxially stretched polyester bags were filled with about ~;;
100 g chicken ~reast and 100 ml of a salted (1.16%) and 30 peppered ~0.05$) agueous ~olution composed of a clear soup ~`
extrzct (2.5S), with various acids in different concentrations ~dded. The clear ~oup extract was used to improYe the ta~te of thQ product. The ~ags were evacuated, ~`
cook~d for 30 ~in at g5C in an open water bath,~`cooled and stored under a~bient conditions.

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W092/03938 2 0 9 0 3 3 3 PCTtGB91/01469 ,. ............... - ..................... : .

of the three ~eat sources used in this Example, chick~n was the best for thi~ acidification method. It al80 had textural advantages. A~ter cooking tthe ln-pouch cooking method was used) the unacidified chicken had a very so~t texture and fell ~part, while the acidifisd ~amples had a fir~er texture and b4tter cohe~ion of fibres. They could be cut easily without unravelling and were also easy to chew. The pH was decreased to a value of 4.0 by acidifying chicken wit~ a ~ixture o~:

0.4% Protacid F 120;
0.4S% hydrochloric acid; and 0.4% glutamic acid, or by using 0.5% Protacid F 120;
0.4% hydrochloric acid; and 0.4% asp~rtic acid (based on the weight of cooking solution).

At thi~ very low pH, both products had a short-lived, slightly sour taste, but the first was rated less sour. The di~ference i~ mainly caused by the glutamic acid. Aspartic acid was the second best ~mino acid for supporting the alginic acid acidification.
The taste was somewhat independent of concentration. Nearly the ~a~e taste could be nchieved by varying the Protacid F
120 amount fro~ 0.~ - O.6~, the hydrochloric ~cid content from 0.15 - 0.45t and the gluta~ic acid concentrat~on from 35 0.4 - o.6~. The products always had ~ typical coo~ed ' -chicken note co~bined with a slightly sour taste.

SUBSTITUTE S~EET

W092~039~ 2 ~ ~ o 3 ~ ~ pcT/GB9l/ol46s PorX. was the second best ~eat. When pork was cooXed in an open water bath in a solution acidified by the addition of .., . ., ., ,.
- . 0.3~ alginic acid; - .
0.6% glutamic azid; ~nd O.~lSS hydrochloric acid, - .;

(based on tha weight of the cooking solution) ~ :
a product was obtain~d with a p~ value of 4.3. It showed ~ ::
~ood cohesion of it~ ~ibres and had only a slight ~our note.

By decreasing the pH in the meat products for heat treatment in these Examples, ~uch products will have an increased shelf-life sin~e the potential for ~icrobial growth will `~; :
have been severely reduced.
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W092/03938 2 0 9 0 3 3 3 PC~/GB91/01~9 EXAMPL~ 4 ~A~BU~gL

Shelf-stable ha~burger-type producks were produced containing about 60-70% meat bound into shape using an alginate/calciu~ gelling system.

The ~ystem consists of thre~ components, sodium alginate, a calcium donor and a sequestrant. The sodiu~ ~lginate combines with the calcium donor to generate a gel. In order to retard this i~mediate reaction and to gain time for suoh handling steps as mixing, forming and cutting, a sequestrant is usually added.
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A high viscosity sodium alginate (Manugel GMB, Kelco) was lS used ~n order to produce a high strength gel. As calcium donor, calcium lactate or calcium gluconate is added. Under acid conditions these are 100% soluble and therefore fully available for reaction with the sodium alginate. Tetrasodium pyrophosphate wa6 used as a sequestrant. However, sodium tripolyphosphate can be used as an alternative sequestrant, since it has advantages in the desired pH range as compared to tetrasodium pyrophosphat~.

All calcium salts at higher concentration have a bitter :~
taste ~o their quantity mu~t be kept at a fun~tional ~ini~um.

Two typical alginate-bo~nd hamburger recipes ha~e the following composition:

SUBSTITUTE SHEET

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W092/039~ PCT/GB91/01469 ~
2090333 :-:

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parts chic~en 55.6 bacon 6.5 . :
onions 3.0 water 27.67 sodium alginate 1.6 calciu~ gluconate 1.6 : :
~eat stock 0.4 ~
tetrasodium pyrophosphate 0.3 -: -sorbic acid 0.05 .:
glutamic acid 0.4 chicken flavour 0.3 alginic ~cid 0.58 hydrochloric acid (5%) 2.0 (final : :
concentration 0.1%) 100.00 :
:,:
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., SUBSrITUTE SHEFI

, ~ ~ ", i .. ,.. , . ; ' ' . ' ' ~ i ~ ` .
209~333 W092/03938-- PC~/GB91/01469 Beef ~precooked~ 39.50 --Pork tprecoo~.ed) l7.66 Bacon l0.00 Tapioca 6tarch 2.00 Breadcrumb~ 3.00 Chicken flavour 0.30 Dextro~e monohydrate l.D0 Onions (toa~ted~ 3.50 ~eat ~tock o.io Dicalciu~ phosphate 0.50 Sodiu~ tripolyphosphate 0.08 Water 20.00 Sodium alginate 1.60 -- Hydrochloric acid 0.16 Alginic acid - 0.30 -;~
100. 00 The beef and pork were partlally cooked after grinding by `;
being heated up in a solution containing 2.5% meat stoc~, 0.5% alginic acid and 0.25% hydrochloric acid from room tempsrature to about 80C. The total precooking time was eight minute~.

The hamburger recipes contain onions (precooked, dried, '~ ;
` roasted) and a spice and flavour mix adjusted to the ~pecific materiAl used. The sp~ce and flavour mix consists Oe a stock, ~alt, pepper, meat extract and various aro~as.

Alginate-bound hamburgers were prepared using the components ~et forth in the above recipes by ~he following process.
Raw meat was ground and then cooked by frying, oven hea~ing or haating in ~ ~olution. I~ the grlnding ~tep, a 6 ~m plate is used for red meats and an 8 ~ plate is used for ~`
poultry. T~e cook~ng or frying time de~ends ~n the 6ize of the meat pieces.
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SUBSTIT~ITE SHEET
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W092/039~ O ~ ~ ~3 3 22 PCT/GB91tO1~9 The water required ~y the recipe was divided into three parts. In on~ part of the water, the spices, fla~ours, sod~um alginate, seguestrant and other acids were dispersed or di~solved using ~ h~gh ~hear~hi~h speed mixer to ensure opti~um hydration of the gelling agent. The calcium salt was either dissolved or disper~ed, depending on its solu~ility at neutral pH, in ~ ~econd part of the water.
The alginic acid and hydrochloric acid were dissolved in the third part of the water.
1~
- The aqueous phases were mixed in the order first part, sec.ond part and third part with the ground and cooked meat. ~ -The aqueous parts are mixed ln this order in order to control the start of the gelling r2action and to delay the acidificat~on to the latest possible moment.

A~ter thoroughly mixing all the ingredients to ensure homoqeneous blending, the mass is formed into the appropriate ~hape (for instance, ~ slab, di~c or rope).
The gel ~tructure is allowed to develop by storlng the mlxture below 8C. The time for which the mixture is stored is dependent on the amount of ~equestra~t used and can be up to 24 hours (see US-A-4 603 054). ~ ;
i The ~ormed meat ma~s is then heat treated. In a first alternative, the mass is vacuum packed and sealed into a pouch and heat-treated for 25 minutes at 105C. In a second alternativ~, the meat mass is baked at 250C in a conventional or convection oven for 5 to lO ~inutes per s~de ~or 15 to 20 ~inutes in total). In a ~urther alternative, ~h~ ~eat ~a~3 ~ay be fried, for instance in a frying pan or by deep-frying at 160 to 180-C for 5 to 8 minutes depending on ~h~ waight, size and sh~pe of the ~a~s.
The heat tr~ated products are then p~ck~d under norm~l atmosphere or under vacuum ifi a biaxially stretched polyethylene pouch and stored at room temperatura.
SUBSrITUTE SHEET

WO9~/03938 2 0 9 0 3 3 ~3 PCTtGB9l/01469 . . . , :
A series of ha~burg~r products based on the first recipe set out above were produced u~ing ~ variety of combinations o~
acids to produce the appropriate pH. It wa~ discovered that S the best combin~tion of ~cid~ was alginic acid, gluta~7ic acid, ~orbic acid and hydrochloric acid. Hamburgers according to the two recipes ~t out above have a very slight sour t~ste.

For the best poultry-based ~lginate-bound hamburger, the meat w~s cooked in a first ~tep in a stock containing 0.5 alginic ac~d, 0.4% glutamic acid and 0.45% hydrochloric acid. The meat was placed in this solution at ambient temperature ~nd heated up to boiling point. A p~ of 4.4 was achieved without further acidification.

By baking as one o~ the heat treat~ents, good tasting flavour components are developed. Alternative~y by deep frying a crust is for~7ed.
The addition of hydrocolloids positively influences the texture and makes the product firmer. The most effective additions are locust be7an gum ~between 1 and 2~) and a mixture of locust bean gum ~7nd xantha~ or carrageenan (between l.S and 3%). The hamburgers according to the second recipe, containing tap~oca starch and bread crumbs, had a very good7 moist texture. Thus, these components can advantageously be7 used together to producè a good ~extured product.
Other texture in~luencing parameters are the particle size o~ t~7e ground m~at and the statu~ of the meat as originally used (raw, ~ried or cooked). The smaller tbe particles, the fir~er the product becomes. Using raw meat leads to hamburge~s baving a ~ir~er textur~ than those made of precooXed m~at, where binding ~s mainly achieved by the ~inding system.

SUE~S~ITUTE SHEET

`; ' " ; ' . ; ' ' " ,.~ ~ ' ' " ' ' ' WO92/03938 2 0 9 0 3 3 3 24 PCTtCB91/01469 It can therefore be 6een that b~ modifying the type and - concentration of each o~ the sodium alginate, the calcium salts and the hydrocolloid or other texture ~mproving additives, and by varying the particle size and pretreatment S of the meat, it i~ po~sible to change the texture of the product fro~ a very dense product with no recognisable meat pieces to one in which the ~eat pieces are readily perceivable. Preferably, the hamburger has readily . percei~able meat particles set in a homogeneous ~a~s.
, ,,, ~ .
Sa~ples of hamburgers produced according to the process set fort~ above were tested for shelf-life. The samples which were tested had been either baked in an oven at 250~C for 15 to 20 minutes or had been heat-treated at 105C for 25 minutes. The hamburgers were then cooled, packed in polyethylene bags und~r vacuum and stored under ambient conditions. Hamburgers which were 7 to 8 months old were sub~ected to a total plate count test. The pHs of the acidi~ied products were 4.5 or below. They were ~lso tested for enterobacteriaceae, E. coli, sal~onell~e, streptococci, ~actob~ . cereus, yeasts and moulds. No microorganisms grew.

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SUBSI-ITUTE SHEET
, ; . . : ' ' ' ~" "' ' '' ' ' : - ' ' : ' ' , . . . . .

W092/03938 2 0 9 0 3 3 3 PCT/GBgl/ol~9 . EXAMPLE S ~MEAT ~O~VES~ :

Meat loaves are al~o made out of ground meat. The main difference between them ~nd ha~burgers is that thay contain breadcrumbs which have the functions of binding the meat particles and providing typical ~eat loaf taste. ~or the best tasting m~at loaves, with no perceivable sourness, a similar approach as for hamburgers is adopted. However, no alginate binding sy6te~ ~s used. In place o~ the ~lginate binding system, breadcrumbs are used to bind the material together.

The following two recipes were used to prepare meat loaves..

lS ~1) parts precooXed beef29.46 precooked pork13.38 water 28.95 Falt 0.60 spices ~nd flavours 1.71 breadcrumbs 19.34 onions 2.06 bee~ stock concentrate 2.9 alginic acid . 0.6 hydrochloric acid0.19 ~eat powder 0.4~
99.67 ~ :

SUE~STITUTE SHEET

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W092/039~ 2 Q 9 0 3 3 3 26 PCT/GB91/01~9 (2) ~ ~ parts precook~d chicken 44.3 water 29.93 ~alt 0.62 ~piceæ and ~lavours 1.59 breadcru~bs 20.00 pepper 0~18 onion~ 2.13 ~l~inlc acid 0.4 lo glutamic acid 0.4 hydrochloric acid 0.16.
99.71 15 The pro~ess for preparation of the meat loaves is very ~ ~
similar to that for producing hamburgers. The meat is ~ ~ -ground through a 6 mm or 8 ~ plate as appropriate. For the first recipe, the ground beef and the pork were ~ooked separately $or three minutes and one minutie respectively in boiling water And were then mixed. For the second recipe, the chicken was cooked for two minutes in boiling water.
~ ..
The ground meat particles are cooked, preferably in boiling water or in ~tock. If desired, the water or stock can be acid treatad. The cooked meat particles are then drained.

All the ingredients, with the exception o~ the meat, are ~i then mixed thoroughly. The meat is then added and ~ixed in thoroughly with the other components. The mass is then ~orm~d into the appropriate size and shape.

S~nce the meat loaf recipe does not contain any alginate binding system, it i~ not necessary to ~llow it to ~et. ~t can therefore be i~mediately formed and heat treated, for instance by baking at 250~C in an oven, by ~rying in a pan or by deep ~rying in hot oil. A~ter cooXing, the meat loaf is packed into polyethylene pouches as for hamburgers.
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2~90333 W092/039~ PCT/GB91/01~9 In the meat loave~ made with ei~her oP the recipes, the pH
was reduced to about 4 . 4 . - . .

In thi~ meat loaf type product, the breadcrumbs are traditional ingredients and are responsible ~or blnding the precooked meat particl2~ together. Their neutral character ~akes them an ~mportant component of this product.

Nor~ally, ~resh eggs are ~nother constituent of traditional meat loaves. After ac~dification, no textural changes are obserYed in heat-treated scra~bled eggs at a pH of around 4.5. However, a very wea~ sour note can be perceived.
Nonethelesis, this shows ~hat a certain amount of egg or egg protein can be addad to meat loaf-type products and to meat-containing sauces (see below).

The texture of meat loaves produced according to the above ~;
two recipes i5 identical to that of conventional meat loaves. Cooking the r~w meat particles in an ~cid solution modifies the texture. T~e particle surfaces tend to becomecoated with a ~elly which, when cooled; binds the s~all pieces together, thus supporting the textural effect of the breadcrumbs. Pork shows this characteristic more than beef and poultry.
Sa~ples o~ ~eat loaves prepared according to the invention were sub~ect to 6ensory panel testing. Groups consisting of 38 and 32 p~ople respactively were used. With this panel size, statistically significant results are achievable.
A chic~en-based meat lo~f was used for the evaluation. ~ts basic recipe was as shown on page 26 above.

A comparative meat loaf was prepared using the sa~e recipe but without the alginic ~cid, glutamic ac~d and hydrochloric acid.

The two meat loaves were tested in paired comparisons. Five SUBSrITUTE SHEFr .. ... , :

W092/03938 2 0 9 0 3 3 3 28 PCT/GB91/0l~9 products attributes were checked: ~piciness; saltiness;
~read taste; acidity; and meat taste. A clear statement had to be made about the intensity of each of the product parameters or that no difference exists between the two sample~.

The testing confir~ed that the product according to the present ~nvention does not taste sour ~s compared to a - conventional product. No signi~icant difference ~n the acidity level o~ the acidified as compared to the non-- acidified meat loaf was found. In the paired comparisons, in only one product attribute was there a significa~t difference ~etween the non-acidified and the acidified product. The acidified sample was clearly perceived as being slightly ~ore salty, even though the same amount sf salt had been added to each of the sa~ples.
-A meat loaf product was subjected to challenqe testing.The product had a pH of 4.5 and had been treated for 20 minutes at a temperature of 94C.

The basic acidification was achieved by soaking precooked meat particles in an aqueous solutlon of 0.15~ alginic acid and 0.11% hydrochloric acid. Further acidification was achieved by adding 0.14% alginic acid ~nd 0.22S hydrochloric acid to all the ingredients. Hydrochloric ac~d was used ~o ad~ust the pH to ~5.

Tho meat loaf mass was inoculated with E. coli (concentration of E. col~ - 250 colony forming units per gram~, filled into a polyethylene cup with an ~VOH barrier and sealed with an aluminium lid. ~he pacX~ge contained air. The sealed cups were then heat treated as descri~ed ~bove.
The heat treat~ent of the sample was sufficient to ~top the growth of the inoculated E. coli. No microbiological growth was detected, even after 12 days o~ storage at th~ optimum SUBSTlTlJTE SHEET

209~333 W092/03938 PCT/GB91/01~9 temperature for growth o~ the cha~lenge microorganism. This leads to ~he conclusion that a meat loaf, or any ot~er meat product, with a pH o~ 4.S and having been given a ~ild heat treatment (below lOo~C~ can ~e regarded as safe. This ~indlng is in line with the ~tatemQnts of the Handbook of the Ger~an Food Law~

According to ~rticle No. S of the General Admini~tration Regulation of 11th December 1986 concerning meat hygiene, ~eat i~ considered to be completely ~helf-stabla when it has the following parameter~

Fo value (degree of ~eat treatment~ ~ 3.0; or pH ~alue ~ 4.5; or aw value < o.s1; or aw value < 0.95 and pH < 5.2.

Thus, meat products can be made acceptable under these regulations by an appropriate combination of the "hurdlesn of pH, aw and heat treatment.

The "hurdle pr,inciple" can ~e used in conjunction with the acid heat-treatment described in the present application.
Presently, it is preferred that a proteinaceous product of the present invention should have a pH well below 4.5. This alone leads to shelf-stability without the need to change aw. Additionally, aw can be decreased and controlled by drying, deep ~rying or baking. ~eduction f aw further improves ~helf-stab~lity.
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`~

W092/03938 2 0 9 o 3 3 3 30 PCT/GB91/01469 - EXAMP~ 6 (IMPROVE~ ~L~NCHED SAUSaÇ~L
.. . . ................. . .
Various recipe~ have been developed from the basic standard recipe for the Lyon type sausage referred to in Example l.
S In ome recipes, the meat content was reduced ~rom 58~ to 45%. The amount& of bacon ~20%), water (20%), curlng salt and ~odium diphosphate are alway~ kept const~nt. The flavour ~ix w~ ad~usted to the differant meat materials used. Hydrocolloids ~nd ~eat extender~ were added ~or improving the texture. The process for the preparation of the ~eat e~ulsion was kept unchanged.

Heat treat~ent in polypropylene c'1ps with an EVOH protective layer was carried out for 40 ~inutes at 105C as previously described. Heating by dry-frying was also as previously described.
.
In some cases, the packaging was changed. The meat emulsion was filled into a standard cellulose based sausage cas~ng and then heat-treated under the same conditions as were used for hea~-treated in polypropylene cups.

In a series o~ trials, in which the meat material, the type o~ hydrocolloid, the type, combination and concentration of alginic ~cid, low mol~cular weight organic and inorganic acid wQrQ changed, the best product had the following r~cipes:

~:,;~,;' .

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'~ :',', SUEISTITUTE SHEET ~ ~ .

W09Z/03938 2 a 9 0 3 3 3 PCTtCB91/01~9 parts chic~en 42.24 bacon 22.3 water 21.65 alginic acid 0.57 gluta~ic acid 0.57 sor~ic Acid 0.05 hydrochlorlc ~cid 0.143 locust bean g~m 1.43 breadcru~b~ 2.86 soya isolate 2.86 curing salt 1.86 sodiu~ diphosphate 0.25 ~ -pepper 0.16 ~ace 0.05 coriander 0.08 nutmeg 0.05 dextro~e monohydrate 0.19.
97.383 ~hQ last 5 components compr~se the fl~vour mix. The curing salt and sodium diphosphate were added as processing aids (~or use in cutting the raw ~ea~), for colour development and ~or water bindlng ~8 in traditional sausage processes.
The locust bean gum, breadcrumbs and ~oya isolate were added to improve texture by avoiding shrinkage due to water and ~at 108~

Soya i~olate ha~ ~ twofold function. In ter~s o~ ta~te, it improves the tastQ of products containing locust bean gum or breadcru~bs if these ~re used. From a nutrition~l point of Vi9W, the u~e of ~oya i~ol~te produce~ a sausage having a reduced calorie content. However, if too ~uch 80ya isolate is u~ed, the final sausages ~xhibit a nutty, leguminous taste.

SUBSTITUTE SHEET
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W092/039~ ~0 9 o '~ '~ 3 PCT/GB91/01~9 A ~econd recip~ co~prises:
parts lean porlc 42 . ~A
fat por~ 14.16 bacon 18.87 water 18.87 ~lgini~ acid l.00 lactic ~cid 0.5 locust bean gum 1.44 lo sodium dlphosphate 0.28 curing ~ialt 2.08 pepper 0.1~
mace o.og coriander 0.05 nutmeg o.oS.
100.92 In these blanched ~ausages, the pH was reduced to between 4.4 and ~.5. The texture ~mprovers which were used in these examples have a positive influence on taste. In some product~ containing hyd~ocolloids such as gum arabic, collagen products such as drinde, and carbohydrates such as modi~ied waxy ~aize starch, a sour taste w~ perceived.
However, tbe use o~ locu~t bean gum in combination with t~e alginic acid lead~ to a meat product without sourness.
~ocust bean gum can ~l~o be co~bined with other hydrocolloids to produce the same taste.

Taste improve~ent i~ al~o achieved by the u~e o~
breadcrumbs. In relatively ~mall a~ounts, around 3 %, it is not perc~i~abl~, but ~akes the product ~ilder. In Engli~ih and American typ~ sausages, where breadcru~bs represent typic~l ingredient~i, their conc~ntration is r~i6ed to over 20% and provide a clear tast~ adv~ntage.
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SUBSTITUl E SHEE~T ;

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.':' ' ' ' '':' . . '' ,' - ' ` ' " . ' ' , :~ ' ' . , ' . . ' wo g2/039~ - 2 ~ 9 ~ 3 3 3 PCT/GB91/01~9 , - A positiv~ influence on taste can be achieved using tapioca starch. ~eside~ this, it has the ability to replace up to 50 S of the fat end to maintain the ~outhfeel o~ products having higher fat contents. It can al~o replace visible fat s partioles depending on the size o~ the starch granules u~ed.

The texture of ~l~nched ~au~ages can be ~ade comparable with that o~ normal sausages by the use of thickener~. The preferred thic~ener is locust be~n gum. ~owever, it can be combined with agar, carrageenan, xanthan or pectin. Heat treated products containinq locust bean gu~ or combinations thereof with these othar gums maintain their ~hape.

The use of locust ~ean gum and tapioca starch ~an also improve the water- and fat-retaining capacity o~ the sausage. These products ~ct as thickeners and binders, and retain moisture in ~any kinds of food by cwelling and increasing, in the case of tapioca starch, to five times its volume.
Soya isolate behaves in the same way. It was proved in a non-acidified hamburger that with increasing concentration of soya isolat~, frying loss decreases. Limits ar~ set by the influencQ on taste. To achieve the best result, a 50-2S c~lled "pre-gel" has to be made. Soya i~olate and ice water ~in thi~ example a ratio of 1:4 was used) are ~ixed thoroughly in ~ high speed mixer or a bowl cutter. This mixture must gelatinize overnight and can then be combined with the ~eat.
prQtreatment, pre6alting, ig an additional necessary step when a ~alt intolQrant 80ya ~ solate i~ used. For pres~lting, ~e~t, bacon, 80dium diphosphate ~nd curing ~alt ~re mixed one day be~ore use. ~ -:~
In ~ost ~mples, a meat emulsion, ~fter acidificatlon and subsequent heat treatment, show~ a texture which i8 cuttable. When ~ore pres~ure ls put on ~he product, it .. ~.. , ~ .. . .

W092/039~ PCT~GB91/01~9 ~0~333 34 ?
beco~es spreadable. ~he blanched sausage can be brought ; closer to a ~preadable texture by ~dding citric acid estersof ~ono- and di-glyceride~ o~ sa~urated fatty acids.
.
The ~mall amount of ~luid which i8 released during heat treatment i8 V~COUS ~nd clear and gives the product ~ sh$ny appearancs.

The meat emulsion~ used to produce bl~nched sausages were lo treatad in two different w~ys. Firstly,`they were heat -treated t~ produce ~ centre temperature of 105C for 40 minutes. Secondly, the products were dry fried in ~ pan until the centre temperature reached 98C. These products were tored at ambient te~perature and subjected to shelf-life tests by microbiological analysis. -Blanched sausages, heat treated by the first proce6s, afterstorage for 11 mont~s, were analysed on a total plate count and were tested for enterobacteriaceae, E. ~oli, salmonell~, streptococci, Lactobacilli, B. cereus, yeasts and moulds. The p~ of the acidified products varied between 4.3 and 4.9. The tests showed that no microorganisms grew.

The microbiological status of blanched sausages which had been heat treatQd according to the second process and stored for 11 to 12 ~onths was determined. No growth of pathogenic ~icroorganisms, such a~ enterobacteriaceae, E. ~oli, s~l~onell~ or B. cereus was detected.
.
In a ~econd aspect of the shelf-life tests, the s~mples were evnluat~d by trained personnel in sensory tests. In terms o~ appearance And texture, no differences were observed between thQ fre~h product and the ~tored product. Although ~n unknown amount of residusl oxygen was retained in the packag~, the amount of discolouration due to oxidation did not ~ncrea~e. ln terms of taste, no off-taste6 due to oxyg~n or du~ to ~crobiologic~l spoilage developed during the storage procedure.
SUBSTITUTE SHEET

- - - - . ... . . . . . ... ..... , .. - ... . o 20903~3 wo92~o3s38 PCTtGB9l/0l~9 E~A~$E_~_LI~ ovED ~OOXEP ~EATL

The range of ~eats which have been treated by the process of the present invention has now been extended to inçlude tur~ey, lamb, v2~1 and rabbit. ~oreover, the process hai now been applled to a Dycoprote~n sold under the tradename Quorn~. Quorn is a ~eat substitute which is produced by the fungus F. graminearu~. These produets have all ~een shown to have a~ceptable propertie~. -In generfil, the lowe6t pH could be a~hieved using Quorn.
Thi~ finding is in line with its ability easily to absorb flavours. It is therefore understandable that the a~ids are also easily absorbed. Poultry, such as chicken and turkey, showed the smallest decrease in pH, generally to a level of 4.1. All meat products had acceptable tastes. However, turkey and chicken product~ generally were rated as better in taste than pork, beef, veal, rabbit or l~mb products.

As to texture, poultry i5 the best suited ~aterial. Pork exhibits, after being cooked in an acidified solution~ a gelatinous surface. Bee~ and, to a lesser extent, chicken ~nd turkey also behave in a similar fashion. T~e texture of `
acidified ~eat is ~irm and the ~ibres have better cohesion than in non-acidi~ied ~eat.

SUBSTITUTE SHEET
~, ~',, .
- . . . .. , .. , , , . . ~ . -., ` .,.` , . , . , . . . , -W092~0393X ~ 2 0 9 ~ ~ 3 3 PCT/GB91/01469 ~ XAffPLE 8 ~ PFT FOO~S1 The process of the present invention al80 has applications in producing pet foods. The u~e of pasteuri~ation and pH
reduction to increase the ~afety of chilled products and to produce intermediate ~oi~ture and high ~oisture shel~-6table products has been investlgated. These products ~ay be produced by hot-~ill, aseptic fill or in-pack pasteuri~ation . in order to prevent potential contami~at~on with or ~urvival o~ mould spores ~h~ch have potentlal to grow at low pH.
Initial trials ~ith ~eAt-based chilled products indicated that the product aesthetic~ deteriorated b4low a pH of 5~8.
Th¢ products ~eca~e ~oft, cru~bly and had a watery texture. ~-There w~s ~hrinkage in the package and grey discolourations were obtained. However, palatability levels were maintained with both dog and cat products. It is envisaged that it will be possible to improve the ~esthetics of the products by the use of hydrocolloids or other additives as described above.
It is envisaged that a cat or dog food could be produced by u~e of ~n extruder pasteurisation process, combined with low pH and aseptic ~ill. Such products would contain between 20 and 50% moisture and would be shelf-stable. They would not require humectant~ or antimycotics to achieve product stability.

Examples of ~uitable recipes for producing such pet food products are a~ fo1lows.

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SUBSTITUTE SHEEr . -` ` , ` . . ..... .. `` . ~ .` . . ' . . .. .

W092J03938 PCT/GB91/01~9 ~ar f~ g~
parts muscle ~at 50.3 blood plas~a 22.2 , liver 6.6 bee~ lung 5.5 caramel ~olution 2 c~lciu~ c~rbonate 1 .
. s~lt 0.6 w2ter 11~1 to 11.4 al~inic acid 0.3 to 0.5 hydrochloric acid (5 molar solution) . 0.1 to 0.2 :
99.7 - 100.3 pat~ for cat~
parts ~ ~
pig ~aws 19.7 -- :
l~ver 21.4 :~ .
chicken skin 8.5 chicken necks 12.2 beef mel~s 5.2 carrageQnan 0.~6 caramel solution 0.74 blood 1.85 ~.
Wheat ~lour 2.0 : .
blood plasma 1.35 ;~
calcium c~rbonate 0.2 salt 0-33 water . 25.57 to 25~87 ~-alginic a~id 0~3 to 0.5 hydrochloric ~cid ~5 ~ol~r ~olution) 0.1 to 0.2 99.7 - 100.3 SUBSTITUTE SHEET

, . . " . ~ . s . . i--- `

~nter~ediate Moisture Prod~lc'c Por Doqs ;,, .
parts liver 9 . 5 . -trips 6 . 2 greaves g . 5 pork and fat tissue 4.2 whey 4 . 2 bone meal 8 . 9 l o f ish ~craps 3 . o wheat flour 32.7 maize grits 15.1 maize gluten ~lour 1. 2 ::
water 5. 5 alginic acid 0 . 5 to 1 .
hydrochloric acid ~5 molar solution) 0.5 to 1 ~.
101 - 102 ~. :
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SUBSTITUTE SHE~

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' ' ' ' ~'' ' - ' ' ', ~ ' I '` ': ' ' ' : ' ' . ` ' -2Q~33 W092/039~ PCT/GB91101~9 E ~ ~E ~ (ME~T'SLUC~S3 Sauces contai~ing meat have been subjected to the process of the present lnve~tion. For instance, a ~olognese sauce has been produced according to the following recipe.

parts wat~r 44.21 to~atoes 29.74 lo beef 15.0 o~io~ 3-4 vegetable oil 2.38 ~ :
sugar 2.30 . ~odified starch 1.7 powdered stock 1.7 garlic pur~e 0.64 herbs and spices b . 4 6 alginic acid 0.31 salt 0.16.

SUBSTITUTE SHEE~

wo 92/03g~ 2 0 9 0 3 3 3 40 PCT/CB91/01469 A ravioli sauc~ l-avlng the ~ollowing composition has bee~
prepared.
~ parts -- water - - ~ 36.32 tomatoes 24 o 5 . - :
bee~ 15.3 hard rlour 7.9 onion~ 3.25 chapelure 2.39 ;~
vegeta~le oil l.93 sugar l.8 ' powdered stoc~ l.5 whole eggs l.45 modified starch 1.35 herbs and spices 0.71 alginic acid 0.5 garlic ~urée `0.52 -white of egg~ 0.22 `
powdered crea~ 0.18 salt 0.13.

In the a~ove-~entioned two recipes, the ingredients were all mixed to foxm ~ homogeneous dispersion. The mixed disperaion was ~illed into glass ~ars which were sealed.
The ~ealed gla~s ~ars were heat treated for a t~me su~icient to heat treat the contents to produce a ~helf-~table product.
The products are shelf-stable at a~bie~t te~perature and have no adverse acidic fl~vour notes.

It will be appreciated that the present inYention is not .
li~itQd to the particular proce~ses and products described ~ove. It will be readily apparent to those sXilled in the art that variations and alterations can be ~a~e without departing fro~ the scope o~ the inYention.
SUBSTITUTE SH~

. 41 .
. .
In particul~L, various way~ exist to acid~fy masses of meat.
Firstly, acids ~ay be added directly to ~ ~ixture of .ingredients cont~ininq raw meat~ Secondly, the acids may be added to ~n ingredi~nt mixturs containing ~eat which has been precooked in water or in ~eat ~tock. Ihirdly, ~he acids may be ~dded to precooked meat and allowed to ~o~k in for a period o~ ti~e.

lo The efficiency of a ~oaking step i8 $nfluenced by th~ time and te~perature. It has been found that the optimu~ time and temperature for any particular meat is independent of whether it is raw or cooked.

The rate at which the pH can be changed by soaking is hyperbolic. An optimu~ time period for soaking is between 1 and 2 hour~. The optimum temperature i5 between 40 and 60~C.

If desired, the raw meat may be cooked directly in a mixture which has been acidi~ied. ~h$~ may be achieved ~y placing the meat p~rticle~ into a boiling solut~on containing the acids~ Alternatively, the meat particles ~ay be i~mersed in the mixture containing the ~cids nt a~bi~ent temperature.
This ~ixtur~ is then heated up to ~oiling point. This procedure i8 ~dvantageous compared to placing the meat particle~ in ~ bo~ling solution containing the ~cids because in the case of the boiling solution, the ~eat prote$n is denatured tby the h~at a~ well as by the acids) wh~ch can ~ake it more difficult for the acid to penetrate into the meat material ~s compared to non-heat tre~ted r~w meatO
.
~hichever m~thcd i8 used to ini~ially ac~di~y tbe ~eat, it w~ll be possible to ndd acids at later 8tag2s in order to potentiate the lniti~l effect. .

' ' SUBSTITUTE SHEET

W09~39~ ~ ~ PCT/GB9~/01~9 . 42 .

It has been found that, in general, the most effective acid application in terms o~ reducing the pH without introducing acid flavour notes uses a combination of 0.4% alginic acid,~ .
0.4% glutami~ acid ~nd 0~16~ hydro~loric a~id. The same S result can be achieved without glutamic ~cld but by increasing the algin~c acid and hydrochloric acid concentration~ to 0~6S and 0.2% respectively.

In order to test whic~ method of acidification was optimum, the ~irst abvve-mentioned mixture of ncids was us2d a~ to acidi~y -raw minced meat, b) to acidify meat which h~d already been partly cooked in a stock ~nd c) to acidify meat pieces at ambient temperature added to a ~oiling solution containin~ the acids. , ;~
In all three final products, comparable decreases of the pH
were achieved. The pH for b~ was lower ~pH 4.4) than in a) (pH 4.6) and c) ~pH 4.7). Although in the last case a higher pH was achieved, this is the most economical ~ethod because the acid solution can be used 6everal time~ and a continuous cooking process becomes possible.

In compari~on to these results, ~ non-acidified hamburger :~
has a pH o~ ~round 6.2. ~ .
..
It will also be ~ppreciated that different methods of heat treatment can be u~ed. For instance, the product can be vacuum packed in ~ polythene bag and pasteurised, for l~ -. instance in the case of hamburgers for 25 minut~s nt 105-C.
Thig process can be recommended where a half-fini~hed snac~
product is reguired. .

: Alternatively, the product can be heat treated by baking, .-for instan~e in a conventional oven or a convection oven at a te~perature o~ 2S0-C for about 10 to 20 ~inute~.

SUBSTITUTE SHEET

A further ~lternative i8 to use dr~ frying. In this method, whicA has alr~ady ~een applie~ to blanched e~usage~, the product is ~ried in a pan in th2 absence o~ any fat. ~his ~ethod shows good results in developing Slavcurs ~nd in lowering the water actlvity.

In a further alternative, t~a ~at treatment can ~e carried out by deep frying. For instance, ~eat loaves have been deep fried in hot ~egetable oil at te~peratures betwee~ 160 and 180C. Thi~ give~ a good tasting crust on the outside of the product. ~n addition to improving the taste of the product, a fat barrier to invading ~icroorganisms is also provided.

In addition to the products referred to above, i$ shouid be possible to produce liver sausaga and pat~ type products, similar to the paté shown in Example 8, which have been acidified and heat treated to make them shelf-stable. A
further category of products which could be produced are acidified meat or fish pieces embedded in a clear jelly. In this respect, they will re~emble aspia products.

The product o~ the present invention may comprise part of a larger package, ~or instance a shelf-stable ready meal or a a5 shel~-stable snack product.

It will be appreciated that the products of the present invention, and al50 larger packages containing these pro~ucts, need not contain only proteinaceous ~aterials but can also contain vegetables, cereals, spices, herbs or fruits.
, It i~ ~lready known that fermented ~ausages have a significantly longer shelf-life than traditional cooked and blanched s~usages. In these case~, ascorbic acid is often used to speed up fermentation. ~owever, this can cause a sour taste. This sour t~ste could be ~oided by ~he u3e of al~inic ~cid or another polymeric food acceptable acid in W092/039~ PCT/GB91/01469 20~0333 44 ''~`, placo o~ the ascorbic acid.

It w~ll be appreciated that the present invention h~s been :~
described ~bova by way of exa~pl~ only and that variations ~ ~:
~nd modifications can be ~de without depart$ng fro~ the scope of the invention as defined by the app ded clai~s.

, SUBS~ITI.JTE SHEET
"'`' ~ i ` , i ' ' ' - ,.. .. . . . ..

Claims (17)

1. A shelf-stable, acid heat-treated proteinaceous product wherein the acidifying agent is a polymeric food-acceptable acid.

2. A product according to claim 1 wherein the polymeric acid has a cellulosic or saccharide-derived backbone having pendant carboxyl groups such as alginic acid, pectic acid, carageenic acid or carboxymethylcellulose acid.

3. A product according to claim 2, wherein the polymeric acid is alginic acid.

4. A product according to any of claims 1 to 3 wherein the acidifying agent was present in an amount of 0.1 to 5%
by weight of the product during the heat treatment.

5. A product according to any of claims 1 to 5 which has been heat treated additionally in the presence of potentiating acidulant such as hydrochloric, sulphuric, phosphoric, malic, lactic, citric, tartaric, adipic, fumaric, acetic, ascorbic, isoascorbis, sorbic, gluconic or succinic asic.

6. A product according to claim 5 wherein the potentiating acidulant is hydrochloric acid.

7. A product according to any of claims 1 to 6 which has been heat treated additionally in the presence of an amino acid such as glutamic acid or aspartic acid.

8. A product according to any of claims 1 to 7, which has been heat treated additionally in the presence of a thickener such as a hydrocolloid.

9. A product according to claim 8 wherein the hydrocolloid is locust bean gum or a mixture thereof with another hydrocolloid.

10. A product according to any of claims 1 to 9 wherein meat in fresh, precooked or preserved form prior to heat treatment is used as the proteinaceous material.

11. A product according to claim 1 which has been heat treated in the presence of a mixture of alginic acid and hydrochloric acid.

12. A product according to any of claims 1 to 11 which has been heat treated to give a pH in the product of 4.0 to 5.0

13. A product according to any one of claims 1 to 12, which is a meat product.

14. A process for preparing a shelf-stable proteinaceous product which comprises:
(a) bringing a proteinaceous product into contact with a polymeric food acceptable acid, and (b) subjecting the proteinaceous product/polymeric acid combination to a heat treatment sufficient to achieve shelf-stability of the product.

15. A process according to claim 14 when performed to produce the proteinaceous product as claimed in any one of claims 1 to 13.

16. A process according to claim 14 or 15 wherein the heat treatment is a pasteurisation process.

17. A process according to any of claims 14 to 16, wherein, in step (a) the polymeric acid is incorporated into a composite proteinaceous mixture, or included in a curing solution for the proteinaceous product, or is included in a cooking solution for the proteinaceous product.