CA1063863A - Heat coagulated whey protein - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:

A protein food product is described, together with a process for making it. Whey protein derived from milk is adjusted to a pH of 6 to 9 and coagulated by heat, thereby giving a firm, non-brittle material which is a useful protein food in its own right or as a matrix for composite products. Viscous solutions of whey protein, with or without vegetable or other protein, thickener, and optionally containing additives including flavours and colouring, can be extruded and blanched in hot water and cut to form pieces resembling meat offals such as kidney. Granular and particulate solids such as cereals, nuts or animal products can be incorporated in a whey protein matrix to make novel food products. Such products may contain humectant material, such as sugars or polyhydric alcohols, to render them bacteriologically stable with moisture contents of 5-20% and AW 0.50-0.75. Whey protein matrices, coagulated a pH 6 to 9, can also be used in semi-moist formula-tions, for example with moisture contents of 20-45% and AW
0.75-0.85. Whey protein can also be used to improve the texture if meat-containing mixes, for example of sausage type, if coagu-lated by heating the mix at pH 6 to 9. Denatured meats or meat by-products do not interfere with the coagulation of the whey protein but fresh meats and meat by-products require the addition of up to 7?% sequestrant. The products of this invention are useful as protein foods for animals and also for human beings.

Description

,~63~3G3 ~ he prese~t invention relates to protein products that are of value as food, more especiall~ for animals, but also for human beings.
Whey protein (that is, the protein content recover-able from wheys of milk origin) have been obtained having - various functional properties by separation from acidic cheese and casein wheys, followed by spray or other dryiug.
; Separation techniques which have been employed include direct ; acid precipitation of concentrated whey solutions at elevated temperatures, precipitation of acid whey~ as metal-protein , complexes, e.g. ferric whey precipitate a~ pH 2.5, and ;¦ precipitation of the protein by addition o~ salt, e.g.
ammonium sulphate, at pH 4Ø ~he reco~ery of whey proteins by ultrafiltration of acidic wheys has also been described.
~he acidic whey protein obtained by these procedures is ¢oagulable by heat but normally yields a hard, brittle ~ -product of relatively low value as a binding agent. In the recent past therefore, although tech~iques have been established whereby functioni~l whey proteins can be obtained from whey ~ge~erally regarded as a waste product), the whey protein obtained has had limited applications ~nd valueO
We have now found that if the pH value of whey protein is adjusted to within the range 6 to 9 at some stage prior to heat coagulation i~nd îs coagulated at such a p~, -then th~ coagulated product has a firm coherent texture well uited to function as a protein matrix for food products or as the basis for simulated animal products. It is also ;~ . ~ ....
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-1~3863 very valuable as a binder in meat-containing products. The pH adjustment - can be carried out by neutralising normal commercially available, dried~ -acidic whey protein, for example at the time of formulation of the product, but can instead be carried out on the freshly precipitated protein before drying. In any case, a similar product is ultimately achieved after heat coagulation.
Accordingly, one aspect of the present invention provides a method of making a protein food product comprising the steps of: forming a mix com-prising an aqueous solution or dispersion of acidic whey protein, said whey protein having been separated from whey under acidic conditions; adjusting the pH value of said whey protein or mix to within the range 6 to 9; and heat-ing said mix at pH 6 to 9 to coagulate said protein.
Another aspect of the invention provides a protein food product comprising a coherent matrix composed of heat-coagulated whey protein, said whey protein having been separated from whey under acid conditions but having at coagulation a pH of 6 to 9.
A variety of alkaline substances can be used for the neutralisation ~f acidic whey protein. Alkali metal hydroxides, such as sodium or potassium hydroxide, are convenient but other hydroxides, such as calcium hydroxide, or salts of alkaline reaction, such as sodium or potassium carbonates, sodium tripolyphosphate or tripotassium orthophosphate can also be used. Where the neutralisation is carried out at the stage of formulation of the product the use of carbonates can give aeration of the product and result in a product having a texture similar to that of a meat loaf.
~ In the simplest application of the invention, an aqueous solution `~ or dispersion of whey protein is neutralised to within the stated pH range and then heat coagulated to a firm, coherent mass, which can be used, with flavouring, .

~063~63 as a foodstuf~, more especially for non-human use.
If the whey protein solution or dispersion is suffi-ciently viscous, whether by ~irtue of a high concentration of whey protein or by Pddition of thicke~ers, such as guar gum, to ~he dispersion, to which may also be added fats, colourin~ matter and other additives including nutritional ~ -- suppleme~ts, the dispersion may readily be blanched in boiling water (for example after extrusion) to form firm, coherent pieces which simulate offal meats such as kidney, and which may then be used in c~nned food products. ~he ~hey protein dispersion at pH 6 to 9 possesses good fat emulsification properties, so that substantial proportions of fat, which is nutritious but relatively cheap, can be incorporated into the product without giving it an unaccept-able, greasy feel.
~he neutralised whey protein can also be advantage-ou~ly employed in admixture with vegetable proteins such as wheat gluten, cotton seed protein and, more especially soya protein flour~, concentrates or isolates. ~hese proteins alone do not produce firm, coherent chunk~ on blanching in ~ater, but in a dispersion containing whey protei~ at pH 6 to ~ they modify the texture of the chunk, giving increased elasticity and toughness.
j Preferred fo~mula~ions for coagulated, e.g. blanched~
1 25 chu~k products, for example simulating kidney9 based on whey ¦ protein contain 15-70% by weight whey protein, 30-85% water 1 a~d 0-45% other edible material. Where other substances : ' .

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:IL063~63 having a thickening or binding property are present, the proportion of whe~ protein can be less than 15%.
In another typ~ of product in accordance with this invention, meat, meat by-products or other protein of animal origin, e.g. sodium caseinate, is incorporated i~ the whe~ -protein solution or dispersion or, conversely~ neutralised whey protein may be incorporated as a birder in a meat-based product to modify or improve the texture or flavour. Such products can be used for human ~ood or for animal food.
When meat or meat by-proaucts are used in admixture with whey protein it is preferred either to use denatured meats or proteins or a meat of low iron content (e.g. chicken meat), or to àdd a chelating agent for iron, such as trisodium citrate or ~D~A, in proportion to the level of undenatured animal protein. As an example of the use of neutralised whey protein in a meat-based product may be mentioned sausage, where the whey protein can be used to toughen the texture and reduce the amount of binding meat required. The amount of whey protein that can be incorp~rated is limited by the necessity for a high level of chelating agent if much meat is present.
In meat-containing products of this type, preferred ~ormulations contain 15-6~/o by weight whey protein, 40~ 8~/o meat or meat b~-products, 0-45% added water, 0-20~/o other edible materials and 0-7~% sequestrant. It will be appreci-ated that by the term "meat" is meant not only the flesh of mammals but also that of other animals, such as fish, ~ .

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-~0638163 poul~ry or crustacea. Similarly, "meat by-products"
refers ~ot only to blood and offals o~ mammals but also to the corresponding portions of other animals.
Iu yet another modification of the inve~tion, the whey protein coagulated at pX 6 to 9 serves as a protein-aceous matrix to bond other food materials in a composite food. Such other foodstuffs ma~ include cereals, cereal products such as rusk and biscuit, and nuts. ~he added solid foodstuffs may be in the form of ground powder or meal or ; 10 granules or pieces. Fat, flavouring, colouring a~d other ` additives may be included, and the products may serve as complete foods. They can, for example, be adapted for use as complete dog foods, in place of conventional complete dry i dog ~oods, but products of this type can also be suitable - ' ' 15 for human food, depending on the nature of the solid food-'~stu~fs incorporated.
I'Another variant of the inve~tion is to include i~
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''the whey protei~ product a proportion of one or more tha~
' one water-soluble humectant substance sufficient to maintai~
''' 20 a desired moisture content and reduced water activity (Aw) '- in the product, for example in the dry or semi-dry range from 5 to 20% moisture or in the semi-moist range from, say, ~ 20 to about 45%. In this way products can be obtained with I a softer texture, and which may be stored without sophisti-:~ ~ 25 cated'packaging without hardeni~g or bacteriological deterior- ' ' . . .
ation. Suitable humectants include polyh~dric alcohols, ' ~: .
~ugars, salts, other non-toxic low molecular weight water-.. . . '.
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~L~631~63 ~oluble compounds, low molecular weight polypeptides, including fish solubles, or mixtures of these.
Particularly preferred products of this kind have a moisture content in the range 5 to 20%~ and more especially 15 to 2C%~ and a water activity in the range 0.50 to 0~75, - and msre especially about 0.65. This commonly requires a level o~ humectant substances of 15 to 2~/o by weight of the product. Preferred formulations for this semi-dry type of product contain as essential ingredients 5-5~/o by weight whey protein, 0-20% fat and 5-25% humectant, with a moisture conten-t of 5-2~/o and a water activity of 0.60-0.75.
It is e~ually possible to utilize the invention in the preparation of products of hi~her moisture co~tent, for example with moisture contents in the range 20 to 45%, the level of humectant being adjusted to produce a water activity in the product which confers bacteriological stability, notably in the range 0.75 to 0.85~ Preferred formulations for such semi-moist products contain 10-40% by weight whey protein, 10-4~/o humectant, and 0-2~/o other edible material, with a moisture conte~t and water activity in the ranges just mentioned.
Tha various modifications of the invention may be combined. ~hus a whey protein matrix may incorporate a number of particulate or granular ~ood~tuffs and may also

2~ contain a suitable amount of humectant to confer on the product a softer texture which is maintained during storage at ordinary temperatures and relative humidities. A parti-;' ' ~,' ~ ' ' ' , ~

~63~363 .. . :
cularly preferred formulation for such a product contains 5-5~/o by weight whey protein, 0-2~o fat, 15-6~Jo solid food-stuff or edible matter, 5-25% humectant and 5-20% water, and the product has a water activity of 0.60-0.75.
~he ~ollowing are examples of the practice of the inve~tion.
E3cample 1 ~ .
~ his example provides a simulated animal product formed from a whey protein dispersion containing a thickener.
Whey protein (acidic) 30.~/o by weight Water 5~-~/
t Dried blood ~.~/o " "
Dyestuff solution 2.4%
Beef dripping 10~/o Guar gum 1.~/o ¦ Sodium hydroxide 1~/o ll ~l ~he i~gredients were mixed together in a high speed homogeniser, the sodium hydro~ide being first dissolved in the water. ~he mix, which had a pH of 7.5, was then ex-truded through a mincer into a hot water bath at 95 to 100C. -~............... . ..
~he extruded cylinders were cut off into ~-inch pieces at the mincer plate, blanched in the hot water for 3 minutes and cooled.
The product was fi~m and coherent and had a smooth internal texture closely similar to that o~ organ meats such as kidne~ It may if desired be passed throug~ a cutting machine to simulate the sharp edge appearance of cut kidneys.

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' . .! ' ~ ' ; ' ', " ', ' . ~ ' ,"'' '' '" " , ' '' '' ,, , '' ' ' ., ~ f~63F~63 ~ he product was sufficiently tough to withstand mechanical handling. A~ter sterilisation in cans in a meat miX, the product surface readily shed the gra~y and meat mousse background in a similar manner to the surface of real kidney.
~xample 2 Example 1 was repeated but with the substitution of ` 8.3% fresh blood and 1~G% trisodium citrate for the dried ;~ blood. The amount o~ water was adausted accordingly to 46.1%.
- ~he product obtained was similar to that of Example .

Example ~
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Example 1 was repeated with the exception that instead of sodium hydroxide, potassium carbonate was added until a pH of 8.0 was achieved~
~ he resulting product had an aerated texture similar to that of meat loafO
~ le 4 ~h; S example demonstrates the use of vegetable protein in conJunction with the whe~ protein~
Example 1 was repeated but with the substitution of , - 2~h whey protein and 1~/o soya protein concentrate for the ~/o whey pxotein of the original example.
The product obtained was in the form of a very tough chunk with a dense lung-like texture.

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1~63863 ~ his example demonstrates the use of whe~ proteis to bind meats in a sausage type product.
Whey protein (acidic) 25~3% by weight Meat off-cuts 23.~/o ~ripe 11.~/o ll ll ~rotters 15.4% " "
Blood 15.~/o Salt 2.~% " "
Trisodium citrate 5.~/o Sodium hydroxide 1.2% ll 1' ~he sodium h~droxide and trisodium citrate were dissolved i~ the blood and immediately mixed with the meats which had pl~eviously been finely macerated. ~he mix, which had a pH of 7.5, was extruded through a mincer plate and blanched as in Example 1. ~he product was a firm discrete I chunk similar to meat balls prepared in a ~imilar way but ; having the whey protein replaced with expensi~e binding meat.
~he final pH of the product was about 6.60 Example 6 ` ~his example demonstrates the use o~ whey protein ~eutralised prior tv drying.
~o 3 litres of cheese whey was added sufficient hydrochloric acid to reduce the pH of the salution to 4Ø
~he solution was heated to the boil and 5 ml of 30% calcium chloride was added dropwise with stirring. After 15 minutes the mixture was cooled to room temperature and oentrifuged ~1 . . , .,i.
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~ at 5000 rpm for 10 minutes to collect the p~ecipitate.
; After being washed twice with dilute hydrochloric acid solution the sediment3 comprising the whey protein, was neutralised to p~ 700 with sodium hydroxide solution and dried at 60C in an oven~
The following formulation was made up Neutralised whey protein 3~/o by weight ~ ., .
: Water 6~.~%
Dried blood ` 1.~/o 1~ It Dyestuff solution 2~4% " "
Guax gum 1.~/o 't ~l ¦ ~he mixture was heat coagulated as described in Example 1 and produced coherent firm chunks. In contrast, whey protein separated and dried without ~eutralisation9 did not produce chunkæ when used in the same fo~mulation by the I same process, but merely separates as a scum.
¦ ~he two following examples describe the production of complete food products co~taining humectants and anti-mycotics a~d are suitable for storage under ambient oonditions withouO loss o~ textu~e.

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.- Whey protein 12.6% by weight . , .
Sodium caseinate 12.6% " "
Rusk 44.1%
Beef dripping 5.~/o Vitamin mix 4.6%
Choline chloride solution O.ZYo . .
.. Glycerol 5.~/o " "
: 10 Sucrose 1305% " "
.
:~ Salt 1.5% " " :-.~t Potassium sorbate 0.~/oI Dyestuff solution 0.6% " "
;s` Wet mix:
. 15 Dry mix 78.03% by weight I Water - 21.14% " "
I Sodium hydroxide solution 0.83%
(25% W/w) ~he dry ingredients were weighed into a bowl mixer : fitted with a spade attachment and the beef drippi~g .~ (at 60a), dye solution and glycerol, water i~nd sodium hydroxide solution were added during mixing.
The wet mix, which had a pH of 6.5, was spread in a ~-i~ch layer on greased trays9 the sur~ace brushed with fat and the mix baked at 375F for 21 minutes in an air-circulating ovenO
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~0638G3 ~ he final product was cut into ~-inch sized pieces and pac~ed. The product had a moisture content of 15.~/o and a water activity (Aw) of 0.70.
In a dog feeding trial the product was found to have a much higher acceptance than a traditional dry complete dog food, which had a cereal-based structure.
~ he product had a sweet, nutty taste to the human palate and a firm, coherent texture, whereas a similar product prepared without neutralising the whey protei~ had not only a hard, brittle texture but a sour, u~pleasant taste.
After storage for one month at ambient temperature in the relative humidity range of 55 - 8~o the product was found to be bacteriologically stable and had retained its firm, coherent texture.
Ex~mple 8 Dry mix:
Whey protein 130~o by weight Sodium caseinate 13.~/o ~l ... .
Arachis oil 5.0% "
Roasted peanuts 45.~/o ~
Vitamin mix 4.6% " "
Choline chloride solutio~ 0.~/o "
Glycerol 5.oo/o ~
Sucrose 13.5% " "
` Potassium sorbate 0.1% " "
Dyestuf~ solution 0~6% " "

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Wet mix :. Dr~ mix 78.0~% by weight Water 21.14% " 1l Sodium hydroxide solution 0.83% " "
(25% W/W) :~ ~he product was prepared as described i~ Example 7 :
(the mix having a pH of 6.8) and had a firm, coherent texture, and could readily be cut into suitably sized pieces. The final pH of the product was 6Ø

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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 method of making a protein food product comprising the steps of:
forming a mix comprising an aqueous solution or dispersion of acidic whey protein, said whey protein having been separated from whey under acidic conditions; adjusting the pH value of said whey protein or mix to within the range 6 to 9; and heating said mix at pH 6 to 9 to coagulate said protein.

2. A method according to claim 1 including the additional step of incorporating in said solution or dispersion additional solid foodstuffs selected from cereals, cereal products, nuts, meats and meat by-products.

3. A method according to claim 2 comprising the steps of: forming a mix comprising an aqueous solution or dispersion of by weight 15-60% recover-ed acidic whey protein, 40-80% animal products selected from meat and meat by-products and mixtures thereof; adjusting the pH value of said mix to within the range 6 to 9, and thereafter heating said mix at pH 6 to 9 at a suitable temperature and for a period of time sufficient to coagulate said protein.

4. A method according to claim 2 comprising the steps of: forming a mix comprising an aqueous solution or dispersion of by weight 5-50% recovered acidic whey protein, up to 20% fat, 15-60% solid foodstuff selected from the group consisting of meat, meat by-products and cereals, 5-25% humectant and 5-20% moisture, and having a water activity in the range 0.60-0.75; adjusting the pH value of said mix to within the range 6 to 9, and thereafter heating said mix at pH 6 to 9 at a suitable temperature for a period of time suffi-cient to coagulate said protein.

5. A method according to claim 1 wherein a viscous solution or dis-persion of whey protein is shaped by extrusion and coagulated by blanching in hot water to form a firm, coherent product.

6. A method according to claim 5 comprising the steps of forming a mix comprising an aqueous solution or dispersion of by weight 15 to 70%
recovered acidic whey protein, 30 to 85% moisture; flavourant, colorant from 0 to 45% other edible materials; adjusting the pH value of said mix to within the range of 6 to 9; and thereafter heating said mix at pH 6 to 9 at a suit-able temperature and for a period of time sufficient to coagulate said pro-tein.

7. A method according to claim 1 wherein said whey protein is neutralised to pH 6 to 9 and dried prior to the formation of said solution or dispersion.

8. A protein food product comprising a coherent matrix composed of heat-coagulated whey protein, said whey protein having been separated from whey under acid conditions but having at coagulation a pH of 6 to 9, whenever prepared by the method of claim 1 or by an obvious chemical equivalent there-of.

9. A food product according to claim 8 additionally containing solid foodstuffs selected from cereals, cereal products, nuts, meats and meat by-products, said solid foodstuffs being embedded in and bonded together by said matrix, whenever prepared by the method of claim 2, or by an obvious chemical equivalent thereof.

10. A food product according to claim 8 composed essentially of 15-60%
whey protein, and 40-80% animal products selected from meat and meat by-products and mixtures thereof, whenever prepared by the method of claim 3 or by an obvious chemical equivalent thereof.

11. A food product according to claim 8 additionally including at least one water-soluble humectant substance in sufficient quantity to confer bacteriological stability on the product, the food product being composed essentially of 5 to 50% whey protein, 0 to 20% fat, 15 to 60% solid food-stuff, 5 to 25% humectant and 5 to 20% moisture, and having a water activity in the range 0.60 to 0.75, whenever prepared by the method of claim 4 or by an obvious chemical equivalent thereof.

12. A food product according to claim 8 comprising by weight 15 to 70%
whey protein, 0 to 45% other edible materials, 30 to 85% moisture, flavourant and colorant, whenever prepared by the method of claim 6, or by an obvious chemical equivalent thereof.