GB2188526A

GB2188526A - Whey protein

Info

Publication number: GB2188526A
Application number: GB08604074A
Authority: GB
Inventors: John Burton; Paul Skudder
Original assignee: Agricultural and Food Research Council; Milk Marketing Board
Current assignee: Agricultural and Food Research Council; Milk Marketing Board
Priority date: 1986-02-19
Filing date: 1986-02-19
Publication date: 1987-10-07
Anticipated expiration: 2006-02-19
Also published as: GB8604074D0; GB2188526B

Abstract

A proteinaceous material obtained from milk or casein-containing milk products, or an analogue or derivative thereof, comprises a polypeptide or mixture of polypeptides substantially free of native alpha-, beta- and kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the immunoglobulins, and i) remains in solution at pH 4.6 to pH 5.3 at 20 DEG C; ii) is anionic at pH 4.6 to pH 5.3; and iii) forms a gel when an aqueous solution containing at least 12% w/v of the proteinaceous material at 20 DEG C and pH 4,5 or below is allowed to stand for 18 to 24 h. Milk whey at pH 4 to 6 may be contacted with an anion exchange resin, the resin may be eluted with HCl or NaCl and the product may be concentrated by ultrafiltration or thermal evaporation and/or spray dried or freeze-dried.

Description

SPECIFICATION Whey protein The present invention reiates to a novel proteinaceous material which may be obtained from milk or casein-containing milk products, to processes for its production and to its use as a thickening, gelling, emulsifying, stabilising or whipping agent or as a protein supplement in food or drink products, espe ciallydairy products.

Milk is known to contain a number of proteins, the major ones being alpha-, beta- and kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the immunoglobulins. Various methods are known for obtaining these proteins, such as those described in UK Patent No. 1563990 and Chemistry and Industry,7 November1983, pp 810-814 which relates to processes forfractionating the proteins in whey by anion exchange chromatography.

It has now been found that a proteinaceous material having previouslyunrecognised physical properties may be obtained from milk and certain caseincontaining milk products by extraction procedures involving anion exchange chromatograpy and that these surprising properties enable the material to be used as a thickening, gelling, emulsifying, stabilising or whipping agentforfood and dairy products.

Accordinglythe present invention provides a proteinaceous material obtained from milk or caseincontaining milk products, or an analogue or derivative thereof, comprising a polypeptide or mixture of polypeptides substantially free of native alpha-, betaand kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the immunoglobulins, and which i) remains in solution at pH 4.6 to pH 5.3 at 20"C; ii) is anionic at.pH 4.6 to pH 5.3; and iii) forms a gel when an aqueous solution containing at least 12% w/v ofthe proteinaceous material at 20"C and pH 4.5 or below is allowed to stand for 18to 24h.

As used herein the term "analogue" encompasses proteins having an amino acid sequence which are the same as or related to the amino acid sequence ofthe proteinaceous material and are obtained from dairy sources or produced by other means including total synthesis and by DNA recombinanttechniques and the term "derivative" includes protein obtained from milkorcasein-containing milk products oranalogues or such protein which have been chemically or enzymically modified.

As used herein the expression "substantially free of native alpha-, beta- and kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the immunoglobulins" meansthatthe proteinaceous material contains less than 5% w/w of the totai dry protein weight of anyone of these proteins in its native form.

Preferably the total amount of these proteins is less than 5% wlw, and most preferablythe material ofthe invention comprises less than 1% w/w of each of these proteins as determined by quantitative polyacryla midegelelectrophoresisasdescribed by Anderson and Andrews (Journal of Dairy Research, (1977), 44, 223-235) and Hillier (ibid., (1976), 43,259-265).

The proteinaceous material ofthe invention is novel since at acid pH values it is capable of producing significantly more viscous solutions and/or stronger gels than known milk protein fractions.

Proteinaceous material according to the present invention is usually obtained from dairy sources such as milk orwhey, for instance, whey resulting from acid precipitation of curd, rennet casein whey and cheesewhey, and in such cases will often comprise a mixture of polypeptides. It is believed that a part of thins mixture is present in milk and proteinaceous material produced from whey resulting from acid precipitation of curd is likely to be particularly rich in this component.

It is also believed that part ofthe proteinaceous material derives from the action of proteolytic enzymes on casein, especially kappa-casein, and material derived from rennetorcheese-wheyislikelyto be richer in this component. Afurther useful source of the proteinaceous material is casein or caseinate, preferably sodium caseinate, which has been treated with proteolytic enzymes such as rennet; again this is likely to be rich in the casein-derived component. Preferably the proteinaceous material is derived from cow's milk orcasein orcaseinate obtained from cow's milk.

The present invention therefore provides a process for producing a proteinaceous material as defined above which comprises fractionating milkwhey or a casein-containing milk product which has been exposed to proteolytic enzymes and recovering fractions containing a polypeptide or mixture of polypeptides substantially free of native alpha-, beta- and kappacasein, serum albumin, alpha-lactalbumin, beta-lac toglobulinandtheimmunoglobulinsandwhich i) remains in solution at pH 4.6 to pH 5.3 at 20do; ii) is anionic at pH 4.6 to pH 5.3; and iii) forms a gel when an aqueous solution containing at least 12% w/v ofthe proteinaceous material at 20"C and pH 4.5 or below is allowed to stand for 18to 24 h.

Preferablyfractionation iseffectedbyanionexchange chromatography using an ion exchange medium bearing basid functional groups.

In one embodiment the process for producing the proteinaceous material comprises the steps of (a) if necessary, adjusting the pH milkwheytopH4 to6 (b) contactingthewheywith an ion exchange medium having basic functional groups (c) eluting protein fractions from the medium (d) collecting the fractions containing the desired polypeptide or mixture of polypeptides (e) removing excess eluantfrom the fractions so obtained and (f) drying the proteinaceous material so produced.

The whey used in the process may be obtained by any conventional method such as acid or, preferably, rennet coagulation of fresh milk preferably cow's milk.

Conveniently the whey is separated to remove residual fat before being acidified.

Whilst it is not essential it is much preferred that, either beforeor afterthe pH adjustmentstep, the whey The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.

is pasteu rised, for instance at 65 to 76"C, preferably at about 720C, for 10 to 25 seconds, preferably about 15 seconds, and is then centrifuged to remove any protein precipitate. The proteinaceous material obtained when such a pasteurisation step is included has been found to provide substantially stronger gels than when this step is omitted.

The pH ofthewhey is adjusted if necessary, in conventional manner, to pH 4to pH-6, preferably to pH 4.5 to 5.5 and most preferably pH 4.8 to 5.0.

The pH-adjusted whey is then passed through an ion exchange medium having basic functional groups which bind the polypeptide(s) in question. Preferably the ion exchange medium has strongly basic function- al groups. Suitable ion exchange media are Spherosil QMA (Rhone-Poulenc Fine Chemicals), Amberlite IRA 958 (Rohm and Haas Ltd.) and Indion CAE cellulose (Waitaki Refrigeration Co. Ltd.), ("Spherosil", "Amberlite" and "Indion" are Trade Marks). With these media the preferred throughput ofwhey before regeneration ofthe medium is of the order of 10 times the bed volume ofthe medium.

Unadsorbed protein and non-proteinaceous components are washed from the medium using water.

The proteinaceous material ofthe invention is then recovered from the.ion exchange medium by eluting with eluants of suitable ionic strength and pH, for examplehydrochloricacid, preferably 0.1 to 0.2 M hydrochloric acid, or an alkali metal chloride, preferably sodium chloride, most preferably 1 Msodium chloride. The properties of the final product differ slightly according to which eluant is used.

Conventional ion exchange or chromatographic techniques for continuous, semi-continuous or batch production may be employed.

The eluate is collected and some ofthe excess eluant is removed and the proteinaceous material is concentrated. Convenientlythis is achieved by ultrafiltration and the ultrafiltratioin membrane system may also be used to reduce the concentration of eluting agents by diafiltration with water. Preferablythe eluate is adjusted to higher pH, at least greater than pH 4.5 thereby permitting greater degrees of protein concentration without the problem of gellation during the concentration step.

Optionally the protein may be concentrated further by,for instance, thermal evaporation before drying, for instance byfreeze or spray drying. Spray drying is preferred since the protein fraction so obtained has improved shelf life as a dry powder compared with freeze dried proteinaceous material. Suitably spray drying is conducted with an air inlettemperature of about 200"C and an outlettemperature of about 95"C.

In an alternative embodimentthe process for producing the proteinaceous material comprises the steps a) treating resuspended casein or caseinate with proteolytic enzymes, b) adjusting the pH ofthe product of step a) to pH 4to 6, c) removing any precipitated protein, d) if necessary adjusting the pH ofthe remaining solution to pH 4.8 to 5.3, e) contacting the solution with an ion exchange medium having basic functional groups, f) eluting protein fractions from the medium, g) collecting the fractions containing the desired polypeptide or mixture of polypeptides, h) removing excess eluantfrom the fractions so obtained and i) drying the proteinaceous material so produced.

Preferably step a) is conducted at pH 6.0 to 6.7 and 32 Cfor 1 hourusing rennet.

When eluted using an acidic medium the proteinaceous material ofthe present invention does not precipitate over a wide range of pH but forms a strong gel in aqueous solution of 7% w/vorgreaterconcen- tration at ambient temperatures provided the pH is about 4.5 or below. A 10% w/v aqueous solution ofthe proteinaceous material normally has, at pH 3.5 and 20"C, a viscosity in excess of 3000 mPa.s. Accordingly the protein fraction is useful for thickening or gelling acidicfood and drink products, such as sauces, mayonnaises and low-calorie spreads and those subjected to acid and heat such as jams, jellies and heat-treated fruit-juice products.

At pH values over about 4.5 the proteinaceous material ofthe invention does not form gels. Under these conditions it finds applications as an emulsifying agent and as a protein supplement and may be used to avoid the precipitation problems that are encountered when total milk protein or sodium caseinate are employed. The proteinaceous material is also stable over a wide range oftemperature and can be used in products subjected to heating when the addition of otherwhey proteins, such as betalactoglobulin, would cause gellation, provided that the pH remains above 4.5. Furthermore the proteinaceous material is able to stabilize foams in aerated products.

When eluted using a neutral salt-containing medium the properties exhibited by the material are similartothe above but, in general, higherconcentrations are needed to achieve the same effect. Thus, for instance, a concentrate of at least 12% w/v is required at a pH of 4.5 or below to achieve a strong gel in aqueous solution.

The present invention thus provides a liquid or solid food or drink product comprising, as thickening, gelling, emulsifying, stabilising or whipping agent or as a protein supplement; a proteinaceous material as hereinbefore defined.

The invention also provides a processforthickening or gelling a food or drink product comprising admixing a sufficient quantity of a proteinaceous material as hereinbefore defined or an aqueous solution thereof with other ingredients of the food or drink product the aqueous phase ofwhich has a pH of 4.5 or less.

The invention further provides a process for emulsifying or stabilising a food or drink product comprising admixing a sufficient quantity of a proteinaceous material as hereinbefore defined with other ingredients of food or drink productthe aqueous phase of which has a pH of over4.5.

The invention further provides a process for producing an aerated food ordrink product,for instance a milkshake or dessert whip, comprising admixing a sufficient quantity of a proteinaceous material as hereinbefore defined before or at the same time as the product is whipped or otherwise aerated to form a foam.

Fig. 1 shows the results of polyacrylamide gel electrophoresis on samples of the proteinaceous material of the present invention (lanes 3 to 10) and of skim milk and whey (lanes 1 and 2).

The invention will now be illustrated bythefollowing, non-limitative Examples: EXAMPLE 1 Production ofthe Proteinaceous Material from Whey: Whey produced from whole milk by rennet coagulation such as in cheese manufacture was separated to remove residual fat, acidified to pH 4.8 to 5.0, and pasteurised at 72"C for 15 seconds. It was then centrifuged to remove any protein precipitate. The wheywas nextpassed to a column containing a porous ion exchanger with strong base functionality, (Spherosil QMA, Rhone-Poulenc). The throughput of whey was 18.5 litres per kg of dry medium. The protein was eluted from the ion exchanger using 0.1 M hydrochloric acid and collected.

The concentration of protein in the eluate was increased to 8 to 9% w/v ofthe total solids by ultrafiltration. The ultrafiltration equipment employed was a pilot plant supplied by Rhone-Pou lene which was fitted with 2.3 m2 of UFP1 0Atype membranes.

The plant ways operated atambienttemperaturewith inlet and outlet pressures of 3 and 2 bar respectively.

The product was then diafiltered with freshwater to remove most ofthe remaining hydrochloric acid. The diafiltration was continued until the conductivity of the protein concentrate was reduced below a level five times that ofthe diafiltration water. The protein solution was spray dried using an airinlettempera- ture of about 200"C and an outlettemperature of about 95"C.

Properties ofthe Proteinaceous Material: The proteinaceous material contains 95% total solids and 78% crude protein (total nitrogen x 6.38). In addition there is 3 to 5% ash and 1 to 2% fat. The major whey protein components: bovine serum albumin, alpha-lactalbumin and beta-lactoglobulin are absent or present at very low levels as determined by polyacrylamide gel electrophoresis. Polyacrylamide gel electrophoresis in the presenceof8Murea gives rise to a number of protein bands as shown in Fig. 1 and discussed below.

The proteinaceous material contains a proportion of protein which is not precipitated bytri-chloro-acetic acid.

The acid stability of the proteinaceous material was demonstrated by making up 5% w/v aqueous solutions of (a) proteinaceous material, (b) sodium caseinate, and (c) a total whey protein isolate powders, adjusting the pH value of each solution to 6.5 to 7.0 and then running in small quantities of hydrochloric adidto reduce the pH progressively down to 1.5.

Solution (a) showed an increase in turbidityfrom pH 5.5 to pH 3.5 but showed no sign of precipitation or instability. Solution (c), the total whey protein isolate, also showed marked increase in turbidity from pH 5.5 to pH 3.5 but the tu rbidity then reduced until the solution was almost as clear at pH 1.5 as it had been at pH 6.5. Again, there was no sign of precipitation or instability. Solution (b), the sodium caseinate, showed very heavy precipitation from pH 5.5. The precipitate began to redissolvefrom pH 4.0 but a proportion remained even at pH 1.5.

Thetemperature stablility of the protein fraction was demonstrated by making up 10% w/v solutions at pK 6.5 of the three protein powders [(a) to (c) above], placing them in a shaking water bath and heating progressively up to 72 Cwherethe solution of (c) formed a gel.Thetwo remaining samples were heated upto 90"C. Both showed no indication ofgellation, though the proteinaceous material showed an increase in turbidity and a slight reduction in viscosity.

10% w/v solutions ofthe three powders [(a) to (c) above] were made up at ambienttemperature and pH adjusted to 3.5 using food grade hydrochloric acid.

The viscosity, as determined by a Brookfield viscometer, ofthe proteinaceous material (a) was 3160 mPa.s compared to 20 mPa.sforsodium caseinate (b) and 30 mPa.s for whey protein (c). The proteinaceous material was shown to form firm gels when suspended in water at concentrations of 15% and at ambient temperature, but th is phenomenon is restricted to pH values below 4.5.

EXAMPLE2 The process of Example 1 was repeated except that the elution was conducted using 1 Msodium chloride in place of the hydrochloic acid eluant. This resulted in an increase in amount of protein recovered of approximately 30%.

The protein fraction thus obtained was similarto that obtained in Example 1. A 20% w/vsolution in wateratambienttemperature and pH 3.5 had a viscosity of 360 mPa.s (see below).

EXAMPLE 3 The process of Example 1 was repeated except that the pasteurisation step before contacting with the ion-exchange medium was omitted. The protein fraction thus obtained was similar to that obtained in Example 1.

The strength of the gel formed with 10% (w/v) solutions of the products of Examples 2 and 3 decreases with increasing time between the elution step and the final drying of the product, due to proteolysis by enzymes originating from the rennet used in cheese manufacture which are also absorbed and recovered during the ion-exchange process; the pH of the eluate is such that rapid proteolysis takes place. The problem may be overcome either by heat-treatment after elution to inactivate the enzymes or by adjusting the pH of the eluate to above 4.0. It has also been observed that less strong gels are obtained the longerthis powder is held in storage and thus greater amounts of powder are required to achieve the same result.

EXAMPLE 4 The processes of Examples 1 and 2 were repeated exceptthat whey obtained by acidification of milkto pH 4.6 was passed through the Spherosil ion-exchange medium at pH 4.8 to 5.0. Similar results were obtained except that the yield of protein per unit volumeofwheypassedthroughthe medium was reduced by approximately 66% in each case.

EXAMPLE 5 The processes of Examples 1 and 2 were repeated exceptthatinstead of whey a protein-containing solution at pH 4.6, obtained by treatment of a 2.5% (w/v) sodium caseinate solution in milk serum with rennetfor 1 h. at32 C at pH 6.65, was passed through Spherosil ion-exchange medium at pH 4.8 to 5.0.

Similar results were obtained exceptthatthe yield of protein per unit volume of solution passed through the medium was reduced by approximately 33% in each case.

EXAMPLE 6 The processes of Examples 1 and 2 were repeated exceptthatthe whey was contacted with Amberlite IRA 958 acrylic based ion-exchange medium instead of Spherosil QMA and similar results were obtained.

EXAMPLE 7 The process of Example 2 was repeated except that the whey was contacted with Indion QAE cellulose based ion-exchange medium instead of Spherosil OMA and similar results were obtained.

EXAMPLE 8 Milk Shake drinks were produced using a blend of the following ingredients: Comparison Example 8 Skim milk powder 46.59 46.59 Icing sugar 429 429 Calcium caseinate 7.29 7.29 Guargum 1g 1g Flavour/colour 1.89 1.89 Proteinaceous material NIL 2.59 98.59 101g In each case, 50g ofthe blend was mixed with 130ml cold water and whisked well. The mix of Example 8 containing the proteinaceous material of the invention gave a good foaming head which was stable for over 20 minutes.

The comparison containing no proteinaceous material ofthe invention foamed initially but the head rapidly collapsed.

EXAMPLE9 A "DessertWhip" was produced using a blend of the following ingredients: Skim milk powder 359 Icing sugar 329 Calcium caseinate 5.5g Guargum 0.89 Starch 229 Flavour/colour 1.5g Protein product 3.79 50g of the biend was mixed with 1 50mI cold water, whisked with a mechanical whisk and left to stand for approximately 3 minutes. The product held air well.

EXAMPLE 10 The emulsifying capacity of the material as prepared in Exampe 1 was compared with that of a whey protein concentrate and a caseinate using the emul sion test as described by N.B. Webb et al., J. Food Science, 35,501-504, (1970).

The results obtained showthatthe emulsifying capacity is improved overthat of the whey protein concentrate at all concentrations and is similar to, or betterthan, the caseinate. The product of Example 1 also showed better dispersibilitythan the caseinate.

Polyacrylamide gel electrophoresis: The individual proteins or protein fragments present in the recovered fraction were separated and compared with those ofthe major proteins in skim-milk and whey using polyacrylamide gel electrophoresis in the presence of M urrea as described byAnderson and Andrews (Journal of Dairy Re search, (1977), 44,223-235) and Hillier (ibid., (1976), 43,259-265). The protein bands obtained by discontinuous electrophoresis in a 12.5% w/v acrylamide gel using an LKB model 90 01 3124 slab-gel electrophoresis apparatus are shown in Figure 1.

Figure lisa photograph ofthe protein bands obtained afterelectrophoresis of skim-milk, whey and protein fractions obtained in Examples 1 to 7 using 12.5% w/v acrylamide gels in the presence of 8 Murea. The numbered lanes were obtained from the following samples: Lane 1. Skim-milk(14ug protein) 2. Whey(5.4ug protein) 3. Protein fraction obtained after elution of protein adsorbed during the passage of rennet wheythrough Spherosil OMA using 0.1 M-HCI (35 ug protein) (Ex 1) 4. Protein fraction obtained after elution of protein adsorbed during the passage of rennet whey through Spherosil OMA using 1 M-NaCI (35 ug protein) (Ex 2) 5.Protein fraction obtained afterelution of protein adsorbed during the passage of acid whey through Spherosil QMA using 0.1 M-HCI (12 ug protein) (Ex 4) 6. Protein fraction obtained after elution of protein adsorbed during the passage of acid whey through Spherosil OMA using 1 M-NaCl (12 ug protein) (Ex 4) 7. Protein fraction obtained after elution of protein adsorbed during the passage of rennet whey th rough Amberlite IRA 958 medium using 0.1 M-HCI (35 ug protein) (Ex 6) 8.Protein fraction obtained after elution of protein adsorbed during the passage of rennet whey th rough Amberlite IRA 958 medium using 1 M-NaCI (35 ug protein) (Ex 6) 9. Protein fraction obtained afterelution of protein adsorbed during the passage of rennet whey through Indion OAE medium using 1 M-NaCI (35 ug protein) (Ex7) 10. Protein fraction obtained after elution of protein adsorbed during the passage of a solution containing the proteolytic products of rennet on sodium caseinatethrough Spherosil QMA using 0.1M-HCI (35 ug protein) (Ex 5).

Note the relative absence of alpha-, beta- and kappa-casein, and bovine serum albumin, alphalactalbumin and beta-lactoglobulin in the protein fractions loaded in slots 3-7 even though considerably more protein was applied to the gel.

Claims

1. A proteinaceous material obtained from milk or casein-containing milk products, or an analogue or derivative thereof, comprising a polypeptide or mixture of polypeptides substantially free of native alpha-, beta- and kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the im munoglobulins, and which i) remains in solution at pH 4.6 to pH 5.3 at 20 C; ii) is anionic at pH 4.6 to pH 5.3; and iii) forms a gel when an aqueous solution contain ing at least 12% w/v ofthe proteinaceous material at 20"C and pH 4.5 or below is allowed to stand for 18to 24h.

2. A proteinaceous material according to claim 1 which contains less than 1% each of native alpha-, beta- and kappa-casein, serum albumin, alpha-lactal bumin, beta-lactoglobulin and the immunog lobulins.

3. A proteinaceous material according to claim 1 substantially as herein described with reference to any one ofthe Examples.

4. A proteinaceous material according to claim 1 which, when subjected to polyacrylamide gel electrophoresis as herein described, shows a pattern substantially as herein described and illustrated with reference to anyone of lanes 3to 10 in Fig. 1 ofthe accompanying drawings.

5. A process for producing a proteinaceous material as defined above which comprises fractionating milkwhey or a casein-containing milk product which has been exposed to proteolyticenzymes and recovering fractions containing a polypeptide or mixture of polypeptides substantially free of native alpha-, beta- and kappa-casein, serum albumin, alpha-lactalbumin, beta-lactoglobulin and the immunoglobulins and which i) remains in solution at pH 4.6 to pH 5.3 at 200C; ii) is anionic at pH 4.6 to pH 5.3; and iii) forms a gel when an aqueous solution containing at least 12% w/v of the proteinaceous material at 20 Cand pH 4.5Or below is allowed to standfor 18to 24h.

6. Aprocessfor producing the proteinaceous material according to claim 5 which comprises the steps of (a) if necessary, adjusting the pH milk whey to pH 4 to6 (b) contacting the wheywith an ion exchange medium having basic functional groups (c) eluting protein fractions from the medium (d) collecting the fractions containing the desired polypeptide or mixture of polypeptides (e) removing excess eluantfrom the fractions so obtained and (f) drying the proteinaceous material so produced.

7. A process according to claim 6 wherein rennet coagulated whey is employed.

8. Aprocessaccordingto claim 60rclaim7 wherein the whey is pasteu rised before being contacted with ion exchange medium.

9. A process for producing the proteinaceous material according to claim 5 which comprises the steps of a) treating resuspended casein or caseinate with proteolytic enzymes, b) adjusting the pH of the product of step a) to pH 4 to 6, c) removing any precipitated protein, d) if necessary adjusting the pH of the remaining solution to pH 4.8 to 5.3, e) contacting the solution with an ion exchange medium having basic functional groups, f) eluting protein fractions from the medium, g) collecting the fractions containing the desired polypeptide or mixture of polypeptides, h) removing excess eluantfrom the fractions so obtained and i) drying the proteinaceous material so produced.

10. A process according to any one of the claims 6 to 9 wherein the ion exchange medium is eluted with hydrochloric acid or sodium chloride in aqueous solution.

11. A process according to claim 10 wherein the ion exchange medium iselutedwith 0.1 to0.2M hydrochloric acid or 1 Msodium chloride solution.

12. A process according to any one of claims 6 to 11 wherein the ion exchange medium is washed prior to elution.

13. A process according to claims6to 12 wherein the protein fractions collected from the ion exchange medium are diafiltered for removal of remaining eluant.

14. A process according to claim 13 wherein the protein fractions collected from the ion exchange medium are concentrated by ultrafiltration our thermal evaporation.

15. A process according to claims 6 to 14wherein the protein fractions collected from the ion exchange medium are concentrated by ultrafiltration.

16. A process according any one of claims 6 to 15 wherein the proteinaceous material is spray dried or freeze dried.

17. A process according to claim 16wherein the proteinaceous material is spray dried.

18. A process according to claim Sand substantially as herein described with reference to any one of Examples 1 to 7.

19. A milk protein fraction whenever produced by a process according to any one of claims Sto 18.

20. Afood or drink product comprising, as thickening, gelling, emulsifying, stabilising orwhipping agent or as a protein supplement, a protein fraction as claimed in any one of claims 1 to 4, and 19.

21. Afood or drink product as claimed in claim 20 and substantially as herein described with reference to Examples 8 and 9.

22. A processforthickening or gelling a food or drink product comprising admixing a proteinaceous material as claimed in any one of claims 1 to 4 and 19 or an aqueous solution thereof, with otheringre- dients ofthefood or drink productthe aqueous phase of which has a pH or 4.5 or less.

23. A process for emulsifying orstabilising a food or drink product comprising admixing a sufficient quantity of a proteinaceous material as defined in any one of claims 1 to 4 and 19 with other ingredients of a food or drink product the aqueous phase of which has a pH of over 4.5.

24. A process for producing an aerated food or drink product comprising admixing a sufficient quantity of a proteinaceous material as hereinbefore defined before or atthe same time as the product is whipped or otherwise aerated to form a foam.

25. A process according to claim 24 for producing a milkshake or dessert whip.

26. A process according to claim 24 and substantially as hereinbefore described with reference to Example 8 or Example 9.