HK1112374A - Dairy ingredient - preparation and use - Google Patents

Description

Dairy product ingredient-preparation method and application thereof

Technical Field

The present invention relates to a dried milk protein concentrate or dairy concentrate.

Background

The applicant of co-pending application PCT/NZ2004/000142 has demonstrated a method of altering the texture of a milk protein gel comprising Processed Cheese (PC) and processed cheese-like products (PC-like products), spread cheese (spreads), yoghurt and dessert by controlling the pH in a processed cheese pot (PC-kettle) during the cooking stage. However, it is not convenient to control the pH during a PC cooking operation. Processors want to avoid the further complexity and risk of variability, especially in batch processes with fast turnaround times.

The efficiency of the overall process (ultimately converting milk into PC) can be significantly improved if the advantages of texture enhancement in the PC can be pre-established in the protein component used to produce the final product.

Bhaskar et al (WO 2004057971) disclose a method for increasing cheese yield by heat treating calcium-free MPC. Optional pH adjustment may be performed prior to heat treatment, evaporation and drying, and the disclosure states that "as the MPC or MPI passes through the column, its pH increases. If the pH is increased above 7.0, it is usually adjusted to about 6.5-7.0 to make it more palatable. "the method does not teach any textural advantages in PC obtained by heat treatment or pH adjustment of MPC without calcium removal.

Bhashar et al further states that "the cheese prepared by the process of the present invention may be further processed to prepare a reconstituted cheese or a reconstituted cheese-type product. "it is not stated whether the components prepared according to WO2004057971 can be effectively used directly in PC production to modify the PC texture.

Anema, Lowe and Lee, in ("Effect of pH on the acid-induced aggregation of casein micelles in reconstituted skim milk upon heating), -Lebensm. -Wis.u-Technol.2004, 37, 779-787) disclose that the rheology of milk can be altered by heat treatment when the pH is controlled to be between 6.0 and 7.0. However, they reported that "it should be noted that the present study only measures the pH at the onset of aggregation. The nature of the acidic gel formed upon establishment of the final gel is not indicated. "therefore, it does not teach how to use ingredients prepared from a dairy stream treated by the method disclosed in this invention to control the texture of PC (an essentially acidic fat-containing gel having a pH of about 5.6).

The use of heat treatment to control the Rheological behavior of skim milk while controlling the pH between 6.0 and 7.0 is further described by Anema et al, in "Rheological properties of acid gels prepared from skim milk adjusted by hot pH-adjusted" J agricultural. food chem.2004, 52, 337- "milk". The pH adjusted and heat treated skim milk was then re-adjusted back to pH 6.7 and subsequently treated with 2% w/w glucono-delta-lactone (GDL). This publication does not teach the preparation of dry ingredients, the advantage of avoiding adjustment to pH 6.7 or the result of not using GDL.

It is an object of the present invention to provide a dry ingredient or concentrate for use in the preparation of a milk protein gel having an improved texture and/or to provide a method of preparing said milk protein gel and/or to provide the public with a useful choice.

Disclosure of Invention

The present invention discloses a method of modifying milk protein gels, including PC and PC-like products, spread cheese, yoghurt and desserts, by using ingredients prepared as a dairy concentrate and controlling the pH and heat treatment of the concentrate.

Unlike PC production, which is typically run as a short run back operation, long run production runs (long production runs) are used to produce protein products such as Milk Protein Concentrates (MPCs), thus providing conditions that can be controlled over a long period of time to control pH and heat treatment conditions. Surprisingly, applicants have found that controlled pH-heat treatment of the protein component prior to drying results in a product that when ultimately reconstituted and used in a PC cooking machine (pan) can impart improved texture to the PC product. Preferably, the pH adjustment and heat treatment steps are performed after concentration of the protein stream (proteinstream), followed by immediate drying (preferably spray drying).

In one aspect, the present invention provides a method for producing powdered milk, comprising:

(a) providing a liquid dairy starting material comprising casein and whey proteins;

(b) adjusting the pH to a pH range of 5.0-8.0 by adding an acid or base if necessary;

(c) heat treating the pH-adjusted material in the presence of casein to denature whey protein; and

(d) drying the heat treated material to form a powder.

The invention also provides a powder prepared by the method.

Another aspect of the invention provides a method of producing a dairy concentrate comprising:

(a) providing a liquid dairy starting material comprising casein and whey proteins;

(b) if desired, concentrating the material to obtain a non-fat solids content of greater than 10% (w/v);

(c) adjusting the pH to a pH range of 5.0-8.0 by adding an acid or base if necessary;

(d) heat treating the pH-adjusted material in the presence of casein to denature whey protein; and

(e) cooling the heat treated material and storing it in one or more storage vessels;

wherein step (b) may be performed before, during or after step (c).

The invention also provides a dairy concentrate prepared by the method.

The invention is applicable to any dairy stream (high or low in fat) comprising undenatured (native) whey protein and casein. The ratio of whey protein to casein may be that which occurs naturally in milk, or it may be adjusted, for example by removal of whey protein or increased by addition of native whey protein. This ratio may be reduced, for example, by using techniques such as microfiltration, or may be increased by the addition of undenatured Whey Protein Concentrate (WPC). Suitable WPCs are commercially available. Examples of materials that may be used for the dairy starting material may be selected from one or more of skim milk, whole milk, casein, caseinate, milk protein concentrate/retentate and whey protein concentrate/retentate. The term "dairy starting material" does not include materials that have been subjected to a calcium removal step, for example using cation exchange chromatography.

The invention is preferably applied to a milk stream that has been subjected to ultrafiltration to increase the protein concentration relative to the lactose concentration. Ultrafiltration (UF) methods for this purpose are well known in the dairy processing art. The protein rich stream from the UF treatment is the retentate.

The milk stream may be subjected to a pH adjustment-heat treatment step at any stage prior to drying. Preferably, the retentate stream is used and subjected to a pH adjustment-heat treatment after it has been concentrated and before spray drying.

The dried product can be used as an ingredient for preparing a milk protein gel at the desired time and place. Such gels may or may not contain emulsifying salts.

PC and PC-like products (including spread-type reconstituted cheese) are products that have historically been prepared by melting cheese and then producing a smooth homogenous product with other ingredients.

Definition of denaturation

Denaturation refers to the extent to which whey proteins (in particular beta-lactoglobulin) present in the milk stream react with casein. Without being limited by theory, the heat and pH mediated interactions between dairy proteins are complex. A method for measuring the extent of interactions involving whey proteins is described by Anema & Lloyd in "Analysis of while protein inactivation: a comparative method of whey protein denaturation analysis: comparative study of alternative methods), Anema S.G, & Lloyd R.J.Milchwissenschaft, 54(1999) pp 206-210.

Scheme 1 shows a flow chart of a preferred method

The milk stream containing casein and whey proteins may be prepared using milk or skim milk, or by using reconstituted milk powder (preferably low-calorie milk powder). The dairy stream may also be prepared by mixing a casein rich stream with a whey protein rich stream. A reconstitution process may be used to prepare a milk stream enriched in casein or a milk stream enriched in whey protein. The ratio of whey protein to casein may vary in the range of 0.05 to 3, preferably 0.1 to 0.75.

Preferably the milk stream is a concentrated source of casein and whey protein. The concentrated milk stream may be obtained by evaporation or ultrafiltration, or a combination of both, or microfiltration, or a combination of the three. A concentrated dairy stream may be prepared by adding dry ingredients to a liquid stream. The non-fat solids content expressed on a fat-free basis is preferably from 10% to 60%, more preferably from 10% to 60%, most preferably from 20% to 55%.

The pH of the concentrated milk stream prior to heat treatment is preferably in the range 5.0 to 8.0, more preferably 6.0 < pH < 7.5, and most preferably 6.2 < pH < 7.2. A pH in the range of 6.8-7.2 is particularly useful in the case of attempts to increase viscosity. Any conveniently available acid or base may be used to adjust the pH. Depending on the desired pH shift, dilute hydrochloric acid or caustic soda solutions are suitable. It is preferred to add an acid or base to adjust the pH to a target pH range that aids in the preparation of a milk protein gel of the desired texture.

After adjusting the pH, the milk stream is heated to initiate reactions involving the protein. Specifically, whey protein is denatured in the presence of casein by heating. The desired level of denaturation is from 40% to 100%, preferably at least 60%, and most preferably at least 80%. By heating the concentrated milk stream (at the intended pH) to 90 ℃ for about 4 minutes, at least 80% denaturation can be achieved. Alternative time-temperature combinations can be used to achieve equivalent levels of denaturation.

In one embodiment, the heat-treated milk stream is spray dried to a moisture content that produces a shelf stable powder at room temperature. In a preferred embodiment, the dried ingredient is a modified Milk Protein Concentrate (MPC).

In an alternative embodiment, the heat-treated milk stream may be used directly as an ingredient in the production of a milk protein gel.

Another aspect of the present invention provides a method of preparing a milk protein-containing gel, comprising:

(a) dissolving/suspending the powder as described above in an aqueous liquid

(b) The pH is adjusted to 4.5-6.5 by the addition of acid.

(c) The mixture is cooked to form a molten mass.

(d) Cooling the molten mass to form a milk protein gel, wherein step (b) may be performed before, during or after step (c).

In another method, the present invention provides a method of preparing a milk protein gel comprising

(a) Providing a dairy concentrate as described above;

(b) adding acid to adjust the pH to 4.5-6.5;

(c) heating the mixture to form a molten mass;

(d) cooling the molten mass to form a milk protein gel;

wherein step (b) may be performed before, during or after step (c).

The ingredients (powder or liquid dairy concentrate) can be used to prepare a milk protein gel. The powder is dissolved/suspended in an aqueous liquid. The prepared liquid dairy concentrate may be used.

The ingredients may be used at this stage with an acid and optional ingredients such as solvents, edible fats, cheese, carbohydrates, salts, emulsifying salts, flavoring agents, etc. to create a mixture. Sufficient acid is added to adjust the pH to a pH in the range of 4.5 to 6.5, preferably 5.0 to 6.0. The mixture is cooked with stirring using shear forces to produce a homogeneous molten mass. Upon cooking, the material is poured into a suitable packaging system to obtain the desired product. The preferred cooking temperature is from 50 ℃ up to the boiling point of the mixture. Particularly preferred temperatures are from 72 ℃ to 90 ℃. Cooking times can range from 1 second up to about 20 minutes. Ingredients such as solvents, edible fats, cheese, carbohydrates, salt, emulsifying salts, flavoring agents, etc. may also be added during the cooking process.

The ingredients are varied according to the nature of the desired product. For example, for reconstituted cheese, high levels of protein are used together with a fat content that reflects the type of cheese desired. For spread cheese, the fat content is usually increased. For yogurt, stronger acidulants and more water are used, and the protein and fat content is reduced. For dairy desserts, sugar or another sweetener is used together with suitable dessert flavours and the amount of water is increased relative to fat and protein.

Drawings

Figure 1 shows the relationship between texture (G') and the degree of pH-adjusted denaturation of the whey proteins in tables 2 and 3.

Examples

The following examples further illustrate the practice of the invention.

Example 1-method of preparing spread-type reconstituted cheese Using pretreated retentate reconstituted MPC70

A. Recovery and heating step

ALAPRO 4700[ MPC70] (Oakland, Kura-Takara Shuzo Co., Ltd.) was reconstituted to 22% solids and 16% protein using RO water. The water was preheated to 50 ℃ in a water bath. The MPC powder was added to the warm water and the mixture was stirred at 50 ℃ for 30 min. After this time, the retentate solution was cooled to room temperature in cold water and held for 2.5 hours. The retentate prepared was divided into seven subsamples.

The retentate samples were pH adjusted using 1M NaOH or 1M HCl. The pH of each subsample was adjusted according to one of a series of values: starting from the retentate's natural pH of 6.64, +0.6, +0.4, +0.2, 0 (control), -0.2, -0.4 and-0.6 pH units.

The pH adjusted subsamples were allowed to equilibrate for about 2 hours with periodic checks and minor readjustments of pH.

For each pH adjusted retentate, five samples were prepared. Each 600g sample was weighed in a pair of Schott bottles (300 g per bottle) and then heated to 65 ℃ in a 65 ℃ water bath. (splitting the sample facilitates the subsequent heat treatment step.) the preheated sample is transferred to a water bath set at 85 ℃ and heated for the indicated time (0, 4, 6, 8 and 14 min). (7 pH. times.5 heat treatments are given here.) after heating, the sample was transferred to an ice bath and shaken to rapidly cool the sample to a temperature below 70 ℃. After cooling, the samples were transferred to a refrigerator (set at 4 ℃) until the next day for use in the production of reconstituted cheese (part B).

B. Formula of coating type reproduced cheese

Samples of pH and heat treated retentate from part a were used to create spread-type reconstituted cheese using the following recipe.

Formulation of

Component weight (g)

Soybean oil 185.0

pH and Heat treated retentate 360.0

Water 17.5 (7.5 g included for evaporation)

Sodium chloride 6.0

Trisodium citrate 2H₂O (15-X) g (see Table 1)

Citric acid (anhydrate) Xg (see Table 1)

Total 583.5g

Table 1 amount of salt required to obtain a final product with pH 5.75

pH of retentate sample	X
		6.04(-0.6)	2.498
6.24(-0.4)	2.764
		6.44(-0.2)	2.965
6.64(0)	3.20
		6.84(+0.2)	3.29
7.04(+0.4)	3.40
		7.24(+0.6)	3.605

C. Preparation method of smearing type reproduced cheese

Spread-type reconstituted cheese samples were prepared using a 2L capacity Vorwerk Thermomix TM 21 stir-cooker (Vorwerk australia pro.ltd., Granville, n.s.w., australia).

Soybean oil (AMCO, goodmafielder, East Tamaki, new zealand) was heated at a temperature set at 100 and a speed set at 1, which brought the temperature of the oil to about 60 ℃ in 1 minute.

For the control sample (no pH adjustment), 360g of the retentate from A, 11.8g (i.e., 15g-3.20g from Table 1) trisodium citrate.2H₂O (Jungbunzlauer GmbH, Perhofen, Austria), 3.20g citric acid (from Table 1) (Jungbunzlauer GmbH, Perhofen, Austria), 6.0g sodium chloride (Pacific salt, Kliscesche, New Zealand) and 17.5g water were added to the preheated oil.

The mixture was heated at speed 4(2000rpm) for 2min while the temperature of the cooker was set at 90 (about 90 ℃), after which the temperature was reduced to 80 (about 80 ℃) for 7 minutes. The speed was set at the end of every minute as "Turbo agitation" (Turbo) and continued for 3 seconds to thoroughly mix the emulsion and prevent the emulsion from scorching and sticking to the walls of the cooker. The molten reconstituted cheese was poured into a plastic screw-top container, inverted and then stored at 4 ℃. The final pH of the reconstituted cheese was 5.75.

The same operation was repeated to treat the pH-adjusted heat-treated sample.

D. Composition of spread type reproduced cheese

The reconstituted cheese contained 51.8% moisture, 32.1% fat, 10.0% protein, 2.5% lactose and the remainder 3.6% minerals (including other minor ingredients).

Texture analysis

The texture of the samples was measured as the modulus of elasticity (G') at 20 ℃ at 0.1Hz using a Carri-Med CSL100 rheometer (TAInstructions-Waters LLC, New Castle, USA) instrument. The values of G' are shown in Table 2.

TABLE 2 firmness of spread-type cheese samples (G')

pH treatment	G' (Pa) of the Heat-treated retentate (minutes in a Water bath at 85 ℃ C.)
							0	4	6	8	14
6.04	141	181	148	171	205
						6.24	127	144	199	243	263
6.44	103	190	255	316	321
						6.64	101 (control)	228	356	434	554
6.84	115	199	316	445	613
						7.04	152	297	449	472	517
7.24	165	387	492	588	697

The level of whey protein denaturation was assessed using polyacrylamide gel electrophoresis as described below. Table 3 shows the level of denaturation of the retentate after pH-adjusted heat treatment.

TABLE 3 percent denaturation of the treated retentate

pH treatment	Denaturation after heat treatment of the retentate (minutes in a 85 ℃ water bath (%)
							0	4	6	8	14
6.04	0	4.7	21.1	54.5	84.6
						6.24	0	15.0	50.3	67.4	83.9
6.44	0	24.5	54.0	73.6	94.8
						6.64	0 (control)	36.8	58.8	79.5	95.8
6.84	0	29.6	65.3	81.4	95.8
						7.04	0	45.4	75.1	84.0	92.4
7.24	0	58.6	75.9	89.3	96.9

Figure 1 shows the relationship between texture (G') and the degree of pH-adjusted denaturation of whey proteins from tables 2 and 3.

These experiments show that a milk protein ingredient containing casein and whey proteins can be used to subsequently alter the texture of a reconstituted cheese-like product or other milk protein gel, given the combined pH adjustment and heat treatment of the invention. Higher viscosities are achieved with increasing pH and percent denaturation.

Heating the fresh retentate and producing a reconstituted cheese therefrom:

a second series of experiments was carried out to show that a pH adjusted and heat treated ingredient can be prepared from a fresh milk protein source and that this ingredient can be subsequently dried and then used to modify the texture of a cheese-like product.

Production of pH-adjusted and Heat-treated MPC70 powder

1500L of skim milk retentate containing 73% protein (dry weight basis) and a total solids content of about 21% was obtained from Fonterra Whareoa. The retentate was diluted 1: 1 with demineralised water to make up about 3000L. The diluted retentate, having a pH of about 6.95, was divided into four portions, each of about 750L. The first portion (control 1) was evaporated to a solids content of about 30% using a 3-effect Wiegand evaporator without any pH treatment or pre-heat treatment and dried in a Da Laval dryer to produce a control no-heat treated MPC70 powder (about 3% moisture). The same evaporator and dryer were used to prepare the powder from the other three streams. The second stream (without pH adjustment [ control 2]) was heat treated at 90 ℃ for 240 seconds, then evaporated and dried to produce a heat treated control MPC70 powder. The pH of the third stream was adjusted to 7.15 using 10% NaOH solution. This stream was then heat treated at 90 ℃ for 240 seconds to produce a high pH heat treated MPC70 powder. The pH of the last stream was adjusted to 6.59 with 3% sulfuric acid. The resulting low pH retentate was heat treated at 90 ℃ for 240 seconds to produce a low pH heat treated MPC70 powder.

B. Preparation formula of coating type reproduced cheese

Formulation of

Component weight (g)

Soybean oil 185.0

Inventive Dry ingredients 82.7

Water 280.5 (containing 7.5g for evaporation)

Sodium chloride 6.0

Trisodium citrate 2H₂O (15-X) g (see Table 4)

Citric acid (dehydrated) Xg (see Table 4)

Total 561.7g

Table 4 amount of salt required to obtain a final product pH of 5.75

pH of selected retentate samples	X
		-0.3(pH 6.65)	2.859
0 (control 1 and control 2) [ pH 6.95]	3.337
		+0.3(pH 7.25)	3.555

C. Preparation method of smearing type reproduced cheese

Spread-type reconstituted cheese samples were prepared using a 2L capacity Vorwerk Thermomix TM 21 stir-cooker (Vorwerk australia pro.ltd., Granville, n.s.w., australia).

For samples control 1 and control 2 without pH adjustment, 82.5g of MPC70 (prepared as described above) was hydrated in 230g of water and placed in a refrigerator overnight (4 ℃).

At a temperature set to 100 and a speed set to 1, soybean oil (AMCO, goodmanfield, East Tamaki) was heated for 1min (this increased the temperature of the oil to about 60 ℃).

For hydrated MPC70, 11.663 g trisodium citrate 2H₂O (Jungbunzlauer GmbH, Perhofen, Austria), 3.337g citric acid (Jungbunzlauer GmbH, Perhofen, Austria), 6.0g sodium chloride (Pacific salt, Cleister, New Zealand) and 50.5g water were added to the preheated oil.

The mixture was cooked at speed 4(2000rpm) for 2min at a temperature setting of 90 (about 90 ℃), after which the temperature was lowered to a temperature setting of 80 (about 80 ℃) for 7 minutes. At the end of each minute, the speed was set to "Turbo agitation" (Turbo) and continued for 3 seconds to thoroughly mix the emulsion and prevent the emulsion from scorching and sticking to the walls of the cooker. The molten reconstituted cheese was poured into a plastic screw-top container, inverted and then stored at 4 ℃. The final pH of the reconstituted cheese was 5.75.

The same process is also used for hot and pH adjusted ingredients.

D. Composition of spread type reproduced cheese

The reconstituted cheese contained 50.2% moisture, 33.1% fat, 10.4% protein, 2.6% lactose and the remaining 3.7% minerals and other minor components.

Texture analysis

The texture of the reconstituted cheese samples was determined as described above and the texture results are shown in table 5.

The level of denaturation of whey protein was assessed using polyacrylamide gel electrophoresis as described below. Table 5 shows the level of denaturation of the powders prepared.

TABLE 5 texture of the reconstituted cheese samples (G')

Treatment of	Control 1 (unheated, pH 6.95)	pH 6.5+ heating	Control 2 (heating, pH 6.95)	pH 7.1+ heating
					Texture G' (Pa)	300	291	665	913

Denaturation of powder (%)

0

81.7

91.4

90.7

The results in table 5 demonstrate that the texture of cheese-like products prepared using pH adjusted and heat treated dry ingredients is altered based on principles similar to those shown in table 2. Method for determining the degree of protein denaturation of a retentate/MPC sample-modified Polyacrylamide gel electrophoresis (PAGE) analysis

The level of whey protein denaturation, which is caused by heating reconstituted and fresh MPC samples, was detected by non-denaturing polyacrylamide gel electrophoresis (non-denaturing-PAGE). The native PAGE method was similar to that described by Anema & Lloyd (Milchwissenschaft, 1999, 54, pp206-210) and Anema & McKenna (J.Ag. food chem., 1996, 44, 422-428) with the following modifications:

1. the retentate (22% total solids) was diluted 1: 100 with native PAGE sample buffer;

2. the gel was stained with 100ml amide Black (amide Black) (1% amide Black in 10% acetic acid and 25% isopropanol) for at least 1 hour;

3. decolorizing the gel several times with 100ml of 10% acetic acid solution until a clear background is obtained;

4. the gel was scanned with a Molecular Dynamics Model P.D densitometer (Molecular Dynamics Model p.d. densitometer) and integrated using a Molecular Dynamics imaging quant Software associated with the densitometer (all Molecular Dynamics, Sunnyvale, California, USA).

The whey protein denaturation level of the heated MPC samples was assessed by measuring the denaturation level of β -lactoglobulin, since β -lactoglobulin is the predominant whey protein in MPC and milk samples, and the denaturation level of β -lactoglobulin is known to correlate with total whey protein denaturation, as assessed by other methods commonly used to measure whey protein denaturation levels (Anema & Lloyd, michwissenschaft, 1999, 54, pp 206-210). The intensity of the beta-lactoglobulin band in the heated sample was measured as a percentage of the intensity of the beta-lactoglobulin band in the untreated control.

The term "comprising" means "consisting of or" including ". The process of the present invention may have additional steps and components such as salts, flavors, colors, etc. may be added.

The above-described embodiments are illustrative of the practice of the present invention. It will be understood by those skilled in the art that various modifications and changes may be made in the present invention. For example, the casein/whey ratio, cooking temperature, cooking pH, and acids used to change pH may be varied.

Claims (60)

1. A method of producing a dairy powder comprising:

(a) providing a liquid dairy starting material comprising casein and whey proteins;

(b) adjusting the pH to 5.0-8.0 by adding acid or base if necessary;

(c) heat treating the pH-adjusted material in the presence of casein to denature whey protein; and

(d) drying the heat treated material to form a powder.

2. The method of claim 1, wherein the dairy starting material has a weight ratio of whey protein to casein of from 0.05 to 3.

3. The method of claim 2, wherein the ratio is 0.1 to 0.75.

4. The method as claimed in claim 1, wherein the material to be heat-treated has a non-fat solids content of 10% (w/w) to 60% (w/w) expressed on a fat-free component basis.

5. The method of claim 4, wherein the non-fat solids content expressed on a fat free basis is from 20% to 55%.

6. The method of claim 1, wherein the dairy starting material is selected from one or more of skim milk, whole milk, casein, caseinate, milk protein concentrate/retentate, and whey protein concentrate/retentate.

7. A method as claimed in any one of claims 1 to 6 wherein the dairy starting material is concentrated to increase the non-fat solids expressed on a fat free component basis to 10% to 60%.

8. The process of any one of claims 1 to 7 wherein in step (b) the pH is adjusted if necessary to a pH of from 6.0 to 7.5.

9. The method of claim 8, wherein the pH is adjusted to a pH of 6.2 to 7.2, if necessary.

10. The method of claim 9, wherein the pH is adjusted to a pH of 6.8-7.2.

11. A method as claimed in any one of claims 1 to 10 wherein 40% to 100% of the whey protein is denatured after the heat treatment.

12. The method of claim 11, wherein more than 60% of the whey protein is denatured after the heat treatment.

13. The method of claim 12, wherein more than 80% of the whey protein is denatured after the heat treatment.

14. The method of any one of claims 1-13, wherein the drying step is carried out by spray drying.

15. A dairy powder prepared by the method of any one of claims 1-14.

16. A process for preparing a milk protein gel comprising

(a) Dissolving/suspending the powder of claim 15 in an aqueous liquid;

(b) adding acid to adjust the pH to 4.5-6.5;

(c) cooking the mixture to form a molten mass;

(d) cooling the molten mass to form a milk protein gel;

wherein step (b) may be performed before, during or after step (c).

17. The method of claim 15, wherein the product is selected from the group consisting of a processed cheese, a processed cheese-like product, a spread cheese, a yogurt or a dairy dessert.

18. The method of claim 16 or 17, wherein the pH is adjusted to 5.0-6.0 in step (b).

19. A process according to any one of claims 16 to 18 wherein the cooking step is carried out between 50 ℃ and up to the boiling point of the mixture.

20. The method of claim 19, wherein said cooking temperature is from 72 ℃ to 90 ℃.

21. A method according to any one of claims 16 to 20 wherein the cooking step is for a duration of from 1 second to 20 minutes.

22. A method according to any one of claims 16 to 21 wherein the cooling step is carried out while the product is being packaged.

23. The method of any one of claims 16-22, wherein the powder has a casein to whey ratio of 0.05 to 3.

24. The method of claim 23, wherein the ratio is 0.1 to 0.75.

25. The method of any one of claims 16-24, wherein the powder is prepared from one or more of skim milk, whole milk, casein, caseinate, milk protein concentrate/retentate, and whey protein concentrate/retentate.

26. A method according to any one of claims 16 to 25 wherein one or more ingredients selected from fats, cheeses, salts, molten salts, flavourings and colourings are added to the mixture before or during the cooking step.

27. The method of any one of claims 16-26, wherein the powder is prepared from a pH adjusted dairy starting material having a pH of 6.0 to 7.5.

28. The method of claim 27, wherein the powder is prepared from a pH-adjusted dairy starting material having a pH of 6.2 to 7.2.

29. The method of any one of claims 16-28, wherein more than 60% of the whey protein in the powder is denatured.

30. The method of claim 29, wherein more than 80% of the whey protein in the powder is denatured.

31. The method of any one of claims 16-30, wherein the powder is a spray-dried powder.

32. A method of producing a dairy concentrate comprising:

(a) providing a liquid dairy starting material comprising casein and whey proteins;

(b) concentrating the material to provide a non-fat solids content of greater than 10% (w/v), if required;

(c) adjusting the pH to a pH of 5.0 to 8.0 by adding an acid or a base, if necessary;

(d) heat treating the pH-adjusted material in the presence of casein to denature whey protein; and

(e) cooling and storing the heat treated material in one or more storage vessels;

wherein step (b) may be performed before, during or after step (c).

33. The method of claim 32, wherein the dairy starting material has a weight ratio of whey protein to casein of from 0.05 to 3.

34. The method of claim 33, wherein the ratio is 0.1 to 0.75.

35. The method of claim 32, wherein after step (a) or (b), the non-fat solids content expressed on a fat-free component basis is from 5% (w/w) to 60% (w/w).

36. The method of claim 35, wherein the non-fat solids content expressed on a fat-free component basis is from 20% to 55%.

37. The method of claim 32, wherein the dairy starting material is selected from one or more of skim milk, whole milk, casein, caseinate, milk protein concentrate/retentate, and whey protein concentrate/retentate.

38. The method of any one of claims 32-37, wherein the material to be heat treated has a non-fat solids content of 5% to 60% expressed on a fat free component basis.

39. The process of any one of claims 32 to 38 wherein in step (c) the pH is adjusted if necessary to a pH of 6.0 to 7.5.

40. The method of claim 39, wherein the pH is adjusted to a pH of 6.2 to 7.2, if necessary.

41. The method of claim 40, wherein the pH is adjusted to a pH of 6.8 to 7.2.

42. The method of any one of claims 32-41 wherein 40% to 100% of the whey protein is denatured after the heat treatment.

43. The method of claim 42, wherein more than 60% of said whey protein is denatured after said heat treatment.

44. The method of claim 43, wherein more than 80% of said whey protein is denatured after said heat treatment.

45. A dairy concentrate prepared by the method of any one of claims 32-44.

46. A method of preparing a milk protein gel comprising:

(a) providing a dairy concentrate as claimed in claim 45;

(b) adding an acid to adjust the pH to 4.5-6.5;

(c) cooking the mixture to form a molten mass;

(d) cooling the molten mass to form a milk protein gel;

wherein step (b) may be performed before, during or after step (c).

47. The method of claim 46, wherein the product is selected from the group consisting of a processed cheese, a processed cheese-like product, a spread-type cheese, a yogurt or a dairy dessert.

48. The method of claim 46 or 47, wherein the pH is adjusted to pH 5.0-6.0 in step (b).

49. A process according to any one of claims 46 to 48 wherein the cooking step is carried out between 50 ℃ and up to the boiling point of the mixture.

50. The method of claim 49, wherein said cooking temperature is 72 ℃ -90 ℃.

51. A process according to any one of claims 46 to 50 wherein the cooking step is for a period of from 1 second to 20 minutes.

52. A method according to any one of claims 46 to 51 wherein the cooling step is carried out whilst the product is being packaged.

53. The method of any one of claims 46 to 52, wherein the dairy concentrate has a ratio of casein to whey of from 0.05 to 3.

54. The method of claim 53, wherein the ratio is 0.1 to 0.75.

55. The method of any one of claims 46 to 54, wherein the dairy concentrate is prepared from one or more of skim milk, whole milk, casein, caseinate, milk protein concentrate/retentate and whey protein concentrate/retentate.

56. The method of any one of claims 46 to 55 wherein one or more components selected from fat, cheese, salt, molten salt, flavouring and colouring are added to the mixture prior to the cooking step.

57. The method of any one of claims 46 to 56, wherein the dairy concentrate is prepared from a pH adjusted dairy starting material having a pH of from 6.0 to 7.5.

58. The method of claim 57, wherein the dairy concentrate is prepared from a pH-adjusted dairy starting material having a pH of from 6.2 to 7.

59. A method as claimed in any one of claims 46 to 58 wherein more than 60% of the whey protein in the dairy concentrate is denatured.

60. The method of claim 59, wherein more than 80% of the whey protein in the dairy concentrate is denatured.