WO2008079031A2

WO2008079031A2 - Dairy product and process

Info

Publication number: WO2008079031A2
Application number: PCT/NZ2007/000390
Authority: WO
Inventors: Christina June Coker; Satyendra Parshu Ram; Lilian De Barros Ferreira; Diane Joy Sinclair; Siew Kim Lee; David Campbell Wemyss Reid; Christine Joy Thompson
Original assignee: Fonterra Co-Operative Group Limited
Priority date: 2006-12-22
Filing date: 2007-12-24
Publication date: 2008-07-03
Also published as: NZ552352A; WO2008079031A3

Abstract

The invention relates to a calcium- and phosphate-depleted milk protein concentrate or isolate. This may be prepared by use of cation exchange together with one or more of anion exchange, ultrafiltration/diafiltration and electrodialysis. The products are useful in the manufacture of processed cheese, yoghurts, spreads, cheese, dairy desserts and other milk protein products.

Description

DAIRY PRODUCT AND PROCESS

Technical Field

This invention relates to milk protein products, processes for their preparation and use, for example in manufacture of processed cheese, yoghurts, spreads, cheese and dairy desserts.

Background Art

Milk protein concentrates (MPCs) and milk protein isolates are milk fractions that are enriched in protein relative to lactose. These products differ from milk concentrates in that they are high in protein and low in lactose and usually low in fat. They differ from skim milk concentrates in that they are high in protein and low in lactose.

One use for MPCs and MPIs is in cheese manufacture as cheese milk extenders. By addition of these to increase the protein concentration of milk used in the manufacture of cheese, cheese making can be made more consistent and more efficient. Dried MPC is particularly useful for boosting the protein content of the cheese milk and increases the yield of curds and thus cheese for the volume of cheese milk provided.

MPCs and MPIs can be used in processed cheese but are limited by solubility and reactivity.

WO01/41578 discloses dried milk protein concentrates that are calcium-depleted. These have improved properties. They show greater solubility in water at ambient temperatures and a reduction in the fonnation of "nuggets" in the cheese relative to that in cheese where standard MPC was used in cheese manufacture. Nuggets are thin protein gels of a different colour in cheese.

The calcium-depleted MPCs and MPIs can be used in processed cheese manufacture and have improved solubility characteristics. However, it would be desirable to use an ingredient that provides further improved texture. It is an object of the invention to provide an ingredient for use in preparing a milk protein gel having a high protein content and/or to provide a method for preparing the milk protein gels and/or to provide the public with a useful choice.

Disclosure of the Invention

The inventors disclose a method of altering the texture of milk protein gels, including processed cheese and processed cheese-like products, spreads, yoghurt and desserts by the use of an ingredient prepared as a dairy concentrate and the manipulation of the calcium and phosphate content.

The manufacture of protein products such as milk protein concentrates (MPCs), and the like, is made using long production runs, thereby giving the possibility of well controlled conditions to manipulate the mineral content. The applicants have found that lowering of calcium and phosphate in the protein ingredient confers a modified texture to the processed cheese product. The ingredient may be either liquid or dried. When the ingredient is a dried ingredient, the steps to lower calcium and phosphate are preferably performed before concentration of the protein stream immediately prior to drying (preferably spray drying). .

In one aspect the invention provides a method for producing a dairy product comprising:

(a) providing a skim milk or an MPI or MPC, in aqueous solution/suspension

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10- 100%, preferably 20- 100% removal of both ions wherein either:

(1) the solution/suspension is subjected to (in any order) (i) cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions, and one or more processes selected from:

(ii) anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions, (iii) ultrafiltration and/or diafiltration, and

(iv) electrodialysis, or

(2) process (i) and one or more processes of (ii)-(iv) are carried out on at least two separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20-100% depletion of both calcium and phosphate ions.

In one embodiment the invention provides a method for producing a dairy product comprising:

(a) providing an MPI or MPC, in aqueous solution/suspension (b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having

10-100%, preferably 20-100% removal of both ions by carrying out both cation exchange and anion exchange (in either order) wherein either:

(1) the solution/suspension is subjected to both i cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions and ii anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions; or

(2) the two ion exchange steps are carried out on separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20- 100% depletion of both calcium and phosphate ions

(c) drying to prepare a dried product.

In another aspect the invention provides a method for producing a dairy product comprising:

(a) providing a skim milk or an MPI or MPC, preferably having at least 70% dry matter as milk protein in aqueous solution/suspension

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100%, preferably 20-100% removal of both ions by carrying out (in any order) wherein either:

(1) the- solution/suspension is subjected to (in any order) (i) cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions, and one or more processes selected from:

(iv) electrodialysis, or

In a preferred embodiment, the invention provides a method for preparing a dried MPC or MPI, product comprising:

(a) providing an MPI or MPC, preferably having at least 70% dry matter as milk protein, in aqueous solution/suspension

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100%, preferably 20-100% removal of both ions by carrying out cation exchange and anion exchange (in either order) wherein either:

(2) the two ion exchange steps are carried out on separate samples that are combined to give an MPC or MPI with 10-100%, preferably 20-100% depletion of both calcium and phosphate ions

(c) drying to prepare a dried product.

In a further preferred embodiment the invention provides a method of preparing a dried MPC or MPI comprising:

(a) providing a low fat milk solution, for example skim milk, as a solution/suspension.

(b) preparing a calcium and phosphate-depleted solution/suspension having 10-100%, preferably 20-100% removal of both ions by carrying out both cation exchange and anion exchange (in either order) wherein either:

(2) the two ion exchange steps are carried out on separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20- 100% depletion of both calcium and phosphate ions (c) concentrating the solution obtained by ultrafiltration, optionally with diafiltration, to form an MPI or MPC having preferably at least 70% dry weight as protein; and (optionally)

(d) drying to prepare a dried product.

Definitions

The term "milk protein concentrate" (MPC) refers to a milk protein product in which more than 42%, preferably more than 50%, more preferably more than 55%, most preferably more than 70% of the solids-not-fat (SNF) is milk protein (by weight) and the weight ratio of casein to whey proteins is between about 95:5 and about 40:60, preferably between 90:10 and 60:40, more preferably between 90:10 and 70:30, most preferably that of milk. Such concentrates are known in the art.

MPCs are frequently described with the % dry matter as milk protein being appended to "MPC". For example MPC70 is an MPC with 70% of the dry matter as milk protein.

Generally MPCs are prepared by processes involving ultrafiltration either to prepare a stream enriched in casein or a stream enriched in whey protein or both. Streams may be blended to attain desired ratios of casein to whey protein. In another embodiment, the milk protein concentrate may be prepared by blending a stream of skim milk with a stream of whey protein concentrate prepared by ultrafiltration, treating either the skim milk stream or the combined stream by cation exchange and at least one of anion exchange, ultrafiltration/diafiltraiton and electrodialysis and optionally concentrating or drying.

Generally milk protein concentrates are low in fat (up to 5% w/w total solids). Such concentrates can have more than 42%, preferably more than 50%, more preferably more than 55%, most preferably more than 70% of the dry matter is milk protein (by weight). However for some applications MPCs with up to 70% fat are desirable. Fat can be added to an ultrafiltered dairy stream in the desired proportions.

The term "milk protein concentrate" also includes a corresponding blend of casein/ate and whey proteins. The term also includes milk protein concentrates that have been heated-treated to denature whey proteins (for example by the methods of PCT published application WO 2004/057971 and US 2006/0159804 both hereby incorporated by reference). - O -

The term "milk protein isolate" (MPI) refers to a milk protein composition comprising a substantially unaltered proportion of casein to whey proteins wherein the dry matter consists of more than 85% milk protein. Such isolates are known in the art.

The term "skim milk" includes not only fresh skim milk but also reconstituted skim milk and skim milks of altered mineral composition an/or casein to whey ratios.

The term "calcium ion" is used broadly and includes ionic calcium and colloidal calcium unless the context requires otherwise. ■^■

The term "phosphate ion" is used broadly and includes ionic phosphate and colloidal inorganic phosphate unless the context requires otherwise.

The term "low fat milk solution" means that the milk comprises less that 5% total solids as fat (by weight), preferably less than 0.5%.

Preferred Embodiments and Advantages

In embodiments preferred for some applications the resulting calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100%, preferably 20-100% removal of both ions is dried, preferably by spray drying.

^' In some embodiments, the liquid calcium and phosphate depleted MPC or MPI is mixed with another milk or milk protein concentrate solution while maintaining at 10-100%, preferably 10- 100%, preferably 20-100% depletion of both calcium ions and phosphate ions. For dried products this is generally carried out shortly before the drying step.

The preferred cation exchangers are based on resins bearing strongly acidic groups, preferably sulphonate groups.

A preferred strong acid cation exchange resin for use in this and other embodiments of the invention is IMAC HP 1 11 E manufactured by Rohm & Haas. This resin has a styrene divinylbenzene copolymer matrix. The functional groups are sulphonic acid groups that- can be obtained in the Na⁺ form or alternatively converted to .the K⁺ form. The use of the Na⁺ or K⁺ form or a mixture of both is preferred. Another preferred cation exchange resin is Amberlite SRlL, Rohm & Haas.

By manipulating the pH and the choice of ions exchanged,, it is possible to vary the flavour of the product. For some circumstances it will be useful also to provide micronutrient cations in addition to sodium or potassium.

One cation preferred for the use with sodium and/or potassium is magnesium.

The anion exchanger may be in the Cl or OH form. Preferably, the anion exchanger bears weak basic groups e.g. primary, secondary or tertiary amines. A preferred ion exchanger is Al 03 S, Purolite.

In another preferred alternative cation-exchange and anion-exchange steps are carried out at the same time using a mixed bed of the two ion-exchange resins.

The ion exchange steps are preferably carried out at 4-12°C, but may be carried out at temperatures as high as 50°C.

The skim milk or MPC or MPI applied to the cation exchanger and anion exchanger preferably has a pH in the range 5.6-7.0, more preferably 5.6-6.2. Once the MPC or MPI has passed through the column, its pH changes. If it increases above 7.0, it will generally be adjusted to about 6.4-7.0 to make it more palatable.

One embodiment of the invention provides a method for preparing a dried MPC or MPI comprising a method of the invention in which the pH of the ion-exchanged material is adjusted to a pre-selected point in the range 5.0-8.0, preferably 6.2-7.2, more preferably 6.4-7.0, most preferably 6.6-6.8 prior to the spray drying step. This ingredient is particularly advantageous for providing firmness in dairy gels as the pH can be selected so that on cooking the properties of the material can be optimised for its use as an ingredient.

In a variation of the above embodiment, the MPC or MPI at the desired pH is subjected to a cooking step. Following cooking, the pH is preferably adjusted to a pH in the range 4.5-7.5, preferably 4.5-6.2, more preferably 4.8-5.9 before drying. The adjusted pH can be chosen to suit particular requirements of products in which the ingredient is to be used.

Preferred cooking temperatures are in the range 50⁰C and up to the boiling point of the mixture, typically 70⁰C-IOO⁰C. The preferred cooking time varies according to temperature used and the nature of the starting material. Generally times in the range 1 second to 30 minutes are used.

Preferred cooking times may be chosen on the basis that they are sufficient for modification of the casein whey interaction. Casein whey interactions provided by the cooking step provide increased strength of the texture of products produced from the casein whey mixture relative to uncooked controls or controls cooked at a pH of approximately 5.7.

Any suitable agent may be used to make the pH adjustments. Preferably the pH adjustment either before or after the cooking step is carried out by direct addition of an alkali or acidulant. Preferred agents may be selected as allowed by Codex Alimentarius Standard 221-2001 (Codex group standard for unripened cheese including fresh cheese). This may be found at http://www.codexalimentarius.net/standard list.asp or its updates.

The liquid calcium and phosphate depleted MPC or MPI obtained may be dried by standard techniques including thermal falling film evaporation and spray drying. Drying may be preceded ^: by dewatering. The dried MPC and MPI products have the property of good stability on storage. This can be demonstrated by observation of the retention of good cold solubility on storage.

In another embodiment the invention provides a 10-100%, preferably 20-100% calcium- and phosphate-depleted MPI or MPC powder preferably having at least 70% by weight of protein. Throughout the range of calcium and phosphate depletion the powders are useful for preparing nutritional drinks and have the advantage of superior solubility relative to MPC or MPI powders that have no such calcium and phosphate depletion.

In a preferred form of this embodiment of the invention, the MPC or MPI powder has 30-100%, preferably 50-100% depletion of calcium wherein the calcium is substituted by sodium and/or potassium. In another preferred form of this embodiment the MPC or MPI has 30-100% preferably 50-100% depletion of phosphate. These preferred percentage depletions are also preferred in the concentrates and methods of the invention. In another aspect, the invention provides a method for preparing a dairy gel comprising mixing ingredients including milk proteins and water and optionally fats and emulsifiers with heating to 70- 100⁰C and/or acidification to pH 4.5-6.0 to produce a gel, wherein at least a portion of the milk proteins are added as a calcium- and phosphate-depleted MPC or MPI. A particularly preferred method is where the calcium- or phosphate-depleted MPC or MPI is 10-100%, preferably 20-100% depleted in both ions, particularly by cation exchange and at least one of anion exchange, ultrafiltration/diafiltration and electrαdialysis as described above. Dairy gels that may be produced by these methods include cheese, processed cheese, cheese spreads, yoghurts, and imitation cheese.

In another aspect the invention provides a method for the manufacture of processed cheese, yoghurts, spreads, cheese and dairy desserts using calcium- and phosphate-depleted MPC or MPI prepared by the method of these aspects of the invention. The advantages of higher protein concentration in cheese manufacture are obtained but with increase in firmness without texture defects associated with protein insolubility. Generally, the use of the calcium- and phosphate- depleted MPC or MPI prepared by the method allows reduction or avoiding of the use of . emulsifying salts. ^■

In a further aspect, there is provided a method for preparing a processed cheese comprising cooking cheese or another gelled casein rich source together with other optional processed cheese ingredients and a calcium- and phosphate-depleted MPC, preferably prepared by a method of the invention.

In a further aspect there is provided a method for preparing a cheese spread comprising cooking a mixture comprising an oil, a gelled casein source and water with optional flavourings and a calcium- and phosphate-depleted MPC with 10-100% depletion of both ions.

In a further aspect there is provided a method of cheese manufacture comprising including in the cheese milk an MPC or MPI, preferably dried or in concentrated liquid form, treating the resulting mixture with one or more coagulating enzymes to produce a curd and processing the curd, wherein the MPC or MPI is a calcium and phosphate-depleted MPC or MPI with 10-100% depletion of both ions. The term "comprising" as used in this specification means "consisting at least in part of, that is to say when interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present.

Brief Description of the Drawings

Figure 1 shows stirred yoghurt viscosities (in mPa.s at 50/s) at day 7 for yoghurts prepared using SMP, MPC85, calcium-depleted MPC85 and calcium and phosphate-depleted MPC85 (each both low fat and full fat (FF)).

Figure 2 shows set yoghurt consistency (texture area g.s) at day 7 for yoghurts prepared using SMP, MPC85, calcium-depleted MPC85 and calcium and phosphate-depleted MPC85 (each both low fat and full fat (FF)).

Figure 3 shows set yoghurt fracture force (peak g) at day 7 for yoghurts prepared using SMP, MPC85, calcium-depleted MPC85 and calcium and phosphate-depleted MPC85 (each both low fat and full fat (FF)). -

EXAMPLES

The following examples further illustrate practice of the invention.

Example 1

MPC (milk protein concentrate, 70% milk protein, Fonterra) 200 g was mixed with 1800 mL of water at 50°C, chilled to 4⁰C and adjusted to pH 5.95 with 10% HCl.

The pH adjusted solution was passed twice through a one litre bed of cation exchange resin (Amberlite SRlL Na form, Rohm & Haas) to fully substitute sodium for calcium as the counterion associated with the protein in solution. The breakthrough (calcium depleted, sodium form of the proteinate) was recovered and cooled to below 10°C. 2 L of the calcium-depleted solution was passed through 2 L of anion exchange resin (A103S, Purolite, chloride form). A temperature of less than 1O⁰C was maintained throughout the cation and ion exchange steps. The resulting double ion exchanged product was collected and freeze-dried. The product comprised protein 72.36%, moisture 1.36%, calcium 359 mg/kg, phosphate 185 mmol/kg, total phosphorus 10100 mg/kg.

Example 2

Model processed cheese spread preparation at cookpH of 5.7

The model processed cheeses were prepared using an RVA mixture cooker (Newport Scientific,

Warriewood, NSW, Australia). The recipe is as detailed in Table 1.

The required amount of rennet ^• casein (ALAREN 799, 90 mesh, Fonterra, New Zealand) was hydrated in salt solution (trisodium citrate (Jungbunzlauer GmbH, Perhofen, Austria), citric acid (Jungbunzlauer GmbH, Perhofen, Austria) and sodium chloride (Pacific salt, Christchurch, New Zealand) and water) in the aluminium cup. The mixture was hydrated for 5 min. ALACEN 392 and MPC (and lactose if used) were added and the mixture was stirred. Oil was then added and the mixture was stirred to mix..

The mixture was cooked using the following programme:

Time(min) Temp (⁰C) Speed (rpm)

Start

0 25 100

1 25 300

2 25 900 .

3 25 1200

4 85 1500

10 85 1500

Stop, add acid if required

12 85 1500

End

After 10 min cook time, the programme was stopped to allow acid to be added, but in this case, no acid needed to be added. Cooking resumed for another 2 min. The total cooking time was 12 min. The molten processed cheese was poured into plastic screwed cap container, inverted then stored at 4°C. The final pH of the processed cheese was 5.7. Model processed cheese spread preparation at a cookpHo/6.7

The model processed cheeses were prepared using RVA mixture cooker (Newport Scientific, Warriewood, NSW₃ Australia). The recipe is as detailed in Table 1. The required amount of rennet casein (ALAREN 799, 90 mesh, Fonterra, New Zealand) was hydrated in salt solution (trisodium citrate (Jungbunzlauer GmbH, Perhofen, Austria), part of the citric acid (Jungbunzlauer GmbH, Perhofen, Austria) and sodium chloride (Pacific salt, Cnristchurch, New Zealand) and water). The predetermined amount of citric acid used at this stage is shown in Table 2. The mixture was hydrated for 5 min. ALACEN 392 and MPC (and lactose if used) were added and the mixture was stirred. Oil was then added and stirred in to the mixture.

The mixture was cooked using the programme detailed in the sample preparation for cook pH 5.7. After 10 min cook time, the remaining acid (Table 2) was added. Cooking resumed for another 2 min. The total cooking time was 12 min. The molten processed cheese was poured into plastic screwed cap containers, inverted then stored at 4°C. The final pH of the processed cheese was 6.7.

Composition of ^'the model processed cheese spread

All the processed cheeses had been formulated to contain 51.29% moisture, 32.88% fat, 10.01% protein, 1.32% lactose and remainder 4.5 % minerals and others. The firmness of the samples is ^• shown in Table 3.

Table 1 Recipe for model processed cheese spreads made using rennet casein and different MPCs. Whey protein to total protein ratio at 20%.

Ingredients MPC 70 T 7 , ™* _nΛ Ca deplete MPC 85

⁶ deplete MPC 70 ^v

Soya oil 9.804 9.804 9.804

Rennet casein 1.439 1.440 ^■ 1.440

MPC 70 2.143 0 0

Ca and P 04

0 2.076 ^' 0 deplete MPC

Ca deplete MPC 0 0 1.83 WPC (Alacen 392) 0.372 0.372 ; 0.372

Lactose 0 0 0.315

Water . • 16.14 16.207 16.138

Sodium chloride 0.315 0.315 0.315

Trisodium citrate 0.612 0.612 0.636

Citric acid 0.175 0.175 0.150

Total 31 ^' 31 31

Notes: all weight in grams

: weight of water includes allowance of 1 g for evaporation

Table 2. Amount of citric acid (CA) used to achieved cook pH of 6.7

MPC 70 * dTe^ap ?leⁿt.^de 1 M2PLC ^Ca dep ^vlete MPC

CA during

0.335 0.0485 0.0211 cooking

CA at the end of

1.415 0.126 0.129 10 min

Note: all weight in grams

Table 3. Firmness — Variation with pH and cook pH

Ca and PO4

Cook pH MPC 70 Ca deplete MPC deplete MPC pH 5.7 183.9 186.1 183.3 pH 6.7 289.6 296.4 241.5

Note: all results in Pa Example 3

Model for preparation of processed cheese slice

Ingredients:

Control Depleted MPC70

Water 10.13 10.13

Trisodium citrate dihydrate (TSC) 0.82 0.82

Sodium chloride 0.3 0.3

MPC70 (ALAPRO^® 4700) ■ 4.15 -

Ca and PO4 deplete MPC70 - 4.15

High solids cheese 9.78 9.78

Butter 4.58 4.58

Citric acid 0.18 0.18

Note: all values are in grams (g).

Method:

TSC and sodium chloride were added to the water in a plastic pottle. The salts were allowed to dissolve before adding the MPC. The MPC was mixed into the solution and stood for 40 minutes. The remaining ingredients were added and mixed vigorously by hand. The blended material was then transferred to a canister for cooking in the RVA.

Cooking profile: Temperature - the initial temperature was 25⁰C. This was raised to 85⁰C over 4 minutes and then held at 85⁰C for 6 minutes. Total cook time was thus 10 minutes.

Speed - the initial speed was 0 rpm. This was raised stepwise to 800 rpm over 3 minutes and then held at 800 rpm for 7 minutes.

Slice formation:

The cooked processed cheese was poured onto polypropylene film. A second layer of film was placed on top of the molten material. A heavy rolling pin was used to flatten the processed cheese into a 2 mm thick slice, which was then cooled rapidly by placing it on a pre-cooled aluminium tray in a 4⁰C chiller. Observations:

MPC70 (ALAPRO 4700) formed a pale yellow paste during hydration and gave a slice that appeared well emulsified, homogeneous but slightly soft.

The Ca and P 04 depleted MPC70 hydrated more rapidly, was more reactive and formed a translucent gel during hydration. The slice appeared well emulsified and the break of the slice indicated that the structure was firmer and more brittle than the MPC70 slice.

Example 4 Evaluation of calcium depleted and phosphate reduced MPC in Yoghurt

An MPC product prepared as described in Example 1 except that the starting material was MPC85 was trialled in low fat and full fat yoghurt systems. It was compared with skim milk powder (SMP), standard MPC85 and Ca-deplete MPC 4862 (all Fonterra Co-operative Group Limited).

Both low and full fat yoghurt formulations were prepared with a total protein concentration of 4.6%. The test ingredient provided 1.2% protein. Total solids were standardised with lactose. The pH was adjusted to within pH 6.6-6.8 (if necessary)

For the Full fat (FF) system 3.0% fat (from Anhydrous Milk Fat) was added. .

The test ingredients were calcium and phosphate depleted MPC85 (2-IX MPC) or MPC85 (MPC4850) or Ca-deplete MPC 4862. SMP was used in the SMP control. '

Yoghurts were prepared by the conventional method from the yoghurt milk formulations using addition of a standard starter culture.

Results

The results are shown in Figures 1-3. The calcium- and phosphate-depleted MPC provided increased stirred yoghurt viscosity, set yoghurt consistency and fracture force relative to the SMP controls and the MPC 85 additive comparisons. This result occurred with both low fat and full fat yoghurts. The results were similar to those obtained using the -calcium depleted MPC. Any discussion of documents, acts, materials, devices or the like that has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters forms part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date.

The above examples are illustrations of the practice of the invention. It will be appreciated by those skilled in the art that the invention can be carried out with numerous modifications and variations. For example, the material subjected to calcium depletion can show variations in protein concentration and pH, the methods of calcium phosphate depletion can be varied, and the percentage calcium and phosphate depletion and drying procedures can also be varied.

Claims

1. A method for producing a dairy product comprising: ^■

(a) providing a skim milk or an MPI or MPC, in aqueous solution/suspension, and (b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100% removal of both ions wherein either:

(1) the solution/suspension is subjected to (in any order) one or more processes selected from: i cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions, ii anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions, iii ultrafiltration and/or diafiltration iv electrodialysis, or . (2) processes of i-v may be carried out on at least two separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20- 100% depletion of both calcium and phosphate ions.

^■

2. A method for producing a dairy product comprising: . ^• (a) providing an MPI or MPC, in aqueous solution/suspension

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100% removal of both ions by carrying out both cation exchange and anion exchange (in either order) wherein either:

(2) the two ion exchange steps may be carried out on separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20-100% depletion of both calcium and phosphate ions (d) drying to prepare a dried product.

3. A method for producing a dairy product comprising: (a) providing a skim milk or an MPI or MPC, preferably having at least 70% dry matter as milk protein in aqueous solution/suspension

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100% removal of both ions by carrying out (in any order) wherein either:

(1) the solution/suspension is subjected to (in any order) one or more processes selected from: i cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions, ii anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions, iii ultrafiltration and/or diafiltration, iv electrodialysis, or

(2) processes of i-v may be carried out on. at least two separate samples that are then combined to give an MPC or MPI with 10-100%, preferably 20-

100% depletion of both calcium and phosphate ions.

4. A method for preparing a dried MPC or MPI, product comprising:

(b) preparing a calcium and phosphate-depleted MPC or MPI solution/suspension having 10-100% removal of both ions by carrying out cation exchange and anion exchange (in either order) wherein: (1) the solution/suspension is subjected to both i cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions and ii anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions; or (2) the two ion exchange steps are carried out on separate samples that are combined to give an MPC or MPI with 10-100%, preferably 20-100% depletion of both calcium and phosphate ions

(c) drying to prepare a dried product.

5. A method of preparing a dried MPC or MPI comprising:

(a) providing a low fat milk solution, for example skim milk, as a solution/suspension. (b) preparing a calcium and phosphate-depleted solution/suspension having 10-100%, removal of both ions by carrying out both cation exchange and anion exchange (in either order) wherein either:

(1) solution/suspension is subjected to both iii cation exchange on a cation exchanger in the hydrogen, sodium, or potassium form to remove calcium ions and iv anion exchange on a anion exchanger in the hydroxide or chloride form to remove phosphate ions; or

(2) two ion exchange steps are carried out on separate samples that are then combined to give an MPC or MPL with 10-100%,, preferably 20-100% depletion of both calcium and phosphate ions

(c) concentrating the solution obtained by ultrafiltration, optionally with diafiltration, to form an MPI or MPC having preferably at least 70% dry weight as protein; and (optionally)

(d) drying to prepare a dried product.

6. A method as claimed in any one of claims 1-5 wherein the casein to whey ratio is between 90:10 and 60:40 by weight.

7. A method as claimed in any. one of claims 1, 3 and 6 wherein the calcium and phosphate depletion is carried out using cation exchange and anion exchange.

8. A method as claimed in claim 7 wherein calcium removed is replaced by sodium or potassium or both and the phosphate removed is replaced by chloride.

9. A method as claimed in any one of claims 1-8 wherein the calcium- and phosphate- depleted MPC or MPI has 20-100% depletion of both ions.

10. A method for preparing a dairy gel comprising mixing ingredients including milk proteins and water and optionally fats and emulsifiers with heating to 70-100°C and/or acidification to pH 4.5-6.0 to produce a gel, wherein at least a portion of the milk proteins are added as a calcium- and phosphate-depleted MPC or MPI with 10-100% depletion of both ions.

11. A method for preparing a dairy gel comprising mixing ingredients including milk proteins and water and optionally fats and emulsifiers with heating to 70-100⁰C and/or acidification to pH 4.5-6.0to produce a gel, wherein at least a portion of the milk proteins are added as a calcium- and phosphate-depleted MPC or MPI with 20-100% depletion of both ions prepared by a method as claimed in any one of claims 1-9.

12. A method as claimed in claim 10 or claim 11 wherein the dairy gel is selected from the group consisting of a processed cheese, a yoghurt, a dairy spread, a cheese and a dairy dessert.

13. A method for preparing a processed cheese comprising cooking cheese or another gelled casein rich source together with other optional processed cheese ingredients and a calcium- and phosphate-depleted MPC with 10-100% depletion of both ions.

14. A method for preparing a cheese spread comprising cooking a mixture comprising an oil, a gelled casein source and water with optional flavourings and a calcium- and phosphate- depleted MPC with 10-100% depletion of both ions.

15. A method of cheese manufacture comprising including in the cheese milk an MPC or MPI, treating the resulting mixture with one or more coagulating enzymes to produce a curd and processing the curd, wherein the MPC or MPI is a calcium and phosphate-depeleted MPC or MPI with 10-100% depletion of both ions.