WO2007021204A1

WO2007021204A1 - Dairy product and process

Info

Publication number: WO2007021204A1
Application number: PCT/NZ2006/000210
Authority: WO
Inventors: Shao Quan Liu
Original assignee: Fonterra Co-Operative Group Limited
Priority date: 2005-08-19
Filing date: 2006-08-21
Publication date: 2007-02-22
Also published as: TW200744462A

Abstract

The invention is a process for preparing a low lactose, low glucose milk product. A milk starting material is treated with (i) an enzyme having lactase activity or (ii) a lactose fermenting yeast. Subsequently or simultaneously, the milk product is fermented with a galactose non-fermenting yeast or a galactose fermenting yeast. Where option (ii) is used, the lactose fermenting yeast and the yeast used subsequently or simultaneously may be the same yeast.

Description

DAIRY PRODUCT AND PROCESS

Technical Field

The invention relates to a dairy product and a process for preparing it. The product is milk or milk powder having low lactose and low glucose.

Background Art

Lactose is a disaccharide consisting of glucose and galactose, and is the predominant saccharide present in milk. Several processes are available for the production of low lactose milk and milk products suitable for lactose intolerant people (Jelen P and Tossavainen O, Anst. J. Dairy Techno! 58, 161-165, 2003; Harju, Bulletin of the IDF 389, 4-8, 2004). The conventional lactose hydrolysed (low lactose) milk tastes much sweeter than normal milk due to the presence of relatively high levels of glucose and is, thus, unnatural for many consumers. The lactose free milk from Valio still has approximately 1.4% each of glucose and galactose (Jelen P and Tossavainen O, Aust. J. Dairy Techno! 58, 161-165, 2003), and therefore, may not be suitable for diabetic patients and health conscious consumers who are concerned about glycaemic index and glycaemic load.

Slovakian Patent 281153 has described a patented process for the production of D-galactose and ethanol from a glucose-galactose mixture prepared by acid or enzymatic hydrolysis of lactose supplemented with nutrients (an artificial medium) using Saccharomyces cerevisiae S 8 or Saccharomyces oviformis S5.

The object of the present invention is to provide a low lactose and low glucose milk or milk powder that is suitable for consumers finding prior art products excessively high in lactose or glucose or excessively sweet, and/or to provide the public with a useful choice.

Disclosure of the Invention

In one aspect the invention provides a process for preparing a low lactose, low glucose milk product comprising:

(a) treating a milk starting material with (i) an enzyme having lactase activity or (ii) a lactose fermenting yeast, and

(b) subsequently or simultaneously fermenting the milk product with a galactose non- fermenting yeast or a galactose fermenting yeast wherein when a yeast is used in step (a), the yeast in step (b) may be the same yeast.

One embodiment of the invention provides a process comprising:

(a) treating a milk stalling material with an enzyme having lactase activity; (b) subsequently or simultaneously fermenting the milk product with lactose non- fermenting yeast. In one embodiment, the lactose non-fermenting yeast is a galactose non-fermenting yeast.

In another embodiment, the milk product is fermented with a lactose non-fermenting and galactose fermenting yeast. This embodiment produces a low lactose, low glucose and low galactose or sugar-free milk product.

In another embodiment, the milk starting material is fermented with a lactose fermenting and galactose non-fermenting yeast without the enzyme treatment. The product is low in lactose and glucose.

In another embodiment, the milk stalling material is fermented with a lactose fermenting and galactose fermenting yeast without the enzyme treatment. This product is low in lactose, glucose and galactose.

The yeast used may be any strain of yeast having the appropriate properties. Examples of lactose non-fermenting and galactose non-fermenting yeasts (may include subspecies, strains and varieties derived from these yeasts as well as from other genera/species):

Brettanomyces bnaellensis

Candida boidinii

Candida krnsei

Candida iitilis

Hameniaspora iivanim Hameniaspora guilliermondii

Issatchenkia orientalis

Kloeckera apicitlata Pichia membranifaciens Pichia fermentans Saccharomyces bayanus WHHopsis californica WHHopsis mucosa WHHopsis saUcorniae WHHopsis saturnus

Currently preferred yeasts that may be used include lactose non-fermenting and galactose non- fermenting strains of Saccharomyces cerevisiae, Saccharomyces bayanus, WHHopsis saturnus, Kloeckera apiculata and Torulaspora delbrueckii.

Currently preferred yeasts that may be used also include lactose non-fermenting and galactose fermenting strains of Saccharomyces cerevisiae, especially Saccharomyces cerevisiae Laffort- Zymaflore VLl, Saccharomyces cerevisiae Lalvin L2056 and Saccharomyces bayanus Lalvin CVC-NF74 sold under the name Lalvin by Lallemand, Inc.

In one embodiment the enzyme having lactase activity is provided by a microorganism which possesses lactase activity but can metabolise glucose but not galactose. Preferred microorganisms for this purpose are yeasts. Examples of such yeasts are Sporobolomyces lactophilus Sporobolomyces singularis Sporobolomyces sasicola Sporobolomyces tsugae

In another embodiment, examples of lactose fermenting and galactose fermenting yeasts (may include subspecies, strains and varieties derived from the yeasts referred to above as well as from other genera/species). Currently preferred are yeasts from the genera oϊKluyveromyces (especially K. lactis and K. marxianus) and Candida (especially C. kefyr).

Yeasts for use in the invention are available from commercial sources and from culture collections such as ATCC. Two preferred lactose non-fermenting and galactose non-fermenting yeasts are Saccharomyces bayanus R2 and Saccharomyes bayanus SBl sold under the name Lalvin by Lallemand, Inc. In one embodiment the milk is pre-treated with the lactase (also known as beta-galactosidase).

In other embodiments the lactase enzyme may be added along with the yeast or subsequent to the addition of the yeast.

Preferably the fermentation step is carried out at a temperature of 15-35°C for 10-48 hours.

Generally the pH is in the range 5-7.5. The pH used will depend on the stability and activity of the lactase enzyme and/or the yeast.

Preferably the pH is maintained in the range 6.0-7.0, most preferably at the normal milk pH of approximately 6.7.

The fermented milk (and powder prepared from it) has less than 50% of the lactose content of the stalling material, preferably less than 20% of the lactose content of the starting material. Likewise, the glucose content is less than 50%, preferably less than 30% of that present in the lactose of the starting material. Alternatively, both the glucose and galactose content is less than 50%, preferably less than 30% of that present in the lactose of the starting material.

The products of the process of the invention may include galacto-oligosaccharides. These compounds are formed through transferase activity of beta-galactosidases. These oligosaccharides are generally regarded as nutritionally beneficial.

Use of a yeast fermented milk products of the invention may give those products a yeasty flavour. Where that is not preferred, flavourings may be added to mask the yeasty flavour.

Use of anaerobic fermentation is preferred as this has the benefit of minimising or eliminating the need for aeration in the fermentation process.

Potassium phosphate of up to 0.5% (w/v) (preferably 0.1 to 0.2%) is preferably added to the milk before or after milk sterilisation. This serves as a buffer and also as a stabiliser against coagulation should the milk be subsequently dried. Alternatively, the milk pH is maintained at at least pH 5.8 (preferably pH 6.5) if potassium phosphate is not added. In a preferred embodiment an appropriate amount of enzyme (lactase) is prepared aseptically (preferably by aseptic filtration) and added to the sterile milk at the time of yeast inoculation. In another embodiment, sterile milk is pre-treated with lactase before yeast inoculation. The fermentation is conducted at 15 to 35⁰C (preferably 25 to 3O⁰C) for 10 to 48 hours under anaerobic and static conditions. After fermentation, the fermented milk is generally either pasteurised or subjected to a conventional drying process such as spray drying to produce a low lactose and low glucose milk or milk powder.

The currently preferred lactase is a fungal lactase from Aspergillus niger (Validase Fungal Lactase Concentrate, Valley Research, Indiana, USA). A range of commercial lactases (beta- galactosidases) such as those from Aspergillus ory∑ae (Enzidase Fungal Lactase 100,000, Genencor Kyowa Co., Tokyo, Japan) and Kluyveromyces lactis (Enzidase Yeast Lactase, Genencor Kyowa Co., Tokyo, Japan) are also suitable for use in the process of the invention.

The milk used may be from any mammalian species. Preferably the milk is from cows, goats or sheep. Cows' milk is preferred. The milk used in the Examples is cows' milk. The milk may be modified before the treatment, for example it may be converted to skim milk or a reduced fat milk.

In another aspect the invention provides a milk product obtainable by a process of the invention.

In another aspect this invention applies to other dairy streams, for example, whey and whey permeate or milk permeate or milk protein concentrate.

In a further aspect the invention provides a milk having substantially unaltered protein content (although the protein content in the powder prepared from the milk generally increases by - up to 50%, compared with standard milk powder) but having a lactose concentration of less than 1% (w/w), a glucose level of less than 1% (w/w) and a galactose level of greater or less than 1% (w/w).

The low lactose and low glucose (or low lactose, low glucose and low galactose or sugar-free) milk powder can have applications in food and beverages, e.g. yoghurt, ice cream, formulated milks and fermented milks, to meet the increasing demand for low sugar food and beverages for lactose-intolerant people, diabetic patients and health conscious people. The low lactose and low glucose (or low lactose, low glucose and low galactose or sugar-free) milk or milk powder can also be used to control post-fermentation acidification in yoghurt and other milk fermentations. Further, the low lactose, low glucose and low galactose milk or milk powder can be used to manufacture sugar-free yoghurts and other fermented milk products.

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".

Examples

The following examples further illustrate practice of the invention.

Example 1 100 mL of skim milk is sterilised at 115⁰C for 15 minutes. Lactase (Validase Fungal Lactase Cone, Valley Research, Indiana, USA) is added at a rate of 0.1 g per 100 g lactose. A yeast culture(lactose non-fermenting and galactose non-fermenting Saccharomyces bayanus SBl, Lallemand Inc., Rexdale Ontario, Canada) grown overnight in a broth at 3O⁰C is then added ( 1% v/vλ The broth for growing yeast culture contains glucose (2% w/v), yeast extract (0.25% w/v), malt extract (0.25% w/v) and peptone (0.25% w/v) and has an initial pH of 5.0. The inoculated milk is then incubated anaerobically and statically at 3O⁰C for 16 hours. The resulting milk has a lactose level of 0.93% w/v, a galactose level of 1.48% w/v and no detectable levels of glucose.

Example 2 100 mL of skim milk is sterilised at 115⁰C for 15 minutes. Lactase (Validase fungal lactase concentrate) is added at a rate of 0.1 g per 100 g lactose. A yeast culture (lactose non-fermenting and galactose non-fermenting Kloeckera apiciύata B9050, Fonterra) grown overnight in a broth (see Example 1) at 3O⁰C is then added ( 1% v/vλ The inoculated milk is then incubated anaerobically and statically at 3O⁰C for 18 hours. The resulting milk has a lactose level of 0.5% w/v, a galactose level of 1.26% w/v and a glucose level of 0.80% w/v.

Example 3

100 mL of skim milk is sterilised at 115⁰C for 15 minutes. Lactase (Validase fungal lactase concentrate) is added at a rate of 0.1 g per 100 g lactose. A yeast culture (lactose non-fermenting and galactose non-fermenting Torulaspora delbrucekii B9053, Fonterra) grown overnight in a broth (see Example 1) at 3O⁰C is then added ( 1% vlv). The inoculated milk is then incubated anaerobically and statically at 3O⁰C for 18 hours. The resulting milk has a lactose level of 0.6% w/v, a galactose level of 1.35% w/v and a glucose level of 0.71% w/v.

Example 4

Two batches of one litre of skim milk (each containing 0.2% w/v of added dipotassium hydrogen phosphate) are sterilised at 115⁰C for 15 minutes. Lactase (Validase Fungal Lactase Cone, Valley Research, Indiana, LTSA) is added to each batch at a rate of 0.1 g per 100 g lactose. A yeast culture (lactose non-fermenting and galactose non-fermenting Soccharomyces bayaniis R2, Lallemand Inc., Rexdale, Ontario, Canada) grown overnight in a broth (see Example 1) at 3O⁰C is then added to each batch (0.5% v/v). One batch of the inoculated milk is then incubated anaerobically and statically at 3O⁰C for 20 hours and the other batch at 25⁰C for 24 hours. The resulting milk incubated 3O⁰C has a lactose level of 0.63% w/v, a galactose level of 1.43% w/v and a glucose level of 0.39% w/v. The resulting milk incubated 25⁰C has a lactose level of 0.50% w/v, a galactose level of 1.42% w/v and a glucose level of 0.68% w/v.

Example 5

The yeasty flavour of the low lactose and low glucose milk prepared in Examples of 1 to 4 may be improved by adding flavourings described below:

Strawberry flavor

Cream Flavor (Danisco) 0.3%

Sucralose 0.01%

Ace K 0.015%

Strawberry flavor (Firmenich) 0.1%

Banana flavor

Cream Flavor (Danisco) 0.3%

Sucralose 0.01%

Ace K 0.015%

Banana flavor (Quest) 0.2%

Example 6

The low lactose and low glucose milk prepared in Example 4 is adjusted to pH 6.2 and is subjected to sterilisation at 9O⁰C for 10 minutes. The sterilised milk after cooling is then inoculated with commercial yoghurt bacteria (1% v/v MY-900, Rhodia) pregrown overnight at 37⁰C in 10% w/v reconstituted skim milk. The inoculated milk is incubated at 42⁰C for 4 hours, followed by further incubation at 3O⁰C for 20 hours. The resulting yoghurt has no detectable level of lactose, a glucose level of 0.27% w/v and a galactose level of 1.73% w/v. The final pH of the resulting yoghurt is 4.57. The resulting yoghurt has a slightly yeasty flavour and can be flavoured as described in Example 5. No significant post-fermentation acidification is observed.

Alternatively, up to 5.0% w/v of skim milk powder can be added to the milk prepared in Example 4 before sterilisation. Preferably up to 2.0% w/v skim milk powder is added and the resulting yoghurt made as such has a final pH of only 4.47, a lactose level of up to 0.41 % w/v, a glucose level of up to 0.32% w/v and a galactose level of up to 1.82% w/v. No significant post- fermentation acidification occurs.

Example 7 Two batches of 100 mL of reconstituted whole milk (one containing 0.2% w/v added dipotassium hydrogen phosphate and the other one without) are sterilised at 115⁰C for 15 minutes. A yeast culture (lactose fermenting and galactose fermenting Klnyveromyces marxiamts ATCC 8640) grown overnight in a broth (see Example 1) at 3O⁰C is then added (1% v/v). The inoculated milk is then incubated anaerobically and statically at 3O⁰C for up to 48 hours. The sugar composition of the resulting milk is shown in Table 1.

Table 1 Sugar composition (% w/v) of the yeast fermented milk in Example 7

Example 8 One thousand-litre of milk is sterilised by UHT process. A yeast culture (lactose fermenting and galactose fermenting Kluyveromyces marxiamis ATCC 8640) grown overnight in a broth (see Example 1) at 3O⁰C is then added (2% v/v). The inoculated milk is then incubated at 3O⁰C with moderate aeration (stirring at about 100 rpm) for up to 24 hours. The pH is maintained at 5.8 during fermentation. After 12 hours fermentation, the milk contains no detectable lactose and galactose with only trace amounts of glucose (0.02% w/v). After 24 hours, the milk is spray- dried after pH adjustment to 6.6. The milk powder contains 39.9% w/w protein, 40.7% w/w fat, but no detectable lactose, glucose and galactose.

The above examples are illustrations of the practice of the invention. It will be appreciated by those skilled in the art that the invention may be carried out with numerous modifications and variations. For example lactase used may come from a different source. The fermentation conditions may be varied in both temperature and time and different fermenting organisms may be used.

Claims

Claims:

1. A process for preparing a low lactose, low glucose milk product comprising: (a) treating a milk starting material with (i) an enzyme having lactase activity or

(ii) a lactose fermenting yeast, and (b) subsequently or simultaneously fermenting the milk product with a galactose non- fermenting yeast or a galactose fermenting yeast wherein when a yeast is used in step (a), the yeast in step (b) may be the same yeast.

2. A process as claimed in claim 1 comprising:

(a) treating the milk starting material with an enzyme having lactase activity, and

(b) subsequently or simultaneously fermenting the milk product with lactose non- fermenting yeast.

3. A process as claimed in claim 2 wherein the yeast is lactose non-fermenting and galactose non-fermenting.

4. A process as claimed in claim 2 wherein the yeast is lactose non-fermenting and galactose fermenting.

5. A process as claimed in claim 1 wherein the milk stalling material is fermented with a lactose fermenting and galactose non-fermenting yeast without enzyme treatment.

6. A process as claimed in claim 1 wherein the milk starting material is fermented with a lactose fermenting and galactose fermenting yeast without enzyme treatment.

7. A process as claimed in claim 3 wherein the yeast is selected from strains the group consisting of: Brettanomyces brnxellensis;

Candida boidinii;

Candida b'usei;

Candida iitilis;

Hanseniaspora nvanim; Hanseniaspora gitilliermondii; Issatchenkia orientalis; Kloeckera apiciikita; Pichia membranifaciens; Pichiafermentans; Saccharomyces bayanus ;

WUUopsis califomica; Williopsis mucosa; Williopsis salicorniae; and Williopsis satiirnns.

8. A process as claimed in claim 3 wherein the yeast is a lactose non-fermenting and galactose non-fermenting strain selected from strains of Saccharomyces cerevisiae, Saccharomyces bayanus, Williopsis satnrmis, Kloeckera apiciύata and Torulaspora delhrueckii.

9. A process as claimed in claim 4 wherein the yeast is a lactose non-fermenting and galactose fermenting strain of Saccharomyces cerevisiae or Saccharomyces bayanus.

10. A process as claimed in claim 5 wherein the yeast is selected from the group consisting of Sporobolomyces lactophihis, Sporobolomyces singidaris,

Sporobolomyces sasicola and Sporobolomyces tsugae.

11. A process as claimed in claim 6 wherein the yeast is selected from a strain from the genus Khiveromyces or the genus Candida.

12. A process as claimed in any one of claims 1-11 further comprising drying of the product.

13. A process as claimed in any one of claims 1-12 wherein the milk starting material is cows' milk.

14. A process as claimed in any one of claims 1-12 wherein the milk starting material is skim milk.

15. A process as claimed in any one of claims 1-12 wherein the milk starting material is whey, whey permeate or milk protein concentrate.

16. A process as claimed in any one of claims 1-15 wherein the pH is maintained in the range 6.0-7.0 for the duration of the process.

17. A process as claimed in any one of claims 1-16 wherein the process is continued until the lactose content has fallen to less than 50% of that of the starting material and the glucose content has fallen to less than 50% of that present in the lactose of the stalling material.

18. A process as claimed in claim 17 wherein the galactose content of the product is less than 50% of that present in the lactose of the starting material.