TECHNICAL FIELD

This invention relates to reduced lactose milk and methods for producing same. BACKGROUND ART

Lactose intolerance is a condition observed at extremely high rates (90-100% prevalence) in the Chinese, Indian and Thai populations, and to a lesser extent (about 10- 40% prevalence) in European populations (Lactose and Lactase, Scientific American, October 1972).

Low lactose or lactose-free products have become increasingly sought after as such populations explore options to live with their condition. In 2009, the company HP Hood LLC sold USD $654 million of Lactaid™ (lactose-free products), representing about 30% of the global market.

In China, less than 1% of 36 million tons of milk was marketed as low or free lactose in 2010. This figure is expected to increase to 10% by 2018 due to the high lactose intolerance in China and the growing number of Chinese consumers desiring added-value functional foods.

Considering this demand not only in China but elsewhere too, there has been significant R&D into production of lactose-free or reduced lactose products over the past 50 years. A variety of lactose-free products have been developed for bread, cheese, yogurt, and milk. Given milk is a base ingredient for all these foods, the process for making lactose-free milk is of particular commercial relevance.

Since about the 1960s, the main process for making lactose-free milk has been incubating purified lactase enzyme with milk, which has typically been reconstituted from milk powder.

A further problem of this mainstay technique is that the lactase enzyme is expensive to purchase or manufacture. When working with large quantities of milk, this expense is not a minor issue, and substantially increases the cost of the milk product, and/or lowers profit margins.

Also, the lactase used is often not microbe free, nor is it sterilised. As such, during incubation with milk to digest the lactose, there is possibility that the milk can be contaminated during the enzymatic process. If the lactase is filtered to remove microbes before the process, the filtration process adds a further step and can be difficult. Furthermore, the lactase enzyme can have a shorter life span outside of its normal environment or can be intolerant to the fat and protein in milk, resulting in inefficient or inaccurate lactose digestion profiles. It is also possible that lactase can lose some activity if not stored correctly.

Regardless, the process of adding purified lactase enzyme in this method has been the mainstay for producing lactose-free milk for over 50 years.

In attempt to address these problems, alternative approaches have been developed with Acidophilus and Kefir milk, which use certain Acidophilus bacteria or Kefir yeast to ferment milk. In the process, the lactase enzyme inherent in the microbe digests the lactose. However, problems seen with Acidophilus and Kefir milk are poor lactose digestion and/or inefficient lactose digestion (meaning long fermentation times), and/or a significant loss of taste and/or sensory perception. Similarly, another hurdle with fermentation is the need to illustrate safety concerns using the microbes.

For these reasons, these milks have not been widely accepted by the public. Alternatively, in attempt to hide the poor taste, manufacturers have resorted to using flavouring, which is also seen as a negative attribute by the public.

Therefore, there has been a general disincentive to develop or improve fermentation processes to make lactose-free milk, and instead to remain with the proven mainstay of using purified lactase for lactose digestion, regardless of its disadvantages.

As such, there is a need to improve or develop new processes that address these issues and provide not only the public but also manufacturing companies new options for consumption and production, respectively, of lactose-free milk. Subsequently, the lactose-free milk may then be used as a base ingredient for other lactose-free food products.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION According to one aspect of the present invention there is provided a method of manufacturing a lactose-free or lactose reduced milk characterised by the step of a) fermenting a milk including lactose with an amount of a fungi which produces the

enzyme lactase and therefore is able to digest lactose, wherein the fungi is selected from the group consisting of Aspergillus Oryzae, Aspergillus sojae, Aspergillus niger, Rhizopus oryzae, and combinations thereof to digest an amount of lactose in the milk; and b) substantially separating the milk from the fungi.

According to another aspect of the present invention there is provided a lactose-free or lactose reduced milk using the method as substantially described above, characterized in that the milk includes less than 4% w/w lactose.

A method of treating or preventing lactose intolerance in an animal, characterised by the step of administering an amount of milk as substantially described above.

The use in the manufacture of a medicament of a milk as substantially described above, for the treatment or prevention of lactose intolerance in an animal in need thereof. Throughout this specification many further advantages compared to the prior art will be discussed in detail. However, it should be appreciated that the main advantages of the method and resulting product include a new process to produce low lactose or lactose-free milk using Asp. Oryzae (or the other claimed fungi), and in doing so provides very effective lactose digestion, is safe, efficient, and does not affect taste or sensory perception of the milk product. Furthermore, the invention provides an opportunity to significantly reduce the overall business chain cycle from raw milk to lactose free milk, and provides the ability for producers to fully self- control the entire process.

PREFERRED EMBODIMENTS AND DEFINITIONS

Throughout this specification, the term "lactose" should be taken as meaning the disaccharide sugar (C1 ₂ H ₂ 2O-11) present in milk for instance from cows, goat, sheep and so forth. Lactose is a carbohydrate, which when digested with lactase, converts the lactose into byproducts that are more easily digested by the body. This is particularly important for those who are lactose intolerant. Throughout this specification, the term "lactose-free milk" should be taken as meaning a milk with substantially no lactose (i.e. less than 0.1 % w/w) remaining in it, as a result of enzymatic breakdown or digestion of lactose in the milk product into other components.

Throughout this specification, the term "lactose reduced milk" should be taken as meaning milk having less than about 4 % w/w lactose. Typically, normal processed milk has between 4 to 6% w/w lactose, often depending on the fat content.

Preferably, the method includes depleting at least 50%, 70%, 90%, 95% 99% or 100% of all the lactose in the milk. For example, a standard 2% fat milk includes about 5% w/w lactose, whereas the present invention most preferably alters the milk to have between 0.0 to 0.5% w/w lactose (although levels below 2% w/w lactose are likely to be commercially acceptable for some purposes). The particular amount of depletion of lactose may be controlled as discussed further below.

Throughout this specification, the term "milk" should be taken as meaning raw milk, pasteurized milk, fat depleted milk, reconstituted milk powers and/or recombined milk. Throughout this specification, the term "fermentation" should be taken as meaning the incubation or culturing milk with a microbial strain of interest to allow the microbe to proliferate in the milk.

Throughout this specification, the term "fungus" or "fungi" should be taken as meaning any species within a large group of eukaryotic organisms that include yeasts and molds. Fungi are distinct from bacteria. One major structural difference which allows fungi to be classified as a distinct organism to bacteria is that fungi cell walls include chitin. Fungi have been used for centuries in fermentation processes in wine, beer, and soy sauce.

Throughout this specification, the term "Aspergillus genus" should be taken as meaning a group of fungi that reproduce asexually and characterised by morphological features (see

http://www.epa.gov/biotech_rule/pubs/fra/fra007.htm). Many of the fungi within this class may not be suitable for fermentation purposes, may have specifically have issues with fungi toxicity, may have poor lactose digestion and/or may have effects on sensory properties of food products.

In 1965, Raper and Fennell reported 132 species within the genus arranged in 18 groups based on distinctive morphological differences. It should also be appreciated that a number of synonyms for the genus Aspergillus have been used in the past, including

- Alliospora (Pirn);

- Aspergillonsis (Spegazzini);

- Cladaspergillus (Ritg); - Cladosparum (Yuill and Yuill);

- Euaspergilus (Ludwig);

- Gutturomyces (Rivolta);

- Raperia (Subramaniam and Grove); - Sceptromyces (Corda);

- Spermatoloncha (Spegazzini); Sphaeromyces (Montagne);

- Sterigmatocystis (Cramer); and

- Stilbothamnium (Hennings) -Bennett, 1985. Preferably, the fungi used in step a) of the method is A. oryzae or genetically modified strains thereof. A. oryzae is one of four fungi in the Aspergillus flavus (A. flavus) group. The other members in the A. flavus group include A. sojae, A. nominus, and A. parasiticus.

It was discovered by the inventor that A, oryzae provides surprisingly beneficial results for milk fermentation in that it: a) is able to efficiently digest lactose in milk using the lactase enzyme inherently produced by the fungi which is excreted from the fungi cells into the milk, and; b) does not have a negative impact on taste or sensory perception of milk compared normal lactose milk or that digested by many other microbial strains such as

Lactobacillus acidophilus. It should be appreciated that the process to make Acidophilus milk is disadvantageous compared to the present invention because of its resulting inherent sour flavour (often not liked by consumers), and also the low level of lactose digestion seen with Acidophilus milk (typically only about 30% digestion). This is compared to the preliminary studies conducted by the Applicant, where close to 100% of the lactose is able to be digested using A. oryzae within a relatively short time frame, and the resulting flavour and sensory perception is comparatively and surprisingly very good.

A. oryzae has never before been applied to the fermentation process of milk. The Applicant envisages that this may be partly due to past experience from traditional fermentation processes - for instance to make yogurt and Acidophilus milk - where the taste is sour and/or lactose digestion is insufficient. A further advantage of A. oryzae is that their use for making other fermented products is known to be safe for human consumption. For instance, A. oryzae have been widely used for centuries in Oriental fermentation processes for preparing soy sauce, sake and miso.

A person skilled in the art would appreciate it would be expected, based on these preliminary results, that certain other related species currently in the A. flavus group, such as A. sojae could also be used in the present invention. Beyond A, sojae, currently the only other two fungi in the group (A. nominus, A. parasiticus) both produce fungal toxins and are not suitable for food fermentation.

Outside the A. flavus group of fungi, the inventor also suspects, based on the surprising results seen with A. oryzae, that a number of other fungi might display similar beneficial results particularly with regards to lactose digestion and resulting sensory perception (i.e. only minor or no substantial change to the flavour, colour and texture of the milk), whilst also avoiding any safety concerns with fungi toxicity.

In particular, Aspergillus niger s another fungi that the inventor expects may portray the same or similar benefits to A. oryzae. A. niger is used industrially in the food industry. Many foods are processed using A. niger particularly for the breakdown of certain complex sugars using enzymes produced by the microbe. However, the Applicant is not aware of any reports of using A. niger for fermenting milk for the purpose of digesting lactose to produce a low/no lactose milk which has surprisingly good sensory/taste profiles. Rhizopus oryzae is another fungi that the inventor considers may potentially portray the same surprising results seen with A. oryzae. These fungi are mainly used in Asia in the food industry and are considered generally safe for use. They also produce lactase, which is excreted from the cells. Again, there appears to be no prior teaching of using these fungi for the claimed invention.

It is suspected that, for the same reasons as discussed regarding Acidophilus and Kefir milk, research and development has stayed away from testing and using fungi such as those outlined above to ferment milk to produce a low or no lactose milk that importantly retains good milk taste and sensory profiles. Preliminary tests are expected to be conducted shortly to assess the inventor's hypotheses.

Other preferred method steps:

Preferably, step a) includes adding 5-10% w/w of A. oryzae to the milk.

After preliminary trials, the inventor found that this range provided efficient and optimal digestion profiles of lactose in the milk, especially when taking into account a preferred timeframe of incubation. However, it should be appreciated that adding less or more starter fungi for the inoculation is certainly possible.

Preferably, prior to the fermentation step, the milk is sterilised (pasteurized). Typical pasteurization conditions may be exposing the milk to temperatures of 85 to 95°C for 15 to 30 seconds in a heat exchanger.

Preferably, prior to the pasteurization step, the milk is raw milk.

Compared to previous processes used to make low lactose / no lactose milk (as discussed above), the present invention allows one to work directly with raw milk following a pasteurization step, such that the milk may be treated immediately with the fermentation step to remove lactose. This has significant advantages over the prior art including complete process control and cost/time savings.

However, it should be appreciated that the fermentation step according to the present invention should not be limited to a method of using raw and/or pasteurized milk. For instance, the fermentation step according to the present invention may equally be applied to pre-processed milk which is shown in the prior art (See Figure 1 ). This may still offer advantages over using purified lactase, including cost savings, avoiding issues with unstable enzyme and/or incomplete digestion, contamination issues, and the advantage of using a naturally derived microbe instead of a GM modified enzyme.

Preferably, the fermentation process includes the addition of an oxygen source. In one embodiment, this is provided through ventilation to the fermentation tank. Fungi such as A. oryzae typically require an added oxygen source for effective proliferation.

Preferably, the temperature during the fermentation step is maintained between 20 to 40°C.

More preferably, the temperature during the fermentation step is maintained between 25 to 38°C. Most preferably, the temperature during the fermentation step is maintained between 28 to 35°C.

Preferably the fermentation step is performed for a period of 5 to 24 hours.

More preferably, the fermentation step is performed for a period of 9 to 20 hours.

Most preferably, the fermentation step is performed for a period of 12 to 18 hours. Based on a preliminary trial, the inventor observed 99% lactose digestion when using the fermentation step of raw (post-pasteurized) milk cultured with A. Oryzae at 33°C for 18 hours. It is expected that reducing the fermentation step to conditions as low as 5 hours at 20°C may still result is acceptable lactose digestion, yet perhaps to only about 90% lactose digestion (equating to about 0.4 % w/w lactose).

Although it is typically preferred to remove as much lactose as possible whilst also considering time efficient processes, it is clear that the fermentation conditions may be varied considerably to result in acceptable results. The trials are also being reproduced on larger scale and over various conditions to exemplify the beneficial results as seen.

Furthermore, these preferred conditions discussed above are different to the conditions used to prepare Acidophilus milk, which disadvantageously uses much higher temperatures of about 55°C and is incubated for at least 24 hours. Yet even then, the lactose digestion is inefficient, and the resulting taste of Acidophilus milk is sour. Comparatively, the temperatures used to make Kefir milk (using a culture of bacteria and kefir yeast grains) is approximately 18°C to 26°C but still requires incubation for longer periods of about 24 to 48 hours. Similar to Acidophilus milk, the resulting Kefir milk has a sour taste and/or unpalatable texture.

Therefore, the Applicant submits the preferred fermentation conditions should not be a limitation to the scope of protection, but do highlight considerable advantages and further inventive features over the production of Acidophilus and Kefir milk, which both claim to be low lactose milk. Specifically, the current invention of using A. oryzae (and/or the other fungi discussed) addresses problems relating to inefficient processing time, inefficient lactose digestion and/or poor taste as seen with Acidophilus and Kefir milk. The resulting milk of the present invention also shows no effect on physical or chemical stability issues compared to normal lactose containing milk or milk digested with purified lactase (according to the mainstay of producing lactose-free milk).

Preferably, following the fermentation step, the method includes removing the fungi from the milk. It should be appreciated that a range of techniques may be used to achieve this step, for instance centrifugation or filtering to remove all or substantially all of the fungi.

Preferably, following the removal of the fungi, the milk is sterilized.

For example, ultra high temperature processing (UHT) is used according to known techniques. Typically this may utilise conditions such as a temperature exceeding 135°C for 1-2 seconds. This step helps to sterilize the overall product for safety, and importantly kills any remaining fungi spores in the milk.

Following sterilization, the milk may then be packaged for storage/delivery and eventually consumption or use in food manufacturing.

Summary of Advantages: - Use of the fungi A. oryzae according to the present invention provides surprising beneficial features relating to lactose digestion and resulting taste/sensory profile (and it is suspected that a number of other fungi discussed herein will display similar beneficial results); - highly effective alternative to efficiently reduce or deplete lactose within relatively shorter timeframe than seen with Acidophilus and Kefir milk production, and current lactose digestion using purified lactase; no substantial effect on taste or sensory perception compared to normal milk and milk digested with purified lactase; - better taste profile and sensory perception compared to Acidophilus and Kefir milk;

- provision of shorter and/or more efficient business chain than status quo allows one to work directly from raw milk. For example, using the fermentation process of the present invention, the process to generate lactase occurs simultaneously with lactose digestion. Comparatively, when using the prior art technique of a separate lactase digestion step, lactase is produced normally by a third party, then sold to a milk company to perform the lactose digestion. This increases overall costs in the manufacturing process, and either results in additional cost to the consumer or profit losses to the manufacturer;

- reduction of manufacturing costs and time;

- avoidance of need for expensive and/or ineffective purified lactase, and other problems associated with lactase treatment;

- avoidance of using GM strains or unnatural additives to produce high lactase / stabilised lactase (both undesirable from consumers, and increases costs);

- a more naturally alternative compared to using purified lactase for digestion; and

- fungi strains are shown to be safe and have been used in the industry and accepted by consumers for hundreds of years.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 Existing process (prior art) to produce low lactose or lactose-free milk using

purified lactase; and Figure 2 Process using A. oryzae fermentation for lactose digestion according to one aspect of the present invention,

BEST MODES FOR CARRYING OUT THE INVENTION

Example 1 : Preferred method of preparing a low lactose or lactose-free milk.

1. Prepare for a pre-sterilized fermentation tank.

2. Pasteurize the raw milk in the heat exchanger for 15 to 30 seconds at 80 to 85°C.

3. Transfer the pasteurized milk to the pre-sterilized fermentation tank.

4. Inoculating the milk by adding a starter of A. oryzae, preferably 5-10% w/w of the milk to the fermentation tank, either before or after the pasteurized milk is added.

5. The fermentation step is performed for 12-18 hours at between 28-33°C, with

ventilation.

6. The milk is then centrifuged or filtered to separate the low/no lactose milk from the fermentation culture.

7. The milk is then UHT treated (at 123°C, 3-5s) or spray-dried into powder prior to

packaging of subsequent use.

Example 2: Alternative method of preparing a low lactose or lactose-free milk

1. Prepare for a pre-sterilized fermentation tank.

2. Pasteurize the raw milk in the heat exchanger for 15 to 30 seconds at 80 to 85°C.

3. Transfer the pasteurized milk to the pre-sterilized fermentation tank.

4. Inoculate the milk by adding a starter of A. oryzae, preferably 5-10% w/w of the milk to the fermentation tank, either before or after the pasteurized milk is added.

5. The fermentation step is performed for 12-18 hours at between 28-33°C, with

ventilation.

6. 70-90% of the fermented milk is then separated from the mycelia (i.e. fungi) and either is UHT treated or is spray-dried.

7. The remaining 0-30% of the fermented milk culture is then used as a starter to add to 70-90% of untreated milk sample in the fermentation tank. Steps 3 to 6 may then be repeated to make a cycle. Example 3: Low lactose milk prepared from the present invention.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.