AU5649190A - Low lactose dairy product - Google Patents

Description

LOW LACTOSE DAIRY PRODUCT

THE INVENTION relates to a low lactose dairy product and has particular applicability to mammalian milk products.

Intolerance to milk and milk products is a nutritional problem that occurs on a massive scale throughout the world. It is well recognised that certain groups of persons in parts of the world are not physiologically equipped to obtain nutrition from dairy products due to their sensitivities both to the milk sugar lactose and to the orotein found In mammalian milk and milk derived products. Considerable research has already been carried out nto lactose intolerance, although the issue of protein sensitivity is only beginning to receive examination as the medical profession explores the role- of dietary proteins in allergy symptomology.

These nutritional problems are causing increasing demands for alternate milk products such as whole goats milk and soy bean based products. However taste, cost and availability problems limit market acceptance of these alternatives.

It is an object of the present invention to provide an effective, taste acceptable, low lactose liquid dairy product. .

In order to assist an appreciation of the merit of the __ present invention, here follows a brief discussion of the energy uptake mechanism of the human body. It is well accepted that only a portion of consumed food is in a suitable form for absorption into the blood or the lymph system. Such things as water, certain mineral salts and vitamins might not need digestive action prior to absorption but the bulk of food must undergo profound chemical changes before-the resulting molecules can be absorbed. The proteins, and the protein-split products must be hydrolysed into amino acids; the polysacchari^'des to simple sugars; and the fats to fatty acids and glycerol, in part at least. Other lipids are also hydrolysed to smaller molecules. The many reactions and enzymatic processes involved in these changes constitute digestion.

A number of factors aid the digestive processes. Cooking of foods produces several changes. It softens certain tissues, breaks the cellulose covering around starch granules allowing better access to digestive enzymes, partially hydrolyses some food components and coagulates the liquid proteins of eggs and other food. Absorption from the intestine by removing digested molecules brings about, by a mass law effect, more nearly complete enzyme action. The most important hydrolytic digestive process is, of course, the action of the enzymes and other specific components of the digestive fluids.

This invention is concerned with the provision of a dairy based nutritional food that is acceptable to lactose- sensitive individuals. Lactose is the sugar uniquely found in mammalian milk and is composed of the monosaccharides glucose and galactose linked together. Lactose is broken down into its constituent monosaccharides by the naturally-occurring enzyme lactase, and in these forms is then absorbed into the body to meet energy needs. Infants generally have an abundance of lactase activity in their intestines which is maintained during the nursing period but which declines on weaning. The age at which this genetically determined level of intestinal lactase is reduced, varies. According to a World Health Organisation report of 1985, lactose alabsorption can be summarised in three categories:

a) Maldigestion (lack of the enzyme lactase results in incomplete digestion of lactose into its components glucose and galactose) ; b) Malabsorption (results in^" incomplete uptake of the sugars from the alimentary tract) ; and c) Intolerance (the incompletely digested lactose then reaches the colon causing nausea, vomiting, meteorism, abdominal pain, flatulence, loss of appetite and watery motions).

In the past, communal intake of dairy foods has corresponded fairly regularly to the predominant lactose capabilities of that community or population. However, modern techniques of processing, storage and distribution have made lactose- containing foods more freely available throughout the world. Further, western influence dictates that milk consumption is on the increase in many countries even though the majority of the population may be poor lactose digesters. Tropical Africa, East Asia and Australia are three areas where the original inhabitants are non-milking peoples. It is in these areas that the incidence of lactose maldigestion may reach levels of 90-100%. On the other hand, nomadic milk-dependent peoples of North Africa, Arabia and Central and Northern . Europe have frequencies of lactose maldigestion of less than 25%. Most other populations exhibit levels of lactose malabsorption of between 30% and 85%.

The W.H.O. report referred to above observes that the most obvious treatment for diseases associated with low lactose activity is to simply avoid milk and dairy products. However, the report continues that such dairy free regimens have predictable nutritional consequences in the western world where these products contribute substantial quantities of highly desirable calcium, riboflavin and digestible protein to the diet. Further, it is pointed out that some conditions producing lactase deficiency, such as inflammatory bowel disease and postgastrectomy, are associated with demineralisation of the skeleton and metabolic bone disease which may be aggravated by the removal of milk based product from the diet. Further, about 70% of the world's population suffers from lactose malabsorption due to genetically controlled lactase deficiency. However, of these, some 80% of individuals can consume up to 250 ml of milk or milk product as beverage without obvious symptoms of discomfort. Thus, use of low lactose milk products increases the quantity of highly nutritional milk an affected person can tolerate.

These unsatisfactory situations can be avoided by the consumption of a low lactose milk product manufactured in accordance with our inventive procedures.

Current technology can produce a lactose hydrolysed product suitable for lactose malabsorbers using enzyme hydrolysis of whole or skim milk. However, there are serious limitations to these techniques, namely:

a) Enzyme hydrolysis methods result in production of a taste profile considerably different from regular fresh milk. b) The toxicity of the enzyme used and the medium in which it is presented, must be thoroughly evaluated together with any residual by-products; c) The cost associated with the production and immobilisation of purified enzymes raises the price of low lactose milk (well above whole milk) ; d) Such technology requires considerable time, and this raises costs and may affect the stability of the resultant product; and e) Stability problems in the finished products have been experienced in relation to storage and transport.

It is an object of the present invention to provide a novel liquid dairy product which ameliorates these problems and which satisfies the nutritional needs discussed above. It is a further object of the present invention to provide a novel method of manufacturing a low lactose dairy product which ameliorates these problems and which satisfies the nutritional needs discussed above.

In accordance with the present invention therefore there is provided a low lactose milk made by the addition of whole milk, skim milk, or reconstituted milk to a solution of water and caseinate.

In accordance with a further form of the present invention there is provided a dairy product containing a low lactose level made by the addition of whole milk, skim milk or reconstituted milk to casein which has been manufactured by any known means after which water may be added as required to achieve normal protein levels found in whole milk.

In accordance with another aspect of the present invention there is provided a low lactose milk made by the addition of whole milk, skim milk or reconstituted milk to a solution of water and caseinate, the caseinate having been prepared by the process of:

a) precipitating the casein from a predetermined quantity of fresh milk, by the addition of acid in a temperature range of 35°-45°C, b) physically separating the thus precipitated casein from the remaining milk fraction, c) restoring the volume of the precipitated casein to 100% of the initial volume of fresh milk by the addition of water, d) optionally adjusting the pH of the thus formed caseinate to between 6.7 and 6.9, e) adding the thus prepared caseinate solution to an approximately equal volume of whole milk, skim milk or reconstituted milk. In a preferred form of the invention, the product contains approximately 50% of the quantity of lactose found in normal bovine milk (4.65g per lOOg) . This level may be varied as low as 5% initial quantity of lactose found in normal milk.

A further preferred form of the present invention is set out in the following table, which indicates a comparative composition of bovine milk and the milk product of our invention:

Nutrient Approximate Composition

Bovine Milk Milk Product

Water 87.7% 87.7%

Fat 3.7% 3.7%

Lactose 4.7% 2.35%

In a further preferred form of the present invention the level of lactose is reduced by non-chemical means, for example, by centrifuge, to avoid products of normal lactose hydrolysation being present, viz. glucose and galactose.

In another form of the present invention, approximately 7-10? of the protein content of the product is hydrolysed in a "pre-digestion" process.

One method of manufacture of this product is described below as an example:-

STEP 1 The first step is to separate the curd (casein) of a predetermined quantity of fresh milk (preferably skim milk) from the whey fraction (lactose, whey proteins, water and minerals). Whole milk or reconstituted milk is however equally useful as a starting material as each of these three types of milk contain normal lactose levels. It is to be appreciated of course that the curd is also a protein.

Casein proteins can be completely precipitated from aqueous solution by the addition of certain acids which form acid- insoluble salts with the protein.

Globular proteins such as milk casein vary considerably in their solubility in aqueous systems. Solubility of casein is minimal at pH 4.8 to 4.9, this pH being the isoelectric pH. At pH values above this the protein molecules have a net charge of the same value. Therefore they will repel each other and prevent coalescence of single molecules into insoluble aggregates. However at the isoelectric pH the molecules have no net charge, so molecules coalesce and a precipitate is formed.

In the first step of this process therefore casein is precipitated from fresh milk by addition of approximately 4% by volume of any appropriate acid, such as sulphuric acid. This process is carried out in a temperature range of 35° to 45°C (preferably 37°C) to optimise curd formation. Alternatively, the curd may be precipitated by a self souring technique through the addition of a culture to produce lactic acid.

It is to be appreciated that the foregoing describes the normal manufacture of casein (that is, curd protein).

It is also to be appreciated that if the starting material is whole milk, the fat content (butter or cream) is firstly removed by known separation procedures before being subject to the above described reaction with acid.

STEP 2 The precipitated casein protein is then physically separated from the remaining milk fractions using a clarifier, desludger, ultra filtration or similar equipment.

In this step the whey including whey protein, lactose, minerals and residual fat is removed. These components of the original milk starting product are treated at the present time as waste product.

STEP 3 The inventive procedure is now applied to the curd (precipitated casein protein) . The essence of the inventive method involves the addition of water to the precipitated curd to restore 100% of the initial volume of the milk starting product.

STEP 4 Preferably, but not essentially, the pH of the solution is then adjusted to between 6.7 and 6.9 using, for example, potassium or sodium hydroxide. This also solublises the curd and forms a caseinate. Optionally, the caseinate may be dehydrated to form a powder for storage or transport, to be reconstituted as necessary.

STEP 5 In a second novel aspect of the present invention, an approximately equal volume of milk is added to the concentrate to approximately double the volume of the concentrate. If whole milk is being produced, adjustment of the product fat content is made here using butterfat. If skim milk is to be produced, there is no requirement to adjust fat content.

STEP 6 Pasteurise.

STEP 7 Homogenise. This step ensures thorough incorporation of the previously precipitated protein into the final liquid product. Homogenisation disrupts the larger fat particles into smaller bodies resulting in a large increase in their surface area. The alpha and beta caseins are absorbed by hydrophobic interactions to the newly exposed surfaces of the small fat bodies.

STEP 8 Finally product is cooled and the removed lactose content may be compensated for by the addition of monosaccharide or disaccharide of choice. This adjusts the sweetness of the product to that of fresh milk.

STEP 9 Product is ready for packaging.

The invention also provides for a concentrate version of the inventive product. This concentrate is the product achieved at the end of step 3 or step 4 above, that is, the product resulting from the addition of water to the casein. This concentrate, being 50% of the volume of the final product, is suitable for economic storage and transport. The final product differs only from the concentrate by the novel addition of 100% whole milk, skim milk or reconstituted milk.

In a preferred form of the invention the level of fat in both the concentrate or the final product may be artificially adjusted.

The net effect of the foregoing inventive procedure is that, for example, using a whole milk starting material, the whey fraction containing the lactose has been substantially replaced by water.

The concentrate comprises an equivalent volume to the initial volume of fresh milk.

As noted above, in another form of the invention, approximately 7-10% of the protein content of the product may be hydrolysed in a "pre-digestion" process. Accordingly, steps 3a and 3b may be added to the above sequence after step 3. STEP 3a In this step partial hydrolysis of the protein is carried out using the acid fungal protease Nutrase (Novo). Nutrase is used extensively in the brewing and baking industries for break-down of proteinaceous matter either moderately or extensively to peptides. It is a clear brown liquid, prepared from a selected strain of the bacteria bacillus subtilis. A metalloenzyme, Nutrase, is added to the substrate at a level of up to 2% to achieve optimal protein hydrolysis. The degree of protein hydrolysis is dependent upon pH, temperature and duration of the enzymatic contact with the substrate.

STEP 3b The concentrate is then heated to 82°C while stirring and held at that temperature for 10-15 minutes to deactivate the enzyme and to pasteurise.

At this stage the concentrate consists of partially hydrolised protein fraction but contains no lactose. The concentrate comprises an equivalent volume of the initial volume of fresh milk. The process may continue with step 4 above.

It has been found that there are a number of advantages inherent in the dairy product the subject of the present invention. These may be summarised as follows:-

The process results in a fresh product with equivalent taste and shelf life to regular milk. Other low lactose products developed to date are mainly available as UHT or powdered products and have unpleasant taste profiles distinct from that of regular milk.

The process is cost efficient compared to other low lactose products. Sweetness. Sweetened milk is commercially attractive, particularly in South East Asia. It has been suggested that milk sweetened with 2-3% of sucrose (sugar) actually reduces gastric emptying rate as it has a higher osmolality than normal milk. Lactose intolerance appears to be related to a number of factors of which gastric emptying is one. Others include the food in which the lactose is consumed, intestinal transit time, compensation by the colon and the age of the individual. As lactose is not particularly sweet when . compared with other forms of sugar, the net result is a sweeter product as the remainder of the sugar content in our invention contains sugars, such as glucose, which are sweeter than lactose.

It is possible at this stage that either sucrose or glucose will be used in the inventive method to sweeten the milk to a taste comparable to fresh liquid milk. Although a sweeter product can easily be produced, this will probably only be done in the case of flavoured milks.

Solubility. Lactose suffers the disadvantage of having a lower solubility than many alternative sugars, such as fructose or sucrose. The inventive product provides a higher percentage of soluble sugars than is found in normal milk lactose.

Galactose. Currently available low lactose milk products necessarily contain significant quantities of galactose, the result of the hydrolysation of lactose into its constituent components glucose and galactose. There is evidence that galactose loading in rats causes cateracts. Consequently, high levels of galactose in humans is thought to be undesirable. Hence, an advantage of the present inventive product is that it does not contain the high levels of galactose found in other low lactose milk products. Lysine. Lactose hydrolysis can result in increased loss of lysine on drying. This loss can range as high as 70%, affecting storage capabilities of the product as well as its nutritional value. The present invention has the capacity of being UHT packed, so it is not expected this disadvantage will be present. Furthermore, the product of the present invention may be dried, for example by spray drying, to produce a dehydrated powder.

In addition to the foregoing physical advantages of the inventive product there are a number of clinical advantages relating to improved weight response to low lactose milk in lactose intolerant individuals. For example, the substitution of low lactose milk for normal milk in the diet of certain Australian aboriginal children resulted in a 70-80% more rapid weight gain overall. Further, 130% more rapid weight gain was found in children suffering diarrhoea prior to the commencement of the study. It was also noted that fat excretion was reduced when low lactose milk was fed to the subjects, indicating improved fat utilisation from the diet.

Other clinical advantages can be summarised as follows. As the product contains reduced lactose, it will be less likely to initiate gastrointestinal complications. The product contains an easily variable level of lactose as its primary sugar. The product is readily adaptable to fortification with butterfat in which case both energy and oil soluble nutrients such as vitamin A.would be fortified, thus providing a readily digestible, easy to eat, highly nutritious food for subjects such as those suffering intestinal diseases, convalescents, infants and elderly persons. The product can also be readily adapted for inclusion in weight reduction programmes in a skim milk form or, conversely, body building and fitness programmes in an energy fortified form. As approximately 70% of the world's population suffers from lactose intolerance, and hence suffers a limited capacity to use dairy products to their full potential, the present invention provides a significant step forward in world nutrition.

In summary, advantages of its use in western and under-developed nations are both physical and clinical and include:-

* fresh, taste acceptable milk with equivalent shelf life to regular milk

* cost effective process

* more soluble "sugar" content

* free from elevated galactose levels

* reduced lysine modification

* can readily be energy fortified

* suitable as liquid fresh or UHT product

* suitable for lactose intolerant individuals

* suitable for individuals suffering or recovering from intestinal diseases, convalescents, infants, and elderly persons

* for routine nutrition of malnourished individuals

* suitable for protein energy malnutrition

* may be useful for oral rehydration therapy

* suitable for food supplementation programmes

* can be presented in UHT form for disaster relief where reconstituting water may be limited

It will be readily apparent to those skilled in the art that numerous modifications and variations can be effected without departing from the spirit and scope of the present invention.

Claims (31)

THE CLAIMS DEFINING THIS INVENTION ARE AS FOLLOWS:

1. A low lactose milk made by the addition of whole milk, skim milk, or reconstituted milk to a solution of water and caseinate.

2. A low lactose milk made by the addition of whole milk, skim milk or reconstituted milk to casein which has been manufactured by any known means after which water is added as required to achieve normal protein levels found in whole milk.

3. A low lactose milk according to any one of the preceding claims, in which the level of lactose is reduced by non-chemical means, for example, by centrifuge, to avoid products of normal lactose hydrolysation being present, namely glucose and galactose.

4. A low lactose milk made by the addition of whole milk, skim milk or reconstituted milk to a solution of water and caseinate, the caseinate having been prepared by the process of: a) precipitating the casein from a predetermined quantity of fresh milk, by acidification in a temperature range of 35°-45°C, b) physically separating the thus precipitated casein from the remaining milk fraction, c) restoring the volume of the precipitated casein to 100% of the initial volume of fresh milk by the addition of water, d) optionally adjusting the pH of the thus formed caseinate to between 6.7 and 6.9, e) adding the thus prepared caseinate solution to an approximately equal volume of whole milk, skim milk or reconstituted milk.

5. A low lactose milk according to claim 4 in which the acidification in step (a) is achieved by the addition of a mineral acid such as sulphuric acid, or by self souring with a culture to produce lactic acid.

6. A low lactose milk according to either claim 4 or claim 5 in which the amount of acid added is approximately 4% by volume of the milk.

7. A low lactose milk according to any one of claims 4 to 6 in which hydroxide such as potassium or sodium is used to adjust the pH in step (d).

8. A low lactose milk according to any one of claims 4 to 7 in which the following further steps are included after step (e):

(f) pasteurising

(g) homogenising

(h) cooling and optionally adding sugar in the form of - monosaccharide or disaccharide. (i) packaging the final milk product.

9. A low lactose milk according to any one of claims 4 to 8 in which the said caseinate is dehydrated to form a powder and reconstituted prior to addition of the approximately equal volume of whole milk, skim milk or reconstituted milk.

10. A low lactose milk according to any one of the preceding claims which contains between 5% and approximately 50% of the quantity of lactose found in normal bovine milk.

11. A low lactose milk according to any one of the preceding claims in which the composition of the milk is as follows: Nutrient Approximate Composition

Water 87.7%

Fat 3.7%

Lactose 2.35%

12. A low lactose milk according to any one of the preceding claims in which approximately 7-10% of the protein content of the product is hydrolysed in a "pre-digestion" process.

13. A low lactose milk according to claim 12 in which the "pre-digestion process" comprises the additional steps after step (b) of: b)(i) partially hydrolysing the protein content using the acid fungal protease Nutrase, and

(b)(ii) heating the concentrate to 82°C while stirring, holding at that temperature for 10-15 minutes to deactivate the enzyme and to pasteurise the milk.

14. A low lactose milk according to anyone of the preceding claims in which the final milk product is dehydrated to form a powder or UHT treated.

15. A low lactose milk product in concentrate form, prepared by the process of: a) precipitating the casein from a predetermined quantity of fresh milk, by acidification in a temperature range of 35°-45°C, b) physically separating the thus precipitated casein from the remaining milk fraction, c) restoring the volume of the precipitated casein to 100% of the initial volume of fresh milk by the addition of water, d) optionally adjusting the pH of the thus formed caseinate to between 6.7 and 6.9.

16. A low lactose milk product according to claim 15 in which the concentrate is further dehydrated to form a powdered concentrate.

17. A low lactose milk or milk product according to any one of the preceding claims in which the level of fat is artificially adjusted.

18. A process for preparing a low lactose milk in which the level of lactose is reduced by non-chemical means, for example, by centrifuge, to avoid products of normal lactose hydrolysation being present, namely glucose and galactose.

19. A process for preparing a low lactose milk, comprising the steps of: a) precipitating the casein from a predetermined quantity of fresh milk, by acidification in a temperature range of 35°-45°C, b) physically separating the thus precipitated casein from the remaining milk fraction, c) restoring the volume of the precipitated casein to 100% of the initial volume of fresh milk by the addition of water, d) optionally adjusting the pH of the thus formed caseinate to between 6.7 and 6.9, e) adding the thus prepared caseinate solution to an approximately equal volume of whole milk, skim milk or reconstituted milk.

20. A process for preparing a low lactose milk according to claim 19, in which the acidification in step (a) is achieved by the addition of a mineral acid such as sulphuric acid, or by self souring with a culture to produce lactic acid.

21. A process for preparing a low lactose milk according to claim 19 or 20, in which the amount of acid added is approximately 4% by volume of the milk.

22. A process for preparing a low lactose milk according to any one of claims 19 to 21 in which hydroxide such as potassium or sodium is used to adjust the pH in step (d).

23. A process for preparing a low lactose milk according- to any one of claims 19 to 22 in which the following further steps are included after step (e).

(f) pasteurising

(g) homogenising

(h) cooling and optionally adding sugar in the form of monosaccharide or disaccharide. (i) packaging the final milk product.

24. A process for preparing a low lactose milk according to any one of claims 19 to 23 in which the said caseinate is dehydrated to form a powder and reconstituted prior to addition of the approximately equal volume of whole milk, skim milk or reconstituted milk.

25. A process for preparing a low lactose milk according to any one of claims 18 to 24 in which approximately 7-10% o the protein content of the product is hydrolysed in a "pre- digestion" process.

26. A process for preparing a low lactose milk according to claim 25 in which the "pre-digestion" process" comprises the additional step after step (b) of:

(b)(i) partially hydrolysing the protein content using th acid fungal protease Nutrase,

(b)(ii) heating the concentrate to 82°C while stirring, holding at that temperature for 10-15 minutes to deactivate the enzyme and to pasteurise the milk.

27. A process for preparing a low lactose milk according to any one of claims 18 to 26 in which the final, milk product is dehydrated to form a powder or is UHT treated.

28. A process for preparing a low lactose milk product in concentrate form comprising the steps of: a) precipitating the casein from a predetermined quantity of fresh milk, by acidification in a temperature range of 35°-45°C, b) physically separating the thus precipitated casein from the remaining milk fraction, c) restoring the volume of the precipitated casein to 1QQ%, of the initial volume of fresh milk by the addition of water, d) optionally adjusting the pH of the thus formed caseinate to between β.7 and 6.9.

29. A process for preparing a low lactose milk according to claim 28 in which the concentrate is further dehydrated to form a powdered concentrate.

30. A low lactose milk or milk product, substantially as described herein in conjunction with the example.

31. A process for producing a low lactose milk, substantially as described herein in conjunction with the example.