NZ240002A - Method of producing a dry powder containing lactose and "oligosaccharides" - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £40002 NEW ZEALAND PATENTS ACT, 1953 No.: 240 002 Date: 30 September 1991 COMPLETE SPECIFICATION METHOD FOR PRODUCING A FREE-FLOWING OLIGOSACCHARIDE CONTAINING POWDER We, THE LACTOSE COMPANY OF NEW ZEALAND LIMITED, a New Zealand company, of 76-78 Argyle Street, Hawera, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- / 4 0 0 The present invention relates to a method for producing a dry free flowing spray dried powder containing lactose and oligosaccharides.

Oligosaccharides expressed by the formula Gal-(Gal)n-Glc (wherein Gal denotes a galactose residue; Glc, a glucose residue; and n, an integer of 1 to 4) hereinafter referred to as "oligosaccharides" are components of oligosaccharides in breast milk and selectively metabolized by Bifidobacteria, acting as growth promoters for these bacteria. Bifidobacteria are useful bacteria in human intestines particularly in infants.

Oligosaccharide is typically produced by reacting a concentrated solution of lactose with 6-galactosidase enzyme from the fungus Aspergillus oryzae, as described in NZ Patent 222,301.

Such a process will typically yield a solution containing 31% oligosaccharides, 43% lactose and 26% monosaccharides.

This solution is extremely difficult to dry commercially, and purification of the oligosaccharide component is expensive. Therefore, commercial oligosaccharide products are usually sold as relatively crude liquids.

Liquid products are more difficult to handle, and more expensive to package and transport than dry powders. They are also usually less stable than dry powders.

Accordingly, a need exists for a process for producing a dry oligosaccharide containing product. It is believed that such a product would find widespread acceptance, in the food and infant formula industries. -3- ?40002 It is therefore an object of the present invention to go some way towards meeting the above mentioned desideratum or at least to provide the public with a useful choice.

Accordingly, the present invention consists in a method for producing a dry free-flowing powder containing lactose and oligosaccharides from an aqueous solution containing oligosaccharides, lactose and monosaccharides comprising: (a) seeding the solution by the addition of lactose crystals, (b) cooling the solution to about 20°C or below and maintaining the solution at that temperature until crystallisation of lactose has substantially ceased; (c) adding lactose crystals and water to the solution in amounts sufficient to produce a slurry containing from about 50% to about 70% by weight total solids and from about 5% to about 25% by weight oligosaccharides on a dry basis; and (d) spray-drying the resultant slurry.

Preferably the initial solution contains about 30% oligosaccharides, 50% lactose and 20% monosaccharides.

Preferably the initial solution is prepared by reacting lactose with 6-galactosidase irom Aspergillus oryzae, wherein the concentration of lactose in the enzyme reaction mixture is between 50 and 90% by weight and the reaction temperature is within the range from 55°C to a temperature lower than the inactivation temperature of 6-galactosidase in the reaction mixture.

Preferably the initial concentration of lactose in the reaction mixture is about 60% by weight, and the reaction temperature is about 65°C.

Preferably the lactose crystals are finely ground. ? 4 0 0 0 2 Preferably in step (a) the quantity of lactose added is from about 1 to about 10% lactose by weight with respect to the quantity of lactose used to prepare the initial solution.

Preferably in step (b) the temperature is about 20°C and the solution is left for from about 5 to 10 hours for crystallisation of lactose to take place.

Preferably the solution is left for ten hours.

Preferably in step (c) water is added in a sufficient quantity to produce a slurry containing from about 55 to about 65% by weight total solids (eg 65% w/w).

Preferably in step (c) lactose is added in a sufficient quantity to produce a slurry containing from about 5 to about 20% by weight oligosaccharides, (eg 15%), on a solids basis.

Preferably the slurry is spray-dried using nozzle or disc atomization.

Preferably the process is substantially as hereinafter described.

In a further aspect the present invention also consists in a dry free-flowing powder containing lactose and oligosaccharides when produced by a process as herein described.

In a further aspect the present invention consists in an infant food formulation including a dry free-flowing powder containing lactose and oligosaccharides produced by a process as herein described.

A preferred form of the process of the present invention will now be described in detail. ? 4 0 0 A solution containing approximately 30% oligosaccharide, 50% lactose and 20% monosaccharides is prepared using a method analogous to New Zealand Patent 222 301, the contents of which are incorporated herein by reference.

Drying this solution would be difficult because the resulting material would be extremely hygroscopic and thermoplastic.

To enable this solution to be spray dried in a standard commercial spray drier of the type commonly used to dry milk powder it is necessary to first seed it with lactose crystals, preferably finely ground lactose crystals.

Seeding of the solution can occur at any stage during the cooling process after heating the solution to inactivate the enzyme. The solution is then cooled slowly to less than 20°C and held at that temperature for typically 5 to 10 hours.

It is important to crystallise as much of the lactose in solution as possible in order to reduce the hygroscopicity of the resulting powder.

After the crystallisation process is complete the reaction mixture is mixed with more finely ground lactose crystals and water to produce a slurry of typically 50% to 70% by weight (more preferably 55 to 65%) total solids and between 5% and 25% by weight (more preferably 5 to 30%) oligosaccharide on a dry basis.

The resulting slurry is spray dried using nozzle or disc atomization.

The product feed temperature to the drier is kept below 20°C to minimise the amount of sugar in solution and therefore reduce the hygroscopicity of the resulting powder, which will typically contain 5 to 20% oligosaccharide, 3 to 15% monosaccharide and 65 - 92% lactose.

Example .4 kg refined lactose and 13.6 kg water were mixed and heated to 95°C by circulating through a plate heat exchanger to obtain 34 kg of a 60% (W/W) lactose solution.

This lactose solution was cooled to 65°C and 80,000 units of 6-galactosidase from Aspergillus oryzae were added.

The thus obtained mixture was allowed to react for 4 hours and the reaction mixture was then heated at 90°C for 20 minutes so that the enzyme was inactivated.

Analyses of the sugar component of the reaction mixture showed the contents of oligosaccharides, disaccharides and monosaccharides to be 30%, 50% and 20% respectively.

The reaction mixture was seeded with 1 kg of finely ground refined lactose, cooled slowly to 20°C and held at that temperature for 10 hours with slow agitation.

The reaction mixture was then mixed with 30 kg refined lactose and 20 kg water.

The resulting slurry was spray dried with a product feed temperature of 20°C to produce a white free flowing powder containing 12% oligosaccharide, 7% monosaccharide and 81% lactose.

It is believed that the primary application for the product of the invention will be the manufacture of infant formula. Currently large volumes of lactose are used in the manufacture of infant formula. The present invention uses lactose as a carrier for oligosaccharide, and it is believed that it will provide a cost effective and convenient method for adding oligosaccharide to infant formula. For example, an infant food could be prepared by adding about 350g of a free flowing powder containing lactose and oligosaccharides according to the present invention to about lkg of wholemilk powder. ?4Q0 There may also be other food or pharmaceutical applications where lactose is currently used, eg, confectionery, bakery and small goods products for which the process of the present invention will find application.

While the invention has been described with reference to a particular embodiment, many variations and modifications will be apparent to those skilled in the art which may be used without departing from the scope of the invention as defined in the following claims. =24 0 0 0

Claims (16)

WHAT WE CLAIM IS:

1. A method for producing a dry free-flowing powder containing lactose and oligosaccharides as defined on page la from an aqueous solution containing oligosaccharides, lactose and monosaccharides comprising: (a) seeding the solution by the addition of lactose crystals; (b) cooling the solution to substantially 20°C or below and maintaining the solution at that temperature until crystallisation of lactose has substantially ceased; (c) adding lactose crystals and water to the solution in amounts sufficient to produce a slurry containing from substantially 50% to 70% by weight total solids and from substantially 5% to 25% by weight oligosaccharides on a dry basis; and (d) spray-drying the resultant slurry.

2. A method as claimed in claim 1 wherein the initial aqueous solution comprises about 30% by weight oligosaccharides, 50% by weight lactose and 20% by weight monosaccharides.

3. A method as claimed in claim 1 or 2 wherein the initial aqueous solution containing oligosaccharides, lactose and monosaccharides is prepared by reacting lactose with 6-galactosidase from Aspergillus oryzae, wherein the concentration of lactose in the enzyme reaction mixture is between 50 and 90% by weight and the reaction temperature is within the range frorn Si-C . to a temperature lower than the inactivation temperature of6-g&lactosidase /Ta/ f in the reaction mixture. |s£ ^ ^ "40002

4. A method as claimed in claim 3 wherein the initial concentration of lactose in the enzyme reaction mixture is about 60% by weight.

5. A method as claimed in claim 3 or 4 wherein the reaction temperature is about 65°C.

6. A method as claimed in any one of claims 1 to 5 wherein the lactose crystals used in step (a) are finely ground lactose crystals.

7. A method as claimed in any one of claims 1 to 6 wherein in step (a) the quantity of lactose added is from substantially 1% to 10% by weight with respect to the quantity of lactose used to prepare the initial aqueous solution.

8. A method as claimed in any one of claims 1 to 7 wherein in step (b) the temperature of the solution is about 20°C.

9. A method as claimed in any one of claims 1 to 8 wherein in step (b) the solution is left from substantially 5 to 10 hours for crystallisation of lactose to take place.

10. A method as claimed in any one of claims 1 to 9 wherein in step (b) the solution is left for about ten hours for crystallisation of lactose to take place.

11. A method as claimed in any one of claims 1 to 10 where in step (c) water is added in a sufficient quantity to produce a slurry comprising from substantially 55% to 65% by weight total solids.

12. A method as claimed in any one of claims 1 to 11 where in step (c) water is added in a sufficient quantity to produce a slurry containing from substantially 5% to 20% by weight oligosaccharides on a solids basis. .10. _ - 0 0 0 2

13. A method as claimed in any one of claims 1 to 12 wherein in step (d) the slurry is spray-dried using nozzle or disc atomization.

14. A method of preparing a dry free-flowing powder containing lactose and oligosaccharides substantially as herein described with reference to the example.

15. A dry free-flowing powder when prepared by a method as claimed in any one of claims 1 to 14.

16. An infant food formulation including a dry free-flowing powder as claimed in claim 13. 'lhzJ,^X^BZ...£cmpnLj ePsKa ?(?r>\rrc\ Li By the authorised agants A J PAR} Per 15 OCT 1993 r. *