GB2062441A - Sterilising foodstuffs - Google Patents

Abstract

The invention relates to a means for sterilising foodstuffs, which includes sealing foodstuffs such as milk and other liquid foodstuffs, into a plastics sachet, and in particular a sachet constructed of an ultra-high molecular weight, high density, polyethylene plastic material. The plastic sachet is then subjected to an ultra-high temperature, of between 110 DEG C and 145 DEG C for a period of between 3 and 20 minutes. This serves to sterilise both the sachet and its contents.

Description

SPECIFICATION Method of sterilising foodstuffs This invention relates to sterilising of foodstuffs and has particular, although not sole application, to the packaging and sterilising of liquid foodstuffs, such as milk.

Up until this time, liquid foodstuffs such as milk, have been packaged in bottles, cartons, and flexible packs of laminated foil, and cans. Priorto the packaging of such foodstuffs, it has been necessary to sterilise the milk and to also place the milk into a sterilised or sterile bottle, carton or can. This has required careful handling to ensure that the sterile liquid and sterile package are not contaminated before sealing.

This has generally been an expensive operation requiring equipment and buildings of high capital cost and operators of high technical expertise, and it is an object of this invention to go at least some way towards overcoming this problem, and it is a further object of this invention to provide an improved method of sterilising foodstuffs.

It is a further object of this invention to provide the public with a useful choice.

According to one aspect of this invention, there is provided a method for the sterilising of foodstuffs, including sealing a foodstuff into a plastic sachet and thereafter subjecting the foodstuff and plastics sac hetto an ultra-high temperature (as herein defined) for a predetermined period of time, to sterilise the sachet and its contents.

The invention will now be described by way of example only, and it should be appreciated that modifications and improvements can be made to the invention without departing from the scope thereof as defined by the appended claims.

The invention will be described by way of example only, with reference to the packaging and sterilising of milk. This is however by way of example only, and it will be appreciated that the invention has equal application to the sterilising of other foodstuffs and liquid foodstuffs, other than milk.

Throughout the specification and claims reference will be made to "ultra-high temperature". This term is defined as a temperature high enough to sterilise the foodstuff and sachet and being between 110"C and 14500.

In the invention, suitable packaging means are provided, to package predetermined amounts of milk into sachets, the sachets being constructed of a plastics material which is of such a material as to withstand the high temperatures necessary for the sterilising of the package and milk.

In one form of the invention, the plastics material is an ultra-high molecular weight, high density, polyethylene material which is formed into sachets surrounding predetermined amounts of milk, it having been determined that this particular material is able to withstand the temperature necessary to sterilise both the sachet and the matter within the sachet.

The reference to ultra-high molecularweight, high density; polyethylene, is hereinafter defined as a polythene material having a high density of greater than .928 grams per cubic centimetre.

In a preferred form of the invention the density is greater than 0.95 grams per cubic centimetre. When referring to the index known as the "melt index" the polythene has an index reading ofgreaterthan 1.

In a further form of the invention, a material is used being a co-extrusion of ultra-high molecular weight, high density, polyethylene; nylon and appropriate bonding material; it having been determined also that this material is able to withstand the high temperature necessary to sterilise both the sachet and the matter within the sachet.

It will be appreciated that in the method of this invention, the liquid foodstuff or milk, is inserted into a sachet and the sachet and milk are then subjected to ultra-hightemperaturesto bring about the sterilising of the sachet and milk. Itistherefore important, that in this form of invention, the sachet be constructed of a plastics material which is able to withstand the temperature necessary to result in the sterilising of the sachet and milk.

In the operation of this invention, suitable machinery such as known machinery is used for the forming of the sachet and the insertion of milk or other foodstuff into the sachets.

Any known suitable means can be used to supply the necessary heat and temperature to the sachets and foodstuffs, but in the preferred form of the invention, autoclaves and the like are used, to apply heat at a steam temperature, for the predetermined period of time necessary to result in the sterilising of the sachet and matter within the sachet.

In the preferred forms of the invention, the foodstufs such as milk, within the plastic sachet is subjected to a temperature of between about 11 0or and about 145 C for a period of time of between about 3 and about 20 minutes.

It should be appreciated that the higher the temperature that is supplied to the sachet and milk, the less time is required for the application of the temperature or heat.

In one preferred form of the invention, the liquid foodstuffs being milk in the sachet, is subjected to a temperature of about 12000 for a period of 10 minutes.

Reference will now be made to the following examples.

Example 1: Non-homogenised milk is treated as follows. The milk is passed through a filter to remove undesirable solid matter, and passes to a sachet filling machine.

This machine is capable of injecting a desired amount of milk into an empty sachet, formed of a suitable plastics material such as hereinbefore described. The machine then seals the sachet and the sachet is either taken by way of conveyor, or manually, or by some other suitable means to a steriliserto sterilise the sachet by heat.

The steriliser is in the form of an autoclave which applies steam to the sachet and milk within the sachet.

The sachet is kept within the autoclave for a period steam being applied to raise the temperature of the product to 120"C at approximately 15 PSI gauge for approximately 10 minutes.

Once the milk and sachet have been sterilised, they are cooled and are then removed and stored at room temperature.

Conveniently, the cooling takes place by exhausting the steam from the autoclave and maintaining the pressure within the autoclave by means of compressed air while chilling the sachets with cold water.

Example 2: In an example where milk is to be homogenised, it has been found desirable to heat the incoming milk to approximately 60"C and to pass it thorough a homogenising pump prior to packaging within a sachet and subjecting the sachetto sterilising, as described hereinbefore, at a temperature of between 110"C and 145"C for a period of between 3 and 20 minutes.

Example 3: It has been found that if it is desired to reduce the fat rise within the milk and at the same time to reduce the amount of cream in the milk without the need to separate the milk, water and skimmed milk powder can be added two a high fat milk in orderto reduce the fat content.

The predetermined amounts of water and skimmed milk powder are thoroughly mixed and then the high fat milk is added suitably agitated to form a homogeneous mixture. This mixture is then further heated to 60"C for homogenising (as described in example 2).

The invention has been described by way of example only, with reference to milk being inserted into a sachet. It should be appreciated that a plurality of separate sachets can be used, or alternatively a plurality of integrally joined sachets, end on end can be used.

It will be appreciated thatthis invention has been described with reference to the packaging and sterilising of milk in sachets, but as indicated the invention can be applied to other foodstuffs such as for example, vegetable or fruit pulps orjuices, or any other food stuff.

Claims (10)

1. A method for sterilising foodstuffs, including sealing a foodstuff into a plastic sachet and thereafter subjecting the foodstuff and plastics sachet to an ultra-high temperature (as herein defined) for a predetermined period of time, to sterilise the sachet and its contents.

2. A method as claimed in claim 1 and wherein the plastics material is an ultra-high molecular weight, high density, polyethylene plastics material.

3. A method as claimed in claim 1 and wherein the plastics material is a co-extrusion of ultra-high molecular weight, high density, polyethylene; nylon and bonding material.

4. A method as claimed in any one of the preceding claims and wherein heat is applied at a temperature of between 110 C and 145 Cfora period of time between 3 and 20 minutes.

5. A method as claimed in any one of the preceding claims and wherein heat is maintained at a temperature of 120"C for a period of 10 minutes.

6. A method as claimed in any one of the preceding claims and wherein a foodstuff within a sachet has steam heat applied thereto in an autoclave; said means being applied at 15 PSI gauge.

7. A method as claimed in claims 1 to 6 and wherein the foodstuff is milk.

8. A method as clamed in claim 1, with reference to example No. 1.

9. A method as claimed in claim 1, with reference to example No. 2.

10. A method as claimed in claim 1,with referpence to example No. 3.