GB2147299A

GB2147299A - A process for treating collagen, and dried collagen produced by that process

Info

Publication number: GB2147299A
Application number: GB08406185A
Authority: GB
Inventors: Geoffrey Patrick Stanh Ballard; Arthur Cecil Brown
Original assignee: ISINGLASS MANUFACTURERS LIMITE
Current assignee: ISINGLASS MANUFACTURERS LIMITE
Priority date: 1983-03-14
Filing date: 1984-03-09
Publication date: 1985-05-09
Also published as: GB8306935D0; GB8406185D0; GB2147299B

Abstract

A dried collagen product is produced by hydrolysing tissue material partially to produce collagen having a 40% to 99% by weight moisture content. This collagen is dried, preferably by freeze drying while maintaining its temperature below 40 DEG C, and the dried product is comminuted. The dried product can be re-hydrated to produce collagen finings.

Description

SPECIFICATION A process for treating collagen, and dried collagen produced by that process This invention relates to a process for treating collagen, in particular to the production from tissue material of solubilised collagen by means of partial hydrolysis for use as finings for potable liquors, and other fermentation processes.

Collagen finings for clarifying potable liquors, such as beer and wine, is added to beer, for example, as an aqueous solution containing usually from 0.3% to 1.5% by weight of collagen, to produce a concentration of up to 350 parts per million in the liquor. The collagen finings aids the precipitation of yeasts, proteins and other suspensoids from the fermented liquor and reduces the storage and filtration capacity required for clarifying the fermented liquors. In the case of beer, the collagen finings solution is used for clarifying traditional draught beer by adding the collagen finings to the fermented beer in cask and allowing the beer to clarify before being dispensed. Similarly, the finings are used to clarify bulk beers prior to processing. The finings may. also have a beneficial effect upon foam stability and long term haze stability.

The tissue material which is usually employed to prepare finings is isinglass collagen which is a very pure form of collagen prepared from the dried air bladders of fish, particularly members of polynemidae, sciaenidae and siluridae families. The isinglass is usually reduced to the form of strips, shreds, or floc, or otherwise reduced in particle size, in which form it is then partially hydrolysed by steeping it in a dilute acid solution, and agitated to produce a homogenous viscous mass.

Other forms of collagenous tissue material are employed as a starting point, particularly animal skin and bone (ossein) which may receive an initial alkaline treatment, for example with lime, followed by controlled swelling with certain salts and a leaching process to remove residual salts. The collagen is then in a state. for further hydrolysis.

Because of the viscous nature of the solubilised collagen it is produced at a strength of only about 4% by weight, and has to be stored and transported to users at that strength, unless it is further concentrated by separation of water by the addition of certain salts. This process produces a paste or pulp-like form of collagen which requires to be reconstituted before use. This concentrating process effectively reduces the air/oxygen content of the finings and this is beneficial to some processing applications.

Concentrated collagen in the solubilised form is particularly susceptible to de-naturing at temperatures approaching 25"C and above. Temperature control of storage facilities is therefore necessary, and there are particular difficulties when shipping collagen in this viscous solubilised form to tropical countries because of the tendency of the finings to deteriorate by de-naturing at relatively high ambient temperatures.

This invention is based on the discovery that collagen can be prepared in a dried form, in which form it is much less susceptible to de-naturing, and can be readily shipped to tropical climates without deterioration.

According to the invention there is provided a process for treating collagen comprising hydrolysing tissue material under acid or alkaline conditions to produce collagen having a moisture content of from 40% to 99% by weight, then drying this collagen while maintaining the temperature of the collagen below 40"C, and comminuting the dried product.

The tissue material may be hydrolysed at a pH of from 1.4 to 5.0 or from 8.0 to 13.0.

After hydrolysis, the collagen may be concentrated by the addition of a salt.

The collagen is preferably dried by freeze-drying.

The preferred tissue material is isinglass.

The freeze-dried collagen can be rapidly re-hydrated to produce collagen finings.

The invention also comprehends dried particulate collagen produced by a process according to the invention.

Under favourable ambient conditions the soiubilised material without full dehydrating may be safely transported and used as a concentrate.

Some examples of the treatment of collagen according to the invention will now be described.

Example I A batch of 10Kg of granulated isinglass was moistened with 15 litres of 1.8N tartaric acid at ambient temperature (between the range 10 C to 18"C) over a period of 3 hours. During this period the moistened granules were regularly stirred to disperse the moisture evenly throughout the batch which was at pH 2.3. The batch was then allowed to stand for 72 hours while the tartaric acid penetrated throughout each particle and the hydrolysis had reached the required stage in which inter-molecular bonds between the triple helices of the collagen molecules are relaxed, leaving intramolecular bondiny.

The resulting viscous collagen mass was of a spreadable consistency similar to bread dough.

This collagen was then spread on freeze-drying trays in layers from 10mm to 20mm thick and the trays were loaded in a vacuum freeze-drying apparatus of conventional kind. The collagen was frozen to about -40 C, and some heat was applied to the trays during vacuum drying to raise the temperature of the trays to about 15"C. The temperature could be up to 25"C.

When the trays were removed the collagen had the form of slabs of pumice-like material which were crushed or flaked to produce particulate solubilised collagen which was packed in sealed bags ready for shipping.

Example Il 500 gms of dry hide pieces were soaked for 24 hours in a solution containing 750 gms anhydrous sodium sulphate dissolved in 5 litres of water.

500 gms of sodium hydroxide were added, to bring the pH to 12.1, and soaking continued for a further 4 days. The hide pieces were then leached free of sulphate and excess alkali, with acetic acid solution to maintain pH5. The resulting Eucollagen was dispersed in 0.3% tartaric acid containing 300 parts per million of sulphur dioxide at pH 3.2 for 24 hours, and was then dispersed by mechanical stirring.

Thereafter the solubilised collagen was further concentrated and dried as described in Example 1.

Instead of freeze-drying, the solubilised collagen of either example could be dried in a vacuum over silica gel.

Before drying the collagen it may be concentrated by the addition of a salt, or salts, for example sodium chloride.

The dried collagen product is thus available in ready-prepared dry concentrated form which is not subject to temperature denaturation and which can be rapidly re-hydrated when required at a controlled temperature usually about 10 C to 180C, but not above 40"C.

The collagen finings produced in this way are of a micro-biological standard suitable for use in the clarification of potable liquors, such as beer and wine.

Claims

1. A process for treating collagen, comprising hydrolysing tissue material under acid or alkaline conditions to produce collagen having a moisture content of from 40% to 99% by weight, then drying this collagen while maintaing the temperature of the collagen below 40"C, and comminuting the dried product.

2. A process according to Claim 1, wherein the tissure material is hydrolysed at a pH of from 1.4 to 5.0.

3. A process according to Claim 1, wherein the tissue material is hydrolysed at a pH of from 8.0 to 13.0.

4. A process according to any one of claims 1 to 3, wherein after hydrolysis, the collagen is concentrated by the addition of a salt.

5. A process according to any one of Claims 1 to 4, wherein the collagen is dried by freeze-drying.

6. A process according to any of Claims 1 to 5, wherein the tissue material is isinglass.

7. A process according to any one of Claims 1 to 6, including re-hydrating the collagen to produce collagen finings.

8. A process according to Claim 1, substantially as described in Example I or Example II.

9. Dried particulate collagen produced by a process according to any one of Claims 1 to 6 and 8.

10. Collagen finings produced by a method according to Claim 7.