Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Depilating hides – bating – or hide treating using enzyme or...
Patent
1997-06-19
1998-11-10
Redding, David A.
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Depilating hides, bating, or hide treating using enzyme or...
8 9418, C14C 100
Patent
active
058342990
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a 35 U.S.C. 371 national application of PCT/DK95/00509 filed Dec. 20, 1995 and claims priority under 35 U.S.C. 119 of Danish application 1456/94 filed Dec. 21, 1994, the contents of which are fully incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a method for dehairing of hides or skins by means of enzymes.
BACKGROUND OF THE INVENTION
The dehairing of hides or skins assisted by means of enzymes was first described around mid- to late 1960's. A typical representative prior art method is described in U.S. Pat. No. 3,840,433 (Aunstrup et al.), which describes dehairing of skins and hides in a strongly alkaline environment by means of certain alkali resistant proteolytic enzymes.
A drawback in relation to methods for dehairing of this kind is the fact that no perfect dehairing can be obtained, because the resulting dehaired hide or skin will either be incompletely dehaired (if the amount of enzyme used is small) or be damaged in the grain (if the amount of enzyme is high).
Another prior art method of this type is described in PCT/DK93/00283. Even if it is possible to obtain a complete dehairing without damaged grain with this prior art method, it uses sulfide and thus is not environmentally friendly.
Hitherto it has not been possible in an environmentally friendly way to produce a completely dehaired hide or skin with undamaged grain by the use of enzymes.
SUMMARY OF THE INVENTION
It is the purpose of the present invention to solve some of the above mentioned problems by providing an environmentally friendly method for dehairing hides or skins by means of enzymes, which will result in a hide or skin which is completely dehaired, and which exhibits an undamaged grain.
Surprisingly it has now been found that hides or skins can be dehaired completely without damaging the grain thereof by means of an environmentally friendly method.
According to the invention the method for dehairing of hides or skins comprises the following steps: exposure to mechanical influence and subjection to at least one protease, characterized in, that the hides or skins are subjected to at least one protein disulfide redox agent at least one time during step 1) to 3).
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have surprisingly succeeded in finding an environmentally friendly method for dehairing hides or skins by means of enzymes, which results in completely dehaired hides or skins with an undamaged grain.
The method can advantageously be used for dehairing skins or hides from bovine and also hides or skins from other provenance, e.g. sheep or goat.
According to the method of the invention the hides or skins exposure to mechanical influence, and subjection to at least one protease, characterized in, that the hides or skins are subjected to at least one protein disulfide redox agent at least one time during step 1) to 3).
The steps 1), 2) and 3) are usually performed in the same equipment, such as a beam house drum, which ensures that the skins and hides are subjected to sufficient mechanical influence. However, the steps may be carried out in different pieces of equipment.
In which of step 1), 2) or 3) the protein disulfide redox agent in question is added, depends on the pH-optimum of said protein disulfide redox agent in relation to the pH of the process.
At pH-optimum the enzyme in question exhibits about 80 to 100% of maximum catalytic activity.
If the protein disulfide redox agent has a pH-optimum about 7, it is preferred that it is added during the main soak in step 2) , as the main soak normally is carried out at pH 7 to 9.
If the protein disulfide redox agent has a pH-optimum at a significantly higher pH (high alkaline protein disulfide redox agents) it may be advantageous to add it together with the protease in step 3). This leads to degradation of keratin immediately after the removal of disulfide cross bonds.
High alkaline protein disulfide redox agents are enzymes showing optimal enzyme activity at pH abo
REFERENCES:
patent: 3480433 (1969-11-01), Haist et al.
patent: 3986926 (1976-10-01), Monsheimer et al.
patent: 4960428 (1990-10-01), Christner et al.
Agris Cheryl
Novo Nordisk A S
Redding David A.
Zelson Steve T.
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