The use of proteases in the leather and wool industries
The leather industry consumes a significant proportion of
the world's enzyme production. Alkaline proteases are used to remove hair from
hides. This process is far safer and more pleasant than the traditional methods
involving sodium sulfide. Relatively large amounts of enzyme are required
(0.1-1.0 % (w/w)) and the process must be closely controlled to avoid reducing
the quality of the leather. After dehairing, hides which are to be used for
producing soft leather clothing and goods are bated, a process, often involving
pancreatic enzymes, that increases their suppleness and improves the softness of
Proteases have been used, in the past, to 'shrinkproof'
wool. Wool fibres are covered in overlapping scales pointing towards the fibre
tip. These give the fibres highly directional frictional properties, movement in
the direction away from the tip being favoured relative to movement towards it.
This propensity for movement solely in the one direction may lead to shrinkage
and many methods have been used in attempts to eliminate the problem (e.g.
chemical oxidation or coating the fibres in polymer). A successful method
involved the partial hydrolysis of the scale tips with the protease papain. This
method also gave the wool a silky lustre and added to its value. The method was
abandoned some years ago, primarily for economic reasons. It is not unreasonable
to expect its use to be re-established now that cheaper enzyme sources are
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This page was established in 2004 and last updated by Martin
6 August, 2014