Removal of keratin, i.e. callous, feather, nail, claw and hair or residual hair, from animal skin for leather manufacture, uses di- and poly-mercapto-alkane compound and peptide bond hydrolysis catalyst, e.g. enzyme

摘要

Removal of keratin from animal skins involves treatment in an aqueous liquor containing, with respect to salted weight, 0.05-5 %, by weight mercaptan(s) (I) or the corresponding alkali(ne earth) metal, ammonium or phosphonium salt(s) and also compound(s) catalyzing hydrolysis of peptide bonds. Removal of keratin from animal skins involves treatment in an aqueous liquor containing, with respect to salted weight, 0.05-5 %, by weight mercaptan(s) of formula (I) or the corresponding alkali(ne earth) metal, ammonium or phosphonium salt(s) and also compound(s) catalyzing hydrolysis of peptide bonds: [Image] R1>H or 1-12 C alkyl, optionally with 1 or more S-H or O-H groups; X1>->4>S-H in at least one case, otherwise H, 1-4 C alkyl, O-H or NHR2>; and R2>H, 1-12 C alkyl or 1-4 C alkyl-C=O. If R1> contains no O-H or S-H, at least one other X1>->4> is S-H, OH or NHR2>. Independent claims are also included for: (1) unhaired hides produced by this process; (2) residual liquor from the process, containing melanine or its degradation products; (3) working up this residual liquor by optionally separating lime, then neutralizing with acid and separating proteins.