Patent ID: 7250062

Claim:
A process for removing horny substances from an animal hide, comprising: treating an animal hide with an aqueous liquor, whereby horny substances are removed from said animal hide, and wherein said aqueous liquor has a pH of from 7 to 12.3 and contains lime which is present in an amount not greater than 0.3% by weight, and which aqueous liquor comprises from 0.05 to 5% by weight, based on the salted weight of said animal hide, of one or more compounds of the following formula I: or a corresponding alkali metal or alkaline earth metal or ammonium or phosphonium salts thereof, the variables being defined as follows: R 1 is selected from the group consisting of hydrogen and C 1 -C 12 -alkyl, unsubstituted or substituted by one or more S—H or O—H groups; X 1 to X 4 are identical or different and are selected from the group consisting of hydrogen, C 1 -C 4 -alkyl, O—H, S—H and N—R 2 ; R 2 is hydrogen or C 1 -C 12 -alkyl or a C 1 -C 4 -alkyl-C═O group; at least one of the radicals X 1 to X 4 being S—H; and, if R 1 contains neither O—H nor S—H, at least one further radical from among X 1 to X 4 is selected from the group consisting of S—H, OH and NH−R 2 ; and further comprising at least one compound which catalyzes a hydrolysis of peptide bonds.