Collagen hydrolysate: 'Soluble skin' applied in post-tanning processes part 1: Characterisation

Upgrading solid wastes of a protein nature means a change in the modality o f "throwing away" proteins and considering their re-utilisation, i.e. in te chnological agricultural applications and as a raw material for the manufac ture of industrial products. The processing of chrome shavings by alkaline-enzymatic hydrolysis leads to obtaining a collagen hydrolysate (CH) and the recovery of the tanning mate rial through the dissolution of the so-called 'chrome cake'. The CH applied in leather manufacturing performs a synergistic action with retanning agents, in addition to its "cosmetic-lubricating" effect that enh ances the leather grain properties and provides greater softness, improving the resistance of the fibrous tissue. Also, there is a 'restoring effect' upon the grain surface of semi-finished leather, thus masking preservation defects and damage marks on the skin. The interaction with dyes is made evi dent by intensified colours and homogeneous dyeing. For a better understanding of the interactions between CH and the agents in volved in the post-tanning processes or for the elaboration of derivative c ompounds for specific purposes, it is important to know certain issues conc erning reactivity in the mixture of the polypeptides contained in collagen hydrolysate. This paper provides an analysis protocol for the characterisation of collag en hydrolysate, which provides relevant data both for the control of the CH and for the appropriate design of its various applications.