Enzyme-induced changes in skin and its implications

Surface charge of the skin matrix is an extremely important parameter in leather making process because effectivity of the chemicals largely depends on the surface charge of the skin matrix. In the present research work, isoelectric point (Ip) and point of zero charge (pzc) are used to predict the distribution of electric potential and charge at the skin tissue–liquid interface after chemical and enzymatic unhairing of the skin. In this study, the determination of zeta potential and isoelectric point for relimed tissues processed by chemical and enzymatic methods was performed using a zeta potential analyzer and a titrimetric method. These results indicate that enzyme-treated tissues had lower isoelectric point than the chemical-treated tissues, which has been explained by studying the amino acid composition of the tissues. The tissue samples were also characterized by FTIR–ATR and solid-state 13C NMR spectroscopy to understand the chemical/structural changes occurred due to enzymatic treatment. The lower Ip/pzc of the tissue obtained by enzymatic process ensured maximum uptake of chemicals, making it an eco-benign process.