Milk provides the basis for an eco-friendly shorter process for skin preservation and leather manufacture

Abstract

The traditional beamhouse method for tanning skins to produce leather uses copious amounts of water, large quantities of chemicals deemed to be dangerous by the public and produces large quantities of liquid waste (90 kg/ton of raw hide) that have become a significant problem due to environmental concerns. In this work, we chart the development of the use of a milk product that both preserves unwashed sheepskins and depilates them, removing the need for salt, sulfide and lime and reduces the copious amounts of water used in the traditional process. This method can completely replace salting and the first five steps of the traditional beamhouse process and the depilated skins can be taken straight to degreasing and tanning. Evaluation of the depilated skins by both eye and high-resolution microscopy showed no apparent damage to the grain or fraying of the collagen bundles. The leather produced from them had physical properties that were either identical or better than those of leather made using the traditional methods. To try and understand the process, microbial culturing of the depilation liquid routinely identified two major bacterial species ( Lactococcus lactis and Lactiplantibacillus plantarum ) and two major fungal species ( Geotrichum candidum and Yarrowia lipolytica ) among other minor species. We predict that the secretion of an unidentified mix of antimicrobial substances and extracellular enzymes from these microorganisms are responsible for the preservation and depilation of sheepskin. This procedure shows potential for further development and could result in a sustainable green beamhouse operation for the leather industry. • A completely sulfide free protocol for sheepskin depilation has been developed. • It uses dairy by-products whey or permeate to preserve and depilate over 3–4 days. • No need to lime, delime bate or pickle so water use is considerably reduced. • The resulting leather has an enhanced appearance compared to normal leather. • The leather's physical properties are the same as those of the traditional product.