By-products Of Leather Industry Research Articles

Degradation of Collagen Increases Nitrogen Solubilisation During Enzymatic Hydrolysis of Fleshing Meat

The meat portion directly attached to bovine hides (fleshing meat) is a by-product of leather industry that is a potential new source of proteins. In literature different enzymatic and chemical methods have been proposed to hydrolyze and solubilize fleshing meat. Enzyme hydrolysis is preferable for the mildness and the lower environmental impact. Enzymatic hydrolysates have never been deeply characterized, nor the specific enzyme efficiency, deeply investigated. In this study, the activity of six proteolytic enzymes was tested in order to determine their efficiency in solubilizing fleshing meat and to characterize at the molecular level the composition of the nitrogen fraction of the obtained hydrolysates. Total nitrogen content and the degree of hydrolysis were determined by Kjeldhal and o-phthaldialdehyde (OPA) methods. Amino acids and peptides were analysed by high performance liquid chromatography (HPLC) and mass spectrometry techniques. The results showed that papain and Alcalase appear to be the most efficient enzymes, and the corresponding hydrolyzates were rich in peptides and amino acids characteristic of collagen, notably absent in the hydrolyzates obtained with other enzymes. Thus, the ability to efficiently hydrolyze collagen seems to be related to the efficiency in fleshing meat hydrolysis.

Reuse of leather shavings as a reinforcing filler for poly (vinyl alcohol)

Leather shavings, the by-products of leather industry, are usually treated by the landfill, which probably makes them hazardous to the human health and the environment due to the oxidation of the containing chromium (Cr) (III) to toxic Cr (VI). Therefore, efficient and environment-friendly reusing of leather shavings is not only of great interest but is also a huge challenge. This article reported a reuse method of leather shavings by combing two novel technologies, that is, the solid state shear milling (S3M) to mechanochemically pulverize and activate leather shavings, and the thermal processing of poly (vinyl alcohol) (PVA) to make them filled with PVA. The related mechanism, the structure, and properties of the obtained composites were investigated. The results showed that S3M method could efficiently pulverize and activate leather shavings through very strong shearing and compressing forces, promoting the formation of more hydrogen bonds and the chelation in the interfaces between PVA and leather shavings, and consequently enhancing their compatibility. In this way, PVA/leather shaving composites with pretty good performances, for example, better mechanical properties, thermal stability, and water resistance as compared with neat PVA, were obtained. This is a convenient, cost-efficient, and environment-friendly technology to recycle hazardous chrome-containing leather shavings.