Development of high value products from animal sheep hair waste

Abstract

Leather industry discards tremendous amount of solid biowaste such as trimmings, fleshings, chrome shavings, and buffing dust. Hair waste is one of the solid substances rejected by the leather industry. In routine operations, industrial hair-saving unhairing process is one of the techniques for hair removal and this has led to the generation of hair waste in increasing quantities each year. However, the disposal of this organic waste is an environmental concern in many developed countries. Hair is very resistant to biodegradation under natural environmental conditions due to its rigid nature and high sulphur content. This waste finds its way into the surroundings causing serious environmental pollution. Some of the hair waste is converted into animal feed, compost, and fertilizer or used as boiler feed in gelatin manufacturing. Hair waste is made of unique fibrous protein called keratin; recycling this hair waste into high-value products with numerous applications is an efficient strategy to counter pollution and close the loop. Keratin is an essential protein that provides structural integrity to hair. Protected solubilization methods such as reduction, oxidation and sulphytolysis methods yield high molecular weight keratin, and unprotected solubilization methods result in low molecular weight keratin peptides. The extraction methods vary based on the end application of the product. In addition, the properties of keratin and its peptides rely upon the solubilization method applied. Among the various animal hair waste generated in a tannery, a large volume of red sheep s hair waste was recovered using the enzymatic paint unhairing method, which has been unknot much explored until now. Keratin samples obtained using various chemical treatments were compared in terms of yield, protein content and cost-effectiveness; the sample obtained using sulfitolysis method was preferred for further in vitro studies. Keratin samples obtained using reduction methods predominantly possess helical conformation along with and#946; sheets and exhibit higher thermal stability. In vitro studies using fibroblast cells indicate that keratin is nontoxic, biocompatible and could be a promising candidate for the preparation of biomaterials in tissue engineering. Due to the fragile nature of keratin, it is tough to develop biomaterials using keratin alone; moreover, it has shortcomings such as less mechanical strength. Biomaterials with efficient mechanical strength can be obtained using single biopolymers or synthetic polymers. However, they are considered as inefficient material in tissue engineering owing to the lack of cytocompatibility and because they do not mimic the extracellular matrix newline