The Influence of Alkaline Hydrolysis of Wool By-Products on the Characteristics of Keratin Hydrolysates

Wool by-products represent an important bioresource for designing new biodegradable materials, alternative to synthetic products for regenerative medicine, cosmetic formulations, food package, fertilizers etc. Keratin is the main structural protein of wool, with highest concentration of cysteine as compared to other proteins. Research has been carried out on the physico-chemical properties of keratin hydrolysates obtained from wool by-products by using different concentrations of sodium hydroxide. The influence of sodium hydroxide concentrations from 8% to 25% on keratin hydrolysate characteristics was shown by chemical analyses, SDS-PAGE electrophoresis, particle size and Zeta potential measurements. It was concluded that the alkaline hydrolyse allows efficient solubilisation of wool by-products and producing of keratin hydrolysates with different molecular weights and cysteine concentrations. The use of 10% sodium hydroxide allows to obtain keratin hydrolysates with high molecular weight and higher concentration of cysteine meanwhile 15% sodium hydroxide represents the threshold for low molecular hydrolysates and low cysteine concentrations. The experiments showed the thresholds for sodium hydroxide concentration related to different properties of keratin hydrolysates.