Resource Utilization of Bovine Hair Recycling from Enzymatic Unhairing during Leather Manufacturing

With the development of enzymatic unhairing technology in the leather industry, enhancing the recycling of bovine hair is a new issue emerging in leather-making. In this work, the effects of alkali concentration, time, and temperature in the pretreatment, as well as enzyme dosage, time, temperature, and pH in the following treatment on the dissolution performance and keratin yield of bovine hair were investigated. Hence, the extraction process of keratin from bovine hair by the alkali-enzyme method was optimized. The results sho that the optimal conditions for the keratin extraction are as follows: for the pretreatment with alkali, the alkali concentration is 0.4 M, the pretreatment time is 1.0 h, the pretreatment temperature is 65°C, and for the following enzymatic treatment, the enzyme dosage is 3324 U/g bovine hair, the action time is 4.0 h, action temperature is 45°C, and the pH is controlled between 8.5-11.5. Compared with the alkali method, the alkali-enzyme method increases the keratin yield from 24.4% to 58.1%, and the alkali dosage is reduced by 50%. The prepared keratin had high in vitro antioxidant activity, which provided a new idea for the resource utilization of bovine hair waste.