Unhairing of goatskin using crude protease enzyme from Alcaligenaceae sp. to reduce chemical usage and wastewater pollution

The present study describes an unhairing process of goatskin by crude protease enzyme derived from Alcaligenaceae sp. offering a sustainable alternative of conventional chemical method that is responsible for significant water pollution. To maximize enzyme activity, the effect of temperature and pH were varied using response surface methodology (RSM) keeping the culture media constant. The model predicted an optimum enzyme activity 26.94 U/mL at 42.78 °C and pH 7.8. The laboratory experiment carried at the optimum condition (temp. 43 °C and pH 7.8) showed enzyme activity of 26.3 ± 0.4 U/mL, confirming 99% accuracy of the model. The experiments under goatskin-to-enzyme ratio 1:1, the process achieved complete unhairing without chemical additives. The proposed method requires only two steps (soaking and pickling) to complete the pre-tanning process within 24 h, whereas the conventional chemical process involves five steps and 72 h. Environmental analysis of unhairing effluent showed remarkable pollution reduction, including 27-60% reduction of total dissolved solids (TDS) and 99% reduction of total suspended solids (TSS) compared to conventional chemical method. The crust leather that produced from enzymatic method demonstrated improved tensile strength, chrome uptake and high shrinkage temperature, indicating enhanced leather quality.