Abstract: Basic protease JRH, glucoamylase TH and basic lipase JZ were adopted to prepare a new complex enzyme as degreasing agent, and its formula was firstly optimized. The obtained complex enzyme was then used in the degreasing process of pigskin. Using a non-ionic degreasing agent as the control, the degreasing effect of the complex enzyme was investigated, and its effects on tissue structure, mechanical property, shrinkage temperature and dyeing property of pigskin were examined, too. The synergistic degreasing mechanism of the complex enzyme was discussed. Finally, the complex enzyme was further applied in the degreasing treatment of cattle hide and sheepskin, and the environmental impact of the resulting degreasing wastewater was evaluated. Results showed that the suitable dosages of JRH, TH and JZ were 20 U, 40 U and 6 U, respectively, per gram of raw skin. Compared with the non-ionic degreasing agent, the complex enzyme exhibited the stronger ability to reduce the fat content in raw skin, and led to the more dispersed collagen fibers and the final leather with better mechanical performance. The complex enzyme also had good degreasing effect on sheepskin and cattle hide. Furthermore, compared to the control, the present wastewater possessed lower amounts of biochemical oxygen demand, chemical oxygen demand and suspended matter, indicating that the complex enzyme has less environmental pollution and is more biodegradable.

Key words: protease, lipase, glucoamylase, degreasing, synergistic effect