Studies on the application of ultrasound in leather enzymatic unhairing.

Enzymatic unhairing is a clean technology for leather industry. However, one problem hinders the utilization of enzymes in leather unhairing is the slow diffusion of enzymes through skins. As another clean technology, ultrasound can be applied to accelerate the diffusion of enzymes through skins. In this work, effects of ultrasound on the enzymatic unhairing were investigated. Effect of frequency of ultrasound on the enzymatic unhairing was compared, and 20kHz was chosen in this work. Under our conditions, ultrasound has little effect on enzyme activities, and also has little influence on the physical and mechanical properties of leather. Ultrasound can enhance the diffusion of enzyme through skins, thus improving the unhairing capacities of enzymes. It is noted that amylase can interact with proteoglycans by attacking saccharide side chains, thus having some unhairing capacity. Ultrasound can improve the unhairing capacity of amylase more effectively. Furthermore, amylase does no harm on the collagen fibrous structure and can be used safely without the need for a high degree of control. So it is possible to use amylase in enzymatic unhairing in combination with protease. In short, using ultrasound in amylase and protease unhairing is a promising clean technology.