Application Of Microbial Transglutaminase In Leather Processing

At present, there are three great problems in leather processing industries: (1) heavy pollution on environment: the main pollution is the waste water from the wet processes; (2) low utilization rate of resources and seriously waste; (3) large water consumption. The rising cost of the materials and chemical agents and the increasing attention of environment protection seriously limit the development of the leather industries, which make them need new change, and the center problem of the change is environment problem. Therefore, cleaner manufacturing practices are significant to leather industries.Enzymes are eco-friendly biological materials with the advantages of specificity, stereo-specificity, activate under mild conditions, non-pollutants, and biodegradability. Applying enzymes as an alternative to the conventional chemicals in leather processing could greatly alleviate the environmental pollution load. Microbial transglutaminase (MTG, E.C.2.3.2.13) plays a variety of function in food process and wool industrial, including improvement of the food texture and nutrition value of protein, preparation of heat-resistant and water-fast film, improvement of the shrink-resistance properties of wool and so on. In this article, MTG was used in leather processing to examine the influence of MTG on the properties of the leather. And in comparison with the prior processes, whether MTG can substitute some of the material that would make pollution on the environment was discussed.The main contents of this dissertation are as follows:(1) In the tanning process, The Ts and softness of leather samples treated with MTG would not be improved obviously as treated without enzyme. However, compared with the samples treated with only chromosal B, the Ts of the samples treated with MTG then with chromosal B decreased 9℃.(2) In the post-tanning process, the MTG modified gelatin-sodium caseinate as the fillers improved the subjective properties such as grain tightness, grain smoothness, and fullness, and did not significantly affected the mechanical properties such as tensile strength, elongation at break, and tongue tear. The scanning electron microscopic analysis indicates that the micro-structure of the leather treated with the fillers became more regular and tighter compared with the control.(3) MTG can improve the mechanical properties (tensile strength and elongation at break) of GC films at the ratios of 2:2, 1:3, and 0:4, and reduce their water absorbed. With the increasing of enzyme concentrations, the elongation at break also increased. The elongation at break of the films treated with MTG at the concentration of 10% turn to the largest. With the increasing of PU composition in the GC system, the mechanical properties and water resistance of the films can be improved obviously. The GC and PU-GC system were applied as coating agents in leather finishing. The properties of finished leather were different with the coatings at varying ratios. It can be concluded that the PU-GC11 system at the ratio of 2:2 was the best coating agents for leather finishing. The GC13 and GC11 modified by MTG, and casein modified by chemical agents were applied as base coatings, it can be concluded the properties of leather samples finished with GC11 were most similar with that finished with casein modified by chemical agents.