Effect of Freeze-Thaw Pretreatment on Thermal Drying Process and Physicochemical Properties of Chitosan

摘要

The effect of freeze-thaw pretreatment on the thermal drying process and physicochemical properties of chitosan was investigated in this study. Results showed that the freeze-thaw treatment changed the form of chitosan paste and reduced 75.6-77.7 of the water content. The freeze-thaw treatment decreased the drying time of chitosan from 16-19 h to 2.75-4 h and the dried product was loosely packed powder. After freeze-thaw treatment, the molecular weight of chitosan was unchanged during the thermal drying. The heat-induced browning effect of chitosan during drying was greatly alleviated by the pretreatment. Furthermore, the pretreatment increased the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity of dried product by 40.4-59.8. The molecular weight, color, and DPPH radical-scavenging activity of the pretreated dried chitosan product were close to those of freezedried product. VC 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41017.