Tailoring physicochemical properties of chitosan films and their protective effects on meat by varying drying temperature

A higher temperature is usually used to increase the evaporation rate and thus reduce the drying time of chitosan films during casting preparation process. The effects of drying temperature (45-85 degrees C) on the microstructure, mechanical and barrier properties of chitosan films were investigated. Chitosan films dried at higher temperatures showed smoother internal microstructures by forming smaller micro-region aggregations and lower ordered crystalline structures. Higher drying temperature also decreased the intermolecular interactions of chitosan chains according to Fourier transform infrared spectroscopy analysis. These together led to the decrease in tensile strength, and the increase in water vapor and oxygen permeability. The film surface hydrophobicity remained unchanged at different drying temperatures, suggesting the applicability for chilled meat preservation. Chilled meat packaged with chitosan films had appropriate drip loss rate values as compared to those of the low-density polyethylene film and the blank sample, with lower thiobarbituric acid reactive substances, aerobic plate count, pH, and total volatile basic nitrogen values during 10 d storage. Moreover, films dried at lower temperatures showed superior juice retention capacity as well as superior preservation effect on chilled meat. The results found in this study can be used to better guide the selecting of drying temperature for chitosan film preparation.