Thermally-induced crosslinking altering the properties of chitosan films: Structure, physicochemical characteristics and antioxidant activity

Herein, thermal-induced modification of the properties of neat chitosan film was studied during the heating process at 90-130 degrees C for 24 h. By tracing the consumption of -NH3+, we found Maillard reaction occurred in heated films, which increased the degree of crosslinking. Heat treated films showed a more compact structure, leading to an increase in their tensile strength with the highest level of 54.3 MPa in the 110 degrees C treatment. Meanwhile, water solubility, swelling degree, water vapor and oxygen permeability of chitosan films decreased after thermal treatment due to the reduction of amino groups and their denser structure. In addition, the heated films had higher antioxidant capacity, while an optimum process displayed at 110 degrees C showed a 90% increase in DPPH center dot free radical scavenging when compared with the control. Summarily, the thermal treatment, especially 100-110 degrees C was a conditionally useful guide to improve the overall performance of chitosan film under the condition of 24 h-reaction time.

Automated summary

This study investigated the thermal-induced modification of neat chitosan film at temperatures ranging from 90 to 130 degrees Celsius. Heating resulted in the Maillard reaction, which increased the crosslinking degree of the film. The heat-treated films exhibited a more compact structure and higher tensile strength. Additionally, water solubility, swelling degree, water vapor and oxygen permeability decreased. The optimum process occurred at 110 degrees Celsius, showing an improved antioxidant capacity.