Improving moisture barrier and functional properties of active film from genipin‐crosslinked chitosan/astaxanthin film by heat curing.

Summary: This research aimed to improve moisture barrier and functional properties of genipin‐crosslinked chitosan/astaxanthin film by heat curing. The effect of heat curing (25, 80 and 105 °C) on film properties was investigated by measuring water vapour permeability (WVP), contact angle, tensile strength (TS), elongation at break (EAB), Young's modulus (YM), opacity, chemical structure and antioxidant activity. Results showed that genipin‐crosslinked chitosan/astaxanthin film and heat cured at 105 °C (CAG‐105) have the lowest (P < 0.05) WVP value which decreased by 55% while a contact angle increased from 50.2° to 74.6°, when compared to CAG‐25 film. Heat curing affected the chemical‐crosslinked interaction between chitosan and genipin with the establishment of new chemical bonds, leading to the improvement of TS and YM by 55% and 42%, respectively, for CAG‐105 film. However, EAB and antioxidant activity of the CAG‐105 slightly decreased. Moreover, heat curing changed the colour of genipin‐crosslinked chitosan/astaxanthin film from light brown to reddish brown and increased the film opacity which can lower light transmission through the film. The developed film not only had better water barrier, TS and YM but, due to its opacity, could also provide light protection, and thus would be appropriate for packaging material of foods that degrade when exposed to moisture or light. [ABSTRACT FROM AUTHOR]