Effects of molecular weight of chitosan in a blend with polycaprolactone and grapefruit seed extract for active packaging and biodegradation

Packaging films was developed by melt blending polycaprolactone (PCL) with chitosan as carrier for grapefruit seed extract (GSE). The influence of molecular weight (MW) of chitosan on the biodegradability and antimicrobial efficacy of the blend was investigated. Lower MW chitosan accelerated the release of GSE leading to significant improvement in plasticization, hydrophilicity and inhibition of the growth of Escherichia coli. Albeit it did not change the film morphology as PCL and chitosan remained in immiscible phases. Biodegradation in soil compost over 16 weeks had films with lower MW chitosan demonstrated faster rates of biodegradation with dry weight loss reaching 27 %. This was due to earlier onset of bulk degradation. Interestingly, it was not accompanied by accelerated depolymerisation as all blended films shared similar rates of decline in molecular weight. The formulation of PCL/GSE using lower MW chitosan offers a promising avenue to strengthen biodegradation and antimicrobial efficacy of packaging films.