Using lignocellulosic fractions of coffee husk to improve properties of compatibilised starch-PLA blend films

The effectiveness of the incorporation of cellulosic reinforcing agents (cellulosic fibres: CF and cellulose nanocrystals: CNC) and antioxidant aqueous extract (AE) from coffee husk at improving the functional properties of compatibilised starch-PLA blend films was studied. Tensile and barrier properties, crystallization pattern and thermal behaviour were analysed in films containing 1 wt% of CF or CNC incorporated by two different methods or 5.8 wt% of antioxidant extract. The antioxidant properties of the films were also tested through their efficacy at preserving sunflower oil from oxidation. Of the cellulosic fractions, CNC directly blended with the starch phase were the most effective at reinforcing tensile properties of the material (148% and 45% increase in elastic modulus and tensile strength, respectively) and at reducing their water vapour and oxygen permeability (28% and 42% reduction, respectively). The AE did not improve the mechanical performance of the blend films, but conferred antioxidant capacity useful for food packaging applications.