Valorisation of fishery industry wastes to manufacture sustainable packaging films: modelling moisture-sorption behaviour

The waste production from the food processing industry causes serious environmental, economic and social problems. However, this waste streams can be used and transformed into added value products for food packaging applications. With this aim, this work is focused on the manufacture of sustainable films by using chitosan derived from wastes of fishery industry. Since chitosan is a hydrophilic polymer, moisture sorption behaviour was analysed in order to provide novel knowledge related to the best use conditions for chitosans as packaging films. Chitosan films were prepared using different contents of glycerol as plasticizer to improve functional properties. Water sorption isotherms were determined in the range of 0.1-0.9 water activity using a gravimetric method. The experimental data were fitted to several sorption models and the Guggenheim-Anderson-de Boer equation was found to best represent the experimental data through the entire range of water activity in order to predict the moisture sorption behaviour of the films prepared in this study. The results revealed that chitosan films show a great potential to be used as packaging films for food products with intermediate moisture sorption. These findings are expected to aid in the suitable design of chitosan-based sustainable food packaging films that contribute to improve consumer perception of food products, valorise a waste product, maintain food quality and thus, reduce food waste and environmental impact caused by conventional packaging systems.