Zein and Spent Coffee Grounds Extract as a Green Combination for Sustainable Food Active Packaging Production: An Investigation on the Effects of the Production Processes

In this work, the effect of different production techniques was evaluated on the physical and antioxidant properties of bio-based packaging intended to prevent the premature oxidation of packaged foods. Spent coffee ground extract, rich in antioxidant molecules, obtained through high pressure and temperature extraction, was loaded on zein polymeric matrices. The techniques adopted in this work are particularly suitable due to their mild conditions to produce active packaging completely based on natural compounds: electrospinning, solvent casting, and spin coating. The novelty of this work lay in the investigation of the dependance of the properties of active packaging on the adopted production techniques; the results clearly indicated a strong dependence of the features of the films obtained by different production processes. Indeed, spin coated samples exhibited the best oxygen barrier properties, while a higher tensile strength was obtained for the casted samples, and the fastest release of active compounds was provided by electrospun mats. The films produced with different methods had different physical properties and the release of extract bioactive compounds can be tunable by varying the production technique, dependent on the variable to be considered. The products developed offer an alternative to traditional packaging solutions, being more eco-sustainable and promoting waste valorization.