The interest in searching an alternative to the condition of "waste" for spent coffee is continuously growing in the scientific community. Indeed, the high content of polyphenols, caffeine, and tannins in this residue can potentially lead to pollution for water and soil, since they show toxicity for various plants, microorganisms, and aquatic organisms. Nevertheless, these same antioxidants find wide applications in the food, cosmetic and pharmaceutical industries, especially caffeine and chlorogenic acid, thanks to their ability to prevent or slow down the oxidation of the substrate.
In the context of active packaging, the use of compounds recovered from spent coffee grounds is promising, since they allow extending the shelf-life of food while maintaining its sensory and nutritional properties.
In this work, High Pressure and Temperature Extraction process was used to extract antioxidants from spent coffee grounds. The obtained extract was used for the fabrication of zein-based films intended for active packaging applications. Biopolymer films loaded with spent coffee grounds extract were prepared using two different techniques: solvent casting and electrospinning. Films were characterized in terms of morphology and antiradical power of the released active components.
Considering the large amount of exhausted coffee produced annually and the global extension of the coffee industry, the proposed application could represent a profitable alternative to conventional waste disposal, as well as an advantage for the environment and the food industry.