Biopolymer-based sachets enriched with acorn shell extracts produced by ultrasound-assisted extraction for active packaging

Acorn shell residue is valorized for the efficient obtention of antioxidant extracts by ultrasound-assisted extraction and applied in the development of biopolymer-based films, studying its influence in different matrices for the subsequent preparation of emitting sachets for active food packaging. The effect of increasing extract addition on the physical, mechanical, optical, and antioxidant properties of biopolymer films is studied. It is observed that the water resistance increases with increasing amounts of extract in PVA films and from 5% extract in chitosan films. Furthermore, 3% extract in both types of matrices increases the UV-light blocking capacity (up to 97%). Considering the mechanical performance, not weakening of the structure is observed because of the extract addition. Films possess radical scavenging activity against DPPH with the incremental amounts of extract. Moreover, acorn shell extract as active additive in biopolymer-based sachets demonstrates an effective delay of soybean oil oxidation during 10 days of storage.