Characterization of active biodegradable films based on cassava starch and natural compounds

Biodegradable films with antimicrobial and antioxidant properties were developed from cassava starch with the addition of minimally processed pumpkin residue extract (PRE) (0 to 6%) and oregano essential oil (OEO) (0 to 2%). The films were characterized regarding their physicochemical, mechanical, barrier, and antioxidant (DPPH and TBARS) properties. The films that had the best barrier, mechanical and antioxidant properties were selected and further characterized by their optical, thermal, and antimicrobial properties. Oregano essential oil and glycerol contributed to increasing the elongation and reducing the tensile strength of the films. The films showed satisfactory antioxidant and antimicrobial activity when tested in vitro. From these results, two formulations were selected to test the protection against oxidation in ground beef (F8, with 4.8% PRE and 1.6% OEO and F12 with 3% PRE and 2% OEO). It was observed that adding pumpkin residue extract was important to provide opacity to the films, but it was not effective in improving the antioxidant or antimicrobial activity when compared to adding essential oregano oil. When applied to ground beef, the films protected the meat against lipid oxidation until the third day of storage.