Antioxidant release, morphology and packaging properties of gallic acid incorporated biodegradable PBAT blended PBS active packaging

Enhancing biodegradable packaging with antioxidative functions effectively improved shelf-life extension capability to reduce food loss and waste. Gallic acid (GA) as antioxidant was compounded with biodegradable polymer blends namely poly(butylene adipate-co-terephthalate) and poly(butylene succinate) (PBAT/PBS) (70/30 and 30/70) at up to 15 % to enhance antioxidant activity. GA addition formed aggregated clumps giving an irregular rough surface, preventing recrystallization and affecting the degree of crystallinity (up to 2-fold) and changes in morphology of each crystalline polymorph, while also modifying mechanical relaxation of the amorphous matrices. Increasing GA content reduced mechanical strength (up to 85 %, and 68 % for 70PBAT/30PBS and 30PBAT/70PBS) and increased permeability (up to 2.4 and 11.8 folds for water vapor and oxygen permeation, respectively) because of a less homogeneous structure. Release of antioxidant capacity was monitored by DPPH radical scavenging activity in aqueous simulants (water, 10 % ethanol, 50 % ethanol and acetic acid) and was mainly dependent on simulant types and GA loading. Radical scavenging activity corresponded with the release of phenolic compounds from the sheets. The 30PBAT/70PBS blend containing GA at 15 % showed the highest antioxidant capacity. Results showed that active biodegradable packaging could be used to prolong the oxidative degradation of foods.