Effects of starch filling on physicochemical properties, functional activities, and release characteristics of PBAT-based biodegradable active films loaded with tea polyphenols.

In this work, the modification of poly(butylene adipate-co-terephthalate) (PBAT) was combined with the development of active packaging films. PBAT, starch, plasticizer, and tea polyphenols (TP) were compounded and extrusion-blown into thermoplastic starch (TPS)/PBAT-TP active films. Effects of TPS contents on physicochemical properties, functional activities, biodegradability, and release kinetics of PBAT-based active films were explored. Starch interacted strongly with TP through hydrogen bonding and induced the formation of heterogeneous structures in the films. With the increase in TPS contents, surface hydrophilicity and water vapor permeability of the films increased, while mechanical properties decreased. Blending starch with PBAT greatly accelerated degradation behavior of the films, and the T30P70-TP film achieved complete degradation after 180 days. As TPS contents increased, swelling degree of the films increased and TP release were improved accordingly, resulting in significantly enhanced antioxidant and antimicrobial activities. This work demonstrated that filling starch into PBAT-based active films could achieve different antioxidant and antimicrobial activities of the films by regulating film swelling and release behavior.

Starch as a smart, cheap, and green gatekeeper for the controlled release of propyl gallate from antioxidant biodegradable packaging films.

Oxidative rancidity of food products and massive consumption of plastic packaging have put the necessity in manufacturing novel antioxidant biodegradable packaging films. A comprehensive investigation was conducted on starch/poly(butylene adipate-co-terephthalate) (PBAT) antioxidant blown films, in which starch acted as a gatekeeper for the controlled release of propyl gallate (PG). PG was well integrated into the matrices and bound to starch molecules by hydrogen bonding. All films showed strong anti-ultraviolet performance, and higher oxygen barrier than the traditional polyethylene film. Increasing starch proportions promoted the swelling of films and the release of PG, thereby causing higher antioxidant activity at the same contact time to free radical solutions. Similar polarity made PG prone to partition and rapid migration into the food simulants with higher ethanol concentration and the high-fat-content peanut butter. The film with 20:80 w/w starch/PBAT proportion and 3% w/w PG content effectively suppressed the oxidation of peanut butter within 300-day storage. Findings demonstrated this strategy for manufacturing starch/PBAT antioxidant films as a long-term active packaging in food industry.