Development of a PLA/PBAT/pomelo peel-based antibacterial and antioxidant multilayer film for fresh raspberry preservation

Abstract

Globally, large amounts of fruit peel waste from food processing remain underutilized. Therefore, in this study, an active packaging layer was manufactured from discarded pomelo peels using a simple, one-step thermocompression process. This active packaging layer (PPF) was then fabricated into a biodegradable multilayer film via a multilayer thermocompression process with polylactic acid (PLA) and a PLA/polybutylene adipate-co-terephthalate (PBAT) blend (PT) as the outer layer. The introduction of a polyester layer significantly increased the film density, resulting in markedly improved mechanical and barrier properties. Among all the biodegradable film structures tested, the PT/PPF/PT trilayer film exhibited the best overall mechanical and barrier performance. Although the PT/PPF/PT film had lower tensile strength and elongation at break, as well as slightly higher water vapor permeability than commercial PE film, it exhibited a lower oxygen transmission-related value and stronger antioxidant activity and retained substantial functional activity after 30 days of storage. This functional stability may be attributed to the protective sandwich structure, which helped retain bioactive compounds within the PPF layer. When applied for raspberry preservation, the PT/PPF/PT film could delay raspberry spoilage and prolong the postharvest life by at least 8 days. The multilayer polyester shell delays the degradation rate without compromising the system's overall degradability.