Sustained release of a novel bilayer packaging film loaded with binary microemulsion of melatonin/pummelo essential oil and its regulation of postharvest energy metabolism in Agaricus bisporus

Bio-based active soft packaging materials have excellent potential to alleviate existing environmental problems caused by conventional packaging products and delay the postharvest aging of fruit and vegetables. In this study, a novel bilayer packaging film (G/T-M-E) of glutenin/tamarind gum loaded with binary microemulsion of melatonin/pummelo essential oil was prepared. The results indicated that the G/T-M-E packaging had superior barrier and mechanical properties. Importantly, the melatonin (MT) and pomelo essential oil (PEO) loaded in soft packaging had good sustained-release properties, which could ensure release characteristics in different food simulants. Among them, MT had the highest release efficiency in 10% ethanol, while PEO is more easily released in distilled water. Meanwhile, MT and PEO migrated from the packaging film from the inside-out via different diffusion effects, which was beneficial for the synergistic effect of active ingredients. G/T-M-E maintained a higher level of ATP of white mushrooms, greater energy charge levels and higher activity of succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO). The energy charge (EC) of mushrooms packaged in G/T-M-E was as high as 0.65, which was 1.43 times higher than that of the G/T treatment group on day 12. The SDH and CCO activity of the G/T-M-E treatment group were 2.62 and 2.19 times higher than those of the G/T group on day 10, respectively. Overall, the G/T-M-E film improved the electron transfer efficiency, reduced the excess active oxygen content, maintained the high energy state, regulated the tricarboxylic acid cycle and electron transport chain pathways, indicating that the film has the active potential to regulate the energy state of postharvest mushrooms.