Characterization of the sodium alginate/essential oil emulsion film and its efficacy in controlling postharvest Penicillium expansum disease in cherry tomatoes.

Plant essential oil exhibits potent antifungal properties, demonstrating particular efficacy in the prevention of postharvest fungal diseases. This investigation focused on formulating a novel edible film composed of sodium alginate (SA) incorporating peppermint essential oil emulsion, systematically examining how varying emulsion concentrations influence the film's structural characteristics and mechanical performance, while also determining its effectiveness in suppressing postharvest fungal infections caused by Penicillium expansum in cherry tomato specimens. The results of rheological and thermal analyses indicated that a high emulsion content disrupted the gel structure and thermal stability of SA, thereby negatively impacting the stability of the gel. Nevertheless, the SA film containing 2.5 % emulsion exhibited both antifungal activity and transparency. When tested on cherry tomatoes, the SA-PE film (with an essential oil concentration of 2.5 μL/mL) demonstrated a significant reduction in Penicillium expansum incidence by 100 % compared to the control. However, it was observed that a high concentration of essential oil increased the respiration rate of tomatoes, which, in turn, accelerated decay and senescence. In contrast to other antioxidant substances, essential oils showed consistent efficacy in both in vivo and in vitro studies. Collectively, these findings demonstrate the promising application prospects of sodium alginate-peppermint essential oil (SA-PE) composite films as active packaging materials for postharvest quality maintenance of fresh produce.