Effects of gelatin/tea tree oil composite coating on postharvest quality and volatile flavor regulation in strawberry fruits

Strawberries are highly susceptible to postharvest microbial infection, leading to rapid quality loss. This study developed a gelatin-based film containing tea tree essential oil. The film showed increased opacity, improved mechanical strength, and enhanced barrier properties. Strawberries were stored at 20 ± 1 °C and 85-95% RH for 8 days. The coating reduced decay, maintained firmness, and limited weight loss. It suppressed the accumulation of reactive oxygen species, including superoxide anion and hydrogen peroxide, as well as malondialdehyde, delayed the decline of ascorbic acid and total phenolics, and enhanced antioxidant enzyme activities, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase. In addition, the coating slowed the reduction of soluble solids and titratable acidity. Volatile metabolomics analysis indicated increased levels of sweet- and fruity-associated aroma compounds and reduced accumulation of fatty- and vegetable-like odor compounds. Overall, the coating delayed decay and preserved flavor quality, showing strong potential for strawberry preservation.