Aloe vera and tea polyphenols composite coating delays passion fruit senescence by promoting phenolic and flavonoid accumulation

Passion fruits are highly perishable during postharvest storage and transportation, prompting the exploration of natural preservatives. This study investigates the synergistic effects of Aloe vera (ALV) and tea polyphenols (TP) coatings on quality retention, ripening modulation, and associated regulatory mechanisms in stored "golden" passion fruit (Passiflora spp.) at 10 °C. The application of a composite coating comprising 40 % ALV and 0.1 g/L TP led to notable improvements in fruit preservation over a 28-day storage period. At the day of 28, quantitatively, the ALV + TP treatment reduced weight loss by 41.60 %, shrinkage index by 28.13 %, and decay index by 50 %, significantly outperforming the control and individual treatments; the treated fruits exhibited enhanced firmness, reduced ethylene production, and the respiration peak was delayed about 6 days. Metabolomic analysis revealed pronounced alterations in key metabolic pathways, notably phenylpropanoid and flavonoid biosynthesis. Specifically, significant increases in metabolites such as phenolic acids (Feruloylmalic acid and Acropyrone) and flavonoids (Okanin-4'-O-glucoside, Apigenin-8-C-Arabinoside, Quercetin-3-O- (2'-O-galloyl) galactoside, and Catechin callate) were observed. Concurrently, transcript levels of key biosynthetic genes including cinnamate 4-hydroxylase (PeC4H), 4-coumarate-coenzyme a ligase (PeC4L), hydroxycinnamoyl transferase (PeHCT) and flavonol synthase (PeFLS) were significantly up-regulated by ALV + TP coating, indicating a robust activation of these pathways. The findings underscore the effectiveness of the ALV + TP composite coating as an environmentally friendly strategy for enhancing postharvest quality by promoting the accumulation of beneficial phenolic acids and flavonoids in passion fruits.