Impact of postharvest ripening on peach quality: Aroma release and formation mechanism.

Peach aroma could be further released during postharvest ripening but the mechanism of aroma formation was still unclear. During peaches stored at 4 °C for 0-8 days (D0-8), flavoromics were performed to reveal aroma release and their formation pathways. γ-Decalactone content in D2 and D4 increased by 83 % and 60 % through oleic acid metabolism compared with D0, strengthening peach-like aroma. Moreover, hexyl acetate, benzaldehyde, and γ-decalactone increased by 12.87 %, 207.22 %, and 59.52 % at D4 via oleic acid, linolenic acid, linoleic acid, and phenylalanine metabolisms, enhancing peach-like and floral characteristics. However, γ-decalactone, hexyl acetate, (Z)-3-hexenyl acetate, and benzaldehyde declined at D6 and D8 causing the aromatic loss. Furthermore, the levels of galacturonate, histamine, and isovaleric acid in D8 were 24.91, 5.21, and 11.21 times of D0, respectively. Specifically, galacturonate promoted softening, histamine triggered allergic inflammation, and isovaleric acid enhanced sour/rancid off-flavor. Therefore, peaches at D2 ∼ 4 had a better aroma with richer peach-like, fruity, and floral attributes.