Effect of Hot Air Treatment on Maintaining Volatile Components in Strawberry Fruits during Postharvest Storage

In this study, the mechanism through which hot air (HA) treatment maintains the volatile components of ‘Benihoppe’ strawberry fruits during postharvest storage was elucidated by analyzing changes in physiological quality, free and bound volatile components and the activity of key enzymes in the lipoxygenase (LOX) metabolic pathway. The results indicated that the optimal HA treatment conditions were 45 ℃ and 4.5 h. In comparison to the control group, HA treated strawberry fruits exhibited higher soluble solid content (SSC) during the mid-to-late storage period (from day 4 to day 7), and maintained its firmness throughout the storage period. After 7 days of storage, fruit firmness increased by 95.3% compared with the untreated group. Despite the 45 ℃/4.5 h treatment showing the highest decay index of 85.1% on the last day (day 7), the decay index increased more slowly during 0–5 days of storage, which decreased by 32.5% compared with the control group on day 5. A total of 41 free volatile compounds and 13 bound volatile compounds were detected during the entire storage period. Furthermore, HA treatment maintained the content of strawberry aroma compounds represented by esters while significantly reducing alcohols associated with spoilage odors. HA treatment increased LOX and alcohol acyltransferase (AAT) activities by 48.12% and 104.71% on day 0 of storage, respectively and decreased alcohol dehydrogenase (ADH) activity by 10.25%. The treatment moderately enhanced LOX and alcohol AAT activities during storage, promoting the generation of volatile alcohols, aldehydes, and esters, which in turn enhanced the fruity aroma. It also delayed premature release of free aroma compounds, and retarded the release of key aroma components through inhibition and regulation of β-glucosidase and ADH activities in the early storage period, achieving a more balanced flavor and prolonging the persistence of the aroma. Finally, HA treatment maintained the volatile content of strawberry fruits, significantly enhancing the stability of strawberry volatile compounds over the storage period.