Volatile components are non-invasive biomarkers to track shelf-life and nutritional changes in apple cv. ‘Golden Delicious’ during low-temperature postharvest storage

In this study, we investigated the time-course variations in the nutritionally important quality attributes of ‘Golden Delicious’ apples kept under postharvest storage at 4 °C. At harvest (0 day) and at day 15, 30, 45, 60, and 90 of postharvest storage, physicochemical properties, primary and secondary metabolites profile, and volatile organic compound (VOC) profiles were measured. Low-temperature storage significantly altered physicochemical characteristics, concentrations of 22 primary metabolites, 12 secondary metabolites, and 41 VOCs in the stored apples. Apples stored for different storage durations could be separated using partial least squares-discriminant analysis with VOCs as variables. In total, 13 VOCs showed variable importance in projection score more than one, and those VOCs are considered as potential shelf-life biomarkers for apples under storage with especial emphasis on α-farnesene. This study added new insights on the systematic metabolic changes occurring in ‘Golden Delicious’ apples under prolonged low-temperature storage. The biomarker VOCs detected in this study showed excellent correlation with storage duration and estimation of those VOCs will help us in the non-destructive prediction of fruit shelf-life. Additionally, metabolite profile data can be used to correlate storage duration with the fruit nutritional level, which is of especial interest to the consumers and the apple industry.