Assessment of sugar content, fatty acids, free amino acids, and volatile profiles in jujube fruits at different ripening stages.

Highlights • Ripening stages showed significant effect on the volatile profiles of jujube fruits. • (E)-2-hexenal was the most abundant component and showed rising trend during ripening. • Jujube at half-red maturity showed better performance in overall flavor quality. • GC–MS coupled with E-nose is an accurate method to identify 4 maturities of jujube. Abstract Volatile profiles of jujube fruits at different ripening stages were characterized by GC–MS and E-nose. Changes in the possible precursors of volatile components were also investigated. Four ripening stages were established: GM, green maturity; YM, yellow maturity; HRM, half-red maturity; RM, red maturity. Fruit maturity showed significant effect on the volatile components and their precursors. (E)-2-hexenal was the most abundant component which showed rising trend from 169.2 μg/kg (GM) to 733.4 μg/kg (RM). Glucose and fructose showed a decreasing tendency during ripening. As the important precursors of jujube flavor, seven fatty acids were identified, the predominant ones were C 16:0 , C 16:1n7 , C 18:1n9c and C 18:2n6c ; twenty-six free amino acids were quantified, in which l -AspNH 2 and l -Pro were the abundant components. Owing to the highest content of total aldehydes (59.33%) and the strongest responses of E-nose, jujubes at HRM stage showed superior overall flavor quality among all the samples. [ABSTRACT FROM AUTHOR]