Characterization of non-volatile and volatile metabolites in dried pepino (Solanum muricatum) from different Qinghai varieties: A metabolomics approach

Varietal differences play a crucial role in determining the quality of dried pepino slices. In this study, four varieties (Qingtianxiang, Qingcanxiang, Qingningxiang, and Qingyuxiang) were evaluated through sensory assessment, color analysis, and metabolomic profiling of both volatile and non-volatile compounds. A total of 1171 non-volatile metabolites and 6290 non-redundant, putatively annotated volatile features were detected across the four varieties; among the non-volatile metabolites, 115 showed significant differences and were mainly enriched in nucleotide metabolism, plant hormone signal transduction, and benzoxazinoid biosynthesis pathways. Based on relative odor activity value (ROAV) analysis, seven key aroma-active compounds (ROAV ≥1) were identified, with ( E )-2-nonenal, ( E )-2-octenal, heptanal, and 2-pentylfuran recognized as characteristic contributors. Integrated analysis indicated that Qingtianxiang exhibited the most favorable overall sensory quality with well-balanced metabolite profiles. This study provides the first systematic characterization of the key metabolites in dried pepino slices, offering a theoretical basis for the selection of processing-specific varieties, quality regulation, and deep processing of pepino.