Drying methods impact bioactive compounds in Siraitia grosvenorii fruit: Metabolomic insights

Siraitia grosvenorii is widely used in functional foods, and drying is essential for long-term preservation. Drying methods significantly impact the fruit quality. Here, we evaluated how hot air drying (HAD), heat pump drying (HPD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD) affect bioactive compounds in S. grosvenorii fruit. HAD-treated fruit showed elevated phenolic, flavonoid, and sugar contents, together with strong ·OH scavenging capacity. In contrast, VFD better preserved green color and native flavor of fresh fruit and yielded higher ascorbic acid and mogroside V contents than thermal drying. Under HAD and HPD, differentially accumulated metabolites (DAMs) were mainly enriched in linoleic acid, tryptophan, and purine metabolism. Under VFD, luteolin-7-O-glucoside was positively correlated with mogroside IV, mogroside V, and 11-oxomogroside V, whereas under HAD and HPD, protocatechualdehyde and vanillin (4-hydroxy-3-methoxybenzaldehyde) were positively correlated with mogroside IV. These findings provide a theoretical basis for selecting appropriate processing strategies for S. grosvenorii fruit.