Integrated volatilomics and metabolomics reveal the dynamic landscape and key transformation phases of flavor compounds in indica rice during hydrothermal cooking

This study employed a novel approach combining GC × GC-O-MS-based volatilomics and UHPLC-MS/MS-based metabolomics to track the dynamic changes of volatile and non-volatile compounds during indica rice hydrothermal cooking. A total of 254 non-volatile metabolites changed significantly, with 63 identified as key differential metabolites ( P < 0.05, VIP > 1.5), primarily lipids, organic acids, and heterocyclic compounds. The initial cooking stage (0–5 min) was critical for these changes. Volatilomics detected 107 volatile compounds: aldehydes, ketones, and heterocyclics increased gradually, while alcohols and esters decreased initially then increased. Based on OAV evaluation, 34 key aroma compounds (OAV > 1) were identified, with 2-acetyl-1-pyrroline, nonanal, (E)-2-nonenal, and (E,Z)-2,6-nonadienal contributing most significantly. Temporal analysis showed important changes in aroma during both initial and final stages (20–30 min). The initial phase was particularly crucial for metabolite and aroma transformation, involving both enzymatic and non-enzymatic reactions that collectively shape rice flavor. These findings offer valuable insights into aroma development during rice cooking. • Volatilomics and metabolomics tracked metabolite dynamics during rice cooking. • Indica rice cooking yielded 34 volatile and 63 non-volatile key metabolites. • Non-volatile/volatile metabolites transform most significantly during initial cooking (0–5 min). • Key non-volatile metabolites are significantly correlated with key volatile metabolites.