Effects of hot water treatment on flavor compounds and storage attributes of fresh tomatoes

• HW treatment promoted desirable esters and suppressed off-flavors like pyridine. • HW treatment maintained quality via upregulated sugar/HSP genes and suppressed ethylene. • HW treatment elevated flavonoids/terpenoids, thus enhancing antioxidants and shelf life. In order to study the effect of 50°C hot water (HW) treatment for 5 minutes on the quality changes of mature tomatoes during storage, the study conducted flavor profiling, transcriptome sequencing, and metabolomic analyses to systematically elucidate the molecular mechanisms that maintain quality during 7 days of storage at 20°C. Physiologically, HW significantly reduced the decline in fruit firmness, maintained skin reddening, and delayed the decrease in total soluble solids (TSS). In terms of flavor, HW treatment promoted accumulation of fruity and floral esters such as butyl 2-methylbutanoate, 2-methylpropyl acetate, and ethyl pentanoate, while reducing levels of off-odor compounds including pyridine, furfural, 2-butanone, and tetrahydrofuran. At the molecular level, HW upregulated lignin-forming anionic peroxidase ( POD ) within the phenylpropanoid pathway while preventing downregulation of phenylalanine ammonia-lyase ( PAL ), it also induced expression of sugar metabolism genes alpha-amylase 2 ( AMY2 ), alpha-amylase 3 ( AMY3 ), sucrose-phosphate synthase 4 ( SPS4 ), and acid invertase ( AI ), activated heat shock protein ( HSP20, HSP90 ), and suppressed ethylene biosynthesis genes 1-aminocyclopropane-1-carboxylate oxidase ( ACO ) and 1-aminocyclopropane-1-carboxylate synthase ( ACS ). Additionally, flavonoid metabolites such as 6-hydroxymyricetin 6,3’,5’-trimethyl ether 3-glucoside and 7- O -methylmyricetin were increased, potentially enhancing antioxidant and defense responses. Together, these results indicate that HW positively regulates pathways including sugar metabolism, the TCA cycle, and phenylpropanoid biosynthesis to synergistically improve postharvest quality and shelf life of fresh tomatoes, providing theoretical support for a green preservation strategy.