Metabolic changes associated with chilling injury tolerance in tomato fruit with hot water pretreatment

Hot water treatment (HWT) of tomato (Solanum lycopersicum L.) fruit reduces the symptoms of chilling injury (CI). The aim of this study was to identify metabolites associated with HWT-induced CI tolerance in tomato fruit cv. Imperial. Mature green tomatoes with HWT (42°C/5 min) and control were stored under chilling conditions (5°C/20 days) and then ripened (21°C/7 days). Methanol extracts from pericarp were analyzed for total phenolics (TP), antioxidant activity (AoxA), and metabolic profiling by UPLC-DAD-MS and GC-MS. After cold storage and ripening, HWT fruit showed less CI, higher TP, and AoxA than control. It also showed an increased accumulation of phenolics, sugars, and some alkaloids that may be mediated by azelaic acid, glutamine, and tryptophan. The levels of N-feruloyl putrescine, esculeoside AII, and hydroxy-α-tomatine II were reduced. The better metabolic performance of HWT fruit under cold storage was associated with a higher accumulation of several metabolites (e.g., antioxidants and osmolytes) in ripening fruit. PRACTICAL APPLICATION: The identification of metabolites associated with the reduction of chilling injury (CI) symptoms in HWT tomato fruit extends the understanding of the mechanisms involved in CI tolerance. This information provides targets that could be used to develop strategies for preventing CI (e.g., genetic improvement of tomato, direct application of key metabolites). The application of such strategies will increase the economic value and decrease postharvest losses.