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 degrees C/5 min) and control were stored under chilling conditions (5 degrees C/20 days) and then ripened (21 degrees 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-alpha-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.

Automated summary

This study investigated the effects of hot water treatment (HWT) on tomato fruit and found that HWT can reduce chilling injury symptoms and increase total phenolics and antioxidant activity in the fruit. HWT also enhanced the accumulation of phenolics, sugars, and some alkaloids, possibly mediated by azelaic acid, glutamine, and tryptophan. After cold storage and ripening, HWT fruit exhibited better metabolic performance, characterized by higher accumulation of antioxidants and osmolytes. These findings provide valuable insights into the mechanisms of chilling injury tolerance in tomato fruit and offer potential strategies for preventing chilling injury and reducing postharvest losses.