Investigation of Brazilian grape juice metabolomic profile changes caused by methyl jasmonate pre‐harvest treatment.

This article investigates the effects of methyl jasmonate (MeJa), a natural plant growth regulator, on the polyphenol composition of grape juice produced from two Vitis labrusca cultivars—Isabel Precoce and Concord—grown in two Brazilian regions with subtropical climates. Using an untargeted LC–MS metabolomic approach, the study found that MeJa treatment notably increased anthocyanin content, especially in Isabel Precoce juices, enhancing their color and potential antioxidant properties regardless of cultivation region. The treatment also influenced hydroxycinnamate glucosides positively and altered other phenolic compounds variably depending on cultivar and region, while newly identified biomarkers such as glutathione and indole lactic acid glucoside suggest improved oxidative protection in the juice. These findings indicate that MeJa application could be a viable, eco-friendly method to improve the quality and health-promoting properties of grape juice produced by traditional low-cost steam extraction in subtropical climates.