Comparative analysis of storage quality and metabolite profiles in onion bulbs according to cultivar and cultivation region

This study investigated the effects of storage on the quality characteristics and metabolite profiles of onion (Allium cepa L.) bulbs from different cultivars and cultivation regions. Physiological traits such as respiration rate, weight loss, and firmness showed a general decline during storage, with only slight but statistically significant differences observed among cultivars and regions. Metabolomic analysis using UPLC-Q-TOF MS combined with multivariate statistics revealed that sugars, organic acids, amino acids, and organosulfur compounds were significantly altered over the storage period. In particular, sucrose and maltopentose increased by up to 3.09- and 4.65-fold, respectively, while glutamyl-S-allylcysteine and glutathione glycylmethyl ester showed increases of 7.22- and 8.12-fold, respectively, especially in the ‘Terius’ cultivar. These compounds are involved in structural degradation, antioxidant defense, and flavor development, reflecting cultivar- and region-specific metabolic regulation. The findings provide insights into the biochemical mechanisms underlying storage-related changes and may inform strategies for improved postharvest management and quality preservation of onions.