Physicochemical characteristics, organic acid, and sugar compositions in bulb, peel, and root of five onion cultivars

In this study, the physicochemical qualities, organic acid, and sugar compositions in bulb, peel, and root of five onion cultivars (‘Tank’, ‘Bomul’, ‘Gujji’, ‘Cobra’, and ‘Hongbanjang’) grown in Korea were investigated. The main organic acids identified in the bulbs were malate, citrate, and oxalate. The primary organic acids in the peels were citrate and malate, whereas citrate and oxalate were the dominant organic acids in the roots. The bulb and peel exhibited higher total organic acid contents than the roots. The main sugar components in the bulbs were glucose, fructose, and sucrose. In the peel, the primary sugar components were glucose and fructose, whereas in the roots, only a trace amount of glucose was detected, and no other sugar components were found. These results provide fundamental data for the potential use of onion peel and root as high-value food materials.