Composition Analysis between Kohlrabi (Brassica oleracea var. gongylodes) and Radish (Raphanus sativus)

Abstract

The major deterring factor of radish consumption is bitter and pungent tastes caused by glucosinolates. Recently kohlrabi was introduced in Korea and mainly cultivated in Jeju Island during winter. Since the texture and taste of kohlrabi are similar to radish, the kohlrabi is expected to substitute radish. This study was done to compare compositional quality between kohlrabi and radish. The kohlrabi contained less reducing sugars, cellulose and pectin than the radish. The kohlrabi had harder texture than the radish. The total amino acid content in the kohlrabi was 2.7-fold higher than that in the radish. Especially hydrophilic amino acids including aspartate, glutamate and arginine, were about 3-fold higher in the kohlrabi, suggesting that the kohlrabi was more palatable than the radish. The total contents of glucosinolates in the radish in inner and outer section were higher than those in the kohlrabi by 12.4- and 28.5-fold, respectively. In a sensory test, the kohlrabi was evaluated less bitter and pungent than the radish. The kohlrabi contained more glucoraphanin, an anticancer compound, than the radish. Furthermore, the sweetness of the kohlrabi was evaluated higher than that of the radish, though kohlrabi contained less reducing sugars, probably due to high contents of hydrophilic amino acids. In conclusion, the kohlrabi was evaluated as more favorable in taste and contained more functional compounds than the radish, and thus it can be a good replacement vegetable for radish.