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Studies were carried out on the factors responsible for the change of pungency in `Kagdugi´ . During fermentation, the pH in `Kagdugi´ decreased to around to 4, while acidity increased continuously. In accordance with the decrease of pungency, the content of 4-methylthio-3-butenyl isothiocyanate (MTB-NCS) in the homogenate of `Kagdugi´ decreased gradually and on 3rd day, the optimum period for good flavor, below 5% of that in the homogenate of fresh radish. The decrease of MTBNCS formation was accompanied by the gradual loss of 4-methylthio-3-butenyl glucosinolate (MTBglucosinolate), which was found to disappear more rapidly than total glucosinolate. Also$gt; the ascorbic acid-dependent myrosinase activity was observed to decline gradually with the fermentation time, although the ascorbic acid content varied above the concentration required for maximal enzyme activity. Thus, it was suggested that the decline of MTB-NCS may be related to the gradual losses of MTBglucosinolate content and myrosinase activity which are both susceptible to the effect of acidic pH.
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