Abstract
The pods of the broad beans (Vicia fava) darken remarkably at room temperature and this browning is considered to be derived from phenolase action, but nothing is known on the properties of phenolase in pod of this bean. The properties of the phenolase was, therefore studied, and the treatment with CO gas which had been found to be effective for the prevention of discoloration of Shiitake mushroom, was carried out. Phenolase was prepared according to the method described and the enzyme activity was measured colorimetrically. The optimal pH of phenolase was 4.0 and optimal temperature was 12°C. As to the substrate specificity, all o-diphenols tested were oxidized and of all, the highest activity was noticed with L-dopa. The enzyme was inactive with p-cresol. The phenolase lost the activity by CO treatment and the browning of the pods of the beans was efficiently prevented by this method, and the most effective period of which was 4 hrs.
