Distribution of Polyphenol Oxidase in some Cruciferae Vegetables

Enzymatic oxidation of polyphenolic compounds in damaged tissue of many fruits and vegetables induced undesirable browning as results in decreased marketability of products. A new type of polyphenol oxidase (PPO) that is “Phloroglucinol Oxidase (PhO)” have been reported in turnip and cabbage, and the purified enzymes also had strong peroxidase (POD) activity. Distribution of PPO from different plant source of cruciferae vegetables were observed. Cabbage, broccoli, turnip and cauliflower PPOs from Indonesia and Japan strongly oxidized 1,3,5-trihydroxybenzenes such as phloroglucinol (Phl) and phloroglucinol carboxylic acid, but not oxidized 1,2,3-trihydroxybenzenes and o-diphenol. On the other side, Chinese mustard, Chinese cabbage, shingensai, Japanese radish root, mizuna, takana, leaf mustard, katsuona and komatsuna also strongly oxidized 1,3,5-trihydroxybenzenes and little oxidized 1,2,3-trihydroxybenzenes such as pyrogallol and gallic acid, but not oxidized o-diphenol. These results indicated that the PPOs in all cruciferae vegetables are a group of a new type of PPO, however, the level activity of 7 varieties of vegetables from Indonesia and 15 varieties from Japan tested showed different activity level of PhO and POD.