STUDIES ON THE PHYSIOLOGICAL AND CHEMICAL -CHANGES IN SHREDDED CABBAGE .3. EFFECT OF AIR-EXPOSURE AT LOW-TEMPERATURE ON PHYSIOLOGICAL ACTIVITIES AND BROWNING OF SHREDDED CABBAGE

Effect of air-exposure at low temperature on the activities of enzymes , ethylene production and browning in shredded cabbage was examined. S hredded cabbage was exposed to circulated cool air (1 degrees C) for 2 hours (these were the treated samples), after that shredded cabbage w as packed with polyethylene bag and stored at 20 degrees C. (1) Browni ng (Delta E (Lab)) and the activities of polyphenol oxidase (PPO), per oxidase (PO) and phenylalanine ammonia-lyase (PAL) of shredded cabbage increased during storage. Browning and the activity of PAL in treated samples were lower than those of control samples, but the activities of PPO and PO of the treated samples were the same as those of Control samples. (2) Ethylene production of shredded cabbage increased until 12 hours, after that it decreased. And the treated samples were lower in ethylene production than control samples. Following the increase of ethylene production, the activation of PAL was noted, and then the ac tivity lowered as the ethylene production decreased. Browning and lign in formation of the treated samples was retarded, but respiration rate , ethylene concentration in package and phenolic content were not affe cted by this treatment. These results indicate that the reduction of e thylene production and PAL activation by the treatment may be concerne d with the retardation of browning in shredded cabbage.