HYDROGEN PEROXIDE AND ASCORBIC ACID CONTENTS, SUPEROXIDE DISMUTASE AND CATALASE ACTIVITIES IN SMOOTH CAYENNE AND QUEEN PINEAPPLES DURING COLD STORAGE
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Pineapples (Annanus comosus L. Murr.) could easily develop chilling injury symptom during storage at low temperature, depending on maturity, cultivar, temperature and duration of storage. Queen pineapples are known to more sensitive to chilling injury than other groups. Low temperature is believed to cause oxidative stress in plant tissues leading to chilling injury symptoms. Queen and Smooth Cayenne pineapples were stored at 10°C for 3 weeks. Queen pineapples developed slight internal browning after only one week of storage and more than 50% showed moderate symptom after 3 weeks. There was no symptom in Smooth Cayenne after 3 weeks of storage. Hydrogen peroxide content in the flesh of Queen was higher than in Smooth Cayenne before and during storage. Ascorbic acid content was also higher in Queen. Superoxide dismutase activity in Smooth Cayenne was higher at the beginning but declined to about the same level as in Queen. Catalase activity in Queen before storage was three times higher than that in Smooth Cayenne. After one week of storage the activity declined considerably. The higher sensitivity to low temperature in Queen as compare to Smooth Cayenne may be explained by the higher H 2 O 2 content, but further study on other antioxidants and enzymes involved are needed.