Effects of Wax Coatings on Active Oxygen Metabolism of Red-fleshed Pitaya Fruit

Key words: 
• Red-fleshed pitaya /
• fruit waxing /
• active oxygen metabolism /
• weight loss rate

Abstract: Red-fleshed pitaya（ Hylocerus polyrhizus） fruit were coated with three waxes（ SP-1,Gaoliang and Lizhangjing） to observe their weight loss rate and active oxygen metabolism. The results showed that wax coatings significantly inhibited the increase of weight loss rate and delayed the decline of total soluble solids（ TSS）content,and hence were beneficial to fruit quality. Wax coatings significantly reduced the lipoxygenase（ LOX）activities of the pitaya fruit at the mid stage of storage（ at days 4-6 after storage）,highly significantly increased the ascorbate peroxidase（ APX） activities at the storage stage and the activities of peroxidase（ POD） and catalase（ CAT） at the late storage stage,and highly significantly inhibited the decrease of superoxide dismutase（ SOD） activities,the accumulation of H₂O₂ contents and the production rate of O₂^-.at the first 6 days of storage. The three waxes had different effects on the weight loss rate,active oxygen production and the activities of protective enzyme of the pitaya fruit. Of the three waxes the SP-1 wax had the best effect on the fruit quality,followed by ‘Gaoliang’wax.