Effect of coating solution containing rice bran wax on postharvest quality of dragon fruit

Dragon fruit (Hylocereus undatus) is an economically important tropical fruit in Thailand. It is a good natural source of nutrients and antioxidants which are believe to be beneficial for human health. However, this fruit has a relatively short postharvest life (approximately 4-8 d) and during the fruit ripening process many factors affect its quality, which directly affect the consumer acceptance. Therefore, the aim of this research was to study the effect of a coating solution that contained rice bran wax, a by-product from the rice bran oil industry, on the postharvest quality of dragon fruit. The fruits were harvested at commercial maturity, selected accordingly and then dipped in a coating solution with 0.1 and 0.2% rice bran wax, commercial wax coating and the uncoated as a control. Fruit in all treatments were and kept at 10°C. The results showed that the coating solution with 0.1% rice bran wax delayed weight loss, reduction of firmness and the color change of the peel and bract of dragon fruit. Furthermore, it could retard the degradation of chlorophyll in bract and it totally maintained the betalain content in the peel of the dragon fruit. Compared to other treatments, dragon fruit coated with 0.1 and 0.2% rice bran wax showed the longest storage life of 21 d, whereas a storage life of 12 d was observed in the control and commercial wax coating according to the bract yellowing. While, the internal quality of the dragon fruit coated with 0.1% rice bran wax such as that the total soluble solid, titratable acidity, total ascorbic acids and total phenolic content showed a slower rate of decline than that of other treatments. The results indicate that coating dragon fruit with a solution that contained 0.1% rice bran wax can be used as an alternative method for maintaining the quality of dragon fruit during storage at low temperatures.