Application of Hydrolytic Enzymes for Improvement of Red Dragon Fruit Juice Processing

Abstract

The objective of this study was to improve the extraction efficiency and quality of the juice extracted from red dragon fruit ( Hylocereus polyrhizus ), by using commercial hydrolytic enzymes, namely Pectinex Ultra SP-L and Viscozyme L. The two enzymes were applied in constant total rate (0.1%), but at different combination ratios, temperatures and enzymatic treatment durations. By the effect of the enzymes, the extraction yield was significantly increased while the juice quality was obviously improved. High extraction yield (86.35%) and reducing sugar content in the juice (28.87 mg/mL) were obtained at temperature 40 o C, in 120 min and with a combination of Pectinex Ultra SP-L and Viscozyme L (70/30). Meanwhile, extraction without enzyme treatment resulted in significantly lower yield (54.04%) and less reducing sugar content in juice (20.63 mg/mL). Also, by application of the enzymes at optimal conditions, the juice relative viscosity was reduced from 1.42 to 1.09, while the total acidity increased from 0.47 to 0.75 (g/100 mL), the TPC from 13.68 to 14.16 (mgGAE/100g puree) and the vitamin C content from 27.94 to 32.29 (mg/100g puree) as compared to the treatment without enzymes. Keywords — Cellulase, dragon fruit, fruit juice, hemicellulase, pectinase