Effects of pectinase treatment on the physicochemical and oenological properties of red dragon fruit wine fermented with Torulaspora delbrueckii

Red dragon fruit is a popular tropical fruit that has been highly prized for its health benefits partially attributed to the high antioxidant content. Nevertheless, besides being consumed fresh, further processing into juice or other products is scarce due to its high pectin content that presents a challenge in industrial processing. In this study, we evaluated the effects of pectinase pre-treatment on red dragon fruit wine fermented with Torulaspora delbrueckii. Pectinase enzyme (Pectinex (R) Ultra SP-L, added at 0.1% v/v) was applied after pasteurization of juice followed by fermentation with T. delbrueckii at 20 degrees C for 14 days. Pectinase pre-treatment did not affect the yeast growth, nor the production of ethanol (8% v/v) and glycerol (6 g/L), but significantly increased juice/wine yield by 16% v/v. In addition, pectinase treated samples after fermentation remained significantly higher levels of residual nitrogen containing compounds, indicating unfavorable fermentation conditions and impaired metabolism of the yeast. Moreover, fermented pectinase treated samples possessed the aroma compound profiles with enriched esters and terpenes but decreased higher alcohols. Furthermore, pectinase treatment increased the total phenolic content, but decreased betacyanins content and color intensity compared to control sample. The findings would have practical significance for diversifying products from red dragon fruit.