Enzymatic treatment for juice extraction and preparation and preliminary evaluation of Kiwifruits wine

摘要

Kiwifruit [ Actinidia deliciosa (A. Chev.)C. F. Liang & A. R. Ferguson] is nutritionally rich fruit with high ascorbic acid content (193mg/100g) but the extraction of its juice is difficult due to slimy pulp.To overcome this problem a combination of enzymes (pectinase 0.025g/kg + amylase 0.025g/kg + mash enzyme 0.05g/kg) were used to macerate pulp (2h at 50oC) and thus, facilitating the extraction of juice. The treatment enhanced the juice recovery (78.46%) compared to the control (58.44%) and the treatment did not affect the TSS, titrable acidity, p H, reducing and total sugars of the clarified juice. A comparison of physico-chemical characteristics of unclarified juice with that of enzymatically clarified showed a drastic decrease in pectin content and consequently, decrease in the viscosity of the juice. The outstanding feature of the juice was its high acidity and high concentration of ascorbic acid which however, decreased by 21% after clarification. The recovered juice was ameliorated with sugar (22 ± 1 oB), 100 ppm SO₂ and 0.1% DAHP, and was fermented by pure culture of Saccharomyces cerevisiae at 22 ± 1 oC. After fermentation, a wine of 9.7% alcohol and 7- 8 oB residual total soluble solids was obtained. Blending with sucrose syrup made the wine palatable. Since, in present study the enzymes combinations were used for a period of 2 h, high yield and clarity of juice were recorded. The sensory panel adjudged the wine with good ranking for colour, aroma, body and overall acceptability.