Clarification of orange juice by crude fungal pectinase from citrus peel
Fungal pectinase enzyme was produced by Rhizopus oryzae on a solid culture containing citrus peel of orange (35% w/v). The crude extract with maximum pectinase activity of 1, 360 u/ml was used to clarify orange juice. The yield, turbidity and viscosity as well as pH, total soluble solids, ascorbic acids and total titratable acidity of the clarified juice were determined. The optimum yield (97%) of juice was obtained at 1% pectinase enzyme concentration, while the turbidity and viscosity decreases with increasing concentration of pectinase enzyme. There were no marked changes in the pH and total titratable acidity of the pectinase enzyme treated juice. Ascorbic acid and total soluble solids increase with increasing pectinase enzyme concentration. There were significant differences (p<0.05) in the pectinase enzyme concentrations on the yield, viscosity, turbidity and total titratable acid of the orange juice while no significant (P>0.05) difference was found in the pH, ascorbic acid and total soluble solids. The results presented citrus peel as substrate for pectinase production and its subsequent use in the clarification of orange juice could enhance fruit juice processing in the tropics.
Keywords: Orange juice, pectinase, clarification
Nigerian Food Journal Vol. 25 (1) 2007: pp. 130-136
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