Continuous wine fermentation using a psychrophilic yeast immobilized on apple cuts at different temperatures

Apple-supported biocatalyst prepared by immobilization of cells of an alcohol-resistant psychrophilic Saccharomyces cerevisiae AXAZ-1 on apple cuts was found to be suitable for continuous wine fermentation at temperatures between 5 and 15degreesC. Wine productivities were much higher than those reported using repeated batch fermentation at low temperatures. Ethanol productivity at 5degreesC was equal to that obtained by traditional fermentation at temperatures of 22-25degreesC. The continuous fermentation bio reactor was operated for 95 days without any diminution of the ethanol productivity. Total and volatile acids were similar to those found in dry wines, The formation of methanol ethyl acetate, propanol-1, isobutanol and amyl alcohols (2-methylbutanol-1 and 3-methylbutanol-1) were also monitored. The concentrations of higher alcohols were at low levels. At temperatures >10degreesC the concentrations of amyl alcohols were lower than those previously reported for repeated batch fermentations. The concentration of ethyl acetate was <100 mg l(-1) in all cases. Preliminary sensory tests carried out in the laboratory ascertained the fruity aroma, fine taste and the overall improved quality of the wines produced compared to other commercially available wines. (C) 2002 Elsevier Science Ltd, All rights reserved.