Wine fermentations by immobilized and free cells at different temperatures. Effect of immobilization and temperature on volatile by-products

A biocatalyst was prepared by immobilization of Saccharomyces cerevisiae, strain AXAZ-1, on delignified cellulosic material (DCM) and gluten pellets (GP). Repeated batch fermentations were conducted using these biocatalysts and free cells, separately, at different temperatures. The volatile constituents were extracted with dichloromethane and the extracts were subsequently analyzed by HRGC/MS. Wines produced by DCM contained higher amounts of esters, at every temperature studied, whereas those produced by GP biocatalyst contained higher amounts of alcohols. Free cells and DCM biocatalyst gave wines with similar contents of alcohols. Wines produced by DCM biocatalyst gave better ratios of esters to alcohols and had dominating fruity aromas. GC/MS analysis proved that cell immobilization did not create serious changes in qualitative composition of the wine aroma. As regards the, quantitative profile, the combined effect of temperature and immobilization resulted in the production of wines with more fruity character because of the higher ratio of esters to alcohols. (C) 2002 Elsevier Science Ltd. All rights reserved.