Wine production using yeast immobilized on apple pieces at low and room temperatures

A biocatalyst was prepared by immobilization of Saccharomyces cerevisiae st rain AXAZ-1 on apple pieces. It was examined by electron microscope and stu died during the fermentation of grape must for batch wine-making. The immob ilized yeast showed an important operational stability without any decrease of its activity even at low temperatures (1-12 degreesC). Specifically, at 6 degreesC the biocatalyst favored wine production within 8 days, which is less time than is required for the natural fermentation of grape must. At 1 degreesC wine production was effected in 1 month. This speeding up of the fermentation could be accepted and adopted by the industry for scaling up the wine-making process. Total and volatile acidities were similar to those found in dry wines. The concentrations of higher alcohols (propanol-l and isobutyl alcohol) were low. The presence of amyl alcohols proved to be temp erature dependent and decreased with the temperature decrease. The values o f ethyl acetate concentrations were relatively high, up to 154 mg/L. This p robably contributes to the fruity aroma and excellent taste of the produced wines. There was no indication of vinegar odor in the product given that t he volatile acidity was <0.47 g of acetic acid/L. From the CC-MS analysis i t was concluded that cell immobilization did not create serious changes in the product (wine) with regard to the qualitative composition of the aroma compounds.