Effect of fermentation conditions and immobilization supports on the wine making

Batch and continuous fermentations at two different temperatures using immobilized cells on apple, quince and pear pieces were carried out separately and the effect of fermentation temperature, type of fermentation and immobilization support on kinetic parameters and on quality characteristics of the produced wines was investigated. Duncan's multiple range test showed that higher temperature (30 degrees C) resulted in higher wine productivity. Statistically higher wine productivity was also observed when quinceimmobilized biocatalyst was used in continuous fermentation compared to batch system at the same temperature. In contrast, wine productivity was statistically higher in batch fermentations compared to continuous process when apple and pear-supported biocatalysts were employed in wine making at 15 degrees C. Although volatile acidity in wines produced by immobilized cells on pear pieces was a little increased and statistically higher compared to wines produced by immobilized cells on apple and quince pieces, it still remained in levels usually found in dry wines. No vinegar odor was observed. Ethyl acetate concentration was higher in wines produced at lower temperature (15 degrees C) contributing to the fruity character of the product. The content of methanol, amyl and higher (propanol- 1 and isobutanol) alcohols in all wines was found in very low levels, leading to improved quality products. Low-temperature (15 degrees C) wine-fermentation resulted in improved quality and the produced wines had a distinctive aromatic profile. Apple appears to have an advantage over quince and pear, as it is widely cultivated, it is considered more compatible with wine taste, while continuous process using immobilized cells on apple pieces resulted in high wine productivity. (c) 2004 Elsevier Ltd. All rights reserved.