Continuous cider fermentation with co-immobilized yeast and Leuconostoc oenos cells

Ca-alginate matrix was used to co-immobilize Saccharomyces bayanus and Leuc onostoc oenos in one integrated biocatalytic system in order to perform sim ultaneously alcoholic and male-lactic fermentation of apple juice to produc e cider, in a continuous packed bed bioreactor. The continuous process perm itted much faster fermentation compared with the traditional batch process. The flavor formation was also better controlled. By adjusting the flow rat e of feeding substrate through the bioreactor, i.e. its residence time, it was possible to obtain either "soft" or "dry" cider. However, the profile o f volatile compounds in the final product was modified comparatively to the batch process, especially for higher alcohols, isoamylacetate, and diacety l. This modification is due to different physiology states of yeast in two processes. Nevertheless, the taste of cider was quite acceptable. (C) 2000 Elsevier Science Inc. All rights reserved.