Controlled malolactic fermentation in cider using Oenococcus oeni immobilized in alginate beads and comparison with free cell fermentation

Cells of Oenococcus oeni (formerly Leuconostoc oenos) immobilized in algina te beads were used as starter culture to conduct malolactic fermentation in cider production. Concentrations of major organic acids and volatile compo unds were monitored during the process, and results were compared to those obtained when using free cells in the same conditions. The rates of malic a cid consumption were similar but lower ethanoic acid content and higher con centration of alcohols were detected with immobilized cells. These features have beneficial effects on the organoleptic properties of cider. A compari son between the kinetic behavior in immobilized and free cells; based on th e data obtained for the melic acid consumption, has been developed solving the homogeneous diffusion model when it is applied to the system with immob ilized cells. (C) 2001 Elsevier Science Inc. All rights reserved.