Use of organo-silica immobilized bacteria produced in a pilot scale plant to induce malolactic fermentation in wines that contain lysozyme

Abstract

The exploitation of organo-silica immobilized lactic acid bacteria (LAB) to perform malolactic fermentation (MLF) in wine is described. The immobilization of a large amount of Oenococcus oeni cell culture was achieved by a two-step process in an original pilot plant. Cells are entrapped in Ca-alginate microbeads, coated with an organo-silica membrane obtained by two treatments: the first a sol suspension of tetraetoxysilane, the second using methyltriethoxysilane in gas phase. The resulting material improves the physico-chemical features of alginate, avoids cell leakage during fermentation, and protects the cells from antimicrobial compounds. In MLFs carried out at the microvinification scale, the activity of immobilized cells did not differ from that of free cells, and no differences were found in the chemical composition of the wines obtained. The use of immobilized bacteria allowed: (1) simultaneous alcoholic and malolactic fermentations in must inoculated with free yeast and immobilized bacteria; (2) the sequential MLF of three wine lots with the same biomass of immobilized bacteria; (3) the achievement of MLF in a wine with lysozyme added to suppress wild LAB and their potential spoilage.