Improved Stability of Immobilized Lactobacillus sp. Cells for the Control of Malolactic Fermentation in Wine

Abstract

Lactobacillus sp. cells were immobilized in 2% K-carrageenan gel and subsequently used in a continuous-flow bioreactor to promote and control malolactic fermentation of wine. With the addition of 5% purified bentonite to the matrix, the half-life of the bioreactor was extended to 46 days, and the minimum retention time (to accomplish malolactic fermentation) was decreased to one hour and 57 minutes. The conversion ratio and the decrease in titratable acidity were equivalent to 53.9% and 64.0% of the original L-malic acid, respectively. Low pH (3.15) and relatively high molecular SO₂ concentrations (0.2 mg/L) did not significantly affect the activity of entrapped Lactobacillus cells nor the secondary products profile and the wine sensory properties.