Continuous fermentation of sugar cane syrup using immobilized yeast cells

Several strains of Saccharomyces sp. and commercial Baker's yeast were immobilized by adhesion onto chrysotile, a fibrous magnesium silicate (Mg 6Si 4O 10(OH) 8). The activity of the cells is higher when immobilized, mainly for fermentation of 30 to 50% w/v glucose solutions. In the medium containing 30% w/v glucose, the initial fermentation rate increased 1.2–2.5 times. Yields were in the range of 80.4 to 97.3% for the immobilized cells and 72.7 to 84.5% for the free cells. A packed bed reactor for continuous fermentation was set up using one of the tested strains immobilized onto chrysotile. An average productivity of 20 to 25 g· l −1·h −1 was obtained in the first 20 d, and an average of 16 g· l −1·h −1 was obtained after 50 d of operation.