Fermentation du lactosérum par cellules immobilisées de Lactobacillus helveticus

Abstract

Lactobacillus helveticus cell suspensions were immobilized in calcium alginate beads. The immobilized concentrated suspensions enabled a 60% reduction of whey fermentation time as compared to a classical fermentation model. The increase in acidification rate with immobilized cells is not directly proportionnai to the increase in cell densities. Thus, at even cell concentrations, immobilized bacteria had an acidification rate 50% lower than that of free bacteria. When the initial concentration of immobilized cells is low, repeated use of the beads result in a gradual increase of fermentative activity. Storing of immobilized cells for two weeks at 4°C in peptone water resulted in a 50% reduction of activity. Alginate content of the beads did not influence fermentative activity. Agitation of beads increased acid production in the first fermentation, but was detrimental when the immobilized cells were reutilized.