CONICET | Buscador de Institutos y Recursos Humanos

The use of lactic acid bacteria (LAB) and yeast in wheat dough fermentation is a new option to obtain products with improvement dough properties, flavor, nutritional value and shelf life. These positive effects depend on the stability of LAB/yeast association. The interaction between them depends on both the competition for the carbon source (maltose, sucrose, glucose and fructose) and the sensitivity to the end products formed during fermentation. The aim of this study was to determine the sugar co-metabolism of Lactobacillus (L.) plantarum CRL 778 (from fermented dough origin and potential application in bakery for their antimicrobial properties) and Saccharomyces (S.) cerevisiae sp (commercial yeast). The microorganisms were grown as pure and mixed cultures at 30 °C for 24 h in broth containing pancreatic digest of casein (Casitone, Difco), K2HPO4, KH2PO4, Tween 80 and each (0.5% w/v) maltose, sucrose, or a mix (1% w/v) of sugars (0.2 % maltose, 0.7% sucrose, 0.05% glucose and 0.05% fructose) in similar proportions to dough. Cell viability, pH, residual sugars and end products (lactic acid, acetic acid and ethanol) were determined by HPLC and enzymatic kits. Results indicate that all sugars were used by L plantarum and S cereviciae as carbon source for growing. The lactobacilli preferently fermented monosaccharides, showing a faster growth rate in presence of these sugars. S. cerevisiae, showed a slower maltose uptake respect to sucrose, which was rapidly metabolized during the first 8 hours, releasing glucose and fructose. Similar results were obtained for the mixed cultures, while lactobacilli showed slow sugar uptake and no monosacharide release. Although, ethanol and lactic acid production were lower (30-70% and 40-60%, respectively) when using mixed cultures, no significant differences (p> 0.05) on the growth were observed respect to single cultures.