Generation of aroma compounds in sourdough: effects of stress exposure and lactobacilli-yeasts interactions

The effects of the interaction between Saccharomyces cerevisiae and Lactobacillus sanfranciscensis strains and of their responses to acid, oxidative or osmotic stress on alcohol and aroma production were studied. The exposure of S. cerevisiae and L. sanfranciscensis cells to oxidative, acid or osmotic sub-lethal stress gave rise to a common or specific responses. γ-decalactone, 2(5H)-furanones and aldehydes were overproduced by LAB following oxidative stress. The acid stress induced both in yeasts and LAB, as well as in their co-cultures, a relevant accumulation of isovaleric and acetic acids and higher alcohols. A cross-exposure of yeasts and LAB to their preconditioned media, generated in S. cerevisiae a release of esters of long-chain unsaturated fatty acids deriving from membrane phospholipids.