The sourdough microflora. Characterization of hetero- and homofermentative lactic acid bacteria, yeasts and their interactions on the basis of the volatile compounds produced

Abstract

Eighty-seven strains (15 species) of sourdough lactic acid bacteria (LAB) (homo-and heterofermentative) and yeasts were characterized and statistically discriminated on the basis of volatile compounds produced during sourdough fermentation. The species differed and, in general, the strains differed within the species. Heterofermentative LAB mainly produced ethylacetate with some alcohols and aldehydes, and homofermentative LAB synthesized diacetyl and other carbonyls, while iso-alcohols were produced by yeast fermentation. L. brevis subsp. lindneri and L. plantarum were the LAB with the most complete profiles. Sourdoughs started with bacterial associations were characterized by a more complete profile (integrations of hetero-and homofermentative volatile compounds) and by a decrease of the percentage amounts of the main products individually synthesized. In association with yeasts (with the exception of L. plantarum DC400 - Saccharomyces exiguus M14 association) both hetero-and homofermentative LAB enhanced the formation of the yeast volatile compounds. Mixed sourdough starters (L. brevis subsp. lindneri CB1, L. plantarum DC400 and S. cerevisiae 141 or S. exiguus M14) were selected to produce sourdoughs with different volatile compound profiles. © 1996 Academic Press Limited.