Study of dairy heterofermentative lactic acid bacilli for cereal-based matrices

Abstract

Forty obligate heterofermentative lactic acid bacilli (HB) isolated from dairy environment as non-starter lactic acid bacteria (NSLAB) were studied regarding their potential as novel starter cultures for fermented foods. Preliminary genotipic and phenotypic tests allowed the selection of 16 strains, identified as Limosilactobacillus fermentum (12 strains), Levilactobacillus brevis (2), Lentilactobacillus buchneri (1) and Weissella confusa (1). They were initially studied at the technological level, focusing on stress factors (low temperature, heat, salt and acidic media), growth in milk, viability after freezing and thawing and growth in cereal-based matrices. Based on this, six strains were chosen for further studies: L. brevis (LB61 and LB66), L. buchneri (LBu39), L. fermentum (LF22 and LF68) and W. confusa (W20). The selected strains grew well in wheat and gluten-free (GF) doughs, produced exopolysaccharides, acetic and lactic acid in a ratio (<1:5) that allowed the inhibition of undesirable organisms without causing off-flavours, and had good salt resistance. Among them, Weissella confusa W20 was used as starter culture for sourdough fermentation to manufacture gluten-free breads, showing noticeable improvements at the organoleptic level in comparison to GF breads fermented only with yeast. This work remarks the importance of studying the potential of wild strains to find alternative matrices beyond those from where they were isolated. With this regard, our investigation allowed the selection of six dairy strains with potential as starter cultures for bread making, which reaffirms that allochthonous strains can be suitable for sourdough preparation.