Use of sourdough fermentation and pseudo-cereals and leguminous flours for the making of a functional bread enriched of γ-aminobutyric acid (GABA)

Lactobacillus plantarum C48 and Lactococcus lactis subsp. lactis PU1, previously selected for the biosynthesis of γ-aminobutyricacid (GABA), were used for sourdoughfermentation of cereal, pseudo-cereal and leguminousflours. Chickpea, amaranth, quinoa and buckwheat were the flours most suitable to be enriched of GABA. The parameters of sourdoughfermentation were optimized. Addition of 0.1 mM pyridoxal phosphate, dough yield of 160, inoculum of 5 × 107 CFU/g of starter bacteria and fermentation for 24 h at 30 °C were found to be the optimal conditions. A blend of buckwheat, amaranth, chickpea and quinoa flours (ratio 1:1:5.3:1) was selected and fermented with baker's yeast (non-conventional flourbread, NCB) or with Lb. plantarum C48 sourdough (non-conventional floursourdoughbread, NCSB) and compared to baker's yeast started wheat flourbread (WFB). NCSB had the highest concentration of free amino acids and GABA (ca. 4467 and 504 mg/kg, respectively). The concentration of phenolic compounds and antioxidant activity of NCSB bread was the highest, as well as the rate of in vitro starch hydrolysis was the lowest. Texture analysis showed that sourdoughfermentation enhances several characteristics of NCSB with respect to NCB, thus approaching the features of WFB. Sensory analysis showed that sourdoughfermentation allowed to get good palatability and overall taste appreciation.