Postbiotic bread with neurotransmitter γ-aminobutyric acid (GABA) by supplementation with Lactiplantibacillus plantarum H64 fermentate of spent probiotic brewer's yeast Saccharomyces boulardii

Spent brewer’s yeast, a brewing by-product, holds significant potential as an innovative and cost-effective source of functional ingredients. Our study aimed to valorize the health-promoting neurotransmitter γ-aminobutyric acid (GABA) from spent Saccharomyces boulardii yeast (SBY) and utilize the GABA-enriched SBY by Lactiplantibacillus plantarum H64 with wheat bran to improve the postbiotics of sourdough bread. From our results, the GABA concentration that was valorized in raw SBY reached 128 μg mL -1 . The probiotic GABA-enriched SBY correspondingly improved bread postbiotic properties with a high amount of GABA (30 μg g -1 ) and strong antioxidant capacity (12%). Molecular dynamics of GABA showed that it remained active after baking. Furthermore, the binding affinity of GABA with the human brain GABA A receptor in an acidic condition was similar to that in a neutral environment. According to the novel finding of this study, SBY from probiotic S. boulardii brewing presents a sustainable potential for valorization of food applications.