Biofortification of multi-grain substrates by probiotic yeast

In the current study, probiotic yeast strain, Saccharomyces cerevisiae AKP1 was assessed for its potential as a starter culture in multi-grain (rice, pulses, and soybean, 3:1:1) substrates fermentation. The impact of fermentation of multi-grain-based food on proximate composition, antinutrients, and antioxidants was evaluated. Fermented product showed significant increments (P <.05) in protein (13.6%) and fiber (1.8%) content. Moreover, the rapidly digestible starch (27.5%) and resistant starch (15.0%) levels were found to increase significantly (P <.05) while the slowly digestible starch level decreased (87.7%) in the fermented food sample. After 4 days of fermentation, total phenolic and total flavonoid contents increased by 83.0% and 69.8%, respectively, with a greater antioxidant potential of 85.9%. The fermented food sample showed a significant reduction in the phytate (64.5%) and trypsin inhibitor activity (19.9%) (P <.05) with a substantial increase in phytase level (P <.05). Fourier transform infrared spectroscopy clearly revealed the alteration of physico-chemical properties during fermentation with S. cerevisiae AKP1. Gas chromatography–mass spectrometry analysis detected the presence of 38 volatile compounds in the fermented food material with the prevalence of fatty acids such as palmitic acid, linoleic acid, among others; alcohols such as isoamyl alcohol, 2,3-butanediol, among others; and esters such as ethyl-2-methylbutanoate. Thus, probiotic yeast S. cerevisiae AKP1 could improve the dietary and functional characteristics of multi-grain substrates and could be regarded as a potential starter for multi-grain substrates fermentation.