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.