Biotransformation of Bioactive Compounds in a Multi-Millet and Sprouted Fenugreek Formulation via Lactobacillus plantarum Fermentation

Abstract

Background: The synergistic fermentation of pseudocereals and legumes holds significant potential for developing functional foods with enhanced bioavailability of phytonutrients. Solid-substrate fermentation of grain and legume matrices with Lactobacillus plantarum has repeatedly been shown to increase free phenolic acid and flavonoid content relative to unfermented controls, largely through microbial esterase and glycosidase activity that liberates bound phenolics from the plant cell wall. Methods: This study evaluates the functional enhancement of a standardized 522 g multi-millet and sprouted fenugreek powder mixture fermented with L. Plantarum. To assess the release of bound phenolic acids and intracellular components by fermentation with bacterial cultures targeted cell lysis via sonication, followed by comprehensive bioactive profiling using high-performance liquid chromatography (HPLC). Results: Fermentation of the 522 g formulation reached peak acid production (1.52 pm 0.05% lactic acid) and a minimum ph of 3.72 pm 0.03 at 48 h. HPLC quantification revealed significant biotransformation across all targeted phenolics. Sonication-assisted cell lysis (F-L) yielded a +189.3% increase in Total Phenolic Content (412.30 pm 12.40 mg GAE100 g DW) and a +176.4% increase in Total Flavonoid Content (188.50 pm 6.80 mg QE100 g DW) compared to unfermented controls. Crucially, cell lysis released an additional 38.2% of total extractable phenolics over the non-lysed fermented group (p < 0.001). Conclusion: Combining L. Plantarum fermentation with sonication-assisted cell lysis significantly enhances the yield and extractability of bound and intracellular bioactive compounds in multi-millet and sprouted fenugreek matrix formulations, providing a novel processing route for bioactive functional food development.