Effects of Different Inocula Fermentation on Physicochemical, Nutritional and Antioxidant Activities of Non-Alcoholic Finger Millet (Eleusine coracana L.) Beverages

Abstract

The rising demand for plant-based, lactose-free functional beverages amid gut health concerns positions finger millet (FM, Eleusine coracana) as a promising substrate. This study assessed sprouting and fermentation inoculum effect: dairy starters (Streptococcus thermophilus and Lactobacillus bulgaricus) or backslopping with commercial Mageu on microbial growth, fermentation dynamics, nutrition, antioxidants, color, and texture of FM beverages. Microbial growth increased modestly over 48 h OD600 = 0.169–0.201, peaking in non-sprouted FM with dairy starters (ND) at OD600 = 0.201). ND showed the fastest pH decline (ΔpH = 2.19), while sprouted FM with dairy starters (SD) or backslopping (SB) had controlled acidification. Total titratable acidity increased from 0.14 to 0.66%, with the highest total soluble solids in sprouted substrates (SD = 11.26 °Brix; SB = 10.97 °Brix). Proximate analysis revealed SB had high crude fiber (2.86%) and SD highest protein (4.02%). Sprouted beverages excelled in minerals (SB Ca = 27.00 mg/100 g; SD Ca = 25.75 mg/100 g), while ND or non-sprouted FM fermented spontaneously (NS) had high Fe (4.31%, 2.65%) and K (48.08%, 38.32%). ND showed peak antioxidants: phenolics 10.54 µg/mL, DPPH 87.80%, FRAP 21.24 µM Fe2+/g, ABTS 79.09%. Sprouted beverages displayed distinct color (L* = 37.67–39.65, C* = 25.94–27.03) versus commercial Mageu (L* = 57.89, C* = 14.50) and favorable texture (firmness 12.78–13.40 g, secondary peak force ~−7.2 g). Controlled fermentation of sprouted FM yields nutrient-dense, antioxidant-rich, vegetarian beverages with superior attributes, affirming its functional potential.