Effect of Natural Fermentation Period on Nutritional, Anti Nutritional, I Total Phenols, Flavonoids and Antioxidant Contents of Finger Millet Flour

Abstract

Aims: This study determined the changes in the chemical and nutritional composition of naturally fermented finger millet studied at ambient temperature (28±2°C) for 72 h. Study Designs: Finger millet seeds were cleaned and fermented (72 h; 28±2°C). Samples were taken at 24 h interval and dried at 50°C for 48 h. Methodology: The fermented finger millet samples were analyzed for microbial, biochemical changes, chemical, proximate and mineral composition. Results: Biochemical changes showed a drop in pH from 6.74 to 6.04 while titratable acidity (lactic acid equivalent) increased from 0.04 to 0.62% after 72 h. The moisture, protein, ash, fat, fibre and carbohydrate were in the ranges of 7.08-9.449%; 5.31-7.274%; 1.10-3.392%, 1.296-2.47%, 1.154-2.46% and 77.44-81.58%, respectively. Significant increase were observed in the mineral composition with phosphorus, potassium, calcium, sodium, and iron identified in the fermented finger millet flour in the ranges of 93.5-176 mg/100 g; 171-247.5 mg/100 g; 87.04-196.5 mg/100 g; 1.30-3.075 mg/100 g and 5.28-11.95 mg/100 g, respectively. Tannin, oxalate, phytate and trypsin were in the ranges of 1.537 to 3.23 mg/100 g; 0.875 to 1.59 mg/100 g; 0.195 to 0.85 mg/100 g. and 2.731 to 6.23 mg/100 g, respectively. The total phenols and total flavonoids ranged between 11.605-40.29 mg/ 100 g and 63.36 -172.872 mg/100g while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) of the flour samples ranged between 28.109 and 68.238 mg/ml. Microorganisms identified were Bacillus cereus, Lactobacillus Plantarum, Lactobacillus casei and Lactobacillus brevis. This study shows that fermentation decreased the anti-nutrients, increased the proximate and minerals contents and also improved the anti-oxidative properties of finger millet flour.