Impact of Lactic Acid Fermentation on the Nutritional Potential and Anti-nutritional Factors of Two Widely Consumed Pulses (Vigna unguiculata and Vigna subterranea) Flours in Côte d’Ivoire

Abstract

Aims: Impact of Lactobacillus plantarum.
 Place and Duration of Study: Laboratory of Biotechnology, Agriculture and Valorization of Biological Resources, between February 2021 and November 2021.
 Methodology: Two pulses (Vigna unguiculata and Vigna subterranea) purchased at the Adjamé market (Abidjan) were subjected, after the unitary operations of sorting, washing drying and grinding of the grains, in fermentation in a sterile flour/water mixture at 37°C for 48 h by Lactobacillus plantarum. The final microbial load was enumerated according to official methods, the fermented flour was dried at 50°C for 48 h and then the antioxidant and anti-nutritional properties were evaluated.
 Results: The sterile conditions of fermentation of the water/flour mixture with the inoculum load of 9.107 CFU/g resulted in final microbial loads of 7.8 109 CFU/g and 6.7 109 CFU/g, in decreased in pH to 3.13 ± 0.06 and 3.27 ± 0.06. This decrease was correlated with an increase in total titratable acidity (4.89 ± 0.02 and 4.26 ± 0.0%) after 48 h of fermentation for cowpea and voandzou flours, respectively. The fermentative activity of Lactobacillus plantarum increased the initial phenolic compound content to 74.28 ± 0.99 mg/100 g (cowpea) and 71.26 ± 0.4 mg/100 g (voandzou) for total polyphenols and 36.52 ± 0.336 mg/100 g (cowpea flour) and 35.33 ± 0.231 mg/100 g (voandzou flour) for total flavonoids after 30 h of fermentation. At the same time, their antioxidant activity doubled from 15 to 30% while initial phytate and tannin levels were both reduced by 47% and 50%, respectively in cowpea and voandzou flours in 30 hours of fermentation.
 Conclusion: In view of all these results, cowpea and voandzou flours fermented with Lactobacillus plantarum could be used as functional foods.