Effect of Fermentation Methods on Chemical and Microbial Properties of Mung Bean (Vigna radiata) Flour

Abstract

Mung flours were fermented using spontaneous and backslopping methods for 72 h and microbial analysis over a period of 72 h fermentation was carried out. The samples were subjected to biochemical test, anti-nutrient and selected mineral and vitamin contents evaluation using standard methods. There was a gradual decline in pH from an initial value of 6.24 in unfermented flour to a pH of 3.68 in spontaneous fermentation and 3.87 in backslopping fermentation after 72 h. The total titratable acidity increased from 0.0085% to 0.0105% in fermented sample. The level of the increase did not differ significantly (p > 0.05) for the methods. Flours from back-slopping fermentation showed higher increase in protein and ash (17.59% and 18.25% respectively) than spontaneous fermentation with 16.70 % and 6.35% respectively. Similar increases were observed for calcium and iron. The decrease in zinc content was higher in spontaneous fermentation method than in back-slopping methods. Back-slopping fermentation sample had higher Vitamin A, lower phytate and tannin contents than spontaneous fermented sample. Samples from spontaneous fermentation showed significantly (p < 0.05) higher increases in microbial load (1.27 x 10⁵ – 4.08 x 10⁵ CFU/ml) than that from the back-slopping fermentation method (0.4 x 10⁵ – 2.9 x 10⁵ CFU /ml) within the same time interval. Back-slopping method improves the nutritional properties than spontaneous methods and could be encouraged at community levels.

Keywords: Mungbean, spontaneous, backslopping, chemical composition, fermentation.