Effect of the fermentation on the microbial population occurring during the processing of zoom-koom, a traditional beverage in Burkina Faso

Zoom-koom is a traditional fermented beverage from Burkina Faso based on cereals such as millet or sorghum. Samples were collected from two local production sites of microenterprises (Zogona and Dassasgho). Microorganisms dynamic during the production of zoom-koom were enumerated using pour plate methods. The titratable acidity, pH and temperature of fermentation were determined using respectively titrimetric and electrochemical methods. The results showed a decrease in pH and an increase in acidity during soaking and fermentation step. While the enterobacteria and yeasts counts decreased (p˂0.05), lactic acid bacteria (LAB) counts increased (p˂0.05). On average, the pH decreased from 5.7 to 4.1; the lactic acid concentration ranged from 0.45 to 0.71 (lactic acid g/100 g) and the LAB ranged from 2.2×10 8 to 5.6×10 8 CFU/g for the millet dough. For the red sorghum dough the pH decreased from 6.2 to 4.2; the lactic acid concentration increased from 0.15 to 0.49 (lactic acid g/100 g) and LAB ranged from 8.9×10 6 to 5×10 10 CFU/g. The ambient temperature and nature of the grains had an impact on the fermentation process. Unfermented red sorghum zoom-koom had the lowest load of yeast and enterobacteria than unfermented millet zoom-koom. Short rods in pair or short chains (3 or 4 rods) bacteria are the main microorganisms responsible of the fermentation process.