Production and Characterization of a Probiotic Sorghum Beverage Fermented with Lactic Acid Bacteria (Lactobacillus fermentum and Bifidobacterium bifidum) and Bil-bil (2023)

Abstract 

The main objective of this study was to determine optimum conditions for aerobic fermentation for the production of a probiotic sorghum beverage using as ferment Lactobacillus fermentum, Bifidobacterium bifidum and bil-bil (a sorghum based traditional beer). Microbiological analyses on bil-bil showed 5x10⁴ CFU/mL total mesophilic flora and 3.5x10³ CFU/mL lactic acid bacteria. Physicochemical characterization on sorghum grains gave a water content, thousand corn weight, germinative energy and germinative capacity of 7.02±0.16%, 19.2±0.1g 99.82±0.11%, 100% respectively. Optimization of physicochemical and microbiological parameters of the beverage through a D-optimal plan after maximizing reducing sugars, polyphenols, vitamin C, total soluble sugars, antioxidant activity, probiotic load and minimizing titratable acidity, pH, turbidity and viscosity, resulted in an inoculation rate of 10 % L. fermentum and B. bifidum and 80 % bil-bil, a fermentation temperature of 37°C and fermentation time of 3 days. These operating conditions resulted in a beverage with a titratable acidity of 3.15 mEqg ac.mal/mL, pH of 3.05, vitamin C content of 74.28 mg/L, polyphenol content of 0.46 mg/mL, reducing sugar content of 0.86 mg/mL, TSS of 4.88°Brix, a probiotic load of 25.11x10⁶ CFU/mL, turbidity of 409.38 EBC, and a viscosity of 5.18 mPa.s. Mix fermentation could be exploited in the production of a probiotic sorghum beer.