Optimisation of fermentation conditions for probiotication of sorghum wort by Lactobacillus acidophilus LA5

Probiotics are considered as significant segments of functional foods. The response surface methodology was used to optimise the fermentation process conditions for the development of a probiotic sorghum wort beverage fermented with Lb. acidophilus LA5. The central composite design was applied with three fermentation parameters such as temperature, inoculation dosage and initial pH. Each parameter was varied at three levels. All parameters had single or interaction significant effects (P < 0.05) on the response variables. The models were highly significant with very low P -values. The optimum fermentation conditions were as follows: temperature 33 °C, inoculation dosage 0.8 OD₆₀₀ and pH 5.3. Under these conditions, a probiotic beverage with viable bacterial cell concentration of 8.0 log10 cfu mL^-1, final pH 3.7, lactic acid 3.2 g L^-1 and total sugar 52.7 g L^-1 can be produced. The validation experiments showed a good agreement between the experimental and predicted values. The results showed that sorghum wort is a suitable medium to produce probiotic beverages fermented with Lb. acidophilus LA5.