Investigation of fermentation conditions for teff (Eragrostis tef) malt-wort by Lactobacillus amylolyticus

Teff is nutritious and gluten-free low risk cereal with the potential as an alternative raw material for gluten-free foods and beverages. The aim of the research was to investigate optimal fermentation conditions for teff malt-wort to be fermented by Lactobacillus amylolyticus. The experimental design and statistical analysis were performed using Design Expert statistical software. High lactic acid formation was observed between 42 and 48°C. An increase and a decrease in temperature beyond the stated range caused a decrease in the formation of lactic acid. Temperature was the dominant factor influencing the three response variables viz. lactic acid to sugar ratio, lactic acid, and pH. However, the main factor influencing extract was time followed by cell concentration. The optimum conditions of the parameters such as temperature, initial pH, initial cell concentration, and fermentation time were 42°C, 5.4, 1.86×10⁵ cells/ml, and 52h, respectively. With this set of condition, a beverage with pH 3.5, lactic acid concentration 9.5g/L, and lactic acid to sugar ratio 0.26 was predicted to be produced. The validation experimental runs demonstrated a good agreement between the experimental and predicted values. The sensory evaluation of the product also shows that it was accepted by the assessors.