Development of a defined mixed starter culture for the improvement of Tej, Ethiopian honey wine

Ethiopian honey wine, Tej, is the most popular traditionally fermented alcoholic beverage in Ethiopia. Owing to the spontaneous fermentation process, the final product is neither predictable nor consistent in quality. Attempts have not been made before to solve this problem. Thus, the aim of this study was to develop a potential mixed starter culture of yeast and lactic acid bacteria isolated from Tej samples for the production of Tej with consistent quality. One hundred seventy-seven lactic acid bacteria and 194 yeasts were isolated from 30 Tej samples collected from southwest Ethiopia. After sequentially testing the isolates towards physiological stress tolerance and desired metabolic products, 10 lactic acid bacteria and 10 yeast isolates were screened. Later, four lactic acid bacteria and four yeast isolates were found to be compatible in co-culture tests. Finally, the combination of lactic acid bacteria and yeast isolates was formulated using the design of expert version 7.0.0 software, and six formulates (F #1-6) were designed. Controlled Tej fermentation was performed under laboratory conditions using six lactic acid bacteria-yeast starter culture formulations. The sensory attributes, in terms of color, flavor, odor, turbidity, and overall acceptance analysis scored 4.8/5.0 (F #2) and 4.7/5.0 (F #6), with mean significant variations (