Production of improved Ethiopian Tej using mixed lactic acid bacteria and yeast starter cultures

Tej has inconsistent quality due to spontaneous fermentation. The aim of this study was therefore to develop mixed lactic acid bacteria (LAB) and yeast starter culture to improve the quality and safety of Tej. A total of 166 LAB and 193 yeasts, were characterized for their starter culture potential. Molecular identification was done for the LAB and yeast isolates. Reduced acid tolerances were recorded for the isolates. Better ethanol tolerances were observed for Lacticaseibacillus paracasei (L7) and Saccharomyces cerevisiae (Y4). A decrease in salt tolerance was recorded for the LAB and yeast isolates as the concentration of salt increased from 5.5 to 10%. The highest tolerance (p < 0.05) was recorded at 35ºC for Lacticaseibacillus paracasei (L8) and Saccharomyces cerevisiae (Y2). Four compatible yeast and LAB isolates were used to produce Tej under controlled conditions. Tej (T5) produced by L. paracasei (L6) and S. cerevisiae (Y6) had significantly higher overall acceptability (4.15 ± 0.47, p < 0.05) compared to Tej produced by other combinations of LAB and yeasts. Tej (T1) produced by L. pentosus and S. cerevisiae has shown equivalent acceptability to the control Tej. The lowest overall mean acceptability score was recorded for Tej (T2) produced by L. paracasei (L7) and S. cerevisiae (Y5). Most of the mixed lactic acid bacteria and yeast starter cultures improved the attributes of Tej.