Physicochemical properties, antioxidant activities and microbial communities of Ethiopian honey wine, Tej

Ethiopian honey wine, Tej, is spontaneously fermented traditional alcoholic beverage, usually made from honey and "gesho" (Rhamnus prinoides). Till now, limited amount of information is available on the characterization of Tej. Thus, the aim of this paper is to reveal the microbiological diversity and physicochemical properties of Tej samples collected from different areas of Ethiopia. High-throughput sequencing, electrochemical and chromatographic techniques, and spectrophotometric methods were used to achieve these objectives. Although there was a statistical difference in the exact values of physicochemical properties between the collected Tej samples, the pH and titratable acidity values of the samples ranged from 2.8 to 3.8 and from 1.81 to 8.65 g/L, respectively. Similarly, the alcohol and sugar contents of the samples were in the range of 6.36-11.34 g/100 mL and from 0.37 to 31.6 g/L, respectively. Moreover, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS) values of the samples were in the range of 37.9-81.0% and 27.4-73.1%, respectively. Furthermore, microbial community structure was predominated by a few fermentative microorganisms. Specifically, the bacterial community structure was dominated by the genera of Lactobacillus (53.15%) and Zymomonas (38.41%). Whereas, the fungal community structure was exclusively dominated by genus of Saccharomyces (99.66%). Additionally, Lactobacillus, Zymomonas and Saccharomyces were the detected core microbiome for the collected Tej samples. Both bacterial and fungal communities had shown no statistically significant differences in alpha diversity analysis based on the area of sample collection. However, the bacterial communities had a statically significant difference in Unweighted Unifrac beta diversity analysis. Generally, the observed shared physicochemical characteristic features and the dominance by certain group of microorganisms might be seen as a boon for the development of direct fermentation system to this traditional alcoholic beverage.