Characterization of Physicochemical and Rheological Properties on Qualities of “Tinsis” Culture and “Tella”: Ethiopian Traditional Fermented Beer.

Abstract

Abstract PurposeTella is one of the most commonly consumed indigenous beverages in Ethiopia. The present study sought to isolate, identify wild yeast under species of Saccharomyces and characterize stress tolerance, physicochemical, rheological, and electrical properties on the quality of tella and "tinsis" culture during the pre- and post-fermentation storage period.MethodsSamples of Tella and “Tinsis” culture were collected from highly consumed areas and tinsis culture were also prepared in triplicate and physicochemical data are recorded, yeast media preparation, propagation, phenotypic characterization and stress tolerant test were followed simultaneously with data recording, and visualization using descriptive statistical analysis.ResultStarch degrading within short period of time, high flocculent, rapid growing, antifungal and antimicrobial resistant and with stand a 3-5 % acetic acid stressful environment and also resilient for killer toxins, yeasts were obtained from Tella and “Tinsis” culture. Yeast isolates from tella tolerated absolute ethanol up to 8-10%, pH from 3.5 to 4.5, hence could grow in osmotic concentration at 12% NaCL and survived in temperature 15 -35℃. Tella had more volatility, Redox potential (ORP) and low in salinity, sucrose content, total dissolved solid (TDS) and dynamic viscosity than that of tinsis culture. hence “tinsis” culture had highest through mean viscosity (7.92 ± 2.32cp), lactic acid (1.03 ± 0.38%) and volatile acetic acid 0.82 ± 0.30 and salinity 1.43 ± 0.43 psu) with low water activity (0.945 ± 0.019). moreover, as storage period increases the electrical resistivity influences with 90% that of redox potential and also resistivity correlates 28% with (ORP), and 46% with pH for tinsis culture. The rate of alcohol production increased with increase in redox potential, total dissolved solid and decreased by 53% with addition of 0.73% w/v of acetic acid to the 912ppm of (TDS) at pH 3.9. ConclusionTemperature, acidity and alkalinity regulation is critical tools to modify the speed of “Tinsis” culture and tella fermentation and for maintaining product shelf-life stability and Organolephtic taste. Species of S. Cerevisiae yeasts isolated from tella and tinsis revealed their potential abilities to substitute for commercial brewing industries.