Isolation and Characterization of Saccaromyces cervisiae Yeasts Isolates from “Tella” for Beer Production

摘要

Saccaromyces cervisiae , isolated from “tella”, may serve as potential strains for commercial beer production. The main objective of the current study was to isolate, identify and characterize potential yeast isolates from “tella”, which can substitute commercial beer yeast. “Tella” yeast isolates were isolated and identified using biochemical test. Qualities of isolates and physico-chemical characteristics of beer were also determined. The degree of contamination was analyzed. Six yeast isolates were identified and designated as S1, S2, S3, S4, S5, S6, and S7 (commercial yeasts). Yeast viability was determined in wort gravity of 12op and 14op and the results were found to be 89 and 83%, respectively,. All isolates showed good fermentative capacity. Isolates S1, S3, S4, S5 and S6 grew in 100, 130 and 150 ml/L of absolute ethanol. The flocculation potential of isolate S3 and S4 were 85% and 82%, respectively. Isolates S3 (4.09±.01 v/v %) and S4 (4.36±.04v/v %) showed statistically higher (p ≤ 0.05) concentration of alcohol than the other isolates. Isolates S1, S5 and S6 showed significantly greater (p ≤ 0.05) original extract than the control. Isolates S5, S2 and S6 showed statistically greater (p ≤ 0.05) apparent extract than the other isolates. Isolates had statistically greater (p≤0.05) apparent degree of fermentation. The physicochemical and other parameters of beers, produced from these isolates, were comparable with those of the commercial S. cervisiae isolates. Other threshold substances found in the produced beer were within the standard values of commercial beer. Therefore, S. cervisiae isolates from “tella” may be used as a substitute for commercial yeast in beer production.