the effect of saccharomyces strain and fermentation conditions on quality prameters of non-alcoholic beer

in this study, the effect of several species of fermenting yeast and fermentation conditions (periodic aeration and temperature) on quality parameters of non-alcoholic beer is assessed. yeast starters with different inoculation percent were added separately into wort with determined gravity. wort was fermented for 48 h in different temperatures under aerobic condition or periodic aeration (every 12 h). growth rate, wort gravity and ethanol content were analyzed for 48 hours (12-h interval). also, 6 trained panelists were asked for sensory evaluation of final product. the highest growth rate and the highest ethanol content were found in treatments with 4×10 7 cfu/ml inoculation fermented at 24˚c under periodic aeration and in those fermented under anaerobic conditions, respectively. the highest gravity was observed for treatments with 10 7 cfu/ml inoculation, periodic aeration and fermentation at 4˚c. the lowest growth rate and ethanol content were observed in treatments with 10 7 cfu/ml, fermented at 4˚c under anaerobic condition and those fermented under periodic aeration, respectively. in treatments with 4×10 7 cfu/ml inoculation, anaerobic condition and fermentation at 4˚c, the lowest gravity was observed. in addition, among yeasts, saccharomyces cerevisiae and saccharomyces rouxii showed the highest and the lowest growth rate, ethanol content and wort gravity, respectively. additionally, treatments containing saccharomyces cerevisiae resulted in non-alcoholic beer with more satisfactory flavor attributes.