The effect of Saccharomyces strain and fermentation conditions on production of Ma-al-Shaeer

Beer is a popular drink worldwide. Due to the disadvantages of alcoholic beer consumption on pregnant women، those with cardiovascular diseases، professional athletes، driving accidents، traffic events، and work-place considerations، there has been being a trend among population to consume non-alcoholic beer with pleasant sensory characteristics. This research investigates the effects of different saccharomyces strains and fermentation conditions on production of non-alcoholic beer. Four strains of saccharomyces (S. cerevisiae 70424، S. ludwigii 3447، S. rouxii 70535 and S. rouxii 70531) were added to the wort with defined gravity in two levels. The wort was fermented in three temperatures for 48 h under anaerobiosis or under periodic aeration (each 12 h). Optical density was assessed by spectrophotometry، and wort gravity and ethanol content by beer analyzer (at 12-h intervals during fermentation) over 48 h. Sensory analysis was performed by a panel group consists of 6 trained panelists. Experiments were performed in triplicate and the ranked orders of means were determined in significance level of 0. 05 (p<0. 05) using two-way ANOVA test from Minitab software (State College، PA، USA). The design was ‘completely randomized design’. Treatments with 4×107 (cfu/mL) inoculation rate and fermentation temperature of 24˚C resulted in the greater growth rate under periodic aeration and the higher ethanol production under anaerobic condition. The greatest wort gravity was seen in treatments with inoculation rate of 107 (cfu/mL)، periodic aeration and fermentation at 4˚C (p<0. 05). Treatments with 107 (cfu/mL) inoculation level، fermentation at 4˚C possessed the lowest growth rate under anaerobiosis and the lowest ethanol production under periodic aeration. Among the yeasts used، the highest and lowest amounts of growth rate، ethanol production and wort gravity were related to S. cerevisiae and S. rouxii، respectively. The greatest scores for flavor in sensory analysis was observed for the sample fermented with S. cerevisiae. Using S. cerevisiae in restricted fermentation methodology under the conditions of 107 (cfu/mL) inoculation level، periodic fermentation and fermentation temperature of 4˚C were found suitable for production of non-alcoholic beer due to its acceptable sensory properties and the alcohol amout less than 0. 5%.