Document Type : Research Paper
Department of Food Science, Engineering and Technology, Faculty of Agricultural Engineering and Technology, University of Tehran, Postal code 31587-77871, Karaj, Iran.
Department of Food Science and Technology, Faculty of Nutrition Sciences, Food Science Technology/National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, P.O. Box 19395-4741, Tehran, Iran.
Fermentation characteristics of four strains of brewer's yeast (Saccharomyces cerevisiae strain 70424, S.
rouxii strain 2535, S. rouxii strain 2531 and Saccharomyces ludwigii strain 3447) in Yeast Moldbroth
containing four different fermentable sugars (glucose, fructose, maltose, or sucrose) were studied. The
aim was to consider the suitability of different strain/sugar treatments for the production of non-alcoholic
beer as well as to devise treatments resulting in greatest growth rate of yeast cells. Experimental
parameters were yeast cell growth, ethanol production, pH drop, and changes in fermenting media attenuation
(°Pl), during a 48 h fermentation period. Fermentation was performed at 24°C using periodic aeration practice. For S. cerevisiae, the greatest growth rate was achieved in presence of sucrose. The maximum and minimum ethanol contents at the end of fermentation were related to sucrose- (0.94% V/V) and glucose-containing (0.4% V/V) treatments, respectively. In the case of S. ludwigii, fructose stimulated the highest growth rate and the maximum and minimum ethanol contents at the end of fermentation were observed in sucrose- (0.49%), and maltose-containing (0.04%) treatments, respectively. For S. rouxii 2535, highest growth rate was observed in the presence of fructose/glucose. The maximum and minimum ethanol contents belonged to the fructose/glucose- (~ 0.40) and maltose/sucrose-containg (~ 0.01%) treatments, respectively. In the case of S. rouxii 2531, glucose and to lesser extent, fructose led to the highest growth rate and the maximum and minimum ethanol contents were observed in glucose (0.01%) and maltose/sucrose (0.00%) treatments, respectively. Applying different strains of Saccharomyces in presence of different types of sugars caused various fermentation characteristics especially with regard to growth rate and ethanol production.