Role of the maltose in the simultaneous-saccharification-fermentation process from raw wheat starch and Saccharomyces cerevisiae

During the simultaneous-saccharification-fermentation from raw wheat starch , amyloglucosidase and commercial yeast, Saccharomyces cerevisiae, the ferm entescible sugars profile, at the beginning of the process, plays a great r ole in the process regulation. From a liquefied wort, fermentescible sugars were glucose, maltose and maltotriose at concentration of 2 g/l, 40 g/l an d 7 g/l, respectively. A complete hydrolysis of starch leads to a potential glucose concentration of 150 g/l. The general mechanism of a simultaneous- saccharification-fermentation occurs into two steps: the production of ferm entescible sugars and the consumption of these by the yeast. In our case, m altose, dominating sugar in the wort, is the most significant sugar in the process regulation because it was substrate not only for the amyloglucosida se but also for the yeast. The maltose consumption by the yeast is represse d by the glucose, itself produced by the saccharification. We demonstrated that the apparent drop of maltose concentration in the wort acts as an acti vator of the amyloglucosidase and this fact allows a rapid ethanol producti on. The process is regulated by different interactions between glucose, mal tose and maltotriose, the three sugars that, on one hand, are produced by t he enzyme and on the other hand are used by the yeast.