Characterisation of maltose metabolism in lean dough by lagging and non-lagging baker’s yeast strains

Baker’s yeast, Saccharomyces cerevisiae , is a key microorganism used in the baking industry. While the preferred substrate for baker’s yeast is generally glucose, the predominant carbohydrate in lean dough is maltose. Therefore, in order to improve the leavening properties of lean dough, it is essential to improve maltose metabolism by the yeast. The objective of this study was to gain better insight into the regulation of the yeast maltose-transporter, maltose permease, and the maltose-cleaving enzyme, maltase, by glucose in lagging and non-lagging strains of baker’s yeast. Gas evolution in a low sugar model liquid dough (LSMLD) medium was used to select five out of ten industrial baker’s yeast strains for further investigation on the basis of varying metabolic characteristics. In all four of the lagging strains tested, both maltose permease and maltase were inhibited by glucose to some extent. In the relative non-lagging strain, which demonstrated the highest performance in LSMLD, it was shown that maltase was not inhibited by glucose. Based on our findings, it indicated that in lean dough leavening, it is the maltase that plays the essential role in maltose metabolism, rather than the maltose permease. Therefore, we propose that the lack of glucose repression on maltase activity is the most critical criterion in the development of non-lagging strains of baker’s yeast.