The fermentability of maltose by baker's yeast containing trehalose

Abstract

Induction period of maltose fermentation can hardly be detected at the early, rather anaerobically grown A 2 and A 3 culture stages of baker's yeast whereas at the aerobically grown precommercial A 4 and commercial A 5 stages it is distinct. According to Brandt, the trehalose content of the corresponding yeast stages is for A 2 and A 3 a maximum of 1%, for A 4 and A 5 3.6% and about 7% respectively, of the dry matter. Trehalose added to the fermentation solution clearly depresses maltose but not glucose fermentation by commercial baker's yeast. The effect is not quite as distinct as with α-methyl glucoside, but still of the same magnitude. The added trehalose prevents maltose fermentation even more strongly than does α-methyl glucoside at the trehalose-low A 3 stage. The inhibitory effect of added trehalose as well as that α-methyl glucoside on the maltose fermentation is demonstrable also with dried commercial baker's yeast. Trehalose, contrary to α-methyl glucoside, definitely depresses maltose fermentation by anaerobically grown brewer's yeast.