Fermentability of maltose

Pure maltose is fermented incompletely, but maltose with at least 1% d-glucose initially present can be fermented to the same extent as d-glucose. The still residues from incompletely fermented maltose solutions can be further fermented to produce the expected quantity of alcohol, but their reducing power is lower than that calculated for the unfermented maltose. The results obtained are consistent with the occurrence of a polymerization reaction as one of a series of competing reactions involved in the fermentation of maltose.