Method for improving ethanol concentration of fermented mature mash

The invention relates to the technical field of fuel ethanol production, in particular to a method for improving the ethanol concentration of fermented mature mash. The method comprises the following steps: 1, dividing a culture medium into an activated culture medium and a basic culture medium which are corn liquefied mash obtained by sterilizing a corn fuel ethanol device and then cooling to room temperature; 2, preparing a seed solution; and 3, ethanol fermentation. The saccharifying enzyme is added in stages, so that inhibition of high sugar concentration on yeast due to too high saccharification rate of raw materials in the initial fermentation stage is effectively avoided, good activity of the yeast can be maintained by supplementing a nitrogen source in the later fermentation stage, the concentration of residual sugar in fermented mature mash is reduced, the wine yield of the raw materials is increased, and the production cost of fuel ethanol is reduced; the method is simple to operate and has importan