Abstract: For saving the heat energy required for alcohol production, processes are provided for subjecting rootstocks (Rhizomes) to enzymatic hydrolysis without conventional cooking with steam in order to obtain a high concentration saccharified material which is then subjected to alcohol fermentation.The first process comprises dipping raw rootstocks in a dilute acid for the purpose of sterilization, then crushing the sterilized rootstocks, macerating the crushed rootstocks, dextrinizing the macerated material by the action of bacterial .alpha.-amylase and adding to the dextrinized material glucoamylase and yeast for alcohol fermentation to effect saccharification thereof and subsequent alcohol fermentation.The second process comprises sterilizing rootstocks with a dilute acid and then crushing it, followed by adding blended maceration enzymes to effect maceration amd saccharification with subsequent alcohol fermentation by yeast.