Studies On Alcoholic Fermentation Using Uncooked Corn Flour

Nowadays the energy sources supply is increasingly serious in China. It is urgent toresearch substitute for petroleum, however, fermentative ethanol is one of substitutecandidates with biggest future potential for its reproducibility. The ethanol production withnon-cooking process has been paid attention to because both energy consumption andequipment investment could be reduced.The optimal conditions were obtained: the addition quantity of glucoamylase as 100U/g,the ratio of material to water as 1:2, with natural pH, uncooked corn flour as material (filteredby 40 screen mesh) and 0.3% addition of ADY, after 60—70h fermentation at 30℃, theethanol concentration could reach 15%, by adding nitrogen source or acid protease ethanolconcentration could further improve to 16%. The alcoholic fermentation went well and nooperation failure occurred, the utilization rate of amylum reached 86—88%. At thebeginning, most of the corn flour was sedimentated in the tank, that was disadvantageous forsaccharification and would postpone the fermentation.In the acidity–controlling test, proper addition of gulcoamylase remained the reducingsugar in low level, adding nitrogen source could improve the nutrition in the fermented mashand maintain the yeast growing in overwhelming predominance. For certain amount ofmaterial, the severe bacteria contamination could occur with the decrease of the ratio ofmaterial to water. Adopting the following conditions: glucoamylase of 100U/g;material towater of 1:2;the yeast inoculation of 0.3%, etc, could effectively repress the contaminationand insure normal fermentation.In the alcoholic fermentation with circumfluent fermenter, the sediment of raw corn flourwas firstly studied. The results indicated that the trend of sediment plot under differentinitial concentrations and initial heights was similar and the relationship between the sedimentlayer height(H) and time(t) was a linear equation, moreover, the initial settling velocitydecreased with the increase of initial concentration. It was also proved that a smallestcirculation flux must exist for corn flour suspension to fulfill compulsory circulation both intheory and in practice. Compulsory circulating fermented mash promoted the process oftransferring mass, improved the growth of yeast cells and raised fermenting efficiency.Based on these studies, ideas of high gravity ethanol production with non-cookingprocess was considered. There was characteristic that distillage was utilized sufficiently, theclean production and lower cost production combined together.