ENZYMATIC AND PROCESS TECHNOLOGIES TO INCREASE CORN DRY GRIND SLURRY SOLIDS BY

In conventional dry grind process, high glucose concentrations (>15 % w/w) and liquefaction viscosities restrict slurry solids contents to 30 to 32 % w/w. High slurry solids fermentations (above 33%) are important in reducing energy costs; decreased water input results in less evaporation, dehydration and distillation. There are numerous challenges associated with high solids fermentations: high slurry viscosities, high glucose concentrations that exert osmotic stress on yeast and high ethanol concentrations that result in loss of cell viability. The objective was to determine an economical and process efficient enzyme combination to be employed during simultaneous saccharification and fermentation (SSF) to reduce slurry viscosities and glucose concentrations at high solids. We also evaluated effects of nitrogen source and dose on high solids fermentation. The enzyme combination we considered for this study consisted of granular starch hydrolyzing enzymes (GSHE), alpha-amylase component of GSHE (GSHE AA) and glucoamylase (GA). In this study, we showed that using low temperatures (55◦C) and a combination of phytase and alpha-amylase during liquefaction reduced slurry viscosities at 35 % solids by 81 % compare