Strategies to improve fermentation characteristics of degermed corn flour

Corn dry milling produces germ, pericarp fiber and grits (endosperm particles). Grits can be ground into flour and fermented into ethanol using a conventional dry grind ethanol process. Combining dry milling before the dry grind ethanol process would allow recovery of germ and pericarp fiber as coproducts prior to fermentation of flour obtained from grits. Fermentation characteristics of dry milled flour were evaluated using two saccharification and fermentation processes. Yellow dent corn samples were tempered, degermed and defibered to recover germ and pericarp fiber. Grits were milled to obtain flour. Flour was mixed with water and liquefied by enzymatic hydrolysis. Liquefied slurry was fermented using either separate saccharification (SS) and fermentation or simultaneous saccharification and fermentation (SSF). Corn germ soak water and Bvitamins were added to the fermentation substrate to study the effect of micronutrient addition. Ethanol and sugar profiles were monitored using HPLC. The SSF process produced higher ethanol yields than SS. Addition of B-vitamins and germ soak water to mash with SSF produced 2.6 and 2.3% (v/v) higher ethanol concentrations respectively compared to control with no B-vitamins or soak water added. Addition of germ soak water and B-vitamins also increased fermentation rates.