Nutrient Enhancement of Corn Distillers Dried Grains by Addition of Coproducts of the Enzyme‐Assisted Aqueous Extraction Process of Soybeans in Corn Fermentation

Abstract

Corn distillers dried grains with solubles (DDGS) are not nutritionally complete as a nonruminant ingredient owing to poor essential amino acid profile, and high fat and fiber contents. Coproducts of soybean enzymeassisted aqueous extraction process, skim (wastewater) and insoluble fiber (IF; solid residue), and/or enzymes (pectinase, cellulase, and acid protease; referred to as PCF) were evaluated as distillers dried grains (DDG) nutritional quality enhancers in corn fermentation. Corn-soy DDG had~10% higher protein,~3% lower fat, and~2% lower fiber contents compared to corn DDG; fiber content was further reduced with PCF treatment (~4% total decrease). Concentrations of all essential amino acids in corn-soy DDG showed at least a threefold increase, except for allo-isoleucine and tryptophan, compared to corn DDG. Corn-soy DDG had~25% decrease in total fatty acid (TFA) and~6% decrease in free fatty acid (FFA) contents compared to corn DDG; TFA and FFA contents further decreased with PCF treatment. Corn-soy DDG had~15%, 3%, and 1.7% lower hemicellulose, cellulose, and lignin contents, respectively, compared to corn DDG; hemicellulose content further decreased with PCF treatment. Mineral composition of corn-soy DDG was in the recommended range, except Na and S were out of range by 0.79% and 0.74%, respectively. All results, except for Na and S, suggest strong potential of using skim and IF as DDG nutritional quality enhancers.

Development and Utilization of Corn Processing by-Products: A Review

“…The yield is large but the price is low. Due to the high acidity and high viscosity of corn distillers grains, the COD (Chemical Oxygen Demand) value can reach 30,000-50,000 mg/L, and the BOD (Biochemical Oxygen Demand) value can reach 20,000-30,000 mg/L, and if the waste is directly discharged, it will not only cause serious pollution to the environment but also be a great waste of resources, so it should be fully utilized [114]. Figure 2 is a typical process flow chart of ethanol production by the corn whole grain method.…”