Use of surfactant and enzymes in dry-grind corn ethanol fermentation improves yield of ethanol and distillers corn oil

Distillers corn oil (DCO) is a valuable co-product of dry-grind corn ethanol process. It can be used for bio-fuel production and in animal feed. DCO can be present in different forms in the fermentation matrix, including oil adhering to solid surfaces such as cell wall and protein matrix, and oil contained in unbroken cells, which is difficult to partition to thin stillage by decanting. Effects of using surfactant (Tween® 80) and enzymes during fermentation on DCO partition to thin stillage and DCO recovery from the condensed corn distillers with solubles (CCDS) were investigated. There was more than 8 ∼ 10% DCO adhered to wet cake solids in whole stillage produced by conventional procedure, and this part of DCO was moved to thin stillage when 500 ppm of Tween® 80 was used during fermentation. Enzymes reduced the particle size of wet cake solids and released more DCO from wet cake to thin stillage. However, the use of protease reduced oil recovery (4.0% versus 7.9% and 17.9%, protease versus control and non-starch polysaccharide hydrolyzing enzymes) by producing partially hydrolyzed protein, which may have acted as emulsifier. Moreover, a synergistic effect between the use of enzymes and Tween® 80 was found on DCO partition in thin stillage and its recovery from CCDS.