Submitted to: Institute of Food Technology
Publication Type: Abstract only
Publication Acceptance Date: 4/15/2009
Publication Date: 6/6/2009
Citation: Liu, K., Han, J. 2009. Changes in Composition and Phosphorus Profile during Dry Grind Process of Corn into Ethanol and DDGS. Institute of Food Technology Annual meeting and Expo. at Anaheim, CA, June 6-10. Interpretive Summary:
Technical Abstract: Demand for alternatives to fossil fuels has resulted in a dramatic increase in ethanol production from corn. Dry grind method has been a major process, resulting in a large volume of dried distiller grains with solubles (DDGS) as a co-product. The process consists of grinding, cooking, liquefaction, saccharification/fermentation, distillation, and co-product recovery. The objective of this study was to monitor changes in proximate composition and different types of phosphorus (P) during dry grind process of corn. Three sets of ground corn, intermediate masses and DDGS were collected from three commercial plants in Iowa. Samples were freeze-dried before chemical analysis. Dry corn contained average of 69.5% starch, 7.9% protein, 3.4% fat, 1.4% ash, 0.20% phytic P, 0.04% inorganic P, and 0.31% total P. There were little changes in proximate composition and P profile before saccharification except for starch conversion to dextrin. Upon saccharification/fermentation, starch/dextrin decreased sharply to less than 6.0%, while protein, oil, ash, non-starch carbohydrate, phytic acid P, inorganic P, and total P increased dramatically. Increases in concentrations of protein, oil, ash, inorganic P and total P were over 3.5-fold of raw corn, but phytic P concentration was about 2.5-fold of corn. Distillation caused little further change. During DDGS recovery, centrifugation divided whole stillage into thin stillage (TS) and wet grains (WG). Compared with WG, TS was lower in protein and non-starch carbohydrate but higher in oil, ash and three types of P. Since concentrated TS were added back to WG for drying, DDGS had similar composition and P profile as whole stillage. Furthermore, the ratio of phytic P/total P generally decreased during the process, while the ratios of inorganic P/total P and inorganic P/phytic P generally increased. The observation suggests that phytic acid underwent some degradation during fermentation, presumably due to activity of yeast phytase.