The effect of commercial production methods on the carbohydrate and amino acid composition of corn distillers dried grains with solubles

Abstract

Six samples from ethanol plants that used different processing conditions were obtained from the Midwest, USA and were analysed for nutrient composition, focussing on the contents of carbohydrates, including starch, non-starch polysaccharides (NSP) and free sugars. The main differences in the processing conditions were temperature, dryer type and duration of drying. The samples varied widely in protein, fat, ash and free sugar contents, with the minima and maxima being 24.2% and 42.2% for crude protein, 2.1% and 16.6% for fat, 3.7% and 10.7% for ash, and 1.4% and 8.3% for free sugars. The total carbohydrate contents averaged around 40% with total NSP and starch both at around 18%, remaining relatively stable across the six samples. Most of the NSP was insoluble with less than 10% being soluble. The main sugars making up the NSP were glucose, xylose, arabinose, galactose and mannose in decreasing order. The essential amino acid levels, when expressed relative to the crude protein level, were similar among all samples. It may be concluded that the major differences in the quality of DDGS samples arise mainly from differences in the protein, ash and fat levels.