Abstract
The production of corn-based ethanol in the U.S. has dramatically increasied in recent years, and consequently so has the quantity of coproduct feed ingredients generated from this segment of the grain processing industry. These streams are almost exclusively utilized as livestock feed, which partially offsets the need for corn in feed rations, but other value-added applications do exist. Because of its use as an animal feed, considerable research has been conducted into the nutritional properties, but to a lesser extent the physical and flowability properties of commercially-produced distillers dried grains with solubles (DDGS). There can be occasions when the quality of coproducts is not consistent. Thus questions regarding the influence of processing operations on the resulting coproduct characteristics must be examined. The objective of this research was to conduct extensive physical and flowability property analyses on DDGS samples which were produced under varying conditions in a pilot plant-scale ethanol plant, in order to investigate the effects of various manufacturing operations (specifically ethanol production and drying conditions) on the resulting properties of the DDGS. Using various laboratory methods, a variety of properties, including bulk density and angle of repose, were determined. DDGS fat content was highly correlated with aerated and packed bulk densities, which indicates that fat level plays a key role in flowability behavior. Future studies should examine this potential relationship in more depth, especially as the industry has moved to fat reduction via oil separation processes.
Highlights
Distillers dried grains with solubles (DDGS) is one of the key coproducts of corn based dry grind fuel ethanol production
Thermal properties and color values were very reflective of the ranges typically found in commercial samples
A series of pilot-scale ethanol production trials were conducted to examine the effects of front end as well as back end processing conditions on DDGS physical and flowability properties
Summary
Distillers dried grains with solubles (DDGS) is one of the key coproducts of corn based dry grind fuel ethanol production. An exponential increase in the ethanol industry, and DDGS, has occurred over the last several years. Each bushel of corn (∼56 bs; 25.4 kg) is converted to approximately lb (7.7 kg) of DDGS, nearly lb (8.2 kg) of ethanol, along with a similar quantity of carbon dioxide (Jaques et al, 2003). DDGS consists of non-fermented starch and sugars, as well as non-fermentable proteins, fibers, lipids, and minerals. It typically contains roughly 86–93% (db) dry matter, 26–34% (db) crude protein, and 3–13% (db) crude fat (Rosentrater and Muthukumarappan, 2006). Because DDGS is highly nutritious, it is primarily utilized as a livestock feed ingredient
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