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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #228762
Title: Surface Properties and their Influence on Flowability of Distillers Dried Grains with Solubles (DDGS)

Author
item BHADRA, RUMELA - SOUTH DAKOTA STATE UNIV+
item Rosentrater, Kurt
item MUTHUKUMARAPPAN, K - SOUTH DAKOTA STATE UNIV

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2009
Publication Date: 8/1/2009
Citation: Bhadra, R., Rosentrater, K.A., Muthukumarappan, K. 2009. Surface Properties and their Influence on Flowability of Distillers Dried Grains with Solubles (DDGS). Cereal Chemistry. 86(4):410-420.

Interpretive Summary: Distillers dried grains with solubles, commonly known as DDGS, is the primary coproduct from corn-based fuel ethanol production. It is almost exclusively used as livestock feed, primarily beef and dairy, but swine and poultry markets are growing as well. Much of the DDGS is transported via rail out of the corn belt to livestock operations around the US. But, flowability of DDGS out of railcars is often hindered due particle bridging and jamming. Shipping and handling of DDGS has thus become a major issue to the livestock and ethanol industries alike. “Caking”, or stickiness, among particles is an important issue related to DDGS flowability. The objective of this study was to investigate the nature of DDGS particles. This study examined the distribution of chemical constituents, including protein and carbohydrate, within DDGS particles, as well as surface fat distributions. Overall crude protein in the DDGS particles ranged from 28.33 to 30.65% db, and neutral detergent fiber (NDF) ranged from 31.84 to 39.90 % db. Examining cross sections of the DDGS particles indicated a higher thickness of protein versus carbohydrate in particle surface coatings, especially from samples that had lower flow function index (thus greater cohesiveness, which indicated possible flow problems). Additionally, greater surface fat distributions occurred in samples with worse flow problems. Results from this study have revealed another aspect of the DDGS flowability puzzle.

Technical Abstract: With an annual production of approximately 6.5 billion gallons of fuel ethanol, and projected growth for the foreseeable future, supplies of coproducts such distillers dried grain with solubles (DDGS) are anticipated to continue to grow as well. DDGS is used primarily as livestock feed. Much of the DDGS must be shipped, often over large distances throughout the country, as much of the livestock (especially large dairies and feedlots) are outside the Corn Belt, where most of the ethanol plants are currently located. “Caking”, or stickiness, among particles is an important issue related to DDGS, especially when it leads to flowability problems when it is stored and shipped, this problem needs to be alleviated. Towards that end, the objective of this study was to understand the surface nature and characteristics of DDGS particles. The study examined the distribution patterns of chemical components of DDGS particles using standard staining biological techniques and stereo light microscopy. Surface chemical composition was also studied using confocal laser microscopy. Crude protein in the samples ranged from 28.33 to 30.65% db, and neutral detergent fiber (NDF) was found to be from 31.84 to 39.90 % db. Cross sectional staining of DDGS particles indicated a higher amount of protein thickness (3.21 µm) versus carbohydrate thickness in surface layers from DDGS that had lower flow function index, and thus greater cohesiveness, which indicated possible flow problems. Additionally, surface fat staining suggests that higher surface fat also occurred in samples with worse flow problems.