QUALITY CHANGES, DUST GENERATION, AND COMMINGLING ...

while high oil and starch contents are desired by corn wet millers. Processors, on the other hand,
want high protein, low linolenic acid, and high stearic acid contents in soybeans (Hurburgh,
1997).
In 2008, the global area planted to GM or biotech crops has increased to 125 million
hectares and amounted to $7.5 billion (James, 2008). Fifty percent of this crop area is located in
the U.S. The GM crops planted are not only for food, feed, and fuel, but also include those for
pharmaceutical and industrial purposes (Maier, 2002).
Intentional threats to grain purity through introduction of contaminants are also a major
concern in grain handling. Grain elevator and storage facilities are among post-harvest sites that
are critical nodes for assessment because of vulnerability to terrorist attack with biological (US
FDA, 2006) or chemical weapons.
1.2 Effect of Handling on Quality and Dust Generation of Grain and Feed
Repeated handling of grain and feed products in an elevator affects their physical quality,
including breakage. Martin and Stephens (1977) repeatedly transferred corn alternately between
two bins in the USDA-ARS, Center for Grain and Animal Health Research (CGAHR), formerly
Grain Marketing and Production Research Center (GMPRC) research elevator at Manhattan,
Kansas. Percentage of breakage of corn kernels increased linearly during the repeated-handling
tests. Converse and Eckhoff (1989) observed increases in broken corn and fine materials during
repeated handling of corn, depending on drying temperatures. Baker et al. (1986) found that
breakage susceptibility of shelled corn increased significantly during handling in pneumatic
conveying systems. Foster and Holman (1973) noted that free-fall height, impact surface, and
corn moisture content and temperature were involved in corn breakage during commercial
handling. Aarseth (2004) studied the susceptibility of feed pellets for livestock to attrition during
pneumatic conveying.
Corn-based feed pellets can be an alternative to shelled corn. Pelleting of feed is
important for improved efficiency in animal feeding and for convenience in feed handling.
Research has shown that animals fed with good quality pellets have better growth performance
and feed conversion than those fed with mash, reground pellets, or pellets with more fines
(Jensen et al., 1962; Jensen and Becker, 1965; Kertz et al., 1981; Brewer et al., 1989; Zatari et
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