Reducing Grain Dust with Oil Additives (1981)

ABSTRACT WHEAT and corn were treated with 0.04 percent Durkex 500 oil and 0.02 and 0.06 percent mineral oil, each with and without added malathion, to reduce grain dust emission during handling and prevent insect attack during storage. A sample without additives served as control. After applying the additives, the grain was conveyed immediately in a small elevator leg and the amount of dust generated was measured. All samples were stored at ambient temperature (15 to 25 C) and the dustiness measured after 1, 3, 6, 9, and 12 months of storage. Dust generation during handling of the grain was drastically reduced by as little as 0.02 percent added oil, however, the effect diminished after 1 month of storage for Durkex 500 oil and 6 months of storage for mineral oil. The application of malathion in combination with Durkex 500 oil or mineral oil did not affect the ef-fectiveness or persistence of malathion on treated wheat or corn. Treatments of oil and malathion had functional (milling and breadmaking) properties of wheat samples after 1, 3, 6, 9, and 12 months of storage. Hydrolytic and oxidative rancidity did not appear to be a problem. Control of the grain dust emitted during grain han-dling is badly needed to improve air quality and in-dustrial safety. Unfortunately, cost-effective control measures for dust have yet to be established. Although separation of dust from dust-laden air by bag filters, electronic precipitators, and cyclone collectors (Brown and Reed, 1926; Martin and Stephens, 1977), can be ef-fective, the costs of installation, operation, and maintenance for such equipment are expensive. This type of dust control allows explosible mixtures to occur. Moreover, the energy required by current methods of removing dust from dusty air may exceed the energy re-quired to move the grain. The problem of dust control can also be approached by prevention of dust emission. There are two broad Article was submitted for publication in July 1980; reviewed and ap-proved for publication by the Electric Power and Processing Division of ASAE in March 1981. Mention of firm names or trade product does not constitute endorse-ment by the U.S. Department of Agriculture over others of a similar nature not mentioned. The authors are: F. S. LAI, Research Chemical Engineer, B. S. MILLER, Research Leader, C. R. MARTIN, Agricultural Engineer, C. L. STOREY, Research Entomologist, L. BOLTE, Food Technologist Cereal, M. SHOGREN, Research Food Technologist, K. F. FINNEY, Research Leader, and J. K. QUINLAN, Research En-tomologist, USDA-SEA-AR, U.S. Grain Marketing Research Laboratory, Manhattan, KS. Acknowledgments: The authors are grateful for the help of G. M. Wyatt, L. E. Shakelford, W. Blodgett, and J. L. Wilson. 1626 categories of methods to prevent emission (a) applic-tion of additives to grain and (b) use of mechanical devices. (This paper deals with the first category; the sec-ond category will be discussed in another paper.) Water, because of its ease in application and low cost, is the ob-vious additive for use in preventing dust generation. Lai et al. (1979) found that water applied under specified conditions did not appreciably increase the moisture con-tent of grain and no spoilage was seen after storage for 1 year. However, water evaporates easily and must be add-ed every time grain is handled. Several kinds of additives merit consideration for use in reducing dust emission. Both animal and vegetable fats and oils are nutritious, but most are subject to ox-idative and/or hydrolytic rancidity. In tests of pregelatinized cornstarch (Hubinger Co., Keokuk, IA) and heated cornstarch paste (Corn Products, North Kan-sas City, MO) at the U.S. Grain Marketing Research Laboratory (USGMRL), application was tedious, the resulting starch film did not remain attached to the grain, and a relative large quantity (5 percent) of starch was needed to coat the grain surface. Guar gum (Henkel, Minneapolis, MN) and molasses were not suitable because of their expense and the difficulty of application. Grain treated with molasses became sticky and lost its free flowing property. Cocke et al. (1978) found that dust levels in wheat were reduced more than 92 percent by treatment with a hydrocarbon-based oil at levels as low as 0.07 percent. They also found that the dust levels were reduced when the additive was applied to shelled corn and soybeans. The objectives of this study were to (a) determine if edible oil can control dust emission, (b) determine the amount of oil needed to prevent dust formation, (c) measure the effectiveness of oil treatment after long periods of storage, (d) investigate the effect of oil and oil-malathion treatments on grain quality, (e) confirm the compatibility and biological effectiveness of oil-malathion mixtures and (f) determine the cost of an ef-fective concentration of oil.