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United States Department of Agriculture

Agricultural Research Service

Title: Hydrocyclone Separation of Dry-Milled Corn

Authors
item Dickey, Leland
item Dallmer, Michael
item Radewonuk, E
item Parris, Nicholas
item Kurantz, Michael
item Craig Jr, James

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 1997
Publication Date: N/A
Full Text Available

Interpretive Summary: Corn germ separation is an essential step in recovering corn oil. This separation is currently only carried out by wet milling plants. In wet milling the first step is to soak the corn in a weak sulfur dioxide solution to weaken the corn structures, allowing fractionation of its components. Since oil is a valuable corn component it must be included in newly developed fractionation processes. This article describes the use o a process to separate the germ from the rest of the corn that has been ground and sieved to a size suitable for protein extraction. The milled corn is then mixed with an aqueous solution of specific gravity equal to the germ and pumped to a hydrocyclone. In the hydrocyclone the particles with low inertia, that is, the lighter particles which includes the germ- rich particles, leave suspended in the overflow. The rest of the corn particles are driven by centrifugal force to the hydrocyclone underflow. Improving the zein market value by developing a practical extraction process will reduce the overall cost of producing ethanol from corn and provide supplies of zein for new products. Zein has potential uses as a coating, fiber or sheet-forming material, and it was once used in all of these forms.

Technical Abstract: Corn milled <1 mm using a screen mill was sieved and the particles > 590 microns were soaked for an hour in solutions with a range of glucose concentration providing liquid specific gravities above and below that of the lighter fraction (corn germ). A suspension of these particles was pumped through a hydrocyclone to separate the germ particles and to rinse water soluble compounds from the corn. The specific gravity of the hydrocyclone streams (suspensions) as well as liquid phase, after solids settling, was measured and product compositions and particle sizes were determined. This work shows that a germ-enriched fraction of corn ground < 1 mm, can be separated with a hydrocyclone. To enable computer simulation of the corn treatment process, the experimental data was used to construct a two component model of the hydrocyclone separation of the milled corn. In the model, the milled and sieved corn is virtually separated into germ and endosperm streams which are fed to paired hydrocyclone models. Hydrocyclone bypassing streams which simulate particles entrained to the contrary outlet (underflow for germ and overflow for endosperm particles) were included in the simulation to bring the model into agreement with the experimental product compositions.

Last Modified: 12/20/2014
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