Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2003
Publication Date: 7/1/2003
Citation: Dowd, M.K. 2003. Modifications to laboratory-scale (100-g) maize wet-milling procedures. Industrial Crops and Products. 18(1):67-76. Interpretive Summary: Corn is milled to produce starch, germ, gluten (protein), and fiber fractions. To better understand how kernel and processing factors affect the separation of these fractions, laboratory scale milling methods are needed. A laboratory-scale procedure was developed to wet-mill 100-g samples of corn. The procedure was based on previously reported methods but incorporated several modifications that are useful for some experimental designs. The results will be of interest to researchers working to improve the recovery of corn kernel components by milling.
Technical Abstract: A modified 100-g laboratory-scale procedure for the wet milling of maize is described that produces starch, gluten, fiber, germ, and soluble components. Changes were made to many of the separation steps of previously reported procedures. Among the changes, germ was recovered by a skimming process that is normally used on larger scale procedures. Starch and gluten were separated on an inclined U-channel by a modified sedimentation (tabling) method that incorporates a different pumping scheme and modifies the flow field at the end of the table. Fiber separation and washing steps were modified to eliminate the partitioning of the mill starch slurry before tabling, and gluten dewatering was conducted on the table overflow. The changes enabled the fiber washing, starch-gluten separation, and gluten dewatering steps to be conducted simultaneously. In comparison to routine tabling operations, starch protein levels were lower (0.42% versus 0.55% for the maize variety tested), although this was achieved at the expense of a slightly lower starch yield (64.4% versus 65.4%). Representative standard deviations for starch, gluten, fiber, germ, and total solubles yields were 0.28, 0.27, 0.24, 0.13, and 0.07%, respectively. The modifications will be beneficial for some designed laboratory-scale wet-milling experiments.