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United States Department of Agriculture

Agricultural Research Service

Title: Variability in Water Absorption of the Germ and Endosperm During Labortaory Corn Steeping

Author
item Dailey Jr, Oliver

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2000
Publication Date: N/A

Interpretive Summary: To develop environmentally acceptable, cost effective technologies for milling corn, water absorption of corn kernels steeped in soak solutions of differing chemical compositions was examined. Starch is the major product of corn wet-milling. Steeping, the first step in the wet-milling process, involves the soaking of corn kernels under carefully controlled conditions of temperature, time, and chemical additives. During steeping the kernels are softened, facilitating separation of the components. The corn kernel is composed primarily of the endosperm (which contains starch and other nutrients) and the germ (which contains the embryo of the corn plant and oil). In these studies, composition of the soak solution did not significantly affect the rate of hydration (moisture uptake over time) of either the germ or endosperm. There was high variability in the measured moisture content of an individual germ or endosperm for a given steep time, ,demonstrating that one or a few kernels may not be descriptive of the bulk material. This research benefits cereal scientists and the corn wet- milling industry in that it gives a better understanding of the steeping process, specifically on the hydration of the germ and endosperm components of corn kernels and the influence of steeping chemicals. Achievement of accelerated hydration of the kernel would result in shorter steeping times and, consequently, lower milling costs.

Technical Abstract: Individual water absorption experiments were performed on yellow dent corn kernels steeped in four different soak solutions [deionized water; 0.50% lactic acid (LA)(w/v); 0.20% sulfur dioxide (SO2)(w/v); 0.50% LA/0.20% SO2] at 52 oC. The studies were conducted on the hydration of the germ and endosperm components of individual corn kernels. Some previous laboratory studies had indicated that the addition of either LA or SO2 results in a change in water absorption in the kernel. However, in these studies there was no significant difference in rate of hydration of either the germ or endosperm at any of the time periods common to all four steeping solutions. There was high variability in the measured moisture content of an individual germ or endosperm for a given steep time.

Last Modified: 7/22/2014
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