Food or edible material: processes – compositions – and products – Contacting food in liquid or solid state with exteriorly...
Reexamination Certificate
2001-09-18
2003-07-15
Yeung, George C. (Department: 1761)
Food or edible material: processes, compositions, and products
Contacting food in liquid or solid state with exteriorly...
C426S482000, C426S518000
Reexamination Certificate
active
06592921
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a method of removing the hull from corn kernels wherein the method involves exposing the corn kernels to ammonia (e.g., gas-phase anhydrous) under conditions effective to remove the hull from corn kernels.
Current technology for the large-scale conversion of corn (maize) to value-added products involves either a wet milling process or a dry milling process. The corn wet milling process begins by steeping (soaking) the corn kernels in water which contains added SO
2
. Steeping may take up to 48 hours in large expensive steep tanks. Steeping softens the corn so that coarse grinding will release the intact germ which can be separated and processed to recover the oil; further grinding then permits separation of the remaining components (e.g., fiber, protein and starch). However, building a corn wet mill requires a large capital investment. In contrast, although less capital intensive, the dry milling process to make food products or fuel ethanol suffers from low co-product value.
The wet milling process and the dry milling process can be modified by removing the hull (pericarp) of the corn kernel as the first processing step. In a modification of the dry-grind process known as Quick-Germ, the germ can be recovered after 12 hours soaking to improve the co-product credits (Singh, V., et al., Cereal Chemistry, 73(6): 716-720 (1996)). Diffusion of water into the kernel during steeping or soaking is slow because the hull (pericarp) covering the kernel forms a waterproof barrier, the time required for steeping in the wet milling process or soaking in the Quick-Germ process can be reduced if the pericarp is removed. Alkali debranning of grains is usually done with a caustic soda (NaOH) solution, which loosens the hulls, so that mechanical equipment may remove and separate the hulls from the grain. (Du, L., et al., Cereal Chemistry, 76(5): 811-815 (1999)); Morgan, A. I., et al., Food Technology, pp. 40-43 (August 1964)). However, treatment with alkali has certain disadvantages: When treating with caustic solution, most of the alkali remains external to the corn. Although the solution can be reused a number of times, it eventually must be discarded and replaced with fresh solution. The consumption of sodium hydroxide is typically 2 to 3% of treated grain. Disposal of the waste can be very expensive.
We have discovered a superior method of removing the pericarp by exposing the grain to ammonia (e.g., gas-phase anhydrous) which diffuses into the kernel more easily than liquid caustic and dissolves in the moisture that constitutes approximately 15% of dry corn. Because the resulting strong base solution will be entirely inside the kernel, the time, temperature and amount of base needed is less than with caustic solution. Ammonia is also less expensive than caustic. Residual ammonia in the corn remaining after debranning and germ recovery can supply the nitrogen requirement for yeast to ferment corn to ethanol. This ammonia treatment loosens the pericarp from whole corn using no more ammonia than needed to supply the nitrogen requirement for yeast fermentation. Ammonia treatment also helps to separate the starch and protein from fiber in the remaining corn.
SUMMARY OF THE INVENTION
The present invention concerns a method of removing the hull from corn kernels wherein the method involves exposing the corn kernels to ammonia (e.g., gas-phase anhydrous) under conditions effective to remove the hull from corn kernels.
REFERENCES:
patent: 5250313 (1993-10-01), Giguere
Notsinger, G.W., et al., “Field Trials Using Extenders for Ambient-Conditioning High-Moisture Corn”,Transactions of the ASAE, vol. 22(5), pp. 1208-1213, 1979.
Singh, V., et al., “Effect of Soak Time, Soak Temperature, and Lactic Acid on Germ Recovery Parameters”,Cereal Chem., vol. 73(6), pp. 716-720, 1996.
Du, L., et al., “Comparison of Alkali and Conventional Corn Wet-Milling: 1-kg Procedures”,Cereal Chem., vol. 76(5), pp. 811-815, 1999.
Morgan, A.I., et al., “Peeling Grain”,Food Technology, pp. 40-43, Aug., 1964.
Eckhoff, S.R., et al., “A Laboratory Wet-Milling Procedure to Increase Reproducibility and Accuracy of Product Yields”,Cereal Chem., vol. 70(60, pp. 723-727, 1993.
Folch, J., et al., “A Simple Method for the Isolation and Purification of Total Lipides from Animal Tissues”,J. Biol. Chem., vol. 226(1), pp. 497-509, 1957.
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Thomas, K.C., et al., “Fuel Alcohol Production: Effects of Free Amino Nitrogen on Fermentation of Very-High-Gravity Wheat Mashes”,Applied and Environmental Microbiology, vol. 56(7), pp. 2046-2050, Jul. 1990.
Strecker, L.R., et al., Corn Oil, InBailey's Industrial Oil and Fat Products, vol. 2, Y.H. Hui, ed., p. 143.
Bagley, E.B., “Decontamination of corn Containing Aflatoxin by Treatment with Ammonia”,J. American Oil Chemists'Society, vol. 56, pp. 808-811, Sep. 1979.
Valco, T.D., “Ammoniation of Aflatoxin-Contaminated Corn”,Texas Agricultural Extension Service, L-2459.
Singh Vijay
Taylor Frank
Fado John
Stover G. Byron
The United States of America as represented by the Secretary of
Yeung George C.
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