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BR-112014028250-B1 - METHOD OF PROCESSING CORN GRAINS

BR112014028250B1BR 112014028250 B1BR112014028250 B1BR 112014028250B1BR-112014028250-B1

Abstract

METHOD FOR FRACTIONATING CORN GRAINS. This refers to anhydrous methods for fractionating corn grains that do not require the use of water, but instead rely on the use of organic solvents. The methods involve contacting whole corn grain flour with at least one organic solvent selected from the group consisting of a C1-C6 alcohol, ketone, ester, or furan to form an addition mixture containing no more than 15% w/w water. The addition mixture is separated into i) a solids fraction enriched with corn fiber and protein and 2) a liquid organic fluid paste comprising suspended starch, dissolved corn oil, and the organic solvent. The starch is separated from the first organic fluid paste to obtain a solid starch fraction with extracted solvent and a clarified organic solution. The clarified organic solution containing dissolved oils is retained and can be evaporated to obtain the corn oil, which can be further refined.

Inventors

  • THOMAS P. BINDER

Assignees

  • ARCHER DANIELS MIDLAND COMPANY

Dates

Publication Date
20260310
Application Date
20130508
Priority Date
20120515

Claims (16)

  1. 1. A METHOD FOR PROCESSING CORN GRAINS, characterized by consisting of: contacting corn flour with a C1-C6 organic solvent selected from the group consisting of an alcohol, ketone, ester, or furan to form a first addition mixture containing no more than 15% by w/w of water; separating the addition mixture into i) a first fraction of solids and protein and 2) a first fraction of liquid organic fluid paste consisting of starch, dissolved corn oil, and the organic solvent; separating the starch from the first organic fluid paste to obtain a solid starch fraction with extracted solvent and a clarified organic solution; retaining the clarified organic solution; evaporating the clarified organic solution to obtain the residue composed of corn oil; additionally, contacting the first fraction of solids and protein with a second amount of the organic solvent to form a second addition mixture containing no more than 15% by w/w of water; separating the second addition mixture into 1) a second fraction of solids and protein and 2) a second fraction of liquid organic fluid paste consisting of starch, dissolved corn oil and the organic solvent; wherein separating the starch from the first organic fluid paste fraction includes combining the first and second liquid organic fluid paste fractions before separating the starch.
  2. 2. METHOD, according to claim 1, characterized by the starch separated from the first and second fractions of organic fluid paste totaling 50% w/w of the starch present in the corn grain.
  3. 3. METHOD, according to claim 1, characterized by the separation of starch from the first fraction of organic fluid paste consisting of one of two separations by density and filtration through a mesh.
  4. 4. METHOD, according to claim 3, characterized by density separation comprising one of two steps: gravity decantation and centrifugation of the first fraction of organic fluid paste.
  5. 5. METHOD, according to claim 1, characterized by additionally including evaporating the solvent from the solid starch fraction with extracted solvent to obtain a purified starch fraction.
  6. 6. METHOD, according to claim 1, characterized by additionally including evaporating the organic solvent from the separated solids fraction, forming a starch-rich fiber and a protein-rich product.
  7. 7. METHOD, according to claim 1, characterized in that the separation step of the organic fluid paste fractions from the starch consists of sieving the first and second mixtures by addition through openings of a size corresponding to a maximum of 80 mesh and a minimum of 200 mesh, wherein the organic fluid paste fractions pass through the openings.
  8. 8. METHOD, according to claim 1, characterized in that the contact of the corn flour with the organic solvent is made at a temperature between 50°C and the boiling point of the organic solvent.
  9. 9. METHOD, according to claim 1, characterized in that the C1-C6 organic solvent is a solvent selected from the group consisting of ethanol, ethyl acetate and acetone.
  10. 10. METHOD, according to claim 1, characterized in that the organic solvent C1-C6 is ethanol.
  11. 11. METHOD, according to claim 1, characterized in that the C1-C6 organic solvent is an alcohol of formula ROH and the starch fraction extracted from the solvent is additionally contacted with an acid catalyst to form an R-glycoside from the recovered starch.
  12. 12. METHOD, according to claim 1, characterized in that the organic solvent C1-C6 is an ester of formula R1OOR2, wherein R1 and R2 may have the same or a different number of carbons and the total number of carbons from R1 and R2 is 6 or less; and in which, furthermore, the starch fraction extracted from the solvent is contacted with a base catalyst to form an ester of R1 and R2 from starch.
  13. 13. METHOD, according to claim 1, characterized by separating the mixture by addition into the first fractions of solids and the first fraction of liquid organic fluid paste, consisting of transporting the mixture by addition from a first end to a second end of a barrel assembly (215, 245) having walls with mesh openings corresponding to a maximum of 80 mesh and a minimum of 200 mesh, wherein the organic fluid paste fraction is collected as an outflow stream from the walls of the barrel assembly (215, 245) and the first fraction of solids is collected as an outflow stream from the second end of the barrel assembly (215, 245).
  14. 14. METHOD, according to claim 13, characterized in that the organic solvent is introduced into the barrel assembly (215, 245) in a flow direction opposite to the direction of the solids fraction exiting the barrel assembly (215, 245).
  15. 15. METHOD, according to claim 1, characterized in that the addition mixture has no more than 10% by w/w of water.
  16. 16. METHOD, according to claim 1, characterized in that the addition mixture has no more than 5% by w/w of water.

Description

BACKGROUND [001] The processing of corn kernels to yield component parts of the kernels as animal feed, food for humans, and raw materials for industrial processes, such as fermentation to produce ethanol, can generally be divided into two categories - wet milling and dry milling. [002] In a classic wet milling operation, corn kernels are “impregnated” (typically for 22 to 50 hours at about 50°C) in an aqueous solution that often includes small amounts of a mild sulfur acid compound, such as sulfur dioxide, hydrogen sulfide, sulfuric acid, or calcium sulfate, which loosens the pericarp tissue (bran) from the inner endosperm and, more importantly, from the germ tissue. Water usage in a corn milling operation is in the range of 18.93 to 34.07 liters (5 to 9 gallons) per sack. The endosperm and germ tissue are separated from each other and from the loosened pericarp by filtration and differential flotation in an aqueous solution involving additional water inputs. Corn oil is extracted from the separated germ using a hydrophobic organic extractor such as hexane, leaving behind an oil-free germ cake enriched with protein useful as animal feed. Through a multi-step process that additionally involves the use of incoming water, the protein is separated from the pericarp and endosperm fractions, forming a protein-rich product called "corn gluten," which in varying degrees of purity may be called corn gluten feed or corn gluten flour. The residual pericarp tissue, referred to as "corn fiber," is typically used only for animal feed purposes, while the highly purified starch granules of various sizes from the endosperm can be used for a variety of purposes, including, for example, producing fermentation products, which are produced by liquefying and saccharifying the starch to form dextrose to feed the fermentation organism to produce the fermentation product – for example, ethanol. Starch granules can also be separated into various sizes and/or ground into food products for human consumption, such as coarse cornmeal and cornstarch. The final corn fiber, corn gluten, and corn gluten feed products are sold commercially as feed additives for animals. [003] In a conventional "dry milling" process, less water is used and the equipment costs for a mill are lower. Typically, the corn is briefly "seasoned" with a small amount of water without a sulfur compound to bring the kernels to a moisture content of 14 to 20% to loosen the pericarp. The seasoned kernels are then subjected to milling to form a coarse corn kernel meal with the endosperm and germ exposed. The starch in the exposed endosperm tissue is saccharified and liquefied to form dextrose. The total liquefied and cracked mixture, which includes the pericarp and germ tissue, is used for a fermentation process to yield, for example, ethanol. Ethanol is separated from the fermentation broth by distillation, and the residual germ, pericarp, and undigested starch components of the grains, along with the yeast biomass produced during the fermentation process, are dried to form a product called "dried distillers grains" (DDGs), which are useful as an ingredient in animal feed. [004] There are several modifications of the dry grinding processing process referred to as “modified dry ground corn” which may include additional or intermediate steps such as aspiration, sieving, flotation and/or filtration to at least partially separate at least one of the pericarp and germ fractions from the endosperm fractions before saccharification for fermentation. These partially separated fractions are less pure than those obtained from a wet grinding operation, but can be used for products similar to those obtained from the wet grinding process. For example, corn oil can be obtained from the partially separated germ and the extracted germ cake can be used as an additive for animal feed. [005] Both types of processes have their respective advantages and disadvantages. In a wet milling process, the best advantage is that the separated components are of relatively high purity and the product streams can be diverted into several different commercial forms depending on market conditions. The biggest disadvantage is the high equipment cost, which is only justifiable for large-scale corn milling operations. The second biggest disadvantage in wet milling is that it consumes large quantities of water. A wet milling operation in total uses more than 75.71 liters (20 gallons) of water per sack. This increases operating costs due to the fact that the water has to be paid for and then reused and recycled. [006] In contrast, for a dry milling process, the best advantage is the relatively low cost for equipment and water usage. A dry milling operation uses approximately 0.38 liters (0.1 gallons) of water per bag for the preparation process. It is evident that plant construction costs increase with modified dry milling operations the closer these modifications are to wet milling operations in terms of grai