Processes of treating grain
Inventors
Johnston, David • Shetty, Jayarama K. • Koops, Bart C.
Assignees
Danisco US Inc • US Department of Agriculture USDA
Publication Number
US-11278041-B2
Publication Date
2022-03-22
Expiration Date
2037-03-27
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Abstract
Processes of treating grain (e.g., corn), involving milling the grain to produce milled grain wherein the grain germ remains intact in the milled grain, and producing a mixture by mixing the milled grain with water and at least one enzyme selected from the group consisting of protease, alpha amylase, glucoamylase, cell wall degrading enzyme, and mixtures thereof, wherein the pH of the mixture is optionally adjusted to a pH of about 3.5 to about 6.5, and incubating the mixture for about 1 to about 3 hours to produce an incubated mixture.
Core Innovation
Processes of treating grain such as corn involve milling the grain to produce milled grain while maintaining the grain germ intact in the milled grain. The milled grain is mixed with water and at least one enzyme selected from protease, alpha amylase, glucoamylase, cell wall degrading enzyme, or mixtures thereof, with the pH optionally adjusted to about 3.5 to 6.5, followed by incubation of the mixture for about 1 to 3 hours to produce an incubated mixture.
The problem addressed includes the limitations of existing fuel ethanol production processes that either lose essential nutrients or starch during dry fractionation or require costly soaking and extended times in wet fractionation processes. The dry milling fractionation process removes germ and pericarp fiber but can lose nutrients necessary for fermentation and a significant amount of starch. Wet fractionation maintains nutrients but requires soaking of kernels for several hours prior to milling, increasing capital costs and processing time.
The innovation simplifies enzymatic germ and fiber recovery by using a milling procedure that keeps the germ intact without the need for soaking prior to grinding. The process utilizes enzymatic treatment at temperatures below starch gelatinization to increase the specific gravity, allowing germ recovery by flotation for germ and fiber recovery. The liquid slurry is then ground, enzymatically treated, fermented, and fractionated to yield coproducts including germ, protein solids, fiber, and optionally a sugar solution. This process reduces capital costs, processing time, and starch loss compared to conventional wet and dry milling processes.
Claims Coverage
The independent claims cover a process of treating grain involving enzymatic incubation, germ preservation, and subsequent fractionation steps with multiple alternatives.
Dry milling with intact germ and enzymatic incubation
The process comprises dry milling grain to produce milled grain with intact grain germ, mixing the milled grain with water and protease and optionally enzymes from a group including alpha amylase, glucoamylase, cell wall degrading enzymes, adjusting pH to 3.5 to 6.5, and incubating the mixture for about 1 to 3 hours at temperatures below starch gelatinization to produce an incubated mixture.
Germ separation and fermentation after incubation
The incubated mixture is separated into germ and liquid slurry, particle size reduction by grinding is performed on the liquid slurry, yeast and amylase are added, followed by fermentation for 30 to 72 hours, ethanol removal, and separation of the liquid slurry into fiber and defibered liquid slurry, with subsequent separation to produce protein solids.
Germ separation with enzymatic hydrolysis to produce sugars
Following separation of germ and liquid slurry and particle size reduction, amylase is added to hydrolyze starches in the slurry, followed by liquid slurry separation into fiber, defibered liquid slurry, and separation of the latter into protein solids and a sugar solution.
Enzymatic liquefaction and saccharification with germ separation
After germ separation and size reduction, the liquid slurry is treated with amylase and heated for 15 min to 2 hours (liquefaction), then glucoamylase is added to hydrolyze starches (saccharification), followed by separation into fiber, defibered liquid slurry, and separation into protein solids and sugar solution.
These claims define a process that maintains grain germ integrity through dry milling, employs enzymatic treatment under controlled pH and temperature conditions below starch gelatinization to facilitate germ recovery and fractionation, and includes multiple downstream processing paths for fermentation, sugar production, and coproduct recovery.
Stated Advantages
Reduction of capital costs relative to existing wet milling and fractionation processes due to elimination of soaking step prior to grinding.
Reduced processing times by shortening enzymatic incubation to about 1 to 3 hours compared to longer soaking times in conventional wet milling.
Minimized starch loss and retention of essential nutrients needed for fermentation by preserving intact germ during milling.
Improved ethanol yields compared to conventional fractionation processes with less than 2.8% decrease relative to conventional controls.
Increased coproduct value through recovery of germ oil and protein fractions with higher economic returns.
Ability to produce multiple coproducts including germ, protein solids, fiber, and sugar solutions for diversified product streams.
Documented Applications
Production of ethanol by fermentation of enzymatically treated and degermed grain slurry.
Recovery of grain germ intact for oil extraction and value-added coproduct production.
Production of protein solids and fiber fractions as coproducts from treated grain.
Preparation of sugar solutions via enzymatic hydrolysis of starch components for ethanol or other uses.
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