Lead Scientist
Voice: 215-233-6428
Fax: 215-233-6406
e-mail:
rmoreau@errc.ars.usda.gov
New Biobased Products to Increase Demand for Grains
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Dr. Robert A. Moreau Lead Scientist Voice: 215-233-6428 |
New Biobased Products to Increase Demand for Grains |
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Kevin B. Hicks, 215-233-6580/6579
Michael J. Powell, 215-836-3789 |
ARS Project #1935-41000-040 Objectives: Develop new valuable products and processes for the conversion of corn and other grains into food and industrial products that will reduce end product cost to consumer and increase revenues to growers and rural processors. Our Approach involves creating new carbohydrate and other products with high market potential using state-of-the-art biocatalytic, chemical, and analytical methods and creative cost-efficient processes for generating these products. 1.
New Co-Products from Corn Fiber and Other Grain Processing Fractions
1. New Co-Products from Corn Fiber and Other Grain Processing Fractions
Scheme 1 outlines the major processes being developed in our laboratories for fractionating corn fiber into value-added products. It is unlikely that the isolation of just one of these products (except perhaps, corn fiber gum) would be economically feasible but isolation of two or more products in the same process could significantly improve overall product profitability. Corn Fiber Oil contains high levels of cholesterol-lowering phytosterols that, according to the FDA can reduce the risk of heart disease. Corn fiber oil can be extracted by organic solvents such as hexane or supercritical CO2 and, depending upon fiber pretreatment conditions, may contain from ~5-30% phytosterols, up to 3% gamma tocopherol, ferulic acid, and a variety of carotenoids. Aleurone Oil. Recent studies have revealed that the single layer of aleurone cells located between pericarp and endosperm tissue contain essentially all the phytostanols (as ferulate esters) present in corn kernels. Knowledge of the cellular location of phytosterols is leading to a new process for isolating oil-enriched aleurone tissue as a new starting material for corn fiber oil extraction. Corn Fiber Gum. Dried and de-starched wet mill fiber contains approximately 50% hemicellulose (arabinoxylan) that can be extracted with alkali hydrogen peroxide (AHP) and processed to yield a valuable food gum. A cooperative R&D agreement between ARS and National Starch and Chemical Company led to a jointly owned patent (US 6,147,206) for the preparation and purification of corn fiber gum. Cellulose/Arabinoxylan (CAX) Complexes. After de-fatted and de-starched fiber has been exhaustively extracted with alkaline hydrogen peroxide, a white powder resembling pure cellulose is produced. Extensive characterization of this product has shown that it is not, in fact, pure cellulose but that it contains almost one-third inextricably linked arabinoxylan, which can absorb up to 100 times their weight in water, making them excellent bulking agents. Polyamine Conjugates. Extraction of fiber with polar solvents such as methylene chloride or ethanol, especially at high temperature, yields the expected corn fiber oil phytosterols plus two unusual polyamine conjuates, diferuloylputrescine (DFP) and p-coumaroyl-feruloylputrescine (CFP). It has been suggested that these conjugates may function as natural pesticides and their biological activity is being tested. L-Arabinose. Corn fiber is one of the richest available sources for L-arabinose, one of nature's few L-sugars. In fact, starch-free corn fiber contains about 25% L-arabinose by weight. L-Arabinose is used in the preparation of chiral drugs and while it commands a high price, the overall market is small. L-Arabinose may also be useful for preparing non-caloric bulking agents to be used with high intensity sweeteners. Selected Publications:
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Leland C. Dickey, 215-233-6640
Michael Dallmer, 215-233-6509
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2. New Economical Processes for Extracting Zein
Chemical Engineer, Leland Dickey, and Chemical To support and improve the economic return of corn starch fermentation to produce fuel ethanol ARS is developing a process to isolate water insoluble proteins, called zeins, which make up about 4-5 weight % of the corn. The ethanol cost is largely determined by the net cost of the raw materials, that is, the cost of corn minus the value of the animal feed byproduct, distillers dried grains (DDG). Dry mill ethanol plants produced over 3.8 million metric tones of DDG in 2002 and are expected in increase this to over 5.5 million metric tones by 2005. Relatively high cost has prevented wide use of commercial zein made from corn gluten. Since pure (corn) starch isn't needed to produce ethanol, the new zein isolate production process will coproduce a starch-containing slurry suitable for fermentation with low cost equipment and make use of the availability of the ethanol distillation facility to recover ethanol used to extract zein. The new process will achieve lower cost primarily by reducing the cost of solvent used to dissolve the zein from corn which has been dry milled and sieved to the preferred size for extraction. The process will be part of an ethanol production facility and therefore economies of scale can be achieved in the recovery of dilute ethanol solutions. Pilot plant testing being carried out under the supervision of Leland C. Dickey will be used to build an Aspen Plus© simulation model. The model represented by the flow sheet, shown below, will then be used to make cost estimates for production from commercial plants, typically 15 million gallons of ethanol per year. Concurrently with the extraction process development the zein product is being evaluated as a coating , adhesive or biodegradable single use molding material by Nicholas Parris. Zein is water insoluble and thus offers water resistance when applied as an outer finish to single use products such as fast food packages or disposable diapers, tablecloths, bed sheets.
Selected Publications:
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Nicholas Parris, 215-233-6453
John A. Minutolo, 215-233-6728
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3. New Biobased Products using Zein Concurrently with the extraction process development, the zeins extracted from dry-milled corn (zein isolate) as with commercial zein are being evaluated as a component in coating, adhesive and ground cover formulations. Similarly novel applications of barley hordeins, a hydrophobic protein, are also being studied. Coating: Paper itself is recyclable. Wax lining, adhesives, plastic coatings and films, foams and other agents applied to paper create problems with the recycling of paper fibers. Waxed corrugated paper boxes, used for packaging frozen foods are not presently recycled because wax particles cannot be separated cleanly from paper fiber during pulping.
Research Chemist, Nick Parris, sprays zein isolate onto Kraft paper.
Adhesives: Zein formulations were modified to produce adhesives or sealants. Adhesive properties of commercial zein proteins and the zein isolate on glass were investigated.
Ground cover: We investigated the effect of commercial zein + plasticizer and zein isolate film mulch on tomato plant growth. Commercial zein films decomposed in 4 days. Samples covered with the zein isolate films reduced water vapor loss 30-35% over a 50-day period compared to the un-mulched plants. In addition the mulched plants were significantly taller, bigger and had almost twice as many blossoms.
These results indicate that zein isolates, prepared from a renewable agricultural resource, are an inexpensive and viable replacement for some synthetic materials. The blend of lipids in the isolate permits casting of clear zein films, and the presence of endogenous FFA obviates the need for additional plasticizers. Storage studies indicated that zein isolates with different film-forming properties could be prepared from preground corn stored under controlled conditions. Selected Publications:
Links and Additional Information:
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| Updated: September 12, 2005 |
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