An Overview of the Integrated Cornbased Biorefinery Project

Ethanol has been used, or proposed for use, as a process fluid or separation agent for a number of biorefining operations. These include oil extraction, solvent exchange, displacement drying, protein extraction, blood plasma fractionation, shellac deposition, protein film deposition, corn zein protein extraction, corn total protein extraction and wheat gluten protein from starch physical separation. Its use is attractive because of its miscibility with solvents and water, low surface tension, low boiling point, low freezing point, low heat of vaporization, low density and manageable capacity for dissolving many crop components. Conservative energy use and enhanced quality of the separated platform chemicals may be attributed to its use. With the growth of ethanol production from grains, availability of inexpensive ethanol for these uses is assured. One application of ethanol based processing of present interest is the refining separation of wheat to its component platforms. Wheat is produced in surplus in the US and greater domestic use in the form of biofuels and biobased products has been sought by the wheat production community to compensate for declining export markets. Although an established industry in the US, Canada and Europe, wheat refining also may be viewed as nascent in terms of its future potential. The industry in the US is not inhibited by an extensive and established infrastructure; hence, nonconventional processing technologies may be considered for new infrastructure. Ethanol based wheat refining to produce concentrated starch and protein is being researched at the Western Regional Research Center. In a patented method, chilled ethanol is applied to a mechanically developed wheat flour batter to physically displace starch and at the same time remove water. The method takes advantage of and uniquely protects the unusual functional properties of wheat proteins so that traditional food markets may be enhanced and new, nonfood markets may be created. The technology may be extended and evolved to include protein subfractionation and may enhance subsequent noncooking alcohol processes. ETHANOL IN BIOREFINING Ethanol or ethanol in aqueous solution enhances the recovery and enrichment of a variety of biological components. In this role it provides quality benefit potential beyond the scope of other solvent systems such as water or petro based solvents. It has been applied to refining of blood plasma, straw, grains, foods and nonfood or biobased products using cold (-15°C) or hot (200°C) temperatures and many concentrations (Table 1). The listing represents two groups: 1) simple refining steps for extractive removal of a single component and 2) more complex, integrated, or intensive processes that have multiple process objects such as extraction and displacement of multiple components and/or simultaneous dehydration of the alcohol.