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United States Department of Agriculture

Agricultural Research Service


item Miller, Kathrine
item Hojilla-evangelista, Milagros - Mila
item Johnson, Lawrence

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Sequential Extraction Process (SEP) is another means to produce ethanol from corn. The ethanol is used in earlier stages of SEP to extract oil and then protein from cracked, flaked, dried corn. During oil extraction, the corn also simultaneously adsorbs water from ethanol, producing 99% alcohol, which can be used for fuel. However, SEP still needs to be improved so that it can produce even drier ethanol (the fuel industry requires no more than 0.5% moisture). In addition, the proteins (zein) that are removed with the oil must be reduced further or eliminated altogether to make SEP more efficient. To accomplish these, factors such as method of extraction, dimensions of corn extraction vessel, type of extraction solvent and extraction temperature were evaluated. When oil extraction was carried out using a long, narrow corn vessel (length-to-diameter ratio of 15) and a mixture of 30% hexanes:70% ethanol at moderate temperature (56 degrees C), nearly all the oil was recovered (95%) and the amount of zein co-extracted was reduced drastically. Drier ethanol was also recovered, thus meeting the fuel industry's specification and making SEP a more cost-effective way to produce ethanol.

Technical Abstract: The Sequential Extraction Process (SEP) uses ethanol to extract oil and protein from cracked, flaked, and dried corn, and the corn simultaneously dehydrates the ethanol. The optimum conditions to reduce zein extraction in the oil extraction/water adsorption step of SEP were a one-pass system using 15 length/diameter ration extraction cells, 30% hexanes: 70% ethanol, ,and 56 degrees C extraction temperature, which improved the efficiencies o oil extraction from the corn and moisture adsorption from the ethanol. The extract contained only 0.1%, and the residual oil content of the corn was 0.18%. Oil recovery was improved from 90.8 to 95.5%. The countercurrent laboratory extraction system confirmed that 30% hexanes: 70% ethanol at 56 degrees C in a single-pass system reduced zein co-extraction with oil while increasing oil extraction and moisture adsorption.

Last Modified: 06/27/2017
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