ARS | Publication request: Use of Field Pea Starch As a Feedstock for Ethanol Fermentation

Submitted to: International Starch Technology Conference
Publication Type: Abstract
Publication Acceptance Date: June 8, 2005
Publication Date: June 8, 2005
Citation: Nichols, N.N., Dien, B.S., Wu, V., Cotta, M.A. 2005. Use of field pea starch as a feedstock for ethanol fermentation [abstract]. International Starch Technology. p. 96.

Technical Abstract: Field peas (Pisum sativum, dry peas) are grown in the North-central and Western U.S. for feeding to swine and ruminants. Production is on the rise, and there is interest in increasing the crop¿s value by further processing. Although field peas are mostly fed whole, the protein (23% wt, db) and starch (46% wt, db) can be easily fractionated by milling and air classification. Separating the two fractions would provide an opportunity to sell the enriched protein product as a high-value protein feed and process the starch for ethanol production. We determined the feasibility of fermenting field pea starch to ethanol. Ground peas were dry milled and separated into starch, protein, and fibrous fractions by air classification. Starch-enriched fractions prepared from whole peas and dehulled peas contained 73.7% wt and 77.8% wt starch, respectively, a nearly 2-fold enrichment compared to whole peas. The fractions were liquefied and saccharified using industrial alpha-amylase and glucoamylase. A final ethanol concentration of 11.0% (w/v) was obtained in 48-52 hr. Yields were 0.43-0.48 g ethanol/g glucose, which are comparable to yields obtained from fermentation of corn starch. Starch present in whole ground peas was also saccharified and fermented, with 97% of the starch fermented when an autoclaving step was included in the liquefaction stage. The fermentation solids were analyzed for protein and amino acid content. The ethanol yields and feed analysis indicate that field peas could supplement corn as a feedstock for ethanol fermentation.