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Ethanol Fermentation of Starch from Field Peas

¹Fermentation Biotechnology Research Unit, National Center for Agricultural Utilization Research, ARS-USDA, Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 309-681-6271. E-mail: nicholnn@ncaur.usda.gov ³New Crops and Processing Technology Research Unit, National Center for Agricultural Utilization Research, ARS-USDA, Peoria, IL 61604.

Field peas (Pisum sativum) were evaluated as a potential feedstock for ethanol production. 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 two-fold enrichment compared with whole peas. The fractions were liquefied and saccharified using industrial α-amylase and glucoamylase at recommended enzyme loadings. A final ethanol concentration of 11.0% (w/v) was obtained in 48–52 hr, with yields of 0.43–0.48 g of ethanol/g of glucose. 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.