Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2005
Publication Date: 1/10/2006
Citation: Wang, D., Wu, X., Bean, S., Wilson, J.P. 2006. Ethanol production from pearl millet by using Saccharomyces cerevisiae. Cereal Chemistry 83:127-131. Interpretive Summary: Fuel ethanol production from renewable resources provides several billion gallons of ethanol for formulated gasoline. The annual production of ethanol in the U.S. is expected to reach 6 billion gallons by 2006. Most ethanol plants are configured for corn or sorghum fermentation, and feedstocks must be compatible with existing systems. The industrial application of pearl millet as an ethanol feedstock was evaluated. The rate of fermentation of pearl millet was 30% greater than rate of fermentation of corn, and DDGS coproducts were higher in protein and fat. Because of the greater value of the coproducts of fermentation and improved rate of fermentation, pearl millet should be an economically superior feedstock for ethanol production in the south.
Technical Abstract: Four pearl millet genotypes were tested for their potential as raw material for fuel ethanol production in this study. Ethanol fermentation was performed both in flasks on a rotary shaker and in a 5-L bioreactor by using Saccharomyces cerevisiae (ATCC 24860). For rotary-shaker fermentation, the final ethanol yields ranged from 8.7% to 16.8% (v/v) at dry mass concentrations of 20 to 35%, and the ethanol fermentation efficiencies were between 90.0% and 95.6%. The ethanol fermentation efficiency at 30% dry mass on a 5-L bioreactor reached 94.2%, which was greater than that from fermentation in the rotary shaker (92.9%). Results showed that the fermentation efficiencies of pearl millets, on a starch basis, were comparable to those of corn and grain sorghum. Because pearl millets have greater protein and lipid contents, distillers’ dried grains with solubles (DDGS) from pearl millets also had greater protein content and energy levels than did DDGS from corn and grain sorghum. Therefore, pearl millets could be a potential feedstock for fuel ethanol production in areas too dry to grow corn and grain sorghum.