Effects of fermentation substrate conditions on corn-soy co-fermentation for fuel ethanol production.
Soy skim, a protein-rich liquid co-product from the aqueous extraction of soybeans, was co-fermented with corn to produce ethanol. Effects of soy skim addition level, type of skim, corn particle size, water-to-solids ratio, and urea on co-fermentation were determined. The addition of 20-100% skim increased the fermentation rate by 18-27% and shortened the fermentation time by 5-7h without affecting ethanol yield. Finely ground corn or high water-to-solids ratio (≥ 3.0) in the mash gave higher fermentation rates, but did not increase the ethanol yield. When the water was completely replaced with soy skim, the addition of urea became unnecessary. Soy skim retentate that was concentrated by nanofiltration increased fermentation rate by 25%. The highest level of skim addition resulted in a finished beer with 16% solids, 47% protein (dwb) containing 3.6% lysine, and an ethanol yield of 39 g/100g dry corn.
Department of Food Science and Human Nutrition, Center for Crops Utilization Research, Iowa State University, Ames, IA 50011, USA.
Linxing
L
Yao
Show-Ling
SL
Lee
Tong
T
Wang
Juliana M L N
JM
de Moura
Lawrence A
LA
Johnson
D000596:Amino Acids / Q000378:metabolism; D056804:Biofuels / Q000032:analysis*; D001709:Biotechnology / Q000379:methods*; D002245:Carbon Dioxide / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects; D005374:Filtration; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D009584:Nitrogen / Q000494:pharmacology; D010316:Particle Size; D013025:Glycine max / Q000187:drug effects / Q000378:metabolism*; D014508:Urea / Q000494:pharmacology; D014867:Water / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
D000596:Amino Acids; D056804:Biofuels; D014867:Water; D002245:Carbon Dioxide; D000431:Ethanol; D014508:Urea; D009584:Nitrogen