Poster Presentation 3-31
Very High Gravity Bio-Ethanol Fermentations
Rasmus Devantier1,2 and Lisbeth Olsson2
1Starch & Fuel, Applied Discovery, Research & Development Novozymes A/S, Laurentsvej 51-53, DK-2880 Bagsvaerd, Denmark
2Center for Process Biotechnology, BioCentrum-DTU Technical University of Denmark, DK-2800 Lyngby
Telephone: +45-4442-1455; Fax: +45-4442-1237; E-mail: rdev@novozymes.com
Very high gravity (>30% dry substance) fermentations using corn as a raw material can be performed using a simultaneous saccharification and fermentation. Some advantages of higher dry substance levels are higher plant capacity, higher ethanol concentrations and less water consumption. Disadvantages are for example viscosity problems and stressing conditions for the yeast.
For this investigation a 5 L high performance bioreactor was used. The set-up was designed to mimic the conditions in industrial very high gravity batch fermentations on dry milled corn. The substrate used was a 35 % dry substance slurry of dry milled corn, which was liquefied by alpha-amylase treatment and jet cooking. In order to monitor fermentations on-line the reactor was specially equipped with a near infrared (NIR) probe.
The aim of this study was to investigate the ethanol production during simultaneous saccharification and fermentation of dry milled corn. The influence of the very high gravity on the performance of the yeast strains (a standard laboratory strain and an industrial fuel ethanol strain) was given special attention. The importance of enzyme dose and the type of enzyme used was investigated. The saccharide profiles during the experiments were determined together with the ethanol production. The resulting ethanol yield and sugar consumption rates during the different experimental conditions were calculated.
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