Research
Airtight storage of moist wheat grain improves bioethanol yields
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* Corresponding author: Volkmar Passoth volkmar.passoth@mikrob.slu.se
1 Uppsala Biocenter, Department of Microbiology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
2 Chematur Engineering, SE-691 27 Karlskoga, Sweden
3 Uppsala Biocenter, Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-751 24 Uppsala, Sweden
4 Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium
Biotechnology for Biofuels 2009, 2:16 doi:10.1186/1754-6834-2-16
Published: 20 August 2009Abstract
Background
Drying is currently the most frequently used conservation method for cereal grain, which in temperate climates consumes a major part of process energy. Airtight storage of moist feed grain using the biocontrol yeast Pichia anomala as biopreservation agent can substantially reduce the process energy for grain storage. In this study we tested the potential of moist stored grain for bioethanol production.
Results
The ethanol yield from moist wheat was enhanced by 14% compared with the control obtained from traditionally (dry) stored grain. This enhancement was observed independently of whether or not P. anomala was added to the storage system, indicating that P. anomala does not impair ethanol fermentation. Starch and sugar analyses showed that during pre-treatment the starch of moist grain was better degraded by amylase treatment than that of the dry grain. Additional pre-treatment with cellulose and hemicellulose-degrading enzymes did not further increase the total ethanol yield. Sugar analysis after this pre-treatment showed an increased release of sugars not fermentable by Saccharomyces cerevisiae.
Conclusion
The ethanol yield from wheat grain is increased by airtight storage of moist grain, which in addition can save substantial amounts of energy used for drying the grain. This provides a new opportunity to increase the sustainability of bioethanol production.