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Airtight storage of moist wheat grain improves bioethanol yields

Volkmar Passoth1 email, Anna Eriksson1,2 email, Mats Sandgren3 email, Jerry Ståhlberg3 email, Kathleen Piens4 email and Johan Schnürer1 email

Uppsala Biocenter, Department of Microbiology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden

Chematur Engineering, SE-691 27 Karlskoga, Sweden

Uppsala Biocenter, Department of Molecular Biology, Swedish University of Agricultural Sciences, SE-751 24 Uppsala, Sweden

Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium

author email corresponding author email

Biotechnology for Biofuels 2009, 2:16doi:10.1186/1754-6834-2-16

Published: 20 August 2009

Abstract

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.


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