Explain why
the wheat that was bought is a bit moist.
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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.
Background
In temperate climates, harvest of cereal grain must often be done at high moisture content as the vegetation period is rather short. This requires high amounts of energy for drying to enable safe storage of the harvested material and avoid mould growth. In Sweden, hot-air drying is often the process during grain production that consumes the highest proportion of input energy, that is, up to 60% [1]. With regard to biofuel production from cereal grains, there are concerns about the energy balance and sustainability of the currently established processes. A recent study showed that the net output of energy in bioethanol production was rather small when using corn as raw material [2]. Substantial improvements of the energy balance of a bioethanol production process can only be achieved by an optimisation of all the partial processes involved. In regions with a temperate climate, a reduction in energy demand for the storage of the raw material will have a large impact on the energy balance. Due to increasing energy prices, this would also substantially decrease the production costs and thus improve the economic viability of the whole process.
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.
Background
In temperate climates, harvest of cereal grain must often be done at high moisture content as the vegetation period is rather short. This requires high amounts of energy for drying to enable safe storage of the harvested material and avoid mould growth. In Sweden, hot-air drying is often the process during grain production that consumes the highest proportion of input energy, that is, up to 60% [1]. With regard to biofuel production from cereal grains, there are concerns about the energy balance and sustainability of the currently established processes. A recent study showed that the net output of energy in bioethanol production was rather small when using corn as raw material [2]. Substantial improvements of the energy balance of a bioethanol production process can only be achieved by an optimisation of all the partial processes involved. In regions with a temperate climate, a reduction in energy demand for the storage of the raw material will have a large impact on the energy balance. Due to increasing energy prices, this would also substantially decrease the production costs and thus improve the economic viability of the whole process.
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