Storage mode of sweet sorghum and sweet pearl millet to avoid sugar deterioration before juice extraction.
Description: The sugary juice contained in sweet sorghum and sweet pearl millet stalks can be extracted and eventually fermented to produce bioethanol. Harvesting of these crops can be made with conventional silage harvester. However, field experiments carried out in 2012 and 2013 showed that the sugar content of chopped biomass decreases quickly after harvesting and must be extracted immediately to avoid sugar degradation. Alternatively, no significant sugar loss occurred even 72 hours after harvesting when the biomass was harvested and stored as whole stalks. An experiment was therefore carried out in 2014 to investigate how long it would take for the sugars in sweet sorghum and sweet pearl millet to degrade if stored as whole stalk after harvesting. In this context, the biomass was harvested with a cutter bar and bundles of whole stalks were stored inside a farm building to protect them from sun and rain. Three bundles of each crop species were chopped and then compressed with a hydraulic press every two or three days for two weeks. Results showed that the volume of extracted juice slowly decreases throughout the days. Extracted sugars also slowly decrease at an average rate of 0.67 to 1 g kgDM-1 day-1 for sweet sorghum and 1.6 g kgDM-1 day-1 for sweet pearl millet. Moreover, no mannitol, an indicator of sugar degradation, was found in the juice extracted throughout the 14 days. Rapid sugar deterioration can therefore be avoided by storing the biomass as whole stalk awaiting juice extraction.
Keywords: Sweet sorghum, sweet pearl millet, bioethanol, sugars, storage
Technical field: Renewable Energy
Conference name: CSBE/SCGAB 2015 Annual Conference, Edmonton, AB, 5-8 July 2015.
Session name: Poster
Publisher: Canadian Society for Bioengineering
Language 1: en
Rights: Canadian Society for Bioengineering