Determination of drying behaviour and ethanol production from fresh and dried sweet sorghum stalks

Abstract

Sweet sorghum, with high photosynthetic efficiency, tolerant to drought and salinity, is rich in sugar and high in biomass which makes it suitable for bioethanol production. However, sweet sorghum is not available throughout the year and stalk can be stored for short period due to high sugar and high moisture content upon harvest. Drying process is known to prolong shelf life of commodity. The drying behaviour of sweet sorghum stalks was determined and ethanol production from sweet sorghum stalks was evaluated. In determining the drying behaviour of the stalks, the predicted shortest drying time using Page equation was 7.99 hours with samples cut into 1-cm chips. The maximum ethanol production was recovered from fresh 10-cm cut samples with cellulase at 221.92 ml per kg dry mass while 168.24 ml of ethanol per kg dry mass was recovered from dried 10-cm stalks. Employing dried and fresh stalk samples for fermentation was proven to be feasible. The fermentation process can be further improved by sugar extraction through agitation and addition of cellulase.