optimization of Sweet Sorghum Processing Parameters
ABSTRACT PRODUCTION of fuel ethanol from renewable biomass sources has gained popularity in recent years. Sweet sorghum is one of the crops identified as an efficient producer of the sugars needed for ethanol production. The juice in the sweet sorghum pith contains the greatest proportion of nonstructural carbohydrates, the presumed fermentable material. Sugar cane milling procedures have previously been used to extract the juices from sweet sorghum. The research reported herein relates to a new method of juice extraction expected to provide higher juice extraction efficiencies than previous methods. The sweet sorghum stalks are chopped and the sugar-laden pith fraction is separated from the fibrous rind-leaf. The pith portion only is then fed through a screw press for juice extraction. Several chopping and separating parameters were evaluated, and a statistical linear regression analysis was employed to evaluate the effects of cutting interval, chopper knife speed, feed rate, and percent of whole stalk mass segregated into the pith fraction on juice yield. Pith fraction had the most significant positive effect on juice yield calculated as a percent of whole stalk mass. The highest pith fraction provided the highest juice yield. Feed rate had a negative effect on juice yield, meaning that slower feed rates were better, but this was the least significant parameter. The chopping interval had a positive effect, meaning that the largest value used in the analysis provided for the highest juice yield. The knife speed parameter had no effect on juice yield.