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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #304386
Title: Estimation methods and parameter assessment for ethanol yields from total soluble solids of sweet sorghum

Author
item BUNPHAN, DARIKA - Khon Kaen University
item JAISIL, PRASIT - Khon Kaen University
item SANITCHON, JIRAWAT - Khon Kaen University
item Knoll, Joseph - Joe
item Anderson, William - Bill

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2014
Publication Date: 11/20/2014
Citation: Bunphan, D., Jaisil, P., Sanitchon, J., Knoll, J.E., Anderson, W.F. 2015. Estimation methods and parameter assessment for ethanol yields from total soluble solids of sweet sorghum. Ind. Crops Prod. 63:349-356.

Interpretive Summary: Sweet sorghum is an excellent source of soluble sugars that can be fermented into alcohol for use an alternative fuel. It is important to develop pure-line or hybrids lines for producers. There are many reports in the literature that estimate ethanol yields from sugar yields of different sweet sorghum genotypes. However, the accuracy of the estimates from different equations is not known. The first objective of this paper was to compare five different reported estimates of ethanol production with actual laboratory values using four sorghum varieties (KKU40, Theis, BJ248 and SPV1411) and one sugarcane (Saccharum hyb.) variety (KK3) at Khon Kaen Thailand. A second objective was to determine relationships of juice traits with ethanol conversion. Ethanol yield estimates calculated from published methods were generally higher than laboratory values. However, estimates based on (Smith et al., 1987) and multiplying theoretical yields by 80% was not significantly difference from laboratory results. Though ethanol yield was heavily correlated with sugar yields, juice traits influenced the rate of fermentation of sugars over time. Nitrogen content in the juice had a positive effect on ethanol concentration after 12 hours of fermentation while multiple juice traits were significantly associated with ethanol concentrations after 48 hours of fermentation.

Technical Abstract: Estimation methods and evaluation of ethanol yield from sweet sorghum (Sorghum bicolor (L.) Moench.) based on agronomic production traits and juice characteristics is important for developing parents and inbred lines of sweet sorghum that can be used by the bio-ethanol industry. The objectives of this study were to compare published indirect methods for the calculation of ethanol yields from sweet sorghum and test them versus direct ethanol production in laboratory, as well as to determine the relationships among total soluble sugar and juice traits with ethanol concentrations over time. Four sorghum varieties (KKU40, Theis, BJ248 and SPV1411) and one sugarcane (Saccharum hyb.) variety (KK3) were compared for juice characters and ethanol yield in a randomized complete block design with four replications. Agronomic and juice traits of sweet sorghum and sugarcane were recorded during maturation and at harvest. Juice of sweet sorghum and sugarcane were fermented by yeast (Saccharomyces cerevisiae) to obtain ethanol yields in the laboratory, which were then compared with ethanol yields calculated based upon five calculation methods from the literature. Ethanol yield estimates calculated from published methods were generally higher than laboratory values. However, estimates based on (Smith et al., 1987) and multiplying theoretical yields by 80% was not significantly difference from laboratory results. Though ethanol yield was heavily correlated with sugar yields, juice traits influenced the rate of fermentation of sugars over time. Nitrogen content in the juice had a positive effect on ethanol concentration after 12 hours of fermentation while multiple juice traits were significantly associated with ethanol concentrations after 48 hours of fermentation.