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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCED END USE QUALITY AND UTILIZATION OF SORGHUM GRAIN

Location: Grain Quality and Structure Research Unit

Title: Assessing Fermentation Quality of Grain Sorghum for Fuel Ethanol Production Using Rapid Visco Analyzer

Authors
item Zhao, Renyong - KANSAS STATE UNIVERSITY
item Bean, Scott
item Wu, Xiaorong - KANSAS STATE UNIVERSITY
item Wang, Donghai - KANSAS STATE UNIVERSITY

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2008
Publication Date: November 1, 2008
Repository URL: http://cerealchemistry.aaccnet.org/doi/pdf/10.1094/CCHEM-85-6-0830
Citation: Zhao, R., Bean, S., Wu, X., Wang, D. 2008. Assessing fermentation quality of grain sorghum for fuel ethanol production using rapid visco-analyzer. Cereal Chem. 85:830-836.

Interpretive Summary: The use of sorghum as a feedstock for the ethanol industry is increasing. Rapid methods for predicting the fermentation quality of sorghum are needed to enhance the production of ethanol from sorghum. The Rapid Visco Analyzer (RVA) was used to characterize the pasting properties of 68 sorghum grains with a standard 23-min temperature profile and relate these properties to ethanol fermentation. The results showed a strong linear relationship between ethanol yield and final viscosity, as well as setback. Ethanol yield increased as final viscosity decreased. The modified RVA procedure is applicable not only for characterization of mashing properties, but also for optimization of alpha-amylase doses for starch liquefaction. Thus, the modified RVA method developed in this work is useful for predicting the fermentation properties of sorghum.

Technical Abstract: The Rapid Visco Analyzer (RVA) was used to characterize the pasting properties of 68 sorghum grains with a standard 23-min temperature profile. The results showed a strong linear relationship between ethanol yield and final viscosity, as well as setback. Ethanol yield increased as final viscosity decreased. A modified RVA procedure (10 min) with an application of alpha-amylase was developed to simulate the liquefaction step in dry-grind ethanol production. There was a remarkable difference in mashing property among the sorghum samples with the normal dosage of alpha-amylase. The sorghum samples, which were difficult to liquefy in the mashing step, had much higher peak viscosities than the samples that were easily liquefied. The results also showed that the relationship between conversion efficiency and mashing property was significant. Tannins were shown to cause high mash viscosities. There was a strong linear relationship between tannin content and final viscosity, as well as peak viscosity. The modified RVA procedure is applicable not only for characterization of mashing properties, but also for optimization of a-amylase doses for starch liquefaction.

Last Modified: 9/10/2014
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