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

摘要

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 ofa-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 a-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. The modified RVA procedure is applicable not only for characterization of mashing properties, but also for optimization ofa-amylase doses for starch liquefaction.