Effect of sequential abrasion on starch composition of five cereals for ethanol fermentation

Abstract

Five cereals were abraded successively on a Satake abrasive test mill to enhance the starch contents of the pearled grains to improve fermentation efficiency of fuel ethanol plants. Tempering the cereals to 12.5% and 15.0% moisture had no consistent effects on rates of grain mass removal by abrasion but final starch losses to the abraded fines could be minimized by optimizing grain moisture content. Increasing abrasion time from 10 to 55s increased the average grain mass removal from 3.5 to 19.5% in four hulless cereals but 70s of abrasion was needed to remove 32.6% of two-row barley to obtain a comparable starch content in the pearled grain. On a dry basis, the pearled grain starch levels were: Canadian Prairie Spring (CPS) red wheat (73.4%); CPS white wheat (72.2%); two-row barley (71.0%); fall rye (70.4%); and triticale (69.1%), which represented, on average, a 12% increase in starch content over those of the original grains. Ethanol yields per tonne of fermentation feedstock were increased by 6.5–22.5% as a result of abrasion, which would substantially increase ethanol plant throughput and grain fermentability.