Effect of Barley Roller Milling on Fractionation of Flour Using Sieving and Air Classification

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Separation of hulls prior to fermentation of barley flour could increase fuel ethanol productivity and the hulls would be an additional coproduct. In a recent study, it was found that the Elusieve process, a combination of sieving and elutriation (air classification), was effective in separating hulls from flour produced by hammer milling of a hulled barley variety Thoroughbred. Roller milling is another common method used for producing flour from grains. The objectives of this work were: 1) to study the effect of roller milling on the efficacy of sieving and air classification for fractionation of Thoroughbred barley flour, and 2) to study the effect of roller milling parameters such as the gap between rollers and number of corrugations per inch in rollers on fractionation. Sieving and air classification were effective for hull separation from roller milled flours. The increase in starch content from 59.6% in the original flour to 62.1%-65.4% in the enhanced flour would increase productivity of fuel ethanol from barley. Loss of starch into the fiber product was low: 0.8%-1.1%. In the cases where barley was milled using an additional set of rolls that had a high number of corrugations per inch, air classification was not needed (sieving alone was sufficient) for producing the enhanced flour. In the cases where either only one set of rolls were used or where the additional set of rolls had low number of corrugations per inch, air classification was needed for producing the enhanced flour.