Cereal Chem. 71:133-139   |  VIEW ARTICLE


Protein Composition and Functionality of High-Protein Oat Flour Derived from Integrated Starch-Ethanol Process.

A. Lapvetelainen and T. Aro. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

High-protein oat flour containing approximately 50% protein was derived as a by-product from an oat starch process integrated with ethanol production. The protein composition of the by-product was characterized in comparison to that of oat groats, the raw material of the process, to evaluate alterations occurring during processing. The proteins were fractionated according to their solubility. Amino acids of the fractions were analyzed as 9-fluorenylmethyl chloroformate derivatives by high-performance liquid chromatography, and molecular weight distribution was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In addition, functionality (in terms of protein solubility, water absorption, and emulsifying capacity) of the high-protein oat flour was compared with that of a commercial soy concentrate at a pH range of 3.0-7.0. Processing caused changes in the proportion of salt-soluble and alkali-soluble fractions, but not in the proportion of water-soluble or alcohol-soluble fractions. In oat groats, the alkali- soluble fraction accounted for 52% of the total nitrogen, and the salt-soluble fraction accounted for 28%. In high-protein oat flour, almost 80% of nitrogen was collected in the alkali-soluble fraction; the salt-soluble fraction accounted for less than 3% of the total nitrogen. The amino acid composition and molecular weight distribution of the protein fractions were not severely altered during processing. Solubility and emulsifying properties of the high-protein oat flour were competitive with those of the soy concentrate. Commercial soy concentrate, however, absorbed three to four times more water than did the oat flour over the pH range studied.