Protein concentrates from oat flours by air classification of normal and high-protein varieties

Oat groats, as well as first and second flours, from a high-protein variety (Garland) and from a normal-protein variety (Sioux) were finely gound and air-classified to yield fractions with protein contents (N × 6.25) ranging from 4 to 88%. Air classification of the oat flours produced a unique fraction (83-88% protein) not previously observed for wheat, rye, corn, soghum, or triticale flours. This fraction (2-5% by wt.) accounted for 14, 16 and 7%, respectively, of the total protein in first and second flours and groats. The next fraction (25-29% by wt.) with 15-39% protein accounted for total protein from flours of 38-48%, and with 21-29% protein from groats, 31-33%. The first and second flours gave a better air classification response then ground oats, and the high-protein variety gave better results than normal-protein oats. Amino acid analysis of all fractions indicated high-lysine levels of 3.9-5.0 g/16 g N and adequate total S amino acids. Data showed that air classification of oat flours and ground groats produced protein concentrates of good amino acid composition and could provide a new food ingredient suitable for a variety of uses.