Nutritional composition and physicochemical properties of oat flour sieving fractions with different particle size

Nutritional constituents, hydration, pasting, and thermal properties of oat flour sieve fractions (74–180 μm) and the relationship between composition and characteristics were studied. Starch constituents, protein components (except for albumins), and saturated fatty acids (SFA) were mostly distributed in small particle fractions, while total protein, albumin, dietary fiber (DF), lipids, and unsaturated fatty acids (UFA) were abundant in large particle fractions. Amino acids (except for Tyr and Gly) of group Ⅰ, Ⅱ, and Ⅲ were significantly lacking in S2 (150–180 μm), and Cys decreased from 2.51% to 1.50% with the decrease in sieving particle sizes. The largest particles showed the highest water solubility index (WSI, 9.90%), the medium particles (100–132 μm) exhibited the highest pasting viscosities (final viscosity of 4148 cP), and the smallest particles had the maximum gelatinization enthalpy (ΔH, 3.2 J/g). Correlation analysis demonstrated that except for the basic components, Glu, Cys, Iso, Phe, C16:0, C18:0, and C18:2n6c also significantly affected the WSI and pasting properties of oat flour, while amylose, Gly, Ala, Val, Met, and C20:1 were highly correlated with thermal properties. The results are useful for oat processing and the development of oat-based products with specific particle size range to achieve desirable characteristics. •A reduction in sieving particle size decreased the WSI of oat flour fractions.•The fractions of medium particles had higher pasting viscosities.•Fractions with the particle size below 74 μm showed the highest ΔH.•Amino acids and fatty acids greatly affected WSI and pasting viscosities of oat flour.