The effect of heat treatment on the soluble protein content of oats

The effect of heat treatment on the soluble protein content in oat groats (Kerstin commercial variety) was evaluated using asymmetric flow field-flow fractionation (AF4) in combination with online multiangle light scattering (MALS) and UV detection. The AF4 method was used to separate the monomeric proteins from globulin hexamer and aggregate proteins and β-glucan polysaccharides in the soluble oat protein fraction. The total amount of soluble protein (with respect to total protein) was reduced to 35.7 ± 4.5 wt. % in heat treated oats from 74.6 ± 5.3 wt. % in non-heat treated oats. The ratio of monomeric to globulin hexamer and aggregate proteins was reduced from 1.82 to 1.48 as a result of heat treatment. Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed the selective elimination of protein bands associated with the albumin and prolamin protein fractions as a result of heat treatment. These results were supported through amino acid analysis by cation exchange chromatography coupled with UV detection which revealed a reduction in amino acid residues associated with prolamin. The globulin proteins were found to be less sensitive to heat treatment.