Composition and functionality differences of oat protein concentrates: Potential of less refined concentrates obtained by wet milling

Abstract

The objective of this study was to determine differences in composition and functionality for oat protein concentrates. This was achieved by comparing preparations extracted at different pH levels using either a twin screw press or alkaline extraction followed by isoelectric precipitation. Extraction by twin screw technology provided a higher protein yield compared to isoelectric precipitation. Analysis by SDS-PAGE revealed similar protein composition regardless of the extraction method or extraction pH except for extraction at pH 6. Extraction at a higher pH led to a higher protein purity and yield, while extraction closer to the isoelectric point of the protein resulted in less pure concentrates. All extracts were freeze-dried, and their composition and functionality were compared. Thermal analysis of the protein concentrates extracted by twin screw pressing showed a higher denaturation enthalpy compared to protein isolates prepared by isoelectric precipitation, suggesting that the native structure of the proteins is preserved to a higher extent. All protein fractions exhibited the typical U-shaped solubility profile, except for the concentrate extracted at pH 6, which showed an increase in solubility with increasing pH. Oat protein concentrates prepared by twin screw pressing had a higher affinity for binding to oil than to water, and this was also higher than for isoelectric precipitated protein extracts. Overall results demonstrate a potential for twin screw technology as a viable alternative to conventional wet extraction methods for producing less refined fractions from oats with tunable functional properties.