Impact of defatting treatment and oat varieties on structural, functional properties, and aromatic profile of oat protein

Abstract

In this study, two naked (ND04034 and Paul) and two hulled (Beach and CDC Minstrel) oat varieties were selected to determine the impact of varieties and flour defatting treatment on extraction performance, structural and functional properties, and aromatic profiles of the extracted oat proteins. The results showed that oat protein extracted from defatted flour (DF) had a higher oat protein content (>86.93%) but a lower extraction yield and recovery yield compared to that from non-defatted flour (NDF) of same variety. Amino acid (AA) analysis indicated that the relative percent of individual AA showed a great similarity among the samples, while oat protein from hulled oat varieties had higher essential AA. SDS-PAGE results suggested the higher proportion of 7S globulins in oat proteins from DF. Both circular dichroism and FT-IR confirmed β-sheet, α-helix and β-turn were the main secondary structures in oat proteins. Differential scanning calorimetry (DSC) results showed that oat proteins from DF had better thermal stability. Scanning electron microscopy (SEM) observed the big flaky plate like structures in oat proteins from DF which may account for the improved solubility. Moreover, oat proteins from DF exhibited better functionalities, including solubility, foaming capacity and emulsifying properties. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) classified oat proteins into 3 groups/clusters on account of aromatic components. Venn diagram allowed us to differentiate oat proteins from different varieties via the aroma makers identified. The findings endow a great potential of preparing oat proteins with superior functionality and aromatic profiles for food applications.