Binding of selected volatile flavour mixture to salt-extracted canola and pea proteins and effect of heat treatment on flavour binding

Binding of homologous and heterological classes of flavours with salt-extracted canola protein isolates (CPIs) and pea protein isolates (PPIs) and the effect of heat treatment on their binding were investigated using GC/MS. Competitive binding was observed when homologous ketones were added to CPIs and PPIs and when homologous aldehydes were mixed with CPIs. Ketone mixtures performed differently than aldehydes in that 2-octanone retained more effectively than 2-heptanone and 2-hexanone by CPIs and PPIs, whereas CPIs exhibited incremental affinity to hexanal rather than heptanal and octanal. For PPIs, the presence of aldehydes increased the proteins' overall flavour-binding capacities probably due to partial unfolding of proteins revealing more binding sites as manifested by the decreased ΔH from the DSC studies. Binding of hexanal to CPIs was significantly increased with increased heating time at 95 °C, while a transition of 2-octanone retention from increasing to decreasing inferred heat-induced protein association released previously bound 2-octanone. Heat treatment at 95 °C for 30 min promoted greater competitive binding when mixed ketones and hexanal and 2-hexanone mixtures interacted with CPIs and PPIs, respectively, while dramatic increases of binding of aldehyde mixtures was observed thought out the heating processes.