Interaction of selected volatile flavour compounds and salt-extracted pea proteins: Effect on protein structure and thermal-induced gelation properties

Characterization of the impact of protein-flavour interactions on protein structure and thermally-induced salt-extracted pea protein gels with selected volatile flavours was studied using a fluorometric method (intrinsic) and small-strain dynamic oscillatory rheology. By monitoring intrinsic fluorescence of proteineflavour mixtures, conformational changes in proteins due to flavour binding were noted with long chain aldehydes resulting in higher degrees of protein unfolding in comparison with ketones. Protein gel forming properties were significantly altered as a function of flavour class (aldehyde and ketone), chain length (6-8 carbon number) and flavour concentrations (0, 250, 500, 1000 ppm). Addition of homologues aldehydes and ketones at 250 ppm decreased gel storage (G') and loss (G '') moduli with long chain aldehydes possessing more prominent effects. Interestingly, protein gel strength was restored with increasing concentration and chain length of aldehydes accompanied by gradual decreases of gelling points, while elasticity and gelling points of protein-ketone mixtures remained constant. The additional protein denaturation observed in the fluorometric study could account for the formation of stronger gels during thermally-induced gel formation. A flavour-induced protein structure/function relationship was presented. In addition, flavour binding produced changes in G' during both heating and cooling phases of gelation. For aldehydes, the change in G' during heating had a more predominant effect, whereas the cooling phase was more responsible for the decrease in G' for ketone flavours. (C) 2015 Elsevier Ltd. All rights reserved.