Influence of heat treatment on emulsifying properties of dry fractionated lentil flour in concentrated oil-in-water emulsions

In this study, two air classified, protein-enriched lentil flour fractions with different starch content (0%, 12.1%) were used to investigate the influence of heat treatment on the structure of 60 wt% O/W emulsions and interfacial layer properties. Therefore, mixtures of different ratios of native and heated samples of these fractions were compared, showing that at high ratios (>80%) of heated sample, gelatinized starch altered the adsorption kinetics of the interfacial layer. The strain resilience of the interfacial layer was determined by the protein’s state and was decreased by a factor of 5–6 by heat treatment, while starch had a neglectable influence. Structure and rheology of the emulsions were significantly altered by starch content at high ratios of heated sample. Gelatinized starch increased the power law consistency coefficient K from 100 to more than 250, and oil droplet diameter (d 43 ) from 15 to 35 μm in emulsions of heat-treated samples. Overall, the thermal treatment of dry fractionated lentil flour had a significant influence on functionality, which was more pronounced at higher amounts of non-protein components. Thus, when selecting a specific degree of refinement of air classified legume flour, the impact of subsequent thermal processes on functionality should be considered. • Gelatinized starch influences the adsorption kinetics of the interfacial layer • Strain resilience of the interfacial layer is determined by the protein’s state • The thermal treatment of carbohydrates has a strong impact on emulsion structure • No synergistic interactions between native and heated material were found • The degree of refinement has a multifaceted influence on functionality