Enhanced thermal stability of potato protein-pectin emulsions: Synergistic effects of bulk and interfacial properties

Proteins and polysaccharides have been used extensively in emulsion formulation, both individually and in conjunction. However, the mechanisms underlying the thermal stability of protein-stabilized emulsions in the presence of pectin require further elucidation. Here, we systematically investigate the effect of thermal processing on such emulsions (with protein-pectin mass ratio of 1:0, 10:1, 5:1, 2:1, 1:1, and 0:1). The thermal behavior (20 ‒ 95°C) of potato protein isolate (POPI) and pectin was studied through: (1) continuous-phase properties (2) interfacial characteristics, and (3) the thermal stability of 45 wt% oil-in-water (O/W) emulsions at pH 4. POPI-pectin mixtures at ratios of 2:1 and 1:1 exhibited smaller particle size and strongly negative zeta potentials compared to higher ratios (10:1, 5:1). Heating and subsequent cooling increased both continuous-phase viscosity and interfacial elastic modulus, most probably through hydrophobic interactions, with a 2:1 ratio achieving higher interfacial elasticity values that exceed those of protein interfaces. Emulsions stabilized by the 2:1 mixture were thermally stable, maintaining small droplet sizes (∼3 μm; compared to ∼8 μm for protein-stabilized emulsions) without aggregation, coalescence, or creaming over 5 days. The enhanced thermal stability is attributed to a synergistic mechanism, in which heating induces gelation in the continuous phase and enhances elastic film formation at the interface. The findings are expected to be relevant for plant protein-stabilized emulsions, of which stability can be improved by clever combination with polysaccharides. • Potato protein and pectin jointly stabilize emulsions • Heating and subsequent cooling increases interfacial elasticity • Heating and subsequent cooling enhances bulk viscosity and storage modulus • Synergistic bulk and interfacial effects improve emulsion thermal stability