Stabilisation of emulsions by blends of potato and lupin protein: Characteristics and dynamics during storage

• Potato and lupin protein isolate differ in their emulsification behaviour • Emulsifying capacity of protein blends does not correlate with composition • Minor amounts of potato protein reduce droplet size and surface load in blends • Protein fractions interact at interface depending on blending ratio • Interfacial composition changes over time Stabilising oil-in-water emulsions with plant proteins presents a challenge due to the systems ’ thermodynamic instability and complexity. We investigated the stabilisation of oil-water interfaces using potato protein isolate (PPI), lupin protein isolate (LPI) and blends thereof over 30 days, evaluating emulsifying capacity, droplet size, surface load and molecular weight. Results revealed that LPI had a significantly higher emulsifying capacity than PPI (615±5 versus 500±5 mL/g). However, PPI formed smaller droplets with a Dx(50) of 7.66±0.54 µm compared to 15.76±1.28 µm for LPI. Surface load indicated higher emulsifying efficiency for PPI (0.47±0.03 mg/m²) than LPI (1.07±0.08 mg/m²). Minor amounts of PPI decreased droplet size and surface load, with the 25% PPI blend showing a significantly lower Dx(50) (12.04±0.49 µm) and surface load (0.80±0.03 mg/m²) compared to 100% LPI. The deviation from being a sum of individual contributions was most pronounced for emulsifying capacity, with PPI dominating up to the 50% blend. Molecular weight analysis of aqueous phases revealed varying interfacial affinities and interactions influenced by protein source, blending ratios, and storage time. The nonlinear behaviour of blends suggests complex interactions, including competition and displacement at the interface. The findings highlight challenges and potentials for improving emulsion characteristics with plant protein blends.