Mix it up : Stability of oil-in-water emulsions made with commercial pea and potato protein isolate as emulsifier

Summary

Vegan foods are increasingly popular. Developing such foods requires commercially available plant-based ingredients that can stabilize an emulsion at suitable pH and after pasteurization. Isolates from pea, potato, or their mixtures might be used as such emulsifiers, but not much is known about which isolate or mixture would be best suited under the required conditions. We thus determined if individual or mixed commercial pea (PePI) and potato protein isolate (PoPI) improve the physical and oxidative stability of oil-in-water (O/W) emulsions at various relevant pH values (3,4,7), after pasteurization and one-week storage. Individual formulations of PePI and PoPI as well as mixtures of PePI and PoPI (PePI-PoPI) were most promising at pH 3, because of the high zeta potential (> 30 mV) and the low average droplet size of the resulting emulsions (< 2 μm). PePI induced droplet flocculation, although the droplet size remained unchanged after pasteurization and storage. When mixtures of PoPI and PePI were used as emulsifier, flocculated droplets partly coalesced. For all emulsions, the measured lipid oxidation products remained below 5 mmol/kg oil after pasteurization and one-week of storage. Mixing PoPI and PePI thus did not improve the physical stability after pasteurization and one-week shelf-life, and we therefore recommend using either PePI or PoPI as emulsifier due to less coalescence. However, at pH 3, we additionally hypothesize that mixing (PePI-PoPI ratio 25:75 or 75:25) could still be relevant for other properties that are important during product development, such as digestibility and taste.