Utilization of mildly fractionated pea proteins for the development of heat-stable beverage emulsions

Pulse proteins are currently being extensively used for the development of various food products. In this work we focused on the utilization of pulse proteins in the development of beverage emulsions. Soluble proteins solution (2.5 wt%), separated from pea protein concentrate (PPC) via centrifugation at 4000×g for 1 minute, was directly used to prepare 5 wt% canola oil-in-water emulsions using high-pressure homogenization. It was hypothesized that soluble protein extracted via mild fractionation would preserve protein functionality and confer better stability to emulsions when compared to original PPC solutions. The emulsions were characterized by measuring the droplet size, zeta potential and creaming velocity. Emulsions were also subjected to environmental stresses including heat treatment, change in pH (2 and 7) and the addition of salt (0.0 M to 1 M). The initial average droplet sizes of pH 7 emulsions were around 300 nm at various salt concentrations, which did not change significantly after 1 week. The pH 2 emulsions initially showed extensive aggregation, with the average droplet and aggregate sizes ranging from 3.0 to 8.8 µm with an increase in salt concentration, which however, decreased significantly to below 1 µm after 1 week, due to breakdown of droplet aggregates over time. Upon heating the emulsions to 90 °C, extensive droplet aggregation was observed in all emulsions leading to emulsion destabilization. To prevent heat-induced emulsion destabilization, soluble protein solution was heated, and the emulsions were made under hot conditions to overcome the problem of protein and droplet aggregation-induced emulsion destabilization. Based on different emulsion characterization tests, it was found that 0.5 M salt-added heated-protein-stabilized emulsion at pH 7 had the highest stability with the lowest average droplet size (below 300 nm). Heat treated soluble pea proteins accompanied with NaCl could serve as a potential high-value emulsifiers for the beverage industry.