Oil-water interface and emulsion stabilization by pulse proteins

Pulses are promising protein sources for the replacement of animal proteins in the protein transition due to their numerous varieties and high global yield. Pulse proteins have shown good emulsifying properties, but their behavior at the oil-water interface and in emulsion stabilization, especially in large and fast deformations is still largely unknown. This study aims to explore the mechanisms by which pulse proteins stabilize oil-water interfaces and emulsions. We extracted lentil, faba bean and chickpea proteins (mixtures of globulins and albumins) by using mild one-pot alkaline extraction, and systematically studied their interfacial adsorption and interfacial mechanical properties in both small and large dilatational deformation, using the general stress decomposition (GSD) to analyze the results. Finally, we investigated the emulsifying activities of these pulse proteins and their performance in stabilizing emulsions during storage and in dynamic conditions. We found that lentil protein had the highest emulsifying activity at low protein concentrations (≤ 0.5 wt%), which is probably due to its highest content of vicilins and convicilins that help to form stiff and elastic oil-water interfaces and better stabilize the newly generated oil droplets during/after homogenization. Faba bean protein has the lowest emulsifying activity and stability under mixing conditions. This is likely due to its highest content of legumins and lowest content of vicilins (plus convicilins), which are not conducive to interfacial adsorption and interface stabilization in large deformations. During emulsion storage, the albumin components seem to promote irreversible flocculation. These findings provide insights on the behavior of pulse proteins at oil-water interfaces and in emulsion stabilization, which might be used to guide the utilization of pulse proteins in emulsion-based food product development.