Pea proteins isolation and characterization of their technological functionality

Proteins, especially those of animal origin, have been widely used in the food industry as emulsifiers to stabilize oil-in-water emulsions; however, in recent years, there has been an increasing interest in the use of plant proteins as emulsifiers, due to greater attention by the food market towards sustainability and formulation of healthy and/or vegan products and meat substitutes. Pea proteins (PP) are the ones that have become more popular, thanks to their low production cost and high nutritional value. Globulins are the major storage proteins and include three fractions: legumin, vicilin and convicilin, firmly linked together and forming a very compact structure; moreover, pea proteins show low surface charge and solubility: all these features prevent a good expression of technological properties and in particular of emulsifying ones. Depending on the raw material and on the unit operations adopted for the isolation of the protein fraction, the technological functionality of PP may vary significantly. High dynamic pressure (HDP), a technology commonly used to homogenize food products, has recently found application as a pre-treatment to modulate technological properties of specific compounds. Aim of this work is thus to provide an in-depth characterization of the technological functionality of pea protein isolates that will be submitted to HDP pre-treatments to modify their functionality in the stabilization of emulsion-based products. Commercial proteins, F85M and C9, were donated by Roquette (Lestrem, France) and Cosucra (Warcoing, Belgium), respectively while a pea protein isolate (IP) was obtained at a laboratory scale. Different analyses were carried out, from a structural and technological viewpoint, to get information at different length scales: circular dichroism, thermal properties, free sulfhydryl groups, solubility, water and oil holding capacity, interfacial properties and emulsifying capacity. The analyses highlighted significant differences between samples, probably due to the isolation procedures, that led to various structural changes and consequently showed different functional properties and emulsifying abilities. DSC and circular dichroism demonstrated that commercial proteins resulted already denaturated, so IP was selected for future structural modifications