EFFECT OF PHOSPHORYLATION ON THE STRUCTURE AND TECHNO-FUNCTIONALITIES OF PEA AND WHEY PROTEINS

Phosphorylation is a structural modification technique useful for altering the colloidal behavior of food proteins, which may be applied to produce protein-rich ingredients displaying improved techno-functionalities. Thus, the objective of this work was to modify whey protein isolate (WPI) and pea protein isolate (PPI), subjected or not to glycation with maltose, and phosphorylated using sodium tripolyphosphate (STP) by two phosphorylation approaches: wet and dry heating. The modified proteins were evaluated for phosphorus content, structural features (free -SH groups, particle size, and size exclusion chromatography – SEC), and emulsifying properties. The PPI samples showed overall greater phosphorus incorporation compared with phosphorylated WPI samples. The highest  phosphorylation level was measured for non-glycated wet-phosphorylated PPI, reaching 61.8 mg/g. The free –SH content revealed that wet treatment enhanced disulfide bond formation in the WPI samples, while no clear trend was observed for the PPI samples. The SEC profile indicated the formation of soluble aggregates in all heat-treated samples. Moreover, when applied to WPI samples, wet phosphorylation induced a greater impact on β-lactoglobulin and α-lactalbumin populations than the dry-phosphorylation approach. Regarding the emulsifying properties, dry-phosphorylated and non-glycated WPI showed improved emulsifying activity compared with the other samples, while no significant effect was observed for PPI samples. Furthermore, the profile of proteins adsorbed into the immiscible interface indicated that glycation limited the contribution of several proteins from WPI and PPI in stabilizing the obtained emulsions. Overall, the results indicate that the nature of the chemical-induced structural modification is crucial in governing the technological properties of proteins.