Changes in properties of food proteins after interaction with free and β-cyclodextrin encapsulated hydroxycinnamic acids

Polyphenol–protein interactions during food processing may cause deterioration in protein nutritional quality status. This limits the possibility to enrich foods in phenolic preparations. The aim of this study was to assess whether encapsulation of hydroxycinnamic acids (HCAs) from green coffee extract (GCE) [using inclusion in β-cyclodextrin (β-CD)] limits polyphenol–protein interactions. Three different protein isolates: egg white proteins, whey protein concentrate and soy protein isolate were exposed to interact with HCAs from GCE. After interactions, a higher increase in molecular mass and higher degradation of essential amino acids, as well as limitation of proteolytic digestion and solubility of proteins were reported, compared with the controls processed without HCAs. On the other hand, the interactions contributed to a higher radical-scavenging capacity in DPPH˙ and OH˙ assays and color deepening of proteins during processing. Inclusion of HCAs in β-CD cavity resulted in the limitation of the protein–HCA interactions, thus decreased the changes in nutritional and physicochemical properties. Adding HCAs in the form of inclusion complexes could be a promising solution for reducing unfavorable protein–polyphenol interactions during processing of foods enriched with phenolic acids.