Interactions of free and encapsulated hydroxycinnamic acids from green coffee with egg ovalbumin, whey and soy protein hydrolysates

The interactions of hydroxycinnamic and chlorogenic acids (all described as CHAs) from green coffee with hydrolysates of proteins from egg ovalbumin (EOH), whey (WPH) and soy (SPH) were studied depending on temperature (25 and 90 degrees C) and CHAs form (free or included in beta-cyclodextrin (beta-CD)). The binding degree was determined by liquid chromatography with Q-Exactive tandem mass spectrometry. The interactions were confirmed by liquid chromatography with ultrahigh resolution hybrid quadruple-time-of-flight mass spectrometry. As the result of binding, the content of CHAs in protein hydrolysates (PHs) ranged from 12.87 to 15.15 g/100 g. Inclusion of CHAs with beta-CD strongly limited these interactions to a level of 0.48-1.32 g/100 g. Thermodynamic parameters of peptide-ligand interactions were determined by isothermal titration calorimetry and energetics of interactions at the atomic level by molecular modelling. The amount of CHAs released during proteolytic digestion was at a relatively low level of 0.06 -1.14 g/100 g, and the availability for absorption of CHAs after proteolysis ranged from 1.26 to 4.05 g/100 g for free form and from 14.67 to 15.39 g/100 g for included form, indicating that encapsulating of CHAs in beta-CD significantly increased their availability from processed food containing PHs after digestion. (C) 2015 Elsevier Ltd. All rights reserved.