Egg yolk protein as a novel wall material used together with gum Arabic to encapsulate polyphenols extracted from Phoenix dactylifera L pits

Abstract In this study, previously delipidated egg yolk protein (EYP) was tested as a novel wall material, together with gum Arabic (GA), for encapsulating Phoenix dactylifera L (date) pit polyphenols. For this purpose, polyphenols were encapsulated by freeze-drying using different ratios of GA and EYP. Moisture content, color, microstructure of the powders, thermo-gravimetric analyses (TGA), encapsulation efficiency, antioxidant activity and an in vitro gastrointestinal simulation were carried out. An increase in the proportion of EYP produced a slight increase in the moisture content of the microparticles and higher ΔE values when the polyphenols were incorporated, but their morphology remained similar independently of the concentration of EYP tested. Furthermore, the microparticles containing a higher amount of EYP showed better thermal stability, higher encapsulation efficiency and better antioxidant properties. Finally, the in vitro gastrointestinal simulation study showed that a higher concentration of EYP than GA resulted in an improvement in the resistance of the microparticles to gastric and intestinal fluids. Overall, the EYP showed certain promising properties when it was used to encapsulate polyphenols.