The aim of this study was to improve the physicochemical properties of the water-insoluble bioactive flavonoid quercetin (Q), to extend its use in various food products as a functional ingredient. Quercetin was encapsulated within soluble complexes of whey protein isolate (WPI)-low methoxyl pectin (LMP), which were obtained via electrostatic complexation at acidic pH. The effect of pH and WPI:LMP ratio was studied to form soluble complexes with optimal physical properties, in terms of the hydrodynamic diameter, ζ-potential, turbidity, and yield. Based on the results, a pH 5.0 and a 2:1 (w/w) ratio of WPI:LMP were selected for encapsulation of quercetin. The stoichiometry of the binding (n) and the binding constant (Kb) of WPI:Q were evaluated at pH values of 5.0 and 7.0 at room temperature. The soluble complexes containing quercetin were produced by mixing WPI with Q (4.28:1 and 0.86:1 of WPI:Q molar mixing ratios were used), followed by addition of LMP and pH adjustment to 5.0. The binding of WPI and WPI:LMP complexes with Q at pH 5.0 and 7.0 was also studied using high resolution <sup>1</sup>H NMR. The soluble complexes containing Q were then characterized for their microstructure, hydrodynamic diameter, ζ-potential, encapsulation efficiency, controlled release, as well as stability against high temperature and UV irradiation. The stability of nanoencapsulated quercetin against UV irradiation was approximately 4 times better than that of free quercetin. Moreover, the soluble complexes containing quercetin were also lyophilized into dry powder and were evaluated for physical stability including particle aggregation and sedimentation, which later they can be useful for practical application in food products, especially as functional non-fat beverage.

Whey protein isolate-low methoxyl pectin soluble complexes as delivery vehicles for quercetin

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.