Microencapsulation of catechin using water-in-oil-in-water (W1/O/W2) double emulsions: Study of release kinetics, rheological, and thermodynamic properties

Abstract

This study is aimed to encapsulate the catechin in a double emulsion (W1/O/W2) using the ultrasonic process. These results indicated that the encapsulation efficiency (EE) is 99.35% and the average sizes of droplets and globules are 63 nm and 10 μm, respectively. Interestingly, the data revealed that pasteurization and flash pasteurization do not alter significantly the encapsulation yield (EE), the size of the mean droplets and oil globule sizes (d[3, 4] and D[3, 4]), and polydispersity index. Yet, the addition of chitosan and sodium caseinate in the inner aqueous phase significantly reduced the amount of catechin released (p < 0.05). Thus, several models have been tested to describe the kinetics of catechin release and the most suitable is the Higuchi model. Furthermore, the thermodynamic parameters were investigated using the equation derived from Eyring expression in transition state theory. Besides, the rheological properties of the double emulsion samples showed that are non-Newtonian fluids with pseudoplastic or shear-thinning behavior. Likewise, the antioxidant activities by DPPH test of the double emulsion samples were also enhanced considerably after it was converted into a double emulsion, which indicated that the addition of chitosan in the inner aqueous phase was higher than in free catechin.