Liposomal Green Tea Extract: Optimization and Physicochemical Characterization

Although Green tea is a rich source of antioxidant, use of this herbal in food industries is limited due to its oxygen and light instabilities.

Green tea polyphenols were encapsulated into liposomes using Mozafari method (with no solvents and detergents) to improve bioavailability of tea polyphenols. Screening design was used to find the major variables within all possible process variables. Then, optimal conditions were studied using response surface.

The most appropriate condition was achieved using phosphatidylcholine of 4.5% (w/w), extract concentration of 0.7%, mixing time of 30 min and temperature of 50 °C. Encapsulation efficiency (EE) depended on concentrations of the green tea extract and phosphatidylcholine. The EE in optimal formulation was reached as 51.34%. The particle size and Z-potential of liposomal green tea extract were assessed at 419 nm and -59.7 mV, respectively. The total polyphenol content (TPC) of green tea included 164.2 mg gallic acid/g extract. Free radical scavenging activities of free and liposomal extracts were calculated as 90.6 and 93.37%, respectively, using 2-2-diphenyl-1-pycrylhydrazyl (DPPH) method.

Results revealed that liposomal green tea extract can be used extensively in food industries due to its high antioxidant activity. No size decreasing methods (e.g. sonication and homogenization) were needed to produce nanosize liposomal extracts to avoid structure instability.