Using different natural origin carriers for development of epigallocatechin gallate (EGCG) solid formulations with improved antioxidant activity by PGSS-drying

Epigallocatechin gallate (EGCG) is the catechin with the highest antioxidant activity present in green tea. Nevertheless, due its low bioavailability, it is necessary to develop EGCG formulations capable of improving its stability resulting in increased bioavailability and thus higher biological activity of this catechin (e.g. antioxidant activity). The purpose of this work was the formulation of EGCG using three distinct natural origin carriers, namely OSA-starch, soybean lecithin and beta-glucan, by particles from gas saturated solution drying (PGSS-drying). Non-cytotoxic solid formulations of EGCG in the range of micrometers and encapsulation efficiencies up to 80.5% were obtained. An improved antioxidant activity (AA) determined by the oxygen radical absorbance capacity (ORAC) method was obtained for all formulations. Furthermore, lecithin: EGCG and beta-glucan: EGCG presented higher cellular antioxidant activity (Caco-2 cells) values than free EGCG at the same concentrations tested (around 1.5-fold higher values). Moreover, the solid formulations presented preservation of the AA over 4 months, and an improved storage stability in comparison with non-encapsulated EGCG over 48 h at 328 K in the absence of light (accelerated storage). These results show that PGSS-drying conditions enabled the preservation of the bioactive properties of catechin, allowing the formulation of solid particles with enhanced features.