Nanoemulsion based delivery system for improved bioaccessibility and Caco-2 cell monolayer permeability of green tea catechins

The strong antioxidant activities of green tea catechins are shown to exert protective effects against chronic diseases. However, poor chemical stability and low oral bioavailability limits its usage as a potent nutraceutical. Hence, the objective of this study was to investigate the effect of nanoencapsulation on the physicochemical stability, in-vitro bioaccessibility and epithelial permeability of green tea catechins. Soy protein stabilized nanoemulsions containing 0.3 or 0.5 wt% green tea catechins were prepared and stability under different storage conditions (4 +/- 1 degrees C, 28 +/- 2 degrees C, 40 +/- 1 degrees C) was assessed for a period of 15-20 days. At refrigeration temperature, the nanoemulsion containing 10% oil and 0.5% catechins was stable against creaming, phase separation, sedimentation and changes in droplet size, pH and catechin content. There was an observed 2.78 fold increase in the bioaccessibility of major catechins in the nanoemulsified form compared to unencapsulated catechins. Further, there was a significant increase in intestinal permeability of catechins as assessed by Caco-2 cell model. The results indicate the ability of soy protein based nanoemulsions to improve the stability, bioaccessibility and permeability of green tea catechins. (C) 2016 Elsevier Ltd. All rights reserved.