Co-encapsulation of hydrophilic L-ascorbic acid and hydrophobic quercetin through complex coacervation

• 1、School of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu

Abstract：Co-encapsulation of hydrophilic and hydrophobic nutraceuticals has attracted widespread attention due to its synergistic effect and nutrient collocation. L-ascorbic acid and quercetin were chosen as co-encapsulated models to fabricate a two-step emulsification prior to complex coacervation, including preparation of primary emulsion, gelatin/sodium carboxymethyl cellulose complex coacervation and tannic acid as the cross-linker. The microcapsules had an average particle size of 69.56 μm and the encapsulation efficiency of L-ascorbic acid and quercetin were 65.31% and 89.61%, respectively. Moreover, micro-morphology analysis showed that at 2% total biopolymer concentration, microcapsules exhibited a mononuclear ellipse-like shape with some dents and shrinkages on their surface. X-ray diffraction spectroscopy showed that the co-encapsulated L-ascorbic acid and quercetin were transformed into an amorphous structure in the microcapsules. Also, thermogravimetric analysis indicated better stability at higher thermal degradation temperature. The co-encapsulated L-ascorbic acid and quercetin were both well protected in the gastric phase, while obtaining controlled release in the intestinal phase, significantly improving the stability in vitro release. Compared with free L-ascorbic acid and quercetin, the bioavailability of the encapsulated ones had a fourfold increase.

Keywords： Co-encapsulation Double emulsions Complex coacervation L-ascorbic acid Quercetin