Micro- and nano-encapsulation and controlled-release of phenolic compounds and other food ingredients:

The health promotive properties of phenolic compounds attracted a lot of attention in recent years because of their biological and pharmacological effects including antioxidative and cytoprotective functions. Green tea catechins and curcumin have been extensively studied and they both show strong anti-oxidant and anti-inflammatory properties, but low bioavailability is always a problem. Therefore, effective delivery systems could be a solution to enhance their oral bioavailability. In this study tea catechins were encapsulated in two W/O/W double emulsion systems, protein-polysaccharide complex coacervates and emulsifiers/polysaccharide stabilized double emulsion. Physicochemical characteristics were determined for both systems. The coacervate encapsulation achieved 90.5% encapsulation efficiency, and the other double emulsion reached 94.5% efficiency. Coacervate-encapsulated catechins were stable in artificial gastric juice, and could target-release catechins in small intestinal juice triggered by pH. Curcumin was dissolved in medium chain triglyceride (MCT) and further emulsified in water. Curcumin nano-emulsions had average particle sizes of 150.5nm and 148.4nm for 1% and 1.5% curcumin, respectively. The encapsulation efficiencies were 77.5% for 1% curcumin emulsion and 71.5% for 1.5% emulsion. Oral administration of nano-emulsified curcumin could inhibit TPA-induced edema on mouse ears by 100%, and significantly inhibited pro-inflammatory factors IL-1beta, IL-6, MMP-9, and cyclin D1 dose-responsively. The anti-inflammatory effects directly indicated enhanced bioavailability of curcumin. Protein-polysaccharide coacervation was further applied to enzyme encapsulation. α-Amylase can form coacervate with κ-carrageenan under optimized conditions, and reach 99.3% encapsulation efficiency. Enzyme kinetics showed that encapsulation could strongly protect α-Amylase from acid denaturation, suggesting that the stoichiometric complexation of α-amylase did not alter the active binding sites of enzyme. In summary, low cost, convenient and highly efficient encapsulation methods using food grade natural biopolymers have been developed to encapsulate nutraceuticals or enzyme. The encapsulation systems have protective, target-releasing, and bioavailability enhancing functions.Ph.D.Includes bibliographical references (p. 122-130)by Yan Jian