Encapsulation of α-tocopherol in protein-based delivery particles

Two types of proteins, including beta-lactoglobulin (BLG) and hen egg white protein (HEW), were examined for their ability to encapsulate alpha-tocopherol (alpha-TOC) after salt-induced gelation of the proteins. Parameters affecting encapsulation efficiency were investigated including the type of salt, as well as concentrations of salt, protein, and alpha-TOC. Concentrations of protein and alpha-TOC revealed to have an influence on encapsulation efficiency. The optimum preparation condition of BLG-encapsulated alpha-TOC was as follows: BLG of 0.5% (w/v); alpha-TOC of 100 mM; and CaCl2 of 25 mM. The optimum preparation condition of HEW-encapsulated alpha-TOC was as follows: HEW of 4.0% (w/v); alpha-TOC of 50 mM; and ZnCl2 of 25 mM. With the selected preparation conditions, encapsulation efficiency by BLG aggregates was approx. 20% and that by HEW was approx. 32%. From the in vitro estimation, the release of alpha-TOC was nearly 100% in simulated gastric condition. Alginate was therefore used for coating of these encapsulated particles to prolong the release of alpha-TOC till simulated intestinal condition. The alpha-TOC of approx. 55% and 38% were retained and released in the simulated intestinal condition from BLG- and HEW-encapsulated particles, respectively. (C) 2009 Elsevier Ltd. All rights reserved.