Random centroid optimization of phosphatidylglycerol stabilized lutein-enriched oil-in-water emulsions at acidic pH

Lutein has been identified by various studies as a dietary compound that may help delay the onset of macular degeneration. Random centroid optimization was applied to design, prepare and characterize lutein-enriched oil-in-water (o/w) emulsions containing corn oil (15-25%), whey proteins (1.5-3.5%), phosphatidylglycerol (0.03-0.3%), KCl (80-100 mM), lutein (0.025-0.031%), and pH at 3.8-4.8. After nine experiments in the first random cycle and four experiments in the centroid cycle, optimal conditions for the preparation of stable lutein-enriched oil-in-water emulsion were: corn oil, 20%; whey proteins, 2%; phosphatidylglycerol, 0.157%; KCl, 93.7 mM; lutein, 0.0282%, and pH 4.55. The half life stability, stability index, and zeta potential values for freshly prepared emulsions were higher when stabilized with phosphatidylglycerol than with phosphatidylcholine. Phosphatidylcholine-stabilized emulsions collapsed after heating at 90° C for 5 min. Emulsion parameters for phosphatidylglycerol-stabilized emulsions heated at 90° C for 5 min or stored at 4° C for 24 h were not significantly different from values obtained with freshly prepared emulsions. Lutein remained stable in fresh and heat-treated emulsions. The potential of phosphatidylglycerol and lutein as health enhancing bioactive compounds is discussed. © 2005 Elsevier Ltd. All rights reserved.