Formulation and characterization of O/W nanoemulsions encapsulating high concentration of astaxanthin

Abstract

This study evaluates the effect of modified lecithin (ML) and sodium caseinate (SC) on the formulation, stability and bioaccessibility of astaxanthin (AXT) loaded oil-in-water (O/W) nanoemulsions. These nanoemulsions were formulated using high-pressure homogenization in four passes at 100 MPa. The volume mean diameter (d4,3) of nanoemulsions produced by ML and SC were 163 ± 5 and 144 ± 12 nm, respectively. The physiochemical stability of nanoemulsions was recorded at 25 °C. The nanoemulsions prepared by ML were stable for 30 minutes against a wide range of pH and heating temperatures (60–120 °C). However, ML-stabilized nanoemulsions showed droplet growth when treated at high NaCl concentrations. In comparison, droplet growth was observed in SC-stabilized nanoemulsions at pH 4 and at high temperature treatment. However, SC-stabilized nanoemulsions were stable at high NaCl concentration (500 mM). The SC-stabilized nanoemulsions showed good physical and chemical stability (> 70%) after 30 days of storage. The bioaccessibility of AXT in nanoemulsions was significantly higher in ML (33%) than in SC-stabilized nanoemulsions (6%), indicating a strong influence of emulsifier on bioaccessibility. These findings provide valuable information in designing nutritional products such as aqueous based AXT fortified beverages.

Keywords Astaxanthin (AXT), Nanoemulsions, Fortified beverages