Effect of pH, Polysaccharide Concentrations on Properties of Lutein-loaded Oil Whey Protein Isolate in water based Emulsions

Physicochemical properties of emulsion based systems are influenced by various factors. In this study, lutein-loaded oil in water emulsions was prepared with whey protein isolate and selected anionic polysaccharides. Our results revealed that 0.2-1% (w/v) pectin and 0.1-0.7% (w/v) of Carboxymethyl cellulose to 1% (w/v) whey protein isolate significantly changed the electrical charge. At pH 3, the increase of HMP and LMP concentration to 1% (w/w) changed the zeta potential from +21.34 mV to -8.98 mV, while at pH 4 and 5, the increase of HMP and LMP concentration to 1% (w/w) shifted the zeta potential from 13.8 to -33.9 mV and -1.05 to -38.8 mV respectively. Increasing CMC concentration, led to change in zeta potential from +21.34 to -15.67 mV at pH 3, +13.8 to -40.22 mV at pH 4 and -1.056 to -42.45 mV at pH 5 respectively. The solubility study in MCT oil at different temperature and time 25C for 12 h, 50C for 6 h, 100 and 150C for 3 min was done. Lutein solubility significantly increased with increasing solubilization temperature while lutein solubilization reached the maximum between 1 and 3% (w/v) and the solubility decreased afterward. Encapsulation efficiency was significantly high in WPI emulsion compared with other emulsion systems. However, the increase in pH from 3 to 5 decreased the encapsulation efficiency in all systems. Light microscope images of emulsion samples revealed that all droplets were spherical and this might be the anionic polysaccharides that uniformly got deposited onto whey protein isolate during homogenization. It was concluded that lutein emulsions based delivery system could be prepared using whey protein isolate as emulsifier and addition of anionic polysaccharides between their respective pI and pKa.