Preparation and Stability of Nanostructured Lipid Carriers of Phytosterols with Walnut Oil

Nanostructured lipid carriers (NLC) for the encapsulation and protection of phytosterol (PS) were prepared using walnut oil as liquid lipid by high-pressure homogenization method. The average particle size, polydispersity index, Zeta potential and encapsulation efficiency were used as the main evaluation indexes to optimize the preparation process parameters and formulations，and the morphology and stability of the optimized PS-NLC were investigated. The optimal ratio for the preparation of PS-NLC was determined by orthogonal tests as 10% of total lipid concentration, 2:3 of stearic acid and walnut oil, and 1.2% of soy lecithin. The prepared PS-NLC had a spherical appearance, small particle size and uniform distribution. The stability results of PS-NLC showed that PS-NLC was stable in storage at 4 ℃ for 28 days. It was diluted 5~100 times with good dilution stability, when used. And the addition of 2% sucrose had the best effect on the lyophilization protection of PS-NLC. Walnut oil was used as the wall material of NLC to provide a suitable lipid delivery system for phytosterols, which could provide technical support for the construction of PS-NLC in food industry.