Preparation, characterization, and stability of nano-emulsions loaded with the Moringa oleifera seed hypoglycemic peptide MoHpP-2

In a previous study, we successfully isolated and identified novel hypoglycemic peptide MoHpP-2 from Moringa oleifera seed protein hydrolysates. However, the peptide exhibited activity instability. To increase its stability, we employed a high-speed homogeneous emulsification method to prepare a MoHpP-2-loaded nano-emulsion. The optimal conditions for preparing MoHpP-2-loaded nano-emulsions were as follows: 5 % soy lecithin as emulsifier; medium-chain triglycerides as oil phase; water phase to oil phase ratio of 9:1; 0.05 % MoHpP-2 addition; and rotational speed of 19,000 rpm. The encapsulation efficiency of the nano-emulsion was 74.00 % and reached the nano-meter level with mean particle size of 162.05 nm. The resulting nano-emulsion was considered an oil-in-water type, and FTIR analysis confirmed effective embedding of MoHpP-2, and rheological analysis further indicated shear thinning behavior of the nano-emulsion. Moreover, the prepared nano-emulsion had good Na+ and pH stability, and significantly enhanced thermal stability of MoHpP-2 at 80–100 °C. Furthermore, the nano-emulsion had good stability when stored at 4 °C for 36 days. In addition, in vitro gastrointestinal simulation experiments revealed that the release mechanism of MoHpP-2 was found to conform to the Super Case II transport model. Overall, this study provides a theoretical support for the application of high-stability nano-emulsion loaded with MoHpP-2 in functional foods.