Microencapsulation of capsanthin by self-emulsifying nanoemulsions and stability evaluation

The application of natural colorants in food products has been gained more and more attention, not only due to their nutritional advantages, but also their functional properties. The purpose of this research was to encapsulate capsanthin from paprika by nanoemulsions (NEs), and the stability of resultant NEs was evaluated. The NE systems were first optimized by dropwise adding mixed organic phase [5 wt% medium-chain triglyceride (MCT) and 10 wt% surfactant containing span 20 and tween 80 with the weight ratio 1:3 and HLB 13.4] into water phase. Then capsanthin was mixed with MCT as the oil phase. With the presence of capsanthin, the oil phase composition had great impact on the particle size of NEs that the droplet size increased from 30 to 150 nm with increasing capsanthin content. Generally, higher temperature and stirring speed would decrease the particle size, which also depended on the surfactant-to-oil ratio. The stability results demonstrated that there was no obvious change on the capsanthin NE droplet size and entrapped capsanthin content after 1 month storage at ambient temperature. Our results are important for the design of food-grade delivery systems to encapsulate natural lipophilic pigments or ingredients.