Encapsulation of lycopene within oil-in-water nanoemulsions using lactoferrin: Impact of carrier oils on physicochemical stability and bioaccessibility

The influence of physicochemical properties of carrier oils on nanoemulsion stability and the bioaccessibility of lycopene were studied. Lycopene-loaded nanoemulsions were prepared by using sesame oil, linseed oil or walnut oil as the oil phase and lactoferrin as the emulsifier. The stability was investigated by particle size, zeta potential, pH sensitivity, thermal stability and lycopene retention. Results showed that the stability was positively correlated with oil density but negatively related to oil viscosity and unsaturation degree; the lycopene nanoemulsion prepared by sesame oil exhibited greater stability and a slower degradation rate of lycopene compared to the other nanoemulsions. In addition, the lycopene retention in sesame oil-nanoemulsions was significantly higher during the first three weeks of storage. The bioaccessibility of lycopene, as measured by a simulated gastrointestinal model, was greatly improved in the nanoemulsion system. The lycopene bioaccessibility was around 25% in sesame oil- and linseed oil-nanoemulsions, and 18% in walnut oil-nanoemulsions, showing a similar trend with their stability. This information may facilitate the design of more efficacious lycopene-fortified delivery systems.