Preparation and characterization of lutein ester-loaded oleogels developed by monostearin and sunflower oil

The marigold (Tagetes erecta L.) flower is rich in lutein ester with many health-promoting activities. In this study, the effects of vegetable oil type and extracting the temperature on the extraction efficiency of lutein ester in the marigold flower were evaluated. Then, the structuring of the lutein ester-loaded sunflower oil with the addition of different amounts of monostearin and cooling temperatures (4 and 20°C) was investigated. The XRD analysis suggested that these oleogels were stabilized by the network formed by monostearin crystals in the sunflower oil. The textural properties (firmness, cohesiveness, and hardness) of oleogels were positively related to the monostearin dosage, but negatively related to the cooling temperature. According to the rheological results, the oleogels belonged to the pseudoplastic gel and their gelation temperature (T_g ) was only related to the concentration of monostearin. The light stability of lutein ester in the oleogels was also significantly improved in a monostearin dosage-dependent manner. PRACTICAL APPLICATIONS: The edible lutein ester-loaded oleogel for foods developed by structuring the sunflower oil with monostearin is introduced in this study. Its texture and rheological properties can be adjusted to cater to different requirements in the food industry by changing the monostearin dosage and cooling temperature. This study provides a reference for the development of other liposoluble nutraceuticals.