Microemulsion as nanoreactor for lutein extraction: Optimization for ultrasound pretreatment

In the present study, the capability of microemulsion technique, as a novel technique for synchronous extraction and solubilization of lipophilic compounds, on lutein extraction from marigold petals was investigated. Under the optimized sonication (amplitude 100%, 120 s, 25°C), the extraction efficiency increased (85%) using SDS:ethanol (1:2)-based ME. Moreover, sonication led to smaller droplets (12-163 nm) with favorable thermodynamic stability. In addition, the developed MEs showed higher thermal and especially UV stability in comparison to organic solvent extracts which were fainted with first-order kinetics. It was also found that co-surfactant could be eliminated from formulation on the expense of the optimized sonication, was valuable output form industrial point of view. These findings revealed the high potential of ultrasound technique on the extraction and solubilization of lutein by ME technique which can be directly utilized in lutein-enriched functional foods and beverages. PRACTICAL APPLICATIONS: From applicability point of view, the solvent extracted compounds cannot be easily dissolved in food or pharmaceutical systems that are mostly hydrophilic. Therefore, microemulsions (MEs), as green and environmentally friendly food-grade systems, due to their potential capability for simultaneous extraction and solubilization of carotenoids are of great interest. Therefore, the present study confirmed the practical ability of MEs in lutein extraction and protection. All in all, the developed lutein MEs with high lutein extraction capacity and superior lutein chemical stability against thermal treatment and especially UV radiation is an original finding which allows design of new functional foods and could be potentially useful for enriching foods, pharmaceuticals, nutraceuticals, and supplement formulation.