Stability and Bioaccessibility of Fucoxanthin in Nanoemulsions Prepared from Pinolenic Acid-contained Structured Lipid

Fucoxanthin intake has been correlated with the functions of anti-obesity and anti-oxidation, but applications of it in functional food or dietary supplements are still challenging due to its poor water-solubility, chemical instability, and low bioavailability. In this work, to study physicochemical and biological properties of fucoxanthin nanoemulsions, we investigated the influence of emulsion particle diameter on the stability of fucoxanthin during storage time and bioaccessibility in-vitro digestion. The structured lipid that enriched pinolenic acid at sn-2 position was chosen as the oil phase and the fucoxanthin oil-in-water nanoemulsions with droplet diameters of 344, 173, and 98 nm were prepared through a high-pressure microfluidizer. Then fucoxanthin emulsions were stored for 28 days at 4, 37, and 55 °C. Results showed that the physical stabilities of droplets were decreased with increases in the initial size and storage temperature, while the change of fucoxanthin retention indicated that fucoxanthin chemical stability was improved with increasing emulsion particle size. The augmentation of lipolysis and the value of free fatty acids (FFA) released in vitro digestion proved that digestion stability of fucoxanthin emulsion reduced with decreasing initial particle diameter, which was probably attributed to the increased surface area interacting with pancreatic lipase with decreasing droplet size. In addition, the concentrations of fucoxanthin in micelle phase were appreciable increased as droplet size decreased. Therefore, the bioaccessibility of fucoxanthin was improved. These results may benefit the optimization of an emulsion-based delivery system for fucoxanthin in food applications.