Kinetic Extraction of Fucoxanthin from Undaria pinnatifida Using Ethanol as a Solvent

Fucoxanthin (Fx) has been proven to exert numerous biological properties, which makes it an interesting molecule with diverse industrial applications. In this study, the kinetic behavior of Fx was studied to optimize three variables: time (t—3 min to 7 days), temperature (T—5 to 85 °C), and concentration of ethanol in water (S—50 to 100%, v/v), in order to obtain the best Fx yield from Undaria pinnatifida using conventional heat extraction. The Fx content (Y(1)) was found through HPLC-DAD and expressed in µg Fx/g of algae sample dry weight (AS dw). Furthermore, extraction yield (Y(2)) was also found through dry weight analysis and was expressed in mg extract (E)/g AS dw. The purity of the extracts (Y(3)) was found and expressed in mg Fx/g E dw. The optimal conditions selected for Y(1) were T = 45 °C, S = 70%, and t = 66 min, obtaining ~5.24 mg Fx/g AS; for Y(2) were T = 65 °C, S = 60%, and t = ~10 min, obtaining ~450 mg E/g AS; and for Y(3) were T = 45 °C, S = 70%, and t = 45 min, obtaining ~12.3 mg Fx/g E. In addition, for the selected optimums, a full screening of pigments was performed by HPLC-DAD, while phenolics and flavonoids were quantified by spectrophotometric techniques and several biological properties were evaluated (namely, antioxidant, antimicrobial, and cholinesterase inhibitory activity). These results could be of interest for future applications in the food, cosmetic, or pharmaceutical industries, as they show the Fx kinetic behavior and could help reduce costs associated with energy and solvent consumption while maximizing the extraction yields.