Combined process of reaction,extraction, and purification of lutein in marigold flower by isopropanol–KOH aqueous two-phase system

This paper established a viable process for the simultaneous reaction, extraction, and primary purification of lutein in marigold flower by the isopropanol–KOH aqueous two-phase system (ATPS). In this process, the liposoluble lutein esters were translated into water-soluble lutein by saponification reaction in ATPS and distributed to the top phase. Meanwhile, the water-soluble flavonoids in marigold were also extracted and distributed to the bottom phase. The concentrations of phase-forming isopropanol and KOH, the added mass of marigold flower powder, temperature, and time were investigated to evaluate their effects on the extraction and partition behaviour of lutein and flavoniods in ATPS. Under the optimal conditions (38% isopropanol, 18% KOH, 0.05 g of marigold flower powder, 500°C and 1.5 h extraction time), the leaching efficiency, extraction efficiency, and partition coefficient of lutein were 84.64%, 86.73%, and 5.115, respectively, and at this point, the saponification rate of lutein reached 93.98%. Meanwhile, the leaching efficiency, extraction efficiency, and partition coefficient of flavoniods were 96.68%, 78.31%, and 0.2167, respectively. This method shows the superiority to the conventional one for it can not only efficiently extract lutein in marigold flower, but also achieve a high saponification rate of lutein esters and simultaneously separate two major pigments.