Extraction and purification of lutein fatty acid esters from marigold flower

Abstract

This study aims optimize process for purification of free lutein obtained from marigold flowers. First, saponification was carried out to convert lutein fatty acid esters in the marigold oleoresin to free lutein . Then, further purification of free lutein could be achieved by crystallization. At a fixed temperature of 75 ºC, we determined the effects of saponification conditions such as time (0-7 hrs), volume to weight ratio of KOH solution to oleoresin (0.3ml: 1g-1ml: 1g), and the concentration of KOH solution (25%-45%) on the concentration of free lutein. The results showed that the concentration of free lutein increased with an increase in time up to 4 hrs, where the maximum concentration was obtained. Extended saponification above 4hrs resulted in observable product degradation. For saponfication of 1 g of oleoresin at 75 C for 4 hr, the suitable volume of KOH solution and concentration of KOH solution were found to be0.5ml and 40% v/v, respectively The volume and concentration higher than 0.5ml and 40% caused product degradation as free lutein is unstable at extreme pH. After saponification, the purity of free lutein was improved by crystallization. The effect of the system of crystallization solvent (water to ethanol and water to isopropanol), the volume ratio of crystallization solvent (2:0.3-2:1 v/v), and crystallization time (0.25-2 hrs) on the yield and purity of free lutein were studied. The suitable crystallization process was found to be that employing 2:0.5 (water to ethanol) and the crystallization time was 0.5 hrs. The purity and yield of free lutein as analyzed by HPLC were found to be 85.53% and 99.12%, respectively.