An HPLC Method for the Analysis of Marigold Color in Food Using Lutein as an Indicator

摘要

An HPLC method for the analysis of marigold color in food, using lutein as an indicator, was established. Marigold color was extracted from food samples with ether and, after evaporation of the extract, the residue was dissolved in methanol to which 5% sodium hydroxide–methanol was then added. The mixture was occasionally stirred, then allowed to stand for 24 hours at room temperature in a tightly sealed container shielded from light. Subsequently, distilled water was added and the pH of the mixture was adjusted to below 4.5 using hydrochloric acid. It was then purified with a C18 cartridge before being subjected to HPLC analysis. The HPLC conditions were as follows: column, Tosoh TSK gel ODS-80Ts (5 μm, 4.6 * 150 mm); column temperature, 40°C; mobile phase, acetonitrile–water (91); flow rate, 1.0 mL/min; detection wavelength, 460 nm. The average recoveries of the marigold color were over 78.6% from noodles and juice fortified at the concentrations of 25–500 μg/g. The coefficients of variation were 9.1% or less. Twenty-six commercially available foods, such as noodles and juice that had a label stating the use of marigold color were analysed; the detected lutein concentrations ranged from 0.01 to 5.60 μg/g.