Study of Xanthophyll Concentration in Spinach Leaves by Means of HPLC Coupled with UV–VIS and Corona CAD Detectors

Abstract

In this study, the determination of lutein in fresh and frozen spinach leaves has been done. Changes of pigment concentration in spinach leaves were observed in various heating time periods (1–20 min). An improved and simplified analytical method which offers rapid, accurate determination and identification of lutein in spinach samples is reported. During experiments, two detection systems, ultraviolet–visible (UV–vis) spectroscopy and Corona CAD coupled with high-performance liquid chromatography (HPLC), were applied. The determination of lutein in plant extracts was carried out by HPLC–UV–vis. Concentrations of lutein ranged between 0.43 and 0.88 mg/g xfor three frozen spinach samples and 0.83 mg/g for fresh spinach, respectively. Changes of lutein concentration after cooking of frozen spinach were also determined. Primary concentration of lutein in examined frozen spinach sample was 0.43 mg/g. After a 1-min heating time, the concentration of lutein was 0.46 mg/g. After 20 min, it was only 0.11 mg/g. The decreasing of lutein concentration in spinach during the cooking from 2 to 20 min was observed. Over a 20-min heating time of spinach leaves, a loss of primary concentration of lutein was observed. Short cooking time (1–2 min) of spinach has an effect in the increasing of contents of lutein and other biologically active compounds. Long cooking time of spinach induces lutein degradation process.