Stability of lutein under various storage conditions

The stability of lutein, a major xanthophyll, was investigated under various storage conditions. Continuous exposure of lutein‐containing samples to cold white fluorescent light (4600 lux) at 25 °C resulted in the degradation of lutein at 0.8%‐10.7% per day in the samples containing ascorbic acid, ascorbic acid + KOH and H2O (as control) over a period of 75 days. It was found that ascorbic acid could retard lutein degradation (0.04% ‐ 2.5% per day) at temperatures from −30 °C to 50 °C under the alkaline condition in darkness. High temperature promoted the degradation of lutein in all the samples. Under the alkaline condition and at low temperature (‐12 °C), the stability of pure lutein was similar to that of the lutein extracted from the alga Chlorella protothecoides cultivated heterotrophically.