Carotenoid Esters in Vegetables and Fruits: A Screening with Emphasis on β-Cryptoxanthin Esters

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Abstract
Carotenoids are found in food plants in free form or as fatty acid esters. Most studies have been carried out after saponification procedures, so the resulting data do not represent the native carotenoid composition of plant tissues. Therefore, nonsaponified extracts of 64 fruits and vegetables have been screened to determine the amount of carotenoid esters in food plants. Because one of the major problems in the quantitation of carotenoids is the availability of pure standard material, the total carotenoid ester content was calculated as lutein dimyristate equivalents. Lutein dimyristate was independently synthesized from lutein and myristoyl chloride. The highest ester concentrations were found in red chili (17.1 mg/100 g) and orange pepper (9.2 mg/100 g); most of the investigated fruits and vegetables showed concentrations up to 1.5 mg/100 g. Special attention was dedicated to β-cryptoxanthin esters. To enable an accurate detection of the β-cryptoxanthin ester content, β-cryptoxanthin was purified from papaya and used for synthesis of β-cryptoxanthin laurate, myristate, and palmitate, representing the major β-cryptoxanthin esters in food plants. The study proved tropical and subtropical fruits to be an additional source of β-cryptoxanthin esters in the human diet. The contents ranged from 8 μg/100 g β-cryptoxanthin laurate in Tunisian orange to 892 μg/100 g β-cryptoxanthin laurate in papaya. Keywords: Carotenoid; carotenoid esters; β-cryptoxanthin; lutein dimyristate