Separation And Analysis Of Carotenoids In Watermelon

There are many varieties and strains of watermelon which exhibit a wide range of fruit colors, such as red, pink, yellow, and white due to diverse carotenoids. Analysis and detection of carotenoids in watermelon flesh not only can make preparation for studying on watermelon carotenoid production, but also can provide a foundation for the nutritional breeding of watermelon.Such five varieties of watermelon as "Zaohua" B1 ( red in pulp color ), "Hongyihao" B2 (pink ), "96B41" B3 (coral ), "307 Chaofeng" B4 (yellow ), and "Sanbai" B5 (white ) were used as experimental materials. Carotenoids were extracted from the fruit pulps of five varieties of watermelon with petroleum ether respectively, and then were separated by open-column chromatography. Magnesium oxide and silica (1:1, w/w) were used as the adsorbent in a column. The chromatogram was developed with acetone-petroleum ether mixture of increasing concentration of acetone from 0% to 30%. The fruit pigments of the watermelon variety Zaohua, for example, were separated into six carotenoids by open-column chromatography. The identity of carotenoids separated was determined primarily after absorption spectra of the colorful bands eluted from the column were measured on a spectrophotometer. Phytofluene,β-carotene, lycopene, and so on were obtained by further purification of the pigments on open column. The results show that open column chromatography is suited to the separation and assay of watermelon carotenoids and may obtain phytofluene, 8-carotenoid, and lycopene which can be used in the following HLPC experiment.Vydac 201TP54 C₁₈ colum, methanol-acetonitrile-THF as the mobile phase at a flow rate of 1 mL/minute, coulum temperature of 20℃, and the detection set at 450nm and 366nm were used in HPLC for watermelon carotenoid analysis. The caroetenoid contents of the 5 watermelon varieties were measured with external standard method. Lycopene is the major pigment for the 3 red-fleshed watermelon varieties and can not be detected in the white-fleshed wtaremelon.