Evaluation of extraction method for the analysis of carotenoids in fruits and vegetables

This study evaluated a suitable extraction method for a wide range of sample matrices in carotenoid analysis. Using canned tomato juice as a representative sample, it is shown that two solvents of low biological hazard, ethanol and hexane are the most suitable for extracting carotenoids from the matrix. The use of double extraction, each with 35 ml of ethanol:hexane mixture (4:3, by volume), resulted in good recoveries of carotenoids (lycopene 96%, α-carotene 102% and β-carotene 93–100%). Coefficients of variation conducted on different days were: lycopene 5% and β-carotene 7%. An application of the established method to various kinds of fruit and vegetable matrices is also shown, using carrot and spinach as representative samples of root and leafy vegetables, for determining recoveries of added carotenoids. The average percent recoveries of added carotenoids from canned tomato juice, carrot and spinach were: 101, 99.8 and 101% for α-carotene (12.4, 24.8, 49.6 and 99.2 μg/10 ml of added α-carotene); and 98.1, 99.7 and 96.1 percent for β-carotene (25.5, 50.9, 101 and 201 μg/10 ml of added β-carotene). These similar recoveries over the explored concentration ranges confirm that the application of established extraction method is unaffected by differences in matrix composition of the samples.