Rapid method for total carotenoid detection in canary yellow-fleshed watermelon

Yellow-fleshed watermelons (Citrullus lanatus[Thunb.] Matsum. and Nakai) contain many different carotenoids, all in low to trace amounts. Since there is not 1 predominant carotenoid in yellow-fleshed watermelon, testing the total carotenoid content among watermelon lines is important in determining the antioxidant potential and thus potential health benefits of different varieties. Unfortunately, current methods to assay total carotenoid content are time consuming and require organic solvents. This report describes a rapid and reliable light absorption method to assay total carotenoid content for yellow-fleshed watermelon that does not require organic solvents. Light absorption of 78 watermelon flesh purees was measured with a diode array xenon flash spectrophotometer that can measure actual light absorption from opaque samples; results were compared with a hexane extraction method. The puree absorbance method gave a linear relationship (R(2)= 0.88) to total carotenoid content and was independent of watermelon variety within the total carotenoid concentration range measured (0 to 7 mug/g fresh weight).