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Title: A rapid hexane-free method for analyzing total carotenoid content in canary yellow-fleshed watermelon

Author
item Davis, Angela
item Collins, Julie
item Fish, Wayne
item Webber Iii, Charles
item Perkins Veazie, Penelope
item TADMOR, YAAKOV - NEWE YA'AR RES.CTR.ISRAEL

Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2006
Publication Date: 9/15/2006
Citation: Davis, A.R., Collins, J.K., Fish, W.W., Webber III, C.L., Perkins Veazie, P.M., Tadmor, Y.K. 2006. A rapid hexane-free method for analyzing total carotenoid content in canary yellow-fleshed watermelon. In: Cucurbitaceae 2006, September 17-21, 2006, Asheville, North Carolina. p. 545-552.

Interpretive Summary: Lycopene is the compound that makes red watermelon red and pro-lycopene is the main pigment in orange watermelon. However, yellow watermelons contain many different pigmented compounds, all in low to trace amounts. Since these pigmented compounds, known as carotenoids, have antioxidant properties and potential health benefits, selecting varieties with high concentrations of these valuable pigments is important for breeding lines. Unfortunately, current methods to assay for carotenoid content are time consuming and require hazardous chemicals. This report discusses a rapid and reliable method to assay carotenoid content for yellow watermelon that does not require hazardous chemicals. Sixty seven watermelons were used in this study to demonstrate the reliability of this new method.

Technical Abstract: Lycopene is the predominate carotenoid in red watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) and pro-lycopene is the predominant carotenoid in most orange watermelon. However, yellow watermelons contain many different carotenoids, all in low to trace amounts. Since carotenoids have antioxidant properties and potential health benefits, selecting varieties with high concentrations of these valuable pigments is important for breeding lines. Unfortunately, current methods to assay total carotenoid content are time consuming and require organic solvents. This report discusses a rapid and reliable light absorption method to assay total carotenoid content for yellow watermelon that does not require organic solvents. Light absorption of 67 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=0.85) to total carotenoid content and was independent of watermelon variety within the total carotenoid concentration measured (0 ug/g to 7 ug/g fresh weight).