Phytochemical Analysis of Grapefruit Cultivars

High-performance liquid chromatography-photodiode array mass spectrometry (HPLC-PDA-MS) analysis of methanol and water extracts of fresh and steam-exploded Star Ruby, Rio Red, and Ruby Red GP and WG were completed. Water extracts were prepared by taking a 1:3 ratio of deionized water to fresh and steam-exploded Star Ruby, Rio Red, and Ruby Red GP and WG and homogenizing and or blending (Omni International homogenizer, Model GLH-01, Omni International, Marietta, GA, USA or Waring Commercial Blender, Model# 7011S, Waring Commercial, Tarrington, CT, USA). The samples were microcentrifuged, and the supernatants were used for analysis. Methanol extracts were prepared by taking 1.5 g of fresh Star Ruby, Rio Red, and Ruby Red GP or WG and homogenizing (Omni International homogenizer, Model GLH-01, Omni International, Marietta, GA, USA) in approximately 30 ml of methanol. The sample was then vacuum filtered. This was repeated two times more, and the filtered extracts were pooled and brought to 100-ml volume with methanol. A 15 ml portion was dried in a concentrator (SpeedVacConcentrator, SVC 200H, Thermo Scientific, Waltham, MA, USA) and brought to 4 ml with dimethylsulfoxide and was used for analysis. HPLC-PDA-MS analysis of methanol and water extracts of fresh and steam-exploded Star Ruby, Rio Red, and Ruby Red GP and WG was completed as described previously (18 (link)). The flavanones naringin-4′-O-glucoside, hesperidin glucoside, narirutin, naringin, naringin-6”-malonate, isosakuranetinrutinoside, and poncirin were quantified and qualified by UV-Vis at a wavelength of 285 nm. The coumarins dihydroxy-osthol and marmin were quantified and qualified by UV-Vis at a wavelength of 320 nm. Averages of triplicate flavonoid analyses and their SDs were reported. The values used to calculate the averages and SDs can be found in Supplementary Tables 9–13 of the Supporting Information section. A sample chromatogram can be seen in Supplementary Figure 7.