We investigated the morphological characteristics and food functionalities of seven cultivar of Okinawan Welsh onions (Allium spp. 'Tsuken', 'Ginowan', 'Nakagusuku', 'Taketomi', 'Haneji', 'Bise', and 'Makabe') and cultivars of two other Welsh onions (Kujyo and Nagasaki of Kyoto and Nagasaki Prefectures, respectively) as controls. Further, their volatile aroma compounds were examined using gas chromatography (GC) and GC-mass spectrometry. Among the tested Welsh onions, only Tsuken, Ginowan, and Kujyo showed flower-bud formation with wide leaf sheath diameter (Type I). Among the Welsh onions, excluding the Type I cultivars, Nakagusuku, Taketomi, and Nagasaki were confirmed to have a dormant season (Type II), while the remaining three cultivars (Haneji, Bise, and Makabe) had no such dormant season (Type III). The volatile aroma compounds of all the tested cultivar samples consisted of four functional groups: primary thiols, sulfides, alcohols, and aldehydes. Two-dimensional principal component analysis was used to assess the relative concentrations of the four functional groups to classify the aroma characteristics; the classified compounds were found to be closely related to the morphological characteristics, except for those of Makabe. Further, to evaluate the food functionalities, the total polyphenol contents and antioxidant activities of the Welsh onions were determined. All the samples contained a polyphenol and showed antioxidant activities,; however, the activities had little association with each morphological characteristic of the seven cultivars.
