Bulbs of onion (Allium cepa L. cv. Tenshin) were harvested at the experimental farm of Rakuno Gakuen University on 28 July 2002. The dry outer scales were removed and bulbs were stored at −40°C until use. All the experiments were performed in triplicate. Standard sugars were prepared as follows. Crystalline 1-kestose (3a: 1F-β-d-fructofuranosylsucrose, 1-kestotriose) and nystose (4a: 1F(1-β-d-fructofuranosyl)2 sucrose, 1,1-kestotetraose) were prepared from sucrose using a Scopulariopsis brevicaulis enzyme (Takeda et al., 1994). Neokestose (3b: 6G-β-d-fructofuranosylsucrose, 6G-kestotriose) and 1F(1-β-d-fructofuranosyl)m-6G(1-β-d-fructofuranosyl)n sucrose (4b: m = 0, n = 2 (1,6G-kestotetraose); 4c: m = 1, n = 1 (1 and 6G-kestotetraose); 5a: m = 3, n = 0 (1,1,1-kestopentaose); 5b: m = 0, n = 3 (1,1,6G-kestopentaose); 5c: m = 2, n = 1 (1,1 and 6G-kestopentaose); 5d: m = 1, n = 2 (1 and 1,6G-kestopentaose); 6b: m = 0, n = 4 (1,1,1,6G-kestohexaose); 6c: m = 3, n = 1 (1,1,1 and 6G-kestohexaose); 6d1: m = 1, n = 3 (1 and 1,1,6G-kestohexaose); 6d2: m = 2, n = 2 (1,1 and 1,6G-kestohexaose); 7: m+ n = 5; 8: m + n = 6; 9x: m+ n = 7) were obtained from asparagus roots as described in previous papers (Shiomi et al., 1976, 1979; Shiomi, 1981). 1F(1-β-d-Fructofuranosyl)m sucrose (6a: m = 4 (1,1,1,1-kestohexaose) and 7a: m = 5 (1,1,1,1,1-kestoheptaose)) were prepared from Jerusalem artichoke tubers. Fructan nomenclature is not simple since the structures are very complex; the nomenclatures for fructo-oligosaccharides proposed by Lewis (1993) and Waterhouse & Chatterton (1993) were also used herein.