The products formed by a fructan [ratio ] fructan fructosyltransferase (FFT) activity purified from Lolium rigidumGaudin were identified after gas chromatography-mass spectrometry of partially methylated alditol acetates,electrospray ionization-mass spectrometry and reversed-phase high-performance liquid chromatography. TheFFT activity synthesized oligofructans up to degree of polymerization (DP) 6, but did not synthesize fructans ofDP > 6 even when assayed with (1,1,1)-kestopentaose for up to 10 h. The FFT activity when assayed with 1-kestose or 6G-kestose synthesized fructan with fructosyl residues almost exclusively linked by β-2,1-glycosidiclinkages. When assayed with 1-kestose, the FFT activity synthesized tetrasaccharides and pentasaccharides withan internal glucosyl residue. The predominant tetrasaccharide was (1&6G)-kestotetraose and the predominantpentasaccharide was (1&6G,1)-kestopentaose. By comparison, tetrasaccharides and pentasaccharides extractedfrom L. rigidum also contained predominantly β-2,1-glycosidic linked fructans with an internal glucosyl residue.The only exception was that one of the pentasaccharides contained β-2,1- and β-2,6-glycosidic linked fructosylresidues. This pentasaccharide was not synthesized by the FFT activity. The role of this FFT activity in formation of oligofructans in L. rigidum is discussed.