Nucleic acid molecules are described encoding proteins with the enzymatic activity of a fructosyl transferase. These enzymes are fructosyl transferases (FFT). Moreover, vectors and host cells are described containing the nucleic acid molecules of the invention, in particular transformed plant cells, plant tissue and plants regenerable therefrom, which express the described FFT. Furthermore, methods for the production of long-chain inulin by using the described proteins, hosts, in particular the plant cells and/or FFT produced by them, are described.