PROGRESS IN THE ELUCIDATION OF THE COMPOSITION OF CHICORY INULIN

The structure of inulin is often described as a polydisperse 1-kestose based linear beta(2->1) fructan chain. The mentioning of 1-kestose (1-fructosylsucrose) implies that all inulin molecules necessary would have a terminal glucose unit. The structure of ''native' inulin, as well as of some commercial preparations, was elucidated by means of specific NMR, HPLC, HPAEC and CGC methods, combined with permethylation techniques. It thus was shown that inulin, independent of its origins, is basically a polydisperse very slightly beta(2->6) branched beta(2->1) fructan molecule, with an average DP which is very much dependent on the plant source, and also on the moment of harvesting this plant. In native inulin, most of the molecules have a terminal glucose unit (GF(n)). It was consequently observed however that a small fraction (F(m)) does not contain any glucose units at all. The preparation of pure oligosaccharides and the quantitative determination of the high-DP-fractions still remains a challenge.