Oligofructose Guide

Two different classes of fructooligosaccharide (FOS) mixtures are produced commercially, based on inulin degradation or transfructosylation processes.

FOS can be produced by degradation of inulin, or polyfructose, a polymer of D-fructose residues linked by β(2-1) bonds with a terminal α(1-2) linked D-glucose. The degree of polymerization of inulin ranges from 10 to 60. Inulin can be degraded enzymatically or chemically to a mixture of oligosaccharides with the general structure Glu-(Fru)n (GFn) and Frum, (Fm), with n,m ranging from 1 to 7. This process also occurs to some extent in nature, and these oligosaccharides can be found in a large number of plants, especially in Jerusalem artichoke and chicory. This type of FOS is mainly marketed commercially by Orafti Ltd., Tienen Belgium, which markets the product as Oligofructose (or Raftilose). The company also markets inulin as oligofructose. Other producers include the Dutch company Cosun (which markets the product as Frutafit or Frutalose) and others. The main components of this class are kestose (GF2), nystose (GF3), fructosylnystose (GF4), bifurcose (GF3), inulobiose (F2), inulotriose (F3), and inulotetraose (F4).

The second class of FOS is prepared by the transfructosylation action of a β-fructosidase of Aspergillus niger on saccharose. The resulting mixture has the general formula of GFn with n ranging from 1 to 5. Contrary to the inulin derived FOS, the binding is not only β(1-2), but other linkages do occur, though in limited numbers. This class is mainly produced in Japan by Meiji Seika Kaisha [2].

Because of the configuration of their osidic bonds, fructooligosaccharides resist hydrolysis by salivary and intestinal digestive enzymes. In the colon they are fermented by anaerobic bacteria. In other words, they have a lower caloric value, whilst contributing to the dietary fiber fraction of the diet. Fructooligosaccharides are more soluble than inulins and are therefore sometimes used as an additive to yoghurt and other (dairy) products. Fructooligosaccharides are used specially in combination with high-intensity artificial sweeteners, whose sweetness profile and aftertaste it improves....