Composite inulin

The fact that composite inulin extracts can be fractionated on a commercial scale into reasonably discrete chain length classes allows tailoring of the product to intended market uses. Hence, the chain length condition of the raw product is important in that it is relatively easy to depolymerize inulin to give shorter-chain-length fractions however, current in vivo attempts to create longer-chain-length polymers on an economically viable scale have not been optimistic. 

They prepared the acetate by means of acetic anhydride in dry pyridine and purified it by separation from an acetic acid solution to which warm methyl alcohol had been added n ]n2 = — 22.70° (c = 10, acetic acid), m. p. 206-208°. In the presence of barium hydroxide irisin formed an insoluble product whose composition was represented by 6(C6Hi0O6)-Ba(OH)2. In contrast to inulin, these authors found that Takadiastase at pH 5 to 5.5 did not hydrolyze irisin. 

Difructose anhydride I was first prepared by Jackson and Goergen.18-70 These authors found a molecular weight of 307 for the anhydride and 574 for the acetate, values which indicate its difructose anhydride composition. Almost simultaneously, Irvine and Stevenson71 prepared the acetate of what they believed to be an anhydrofructose by the action of concentrated nitric acid on inulin acetate. This anhydride was later shown72 to be identical with the difructose anhydride I of Jackson and Goergen. Hexamethyldifructose anhydride I waB hydrolyzed by Haworth and Straight7 and the trimethyl-D-fructose that was formed was identified as 3,4,6-trimethyl-D-fructofuranose by quantitative conversion... 

Inulin has no sweetness and possesses a bland taste. Physiologically, inulin behaves as a dietary fibre. At relatively high dose levels (15-40 g/day) it can have a prebiotic effect (i.e. it can selectively promote the growth of beneficial bacteria in the colon) and at high dose levels it may also have a laxative effect (Kolida el al., 2002). This is dependent on the specific composition of the product and the degree of polymerisation, which can vary. The caloric value for inulin is 1 kcal/g. Its use in soft drinks is as a fibre source, prebiotic and partial sugar replacer. 

Inulin was identified as a major (5.9%) component of the roots of E. angustifolia (Heyl and Stanley, 1914). Giger et al. (1989) noted that polymerization of fructans occurred over the course of winter as observed by the reduction in fructose from October and May. The rate of polymerization was faster in E. purpurea than E. angustifolia, suggesting that other polysaccharides may develop in a similar manner. Additional research is needed to identify the effects of harvest time on polysaccharide composition. 

Kiehn, F.A. and Chubey, B.B., Variability in agronomic and compositional characteristics of Jerusalem artichoke. In Inulin and Inulin-containing Crops, Fuchs, A., Ed., Elsevier, Amsterdam, The Netherlands, 1993, pp. 1-9. 

COMPOSITION, STRUCTURE, AND PROPERTIES OF INULIN AND INULIN OLIGOMERS... 

There have been a number of methods developed for the extraction of inulin from Jerusalem artichoke tubers (Aravina et al 2001 Barta, 1993 Ji et al., 2002 Vogel, 1993), a composite of which is illustrated in Figure 5.3. The specific method selected will depend on the end product desired, resources available, volume, and other factors. 

FIGURE 5.3 Flow diagram for the extraction and fractionation of Jerusalem artichoke inulin into various products (a composite of work by Aravina etal., 2001 Barta, 1993 Jietal., 2002 Vogel, 1993). Abbreviations dp = degree of polymerization scFOC = short-chain fructooligosaccharides. 

De Leenheer, L. and Hoebregs, H., Progress in the elucidation of the composition of chicory inulin, Starch/Stdrke, 46, 193-196, 1994. 

To make flour, Jerusalem artichoke tubers are macerated, heated, and spray-dried. In the process, inulin is hydrolyzed to short-chain fructooligosaccharides (Yamazaki et al., 1989). Jerusalem artichoke flour is also used to supplement animal feed. In one study, the composition of a typical Jerusalem artichoke flour was 2.1% (of dry weight) nitrogen, 16.2% insoluble fiber, 4.2% ash, and 77.5% soluble carbohydrate. The carbohydrate comprised fructans with degrees of polymerization of 1 to 2 (33.3%), 3 to 4 (46.4%), and over 5 (20.3%) (Famworth et al., 1993). 

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