Jerusalem artichoke fructans

The term inulin first appeared in the literature in 1818 (Thomson, 1818), predating the discovery of fructose by about 30 years. It was ascribed to a substance, first isolated from elecampagne (Inula helenium L.) in 1804 (Rose, 1804). Jerusalem artichoke was first recorded as a source of inulin in around 1870. The actual linear structure of the molecule was not elucidated until the 1950s, and the small degree of branching that can occur only in the mid-1990s (De Leenheer and Hoebregs, 1994). As a polymer of fructose, inulin is classified as a fructan of which there are several types... 

Aravina, L.A., Gorodetskii, G.B., Ivanova, N.Y., Komarov, E.V., Momot, N.N., and Cherkasova, M.A., Extraction of Inulin and Other Fructan-Containing Products from Jerusalem Artichoke and Other Inulin-Containing Raw Materials, Russian Federation Patent 2175239, 2001. 

Malmberg, A. and Theander, O., Differences in chemical composition of leaves and stem in Jerusalem artichoke and changes in low-molecular sugar and fructan content with time of harvest, Swed. J. Agric. Res., 16, 7-12, 1986. 

Schubert, S. and Feuerle, R., Fructan storage in tubers of Jerusalem artichoke characterization of sink strength, New Phytol., 136, 115-122, 1997. 

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). 

Fructans and fructose extracts, which can potentially be obtained from Jerusalem artichoke, have become attractive to industry for a number of food and nonfood applications because of their health benefits (e.g., Fleming and GrootWassink, 1979 Fontana et al., 1993 Fuchs, 1993 Roberfroid, 2005). Short-chain fructooligosaccharides (degree of polymerization of 2 to 5), for example, are increasingly used as low-calorie sweeteners in processed foods, and their utilization is anticipated to expand significantly in the future. 

Barta, J. and Patkai, G., Complex Utilisation of Jerusalem Artichoke Plant in Animal Feeding and Human Nutrition, 2000, http //didimi.cyberlink.ch/fructan/pubhc/abstracts/. 

Rumessen, J.J., Bode, S., Hamberg, O., and Gudmand-Hpyer, E., Fructans of Jerusalem artichokes intestinal transport, absorption, fermentation, and influence on blood glucose, insulin and C-peptide responses in healthy subjects, Am. J. Clin. Nutr., 52, 675-681, 1990. 

Jerusalem artichoke had a similar methane production potential for repeated cuttings in the Finnish trials, whereas other leafy energy crops assessed, such as giant knotweed (Reynoutria sachalinensis F. Schmidt ex Maxim.) and sugar beet tops (Beta vulgaris L.), had methane potentials that increased at later harvests. Lignin levels were also unusually constant for the tops of Jerusalem artichoke, regardless of maturity, while nonstructural carbohydrates (fructans) increased in the stems... 

Inulin biosynthesis in Jerusalem artichoke occurs via the combined action of two enzymes l-sucrose sucrose fructosyltransferase (1-SST) and l-fructan fructan fructosyltransferase (1-FFT). 1-SST catalyzes the synthesis of inulins of a low degree of polymerization, while 1-FFT catalyzes the synthesis of ffuctans of a degree of polymerization up to 50 (Sevenier et al., 2002a). High... 

Sugar beet has been successfully transformed using Jerusalem artichoke-derived 35s-l-sst and 35s-l-fft constructs, incorporating promoters and selection markers, with fructans accumulating in... 

Soja, G., Dersch, G., and Praznik, W., Harvest dates, fertilization and varietal effects on yield, concentration and molecular distribution of fructan in Jerusalem artichoke (Helianthus tuberosus L.), J. Agron. Crop Sci., 165, 181-189, 1990. 

Fructans in the Jerusalem artichoke are synthesized by the concerted action of two fructosyl transferases that were derived from invertase genes (Van Laere and Van den Ende, 2002). In the initial step (Figure 10.18), the trisaccharide 1-kestose (G-F-F) is synthesized from two sucrose molecules (G-F) in a reaction catalyzed by the enzyme sucrose sucrose fructosyl transferase (SST EC 2.4.1.99). The reaction products are 1-kestose and glucose, and the reaction is essentially irreversible due to the high free energy of hydrolysis (AG = 27.6 kJ-mok1) (Lewis, 1984). 

Three enzymes, sucrose sucrose 1-fructosyl transferase (1-SST), fructan fructan 1-fructosyl transferase (1-FFT), and 1-fructan-p-fructosidase (1-FEH), appear to control fructan polymerization and depolymerization in the Jerusalem artichoke. Each is sequestered in the vacuole of the cells in which they are expressed and has a pH optimum in the acid range (pH 5.0 to 5.5), in keeping with a vacuolar origin (Frehner et al., 1984). 

A relatively small amount of reducing inulo- -oses, fructans without a terminal glucose (Ernst et al., 1996), are formed from fructosyl transfer from inulin to free fructose by 1-FFT. In chicory, they are thought to appear when fructose accumulates during fructan breakdown and 1-FFT activity is still high (Van den Ende and Van Laere, 1996). A similar mechanism is probably operative in Jerusalem artichoke and responsible for the small amounts of inulo- -oses formed (Saengthongpinit and Sajjaanantakul, 2005). 

Darwen, C.W.E. and John, P., Localization of the enzymes of fructan metabolism in vacuoles isolated by a mechanical method from tubers of Jerusalem artichoke Helianthus tuberosus L.), Plant Physiol., 89, 58-663, 1989. 

Frehner, M., Keller, F., and Wiemken, A., Localisation of fructan metabolism in the vacuoles isolated from protoplasts of Jerusalem artichoke tubers Helianthus tuberosus L.), J. Plant Physiol., 116, 197-208, 1984. 

Marx, S.P., Nosberger, J., and Frehner, M., Seasonal variation of fructan- 3-fructosidase (FEH) activity and characterization of a P-(2-l)-linkage specific FEH from tubers of Jerusalem artichoke (Helianthus tuberosus), New Phytol., 135, 267-277, 1997. 

Monti, A., Amaducci, M.T., and Venturi, G., Growth response, leaf gas exchange and fructans accumulation of Jerusalem artichoke (Helianthus tuberosus L.) as affected by different water regimes, Eur. J. Agron.,... 

Noel, G.M. and Pontis, H.G., Involvement of sucrose synthase in sucrose synthesis during mobilization of fructans in dormant Jerusalem artichoke tubers, Plant Sci., 159, 191-195, 2000. 

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