Tuber Composition

The tubers of Jerusalem artichoke typically comprise about 80% water, 15% carbohydrate, and 1 to 2% protein. Data on the composition of Jerusalem artichoke are relatively sparse in comparison to other vegetables, however, and significant variation has been recorded for certain parameters. Differences in cultivar, time of harvest, production conditions, postharvest treatment, and preparation methods most likely account for this variation (Table 5.1). 

Jerusalem artichoke tubers contain little or no starch, virtually no fat, and have a relatively low calorific value. Of the small amount of fat present, trace amounts of monounsaturated and polyunsaturated fatty acids have been reported, but no saturated fatty acids (Whitney and Rolfes, 1999). The polyunsaturated fatty acids linoleic (18 2 cis, cis n-6) and a-linoleic acid (18 3 n-3) have been recorded as present at 24 mg and 36 mg-100 g 1 of raw tuber, respectively (Fineli, 2004). The tubers are a good source of dietary fiber, because of the presence of inulin. 

The protein in Jerusalem artichoke tubers comprises around 1.6 to 2.4 g-100 g 1 of fresh weight (Table 5.1). Protein and nitrogen levels remain relatively constant in the tubers during development (Kosaric et al., 1984). Tuber protein contains all the essential amino acids in favorable proportions. It is rich in lysine and methionine, in comparison to proteins of other root and tuber crops, and is 

Biology and Chemistry of Jerusalem Artichoke Helianthus tuberosus L. 

Composition of Jerusalem Artichoke Tubers (per 100 g Fresh Weight) 

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Figure 10.6. Extraction of potato tuber composite. MeOH. pieihiinpl EtOAc. ethyl acetate.

Tubers Tubers are quite commonly consumed by villagers in Burma. Other tropical countries also report sporadic use of winged bean tubers (59). However, in comparison to the available data on the nutrient, anti-nutrient composition and the protein quality of the seed flour, published data on the nutritional value of winged bean tuber is somewhat limited. The few reported studies dealing with a larger number of varieties grown in different locations (25,67-71) show that tubers are mainly composed of protein and carbohydrates. 

Chemical composition of winged bean tubers grown in different countries... 

The wild species form a polyploid series from diploid (2n = 2x=24) to hexaploid (2n = 6x = 72) in which genomes were classified into five groups A, B, C, D and P by Matsubayashi (1991), with a sixth group E recognized in closely related non-tuber-bearing species. Spooner et al. (2004) summarized the putative genome compositions of the polyploid species, but it is clear... 

Dufresne, A., Dupeyre, D., Vignon, M. R. (2000). Cellulose microfibrils from potato tuber cells processing and characterization of starch-cellulose microfibril composites. J. Appl Polym. Scl, 76,2080-2092. 

Hoover, R. (2001). Composition, molecular structure, and physicochemical properties of tuber and root starches a review. Carbohydr. Polym., 45, 253-267. 

Yusuph, M., Tester, R. F., Ansell, R., Snape, C. E. (2003). Composition and properties of starches extracted from tubers of different potato varieties grown under the same environmental conditions. Food Chem., 82,283-289. Zhu, Q., Bertoft, E. (1996). Composition and structural analysis of alpha-dextrins from potato amylopectin. Carbohydr. Res., 288, 155-174. 

Overall protein composition - potato tuber proteome... 

Bergenstrahle, A., Borga, P, Jonsson, L. (1996). Sterol composition and synthesis in potato tuber discs in relation to glycoalkaloid synthesis. Phytochemistry, 41, 155-161. 

Kolbe, H., Stephan-Beckmann, S. (1997). Development, growth and chemical composition of the potato crop (Solarium tuberosum L.). II. Tuber and whole plants. Potato Res., 40, 135-153. 

Mehta, A., Singh, S. P. (2004). Biochemical composition and chipping quality of potato tubers during storage as influenced by fertilizer application. J. Food Sci. TechnoL, 41, 542-547. 

Galliard, T. (1973). Lipids of Potato Tubers 1. Lipid and Fatty Acid Composition of Tubers from different varieties of Potato. Journal of the Science of Food and Agriculture, 24, 617-622. 

Millard, P. (1986). The nitrogen content of potato (Solanum tuberosum L.) tubers in relation to nitrogen application -the effect on amino acid composition and yields. Journal of the Science of Food and Agriculture, 37,107-114. 

Sharma, M. K., Isleib, D. R., Dexter, S. T. (1959). The influence of specific gravity and chemical composition on the hardness of potato tubers after cooking. Am. Potato J., 36, 105-112. 

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