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Publication no. C-2004-0602-04R
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ARTICLE
Molecular Structure and Some Physicochemical Properties of Buckwheat
Starches.
Yasushi Yoshimoto (1,2), Tamami Egashira (1), Isao Hanashiro (1), Hiroshi
Ohinata (3), Yoshikazu Takase (4), and Yasuhito Takeda (1,5). (1) Department of
Biochemical Science and Technology, Faculty of Agriculture, Kagoshima,
University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan. (2) Present address:
Nihon Starch Co. Ltd., 3-20 Nan-Ei, Kagoshima 891-0196, Japan. (3) Food
Technology Research Institute of Nagano Prefecture, 1-205 Kurita, Nagano
380-0921, Japan. (4) Kirishima Corp., 4-28-1 Shimokawahigashi, Miyakonojo,
Miyazaki 885-8588, Japan. (5) Corresponding author. Phone/Fax: +81-99-285-8641.
E-mail: <takeda@chem.agri.kagoshima-u.ac.jp> Cereal Chem. 81(4):515-520.
Accepted February 25, 2004. Copyright 2004 American Association of Cereal
Chemists, Inc.
The molecular structure and pasting properties of starches from eight buckwheat
cultivars were examined. Rapid viscograms showed that buckwheat starches had
similar pasting properties among cultivars. The actual amylose content was 16–18%,
which was lower than the apparent amylose content (26–27%), due to the high
iodine affinity (IA) of amylopectin (2.21–2.48 g/100 g). Amylopectins
resembled each other in average chain-length (23–24) and chain-length
distributions. The long-chains fraction (LC) was abundant (12–13% by weight)
in all the amylopectins, which was consistent with high IA values. The amyloses
were also similar among the cultivars in number-average DP 1,020–1,380 with
3.1–4.3 chains per molecule. The molar-based distribution indicated that all
the amyloses comprised two molecular species differing in molecular size,
although the weight-based distribution showed a single species. A comparison of
molecular structures of buckwheat starches to cereal starches indicated
buckwheat amylopectins had a larger amount of LC, and their distributions of
amylose and short chains of amylopectin on molar basis were similar to those of
wheat and barley starches.
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