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DOI: 10.1094/CC-83-0143
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ARTICLE
Structural and Retrogradation Properties of Rice Endosperm Starch Affect Enzyme
Digestibility of Steamed Milled-Rice Grains Used in Sake Production.
Masaki Okuda (1,2), Isao Aramaki (1), Takuya Koseki (1), Naoyoshi Inouchi (3),
and Katsumi Hashizume (1). (1) National Research Institute of Brewing, 3-7-1,
Kagamiyama, Higashihiroshima 739-0046, Japan. (2) Corresponding author. Mailing
address: National Research Institute of Brewing, 3-7-1, Kagamiyama,
Higashihiroshima 739-0046, Japan. Phone: +81-82-420-0812. Fax: +81-82-420-0803.
E-mail: <okuda@nrib.go.jp> (3) Department of Applied Biological Science, Faculty
of Life Science and Biotechnology, Fukuyama University, 1, Sanzo, Gakuen-cho,
Fukuyama 729-0292, Japan. Cereal Chem. 83(2):143-151. Accepted September 22,
2005. Copyright 2006 AACC International, Inc.
Structural and physicochemical characteristics of endosperm starch from milled
rice grains of seven Japanese cultivars used in sake production were examined.
Amylose content was 15.2–20.2%, number-average degree of polymerization (DP(n))
of amylose was 900–1,400, and the ratio of short-to-long chain amylopectin was
2.7–3.5, respectively. The degree of retrogradation of purified starch stored
for seven days at 4°C after gelatinization was
20–31%. The degree of retrogradation correlated negatively with the ratio of
short-to-long chain amylopectin. The effect of holding time after steaming on
enzyme digestibility and starch retrogradation of steamed rice grains was
investigated. The longer the holding time after steaming, the greater the extent
of retrogradation, and the less the degree of enzymatic digestibility. The
decreased rate of enzyme digestibility correlated with amylopectin chain length
distribution. Samples with short-chain amylopectin exhibited a slow decrease in
enzyme digestibility. It was determined that the structure and retrogradation
properties of endosperm starch in Japanese rice cultivars affect the decreasing
rate of enzyme digestibility of the steamed, milled rice grains.
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