Environmental factors that affect the ability of amylose to contribute to retrogradation in gels made from rice flour

Philpot, Kim, Martin, Margrit, Butardo, Vito Jr., Willoughby, Doug and Fitzgerald, Melissa (2006) Environmental factors that affect the ability of amylose to contribute to retrogradation in gels made from rice flour. Journal of Agricultural and Food Chemistry, 54 14: 5182-5190. doi:10.1021/jf060666y

Author Philpot, Kim
Martin, Margrit
Butardo, Vito Jr.
Willoughby, Doug
Fitzgerald, Melissa
Title Environmental factors that affect the ability of amylose to contribute to retrogradation in gels made from rice flour
Journal name Journal of Agricultural and Food Chemistry   Check publisher's open access policy
ISSN 0021-8561
Publication date 2006-07-12
Sub-type Article (original research)
DOI 10.1021/jf060666y
Open Access Status
Volume 54
Issue 14
Start page 5182
End page 5190
Total pages 9
Place of publication United States
Publisher American Chemical Society
Language eng
Abstract Retrogradation in rice is a trait that describes the hardening of cooked rice after storage or cooling, and it has significant implications for many consumers of rice, since many people cook rice in the morning and consume it several hours later or the next day. Tools to select against retrogradation in breeding programs are yet to be described. Here, we aim to determine the effect on retrogradation of storage time and temperature and the role of starch, protein, and lipids using gels made from Koshihikari grown in either Australia or Japan. Immediately after cooking, cooling from 60 to 40°C had a minimal effect on firmness, but cooling to 20°C led to significantly firmer gels. Storing the gels at low temperatures did not have an additional effect on the firmness as compared with storing the gels at 20, 40, or 60°C. The removal of proteins led to significantly softer gels at all storage treatments but did not affect the change in firmness on cooling. The removal of lipids increased the rate of retrogradation and the firmness of gels significantly for all treatments. Koshihikari grown in Japan retrograded much less than Koshihikari grown in Australia. The amount of amylose that could be washed from gels made from Australian flour was much greater than for gels made from Japanese flour. After storage, only low molecular weight amylose chains were released from the gel and only after rewarming them to 60°C. Despite the fact that flours from both origins were 18% amylose, the amount of long amylose chains that were complexed with lipids was much greater for the Japanese rice, and the unavailability of the complexed long amylose chains explained the lack of retrogradation in the Japanese rice. Once the long chains were released from amylose-lipid complexes, the Japanese rice retrograded. Thus, the environmental factor affecting retrogradation in this variety is type or amount of lipids synthesized, and the degree of retrogradation was determined by the availability of long chains of amylose.
Keyword Retrogradation
Eating quality
Amylose-lipid complexes
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
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