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United States Department of Agriculture

Agricultural Research Service

Title: Historical structures of cooked rice grain

Authors
item Ogawa, Yukiharu - FOREIGN RES. ASSOC.
item Glenn, Gregory
item Orts, William
item Wood, Delilah

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2003
Publication Date: November 1, 2003
Citation: Ogawa, Y., Glenn, G.M., Orts, W.J., Wood, D.F. 2003. Historical structures of cooked rice grain. Journal of Agricultural and Food Chemistry. 51:7019-7023.

Interpretive Summary: Whole sections of raw and cooked milled rice grains were compared by microscopy in order to determine the structural changes a grain undergoes during the cooking process. Milled, raw grains contain fine cracks throughout the endosperm and the cooked grains have wider, more defined cracks. The cracks probably serve as channels for water migration into the grain during cooking. Water penetrates unequally into the grain during cooking: low water penetration produces dense regions with minimal starch gelatinzation and high water penetration produces large voided areas. The voids occur in the transverse orientation of the grain and are the main of cause grain expansion during cooking. Using such a method will allow scientists to quickly determine the relationships between kernel cellular components, how the components differ between cultivars, and how the components change during or as a result of processing. The work is expected to expand on the definition and determination of quality attributes in rice.

Technical Abstract: Raw and cooked whole grain sections of milled, medium grain California rice were compared for gross histological and morphological features using fluorescence and scanning electron microscopy (SEM). Cooked and raw grains were compared and the differences assessed by autofluorescence of the cell walls and correlating fluorescence to SEM images. Milled, raw grains contain fine cracks throughout the endosperm. Cooked grains have wider, more defined cracks suggesting that they serve as channels for water migration into the grain during cooking. Water penetrates unequally into the grain during cooking: low water penetration produces dense regions with minimal starch gelatinzation and high water penetration produces large voided areas. The voids occur in the transverse orientation of the grain and are the main of cause grain expansion during cooking.

Last Modified: 12/18/2014
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