17C-22 |
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K. S. KIM1, H.-J. Kang2, I.-K. Hwang2, H.-G. Hwang3, T. Y. Kim3, and H.-C. Choi3. (1) Genetic and breeding, National Institute of Crop Science. R.D.A., 151, Seodun-dong Gwonseon-gu, Suwon, 441-857, South Korea, (2) Department of Food and Nutrition, Seoul National University, 13-425, 56-1 Shilim-dong, Kwanak-Gu, Seoul, Seoul, 151-742, South Korea, (3) Rice Genetic and Breeding Division, R.D.A., 250 Seodun-dong, SUWON, 441-857, South Korea A new rice variety Suweon 464 (S-464) developed from a high-quality japonica rice, Ilpumbyeo (IP), revealed extreme differences in cooking quality, physicochemical properties and the content of basic components. The objective of this study is to determine how the differences existing between the two would reflect in ultrastructure of endosperm cells in situ and isolated starch granules. For SEM, the midregion of whole grains and isolated starch granules were viewed whereas for TEM, starch endosperm of 20 DAF were prepared by a conventional method. In SEM, IP starch granules, in intercellular cleavage planes, were embedded in the matrix material made presumably of the remains of degenerating cytoplasmic constituents (cytosol + organelles). Large compound starch granules of IP were readily splitted during fracturing exposing clustered individual starch granules within them in intracellulary cleaved cells. In S-464, compound starch granules were enclosed within a sac-like structure tolerant to fracturing, retaining their structural integrity. In isolated preparation, IP starch consisted entirely of individual starch granules whereas S-464 consisted mostly of large compound starch granules still enclosed within the sac apparently survived the harsh treatments received during the isolation process preventing the release of the individuals. In TEM, S-464 starch granules, solidly condensed in appearance, were highly contrasted by the presence of intergranular spaces whereas those in IP, fluffy in appearance, were tightly appressed each other causing some of them to fuse with adjacent ones. The boundary of amyloplasts and starch granules were coated by a thin proteinaceous layer, presumed to be the counterpart of the sac that encloses the compound granules observed in SEM. The capability of retaining structurally intact compound starch granules after the various harsh treatments, fracturing and isolation process appeared to be unique to S-464, and it may be a major determinant in the contribution to its characteristic physicochemical properties.
Session 17C, Food Chemistry: Cereals, grains, legumes and their products
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