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Title: TWO DIMENSIONAL VIBRATIONAL SPECTROSCOPY VI: RICE QUALITY AND COOKING

Author
item BARTON II, FRANKLIN
item HIMMELSBACH, DAVID
item MCCLUNG, A. - USDA-ARS-RRU
item CHAMPAGNE, E. - USDA-ARS-SRRC

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2001
Publication Date: 9/1/2002
Citation: BARTON II, F.E., HIMMELSBACH, D.S., MCCLUNG, A.M., CHAMPAGNE, E.L. TWO DIMENSIONAL VIBRATIONAL SPECTROSCOPY VI: RICE QUALITY AND COOKING. CEREAL CHEMISTRY. 2002. V. 79(1). P. 143-147.

Interpretive Summary: The "cooking quality" of rice is highly valued in the countries to which we export our rice. The only way to test it is to cook it. We had shown some time ago what happen to rice during cooking by Magnetic Resonance spectroscopy. This involves the use of instrumentation that is expensive and not readily available in the vast majority of agricultural laboratories. By using vibrational spectroscopy and 2 dimensional analysi we can visualize the components and the important correlations to cooking quality. The study demonstrates that minor components such as free fatty acids and minor proteins can have a significant effect on cooking. These studies will become part of an analysis scheme to determine end use properties of grains from their spectra.

Technical Abstract: Rice samples were taken from a study of rice milling properties which effect quality and were used by a sensory panel for taste and texture. The spectra of milled and cooked samples were taken in the near infrared, mid- infrared and Raman region. These spectra, two regions at a time, were regressed by a two dimensional technique to develop contour maps which indicated the regions of the two spectral regions which were related. Thes relationships demonstrate that it is possible to recognize the hydration effects caused by gelatinization, i.e., cooking from samples that have been cooked in comparison to the milled rice. All three water (O-H stretch) spectral bands, 960, 1445, 1930 nm in the near infrared (NIR) show marked differences between milled and cooked rice. The difference spectra indicated that there were additional phenomena occurring other than the addition of water. These differences are apparent in both C-O-H and N-H bands indicating the water is interacting with both starch and protein. Th two dimensional technique developed in this laboratory was used to get a better interpretation of what occurs during cooking. The Raman spectrum which is relatively insensitive to water (O-H stretch) revealed only changes in protein which could be associated with denaturization.