Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2000
Publication Date: N/A
Interpretive Summary: Rice is traded all over the world and objective methods are needed to evaluate quality. All too often premiums and penalties are assessed on the basis of preferences. Near Infrared (NIR) spectroscopy is used to measure composition on a routine basis, but other spectroscopies could also be useful or even superior in some cases. This study compared NIR, Raman and NMR spectroscopy to see what parameters are best measured by each. Raman and NIR are very complementary for normal compositional analyses, while NMR can yield information about the ratio of 1-4 to 1-6 linked glucans, i.e., the ratio of amylose to amylo-pectin and chain length. These basic studies will provide the information need to determine what simple sensors can be developed for rice quality assessment.
Technical Abstract: Three types of spectroscopy were used to examine rice quality, Near infrared (NIR), Raman, and proton Nuclear Magnetic Resonance (**1H NMR). A total of 96 rice cultivars comprised the 96 samples tested. Protein, amylose, transparency, alkali spreading values, whiteness and milling degree were measured by standard techniques and the values regressed against NIR and Raman spectra data. The NMR spectra were used for a qualitative/semi-quantitative assessment of the amylose, amylo-pectin ratio by determining the 1-4 to 1-6 ratio for glucans. Protein can be measured by almost any instrument in any configuration because of the strong relationship between the spectral response and the precision of the reference method. Amylose has an equally strong relationship to the vibrational spectra, but its determination by any reference method is far less precise, thus an increase in the SECv or SEP of almost an order of magnitude with R**2's equal to that of the protein measurement.