Submitted to: American Bakers Association Agricultural Research Service Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 1999
Publication Date: N/A
Technical Abstract: Three spectral imaging techniques (NMR, MIR and Raman) were used to assess the quality of wheat grains. Each technique provides unique, yet complementary, information. Nuclear magnetic resonance (NMR) imaging was used to detect mobile components such as water and oil in intact or excised parts of wheat grains. Two- and three-dimensional images were obtained that revealed the relative concentration of these components in anatomically distinct regions of the grain. NMR imaging was particularly useful in detecting the degree of water absorption in grains that differ genetically and/or have different environmental histories. It was successfully employed to detect the difference in water absorption in the embryo of dormant and non-dormant grains. The degree to which water penetrates into the bran layer was also observed. The optical imaging methods of mid-infrared (MIR) and Raman were also used. They require cryotoming either thin (6-8 micrometer) or thick (40-80 micrometer) sections, respectively. However, they provide better access to the location of the various chemical components of grains. MIR imaging was used to selectively reveal the locations of lipids, protein, starch and cellulose in and near the aleurone region; plus lipids and aromatics in the pigment strand of wheat grains. Raman imaging was found to be less sensitive for the detection of all components, except aromatics, in these types of tissues. Raman was more sensitive than MIR to presence of aromatics. Thus it was useful for detecting aromatics in the bran wheat grains. Raman imaging the least sensitive to water and thus is the most immune to its interference. The possibility exists for performing all three of the techniques on the same sample.