NMR imaging investigation of rice cooking

The visualization and quantification of the cooking of rice by NMR imaging is reported for Japonica rice (Oryza sativa. L. Japonica cv. Nipponbare) as a test sample. Rice was cooked in a vial for various times and then studied at room temperature by NMR imaging. The multi slice multi echo method was employed to obtain two-dimensional proton images. Images using only the first echo clearly revealed the changes in the water content of the rice grains during cooking. T2 images were obtained from the same experiments but using the first 16 echoes and converted to images of the water distributions using an empirical T2 vs. water content calibration determined from a series of reference water/rice starch mixtures. The total limiting water content within the rice grains was calculated and it agreed with that calculated from the known water/rice ratio used, indicating that both the concentration and distributions of water within the rice grains during cooking obtained from the NMR imaging were quantitatively reliable.