Abstract
In the present study, we applied the multiple measurements of physical properties of individual cooked rice grains to the rice samples with different protein contents. Japonica rice cultivars (Hinohikari, Reiho, Yumehikari) were cultivated in the six experimental plots with different nitrogenous fertilizer application. The subject of our study was to establish a method based on the physical properties to discriminate clearly the effects of nitrogenous fertilizer on the protein contents and the palatability. The kinds of compression tests were carried out as multiple measurements. The overall hardness based on the high compression test (compression ratio:90%) was shown to differ with the rice cultivar rather than with the fertilizer condition. On the other hand, the surface hardness based on the low compression test (25%) was shown to have a positive correlation with the protein contents. The surface hardness could distinguish the difference of protein contents among the rice samples of the same cultivar. With the increase of total quantity of the nitrogen fertilizer applied, the surface hardness increased and the "overall evaluation" by the sensory test decreased. The ratio of stickiness and hardness and hardness on the middle compression test (45%) had a higher correlation with the "overall evaluation" than the protein contents. Therefore, it was clarified that the method based on the physical properties could discriminate the effect of the nitrogenous fertilizer on the protein contents and the palatability.
