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Multiple measurements of physical properties of cooked rice grains were applied to 55 rice samples with waxy to high amylose contents using a single apparatus (Tensipresser). The multiple measurements consisted of low, high, and continuous progressive compression tests (LC, HC, CPC). The overall hardness (H2) determined by the HC test, and the surface hardness (H1) determined by the LC test, were used as indices to classify the samples into the several groups corresponding to amylose content. The surface hardness was more suitable than the overall hardness for differentiating the effect of protein contents. The difference of stickiness among the cooked rice samples could be detected by the surface adhesion distance (L3) using the LC test. The ratio of elastic limit length (RELL), estimated by the back pressure curve on the CPC test, increased with amylose content. These three tests were meaningful in characterizing the physical properties of cooked rice samples with waxy to high amylose contents.

7he tcrture of six varieties of cooked rice with different atnylose contents was meusured with a Texturometer. Masticatory behavior of the rice was ernluuted using electromyography (EMG) of masticatory muscles. Differences in tnasticution patterns among the seven subjects examined were greater than between rice varieties. Masticatory behavior was more related to the adhesiveness and stickiness cf rice as measured using a Texturometer than to the hardness. The number of chews and masticatory time, total duration of mastication and total muscle activities were highly correlated with each other, and were greater in cooked rice with a high arnylose content, which showed low adhesiveness and stickiness values using a Texturometer. Cooked rice with a high amylose content was masticated with high masseter muscle activities. The ratio of jaw-opening muscle activity to the preceding jaw-closing muscle activity was low in high-amylose varieties, which corresponds to the ratio of stickiness to hardness using a Texturometer. Between-.sample differences in mastication parameters were more apparent in the 'Correspondent: Dr. KCION Kohyama, Food

Three types of rices, namely, Thailand rice (Indica), Nipponbare (Japonica), and Himenomochi (Japonica waxy), in grain, flour, and starch forms have been studied for their thermal and physicochemical properties. In grain form, Indica was slender and Japonica rices were bold and thick. Indica had the highest protein and amylose equivalent. Protein contents in isolated starches varied from 0.2 to 0.9%. Cooked Indica grain was hardest and waxy rice was softest; stickiness was highest in Japonica rice. Glass transition temperature (T(g)) was highest in Indica rice flour (approximately 222 degrees C) and almost the same in Japonica rice flours. Melting point was highest for Japonica (approximately 264 degrees C) and almost the same for Japonica waxy and Indica rice flours. T(g) values of starches were almost the same in Indica and Japonica waxy (approximately 237 degrees C); defatting caused reduction in this property in all of the starches. Highest melting point was shown by Indica starch (approximately 276 degrees C) and was almost the same for the other two starches. Protein and fats play a critical role in glass transition and melting points of rice flours and their respective starches. Viscosities of the cooked pastes of flour and starch during cooking in an RVA instrument and their gel and other properties have been discussed.

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Nondestructive analysis of water distribution and structural changes in cooked rice grains, Oryza sativa cv Koshihikari, was performed with Nuclear Magnetic Resonance (NMR) Micro imaging of protons ( 1 H). Using a specially designed holder, high quality images of cooked rice grains were obtained, even when up to 10 grains were studied simultaneously. Internal hollows were observed in all examined cooked rice grains, and we propose a mechanism to explain their formation. The origin of these hollows was hypothesized to be cracks or fissures, and hollows resulted from sealing of such lacerations by gelatinized starch in the peripheral layer in combination with expansion of the grain during cooking.

Fisheries 3-1-1, Kannondai, Multiple physical measurements of individual cooked rice grain were carried out to make clear the relationship between components or eating quality of rice and physical properties of cooked rice, using japonica rice for general use as samples.Three kind of tests such as low compression test (compression ratio: 25%), high compression test (90%) and continuous progressive compression test (CPC test) were adopted as multiple physical measurements. The overall hardness on high compres siontest had a higher single correlation with amylose content than the surface hardness on low compression test. On the other hand, the Elastic limit length on CPC test indicated a correlation coefficient at 1% significant with amylose content.The estimation formulas based on physical properties of cooked rice for each test were made by multiple regression analyses to predict overall, stickiness, and softness on sensory evaluation. It was shown that the formula on low compression test gave a highest multiple correlation coefficient with predicted values of overall and stickiness on sensory evaluation for unknown samples among these three tests. Further, it was made clear that two parameters (peak -H1 and distance L3) related to stickiness of surface layer of cooked rice grain on low compression test were important as indices to evaluate stickiness of cooked japonica rice grains corresponded to sensory test by the instrumental measurement.

Microbial load and quality of rice grains which were exposed to electrons at different acceleration voltages of 170 to 200 kV were examined to evaluate the efficacy of decontaminating rice with low-energy electrons. Electrons at any acceleration voltage between 170 and 200 kV reduced microbial loads of brown rice grains to levels lower than 10 colony-forming units (CFU)/g. Higher acceleration voltages resulted in a lower viscosity and a higher thiobarbituric acid value (TBA). Milling at a yield of 90 or 88% after electron treatment made the viscosity and TBA of rice treated with electrons at 170 kV almost the same as untreated rice. Low and high compression analyses of rice grains which were exposed to electrons at 170 to 180 kV and milled at a yield of 90% followed by cooking showed almost the same hardness and stickiness as untreated grains which were milled at 90%. The results indicate that milling at a yield of 90% or lower removes the portion of rice exposed to electrons at 170 kV and that treatment of brown rice with low-energy electrons enables the preparation of milled rice with extremely low levels of microbial load and little quality deterioration.