Rheological study on the eating process is becoming more and more important with increasing population of handicapped persons having the difficulty in mastication and deglutition. Rheology can also contribute to the development of nutrition science, e.g., understanding the enzymatic digesting process of nutrients, proteins, carbohydrates and lipids. Texture can be modified by using hydrocolloids and this is useful for the food production and cooking because the texture is one of the most important attributes of foods. The importance of texture is also discussed from the viewpoint of eating process. Small deformation oscillatory measurements have been used to under-stand the sol-gel transition which plays a key role in the rheological control of food texture. Temperature dependence of elastic modulus of food gels is also discussed. Rheological properties control not only the texture but also affect the flavour, which is known as a flavour release, and some recent results are discussed. It is necessary to develop the collaborative research among different disciplines, oral physiology, dentistry, food rheology, nutrition science to resolve the problems in the difficulty in mastication and deglutition.

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The measurement method of rheology in food is discussed. The mechanical measurement of food is classified into basic, experimental and simulation methods. By the basic method, fixed values of the viscosity and the elasticity of the basic rheology can be obtained. By the experimental method, the fixed values of the hardness and rupture stress which are related to experimental texture are able to be measured. By the simulation method, the measurement with the instrumental device which imitates process of cooking and mastication is indicated. The measurement in a minute deformation domain is divided into two as follows: static and kinematic viscoelasticity measurement. Creep behavior and stress relaxation behavior in a static method are measured, and delay time and relaxation time also are measured. Creep behavior (activation energy of Dango and creep behavior of Gomatofu), and stress relaxation behavior in a static method are measured, and delay time and relaxation time also are measured. Conversely, the measurement of kinematic viscoelasticity (particle and matrix gel) elucidates a change of aging and denaturation of food. Mechanical properties of a large deformation domain are important since it is compressed and is broken by the mastication while eating. In addition, the preparation of food when it is cooked (pushed, expanded and cut) is directly related to mechanical property of a large deformation domain. In a large deformation domain, the measurement of characteristic texture property, fixed compression rupture stress (particle and matrix gel, nonglutinous rice flour dough) and rheometer (cooked rice, milk jelly, Gomatofu) by instrument measurement are all possible. Furthermore, how to measure of correlation between sensory evaluation and coefficient of elasticity, texture parameter by instrument measurements need to be investigated.

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Fundamental mechanism of myocardial ischemia is myocardial perfusion abnormality. Coronary flow reserve (CFR) has been recognized as a physiological index of the capacity to increase coronary blood flow in response to increased oxygen demand. Therefore, reduced CFR directly reflects impairment of myocardial perfusion. Clinically, positron emission tomography and Doopler guidewire by cardiac catheterization are the common methods to evaluate CFR. However, these methods are relatively expensive or invasive. Recent advance in transthoracic echocardiography has enabled us to measure CFR, especially in the left anterior descending coronary artery territory. This method has been validated by Doppler guidewire and myocardial scintigraphy, and now can be applied for the evaluation of the impairment of coronary microcirculation. CFR measurements by echocardiography is totally noninvasive, reproducible and cost effective, thus would be useful for the assessment of physiological severity of coronary artery stenosis and coronary microcirculatory disorders.

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Liver cirrhosis (LC) is often associated with several hematologic complications, in which anemia is a common feature. Although the exact mechanism of anemia remains controversial, impaired erythrocyte filterability and subsequent hemolysis have been suspected as the causes of anemia associated with LC. We have investigated erythrocyte filterability in relation to the severity of LC. The severity was assessed according to the Child-Pugh classification (grade A, B, and C). The mean erythrocyte filterability of the entire 31 patients with LC (64.6 ± 14.5%) was significantly (P<0.03) decreased compared with that in 5 normal controls (80.5 ± 1.7%). Comparing with the filterability in the controls, the filterability in the LC groups in grade A (70.9 ± 9.6%) was not significantly decreased (p=0.053, n=8), but the filterability in the LC groups in grade B (65.9 ± 11.0%: p < 0.01, n=19) and in grade C (45.9 ± 23.8%: p < 0.02, n=4) were markedly decreased. We found that the impaired filterability reflects the severity of anemia and liver dysfunctions, suggesting that the impairment is one of the causes of anemia. Further, the present study suggested that the impaired filterability arises from the altered erythrocyte membrane properties and a possible mechanical stress due to the accelerated portal hypertension, thus reflecting disorders of the microcirculation.

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