食・健康とレオロジー

Abstract

The importance of rheological study in food and health is discussed in relation with the texture and mouthfeel of foods. Concepts of elastic modulus for solid foods, and viscosity for liquid foods are not sufficient to describe diverse textures of foods, and it is necessary to measure viscoelasticity and fracture behaviour of foods. The reason why the texture is more important in solid foods than in liquid foods is discussed. Rheological behaviours of inhomogeneous foods such as cooked rice and carrots are also described. The rheology of hyaluronan, the main component of synovial fluid, is introduced because elderly persons have serious problems such as arthritis. Then, the typical frequency dependence of complex modulus in foods is explained, and rheological monitoring in food processing such as gelling processes of tofu and konjac as well as retrogradation of starch are described. Since the diversity of foods is necessary to improve the quality of life in ageing society, the texture control is urgently required. Some examples of rheological control of texture by hydrocolloids mainly by polysaccharides are discussed. Temperature dependence of food gels is discussed. Rheological change of foods in mastication and deglutition process is discussed and rheological control of digestion and absorption process using hydrocolloids is also described.