Cooked muscle tissue of five fish species were observed by optical and scanning electron micrography. Species with firm texture had thin muscle fibers with considerable heat-coagulating material between them; species having soft texture had thick muscle fibers with little heatcoagulating material. When the cooked muscles were compressed by a Texturomcter, muscle fibers of the species having firm texture slid or shifted over one another to a lesser extent than those of species with soft texture. The heat-coagulating material seemed to obstruct the disolacement of the fibers. The diameter and mobilitv of muscle fibers are determinative of firmness of fish muscle tissue:

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The perceptibility of grittiness and the threshold value of grittiness were examined in five disperse model systems: aqueous suspensions, low and high viscous suspensions, and soft and hard gels. Fourteen types of microcrystalline cellulose were used having different particle sizes (between 6–79 μm) and physical properties (shape, degree of polymerization, and state at the material stage). In each system, the proportion of people who perceived grittiness increased with increasing particle size and decreased with increasing particle concentration demonstrating that perception of grittiness depended on both particle size and concentration. The proportion of people who perceived grittiness was found by multiple regression analysis to have a high correlation with the logarithm of (particle size × concentration). Each system gave an approximate regression equation representing this relation. The value of particle size × concentration at the grittiness threshold was defined as the point where 50% of people perceived grittiness. These values were calculated to be 6.0 (aqueous suspension). 19.7 (low viscosity), 26.7 (high viscosity suspension), 30.7 (soft), and 42.1 (hard gel). The factor contributing most to grittiness was concentration, followed by dispersion medium and particle size. The proportion of people who perceived grittiness was also expressed by a multiple regression equation which included these three factors. The obtained results suggest the possibility of predicting and controlling grittiness in foods.