The Igusa has strong scum and is not well suited for consumption, but by boiling it in water for 3 minutes the palatability could be enhanced. Dietary fiber contents of Igusa are very high level (63g/100 g-dry weight) in 14 kinds of agricultural products. The antibiotic showed a broad spectrum of activity (MIC; 0.78-100μg/ml) . The bacterial population in a cake (Igusa-free), which have been preserved for 3 days at 30°C, is about 2 orders more than that supplemented with Igusa at a concentration of 40g/100g-cake. The bacterial population in tofu preservative (Igusa-free), which has been kept for 4 days at 15°C, is about 2 orders more than that supplemented with Igusa at a concentration of 0.lg/ml. Consequently, it is thought that Igusa can be used as a keeping quality agent for the purpose of inhibiting bacterial proliferation. Igusa had a superoxide radical scavenging activity of 4200 units/g. In the future, we consider that use of Igusa may be spread from health food industry to medical industry, and should advance in demand for the depressed Japanese Igusa industry by creating a new industry in addition to Tatami mat.

View full abstract

Shrinkage of biological materials during drying takes place simultaneously with moisture diffusion and may affect the moisture removal rate. Hence, the drying model considering of shrinkage phenomena is important for the estimation of the drying rate and design of driers. In this study the objective is to develop a drying model that takes into account shrinkage deformation in visoelastic food accompanying changes in moisture content. Using drying potato sample formed cylindrically, the elasticity and viscosity coefficient were obtained with a stress-relaxation experiment by a generalized Maxwell's model. A model of simultaneous heat and moisture transfer in a cylindrical sample was coupled with the virtual work principle applicable to a body undergoing shrinkage deformation. Nonconstant physical and thermal properties were also incorporated in the model. Governing equations and boundary conditions were solved numerically using Galerkin's finite element method. Comparison between experimental results and predicted ones provides satisfactory agreement.

View full abstract