Tamotsu Inoue

Effect of Time-Dependent Humidity Profiles from Air to Superheated Steam on Drying of a Wetted Starch Sphere

The effects of air humidity when drying with superheated steam (SHS) were examined considering displacement by SHS. A wetted raw starch sphere (ball) was used as the model material. It was found that the humidity profile strongly affects the mass change and properties of the products. The material became porous when it was dried with pure SHS from start to finish, which differs both from products dried with high-humidity air alone, and from products dried with air followed by SHS within a few minutes. A prediction method for adiabatic saturation temperature over a wide range of humidity is also proposed.

Effect of Moisture Content on the Expansion Volume of Popped Amaranth Seeds by Hot Air and Superheated Steam Using a Fluidized Bed System

The effect of the initial moisture content (X0) of amaranth seeds on expansion volume after popping was examined in hot air and superheated steam (SHS), using a fluidized bed system (FBS). The moisturized seeds were prepared under various vapor pressures due to various saturated salt solutions. In hot air, the maximum expansion volume was shown by seeds having X0 of 0.16 at 260 °C for 15 sec, reaching 8.7-fold of the pre-popped seeds. Heating by SHS decreased the volume slightly. Thus, popping of amaranth seeds is influenced not only by the moisture content of the seeds, but also by moisture in the heat media.

Popping of Amaranth Seeds in Hot Air and Superheated Steam

Abstract: Amaranth seeds can be popped by evaporation of contained moisture during heating. The relationships among the expansion ratio by popping and the type of heating media, gas temperature, initial moisture content of the seeds and heating time were clarified based on empirical study. And using a simple calculation model, the popping mechanism and effect of initial condensation of superheated steam were investigated. According to the results, the maximum volume of the seeds after popping was 8.7 times greater than that of raw seeds at optimal conditions. Compared with the case of hot air, the expansion ratio by superheated steam was slightly lower.

Prediction Method for Drying Time of Wet Porous Material in Humid Hot Air and Superheated Steam

The effects of dry-bulb and wet-bulb temperatures on the dryingtime of a wet spherical porous material in humid hot air and superheated steam were investigated. A wet spherical brick was used as the sample porous material. The experimental results revealed that the normalized drying characteristics curves in the falling drying rate period obtained under different experimental conditions were all in good agreement. In addition, the time required to reduce the moisture content below the critical moisture content was almost the same under all wet-bulb conditions at the same constant drying rate, regardless of steam condensation.

Optimal Conditions for Popping Amaranth Seeds

Amaranth seeds can be popped under suitable heating conditions. On the basis of experimental results obtained in our laboratory, we have developed a prototype of a continuous processing system for commercial application. In addition, the effects of gas temperature, flow rate, and feed speed on the popping quality of seeds, such as their volume expansion ratio and yield, were examined. The experimental results showed that the undersized yield ratio increased with the flow speed, whereas it decreased with an increase in the gas temperature. In addition, to achieve a high expansion ratio and maximum output, the feed speed was increased with the gas temperature. Furthermore, measuring the differential pressure in the test section of the experimental apparatus enabled the estimation of the quantity of seeds therein during the popping experiment.