Development of a New Superheated Steam System with Micro Water Droplet and Its Application for Blanching of Potato

Abstract

Applications of superheated steam for food processing have been studied in recent years with several advantages. A new oven system, which generates superheated steam with micro droplets of hot water (Aqua-gas), was achieved spraying heated water into a heating chamber filled with the superheated steam. It was expected that the micro-droplets increased the heat transfer coefficient of the heating medium. It was also expected that water content of foods processed with this oven could be controlled by regulating the amount of the micro droplets in the superheated steam. Heat transfer rates of the Aqua-gas and the superheated steam maintained at 115°C were measured based on surface temperature of a heat flowmeter. The heat transfer rate of the Aqua-gas was larger than that of the superheated steam in the case the temperature of the heat transfer boundary was low. In addition the drying rate of the food sample was lower in the case of the Aqua-gas due to the effect of the micro droplets. An application of this new Aqua-gas system for the blanching of the potato was examined. The potatoes were blanched by the Aqua-gas, superheated steam of 115°C, and boiling hot water. The changes in the color, the rheological properties and the micro structure of the potatoes blanched by the Aqua-gas and the superheated steam were smaller than the potatoes blanched by the hot water. The weight loss of the potato was small in the Aqua-gas and the hot water. In addition, Bacillus subtilis spores were pasteurized effectively by the Aqua-gas.

Superheated steam processing of cereals and cereal products: A review

“…Isobe et al. (2006) proposed a new SS processing system containing water microdroplets (Isobe et al., 2006), which has a higher heat transfer efficiency than that of traditional SS processing. Table 1 lists and compares four types of SS.…”

“…SS containing water microdroplets can be achieved by spraying heated water into a heating chamber filled with SS, significantly increasing the heat transfer coefficient of SS (Isobe et al., 2006). Additionally, the water content of foods can be controlled by changing the amount of water microdroplets, thus avoiding the overdrying of foods.…”

“…SS can be classified based on the operating pressure, namely, atmospheric-, low-, and high-pressure SS. Isobe et al (2006) proposed a new SS processing system containing water microdroplets (Isobe et al, 2006), which has a higher heat transfer efficiency than that of traditional SS processing. High-pressure SS SS generated in the high-pressure environment Much higher temperature compared to atmospheric pressure SS; drying rates can be significantly increased.…”