Odor Recognition of Soy Sauce by Semiconducting Polymer Sensors

In order to recognize the odor of soy sauce, an electronic nose having 32 different semiconducting polymers was used. Prior to the odor analysis of soy sauce, the effect of water vapor in a sample gas on the change in resistance of a sensor was examined using two kinds of spray-dried coffee that exhibited different odors. The effect of the water vapor was eliminated by controlling the humidity of the reference air during baseline determination. Two dark soy sauces produced by different companies were used. The electronic nose recognized the difference in the odors of the soy sauces, of which point mappings formed clusters of odor apart from each other. The change in odor with time caused by exposure to air was also detected.