Taste Sensing Based on Frequency Characteristics of Quartz Resonator with Oleic Acid Film Electrodeposition

Abstract

In this paper, we studied a possibility of a taste sensing using a quartz crystal microbalance (hereafter cited as QCM) sensor. We modified oleic acid film to Au electrode of the quartz resonator by an electrodeposition method. The electrodeposition film was used as the adsorber for taste substances. We consider that oscillation frequency decreases with the mass changes due to adsorption. Frequency characteristics differed in each basic taste solution. Their characteristics were based on chemical nature of taste substances. Ions or organic molecules were attached to electrodeposition film by electrostatic interaction or hydrophobic interaction respectively. Moreover, we studied the taste evaluation of sweetness solutions and sourness solutions. As a result, in case of sweetness solutions, the frequency changes correlated with Brix (%) (r = -0.98). In case of sourness solutions, especially, the frequency changes correlated in pH (r = 0.89) of organic acids. Differences of the frequency changes depended on the amount of undissociated molecule in the acid solutions. Additionally, taste evaluation by the QCM sensor related to gustatory sense of human. Therefore, we suggested the validity of the QCM sensor for evaluation of the taste solutions.