Effect of copper speciation at different pH on temporal sensory attributes of copper

The effect of copper solubility on temporal characteristics of copper sensation was investigated by evaluating bitterness, astringency, and metallic sensory characteristics of samples containing copper (39.4 and 78.8 μM) at two pH levels (pH 5.5 and pH 7.5) using the time–intensity test. Concentration of soluble copper in samples was measured with atomic absorption spectroscopy after filtering samples through 0.2 μm filter to remove insoluble copper particles. Decrease in copper concentration significantly inhibited metallic flavor. Astringency was not significantly affected by copper concentration, but changed as a function of pH. The level of soluble copper at pH 7.5 decreased by 50% compared to that at pH 5.5. There was a significant positive relationship between soluble copper concentration, overall sensory response, and intensity of metallic flavor. The result suggested that soluble copper species influence the perception of copper sensation by controlling metallic flavor.