Water quality and taste sensitivity for basic tastes and metallic sensation

The aim of the study was to investigate the influence of water quality on taste sensitivity for basic tastes and metallic sensation. To familiarize subjects with sensory analysis, they were asked to recognize tastes, distinguish between different concentrations of basic tastes, and realize their own taste sensitivity. The International Standard ISO 3972 describes a set of tests to measure taste sensitivity. A “neutral, tasteless, still and odourless water, preferably of known hardness” is recommended for preparing the dilutions and for rinsing the mouth. The standard also recommends a series of dilutions for acid (citric acid), bitter (caffeine), salty (sodium chloride), sweet (sucrose), umami (monosodium glutamate) and metallic (iron(II)sulfate). The question arises if water quality affects taste sensitivity.MethodsTwenty-three female subjects (mean age: 22), who were recruited at the University of Applied Sciences Hamburg, Faculty of Life Sciences, were tested. Deionized water, spring water and tap water were used for taste dilutions. In each experiment, subjects were initially familiarized with the basic tastes.ResultsIn comparison to taste thresholds in spring water, the recognition thresholds are higher using tap water, and lower using deionized water. When using deionized water, sour was detected by all subjects at the lowest concentrations. Iron(II)sulfate could best be matched to metallic sensation in deionized water. Results indicate that taste sensitivity is influenced by water quality.