Correlation between electronic tongue measurement results and human sensory evaluation difference th

German physiologist Weber did such an experiment: a person holds a weight of 300 grams in his right hand, and puts a weight of 305 grams on his left hand. He will not feel much difference until the weight of the left hand is increased. It will feel a bit heavy when it reaches 306 grams. If the right hand holds 600 grams, then the weight on the left hand must reach 612 grams to feel heavy. In other words, the heavier the original weight, the greater the amount added later to feel the difference. This phenomenon is called "Weber's law". Weber found that the difference in the amount of the same stimulus must reach a certain ratio in order to cause the difference feeling. This ratio is a constant, expressed by the formula: △r (stimulus difference)/r (stimulus) = k (constant), which is Weber's law.

Weber's law shows that if the discrimination ability of a certain feeling of the same individual is to be compared but the standard stimuli used are different, the absolute value of the difference threshold cannot be used for comparison, but the Weber score should be used for comparison. The smaller the Weber score, the more sensitive the discrimination. Zhang Aixia and others studied the difference threshold and Weber score of the electronic tongue for the basic flavors of sour, sweet, bitter, salty and umami. (The following data and results are from Dr. Zhang Aixia's thesis "Research on Application Methodology of Electronic Tongue Based on Difference Test")

According to the above research results, it is found that the detection sensitivity of the electronic tongue to substances such as citric acid, tartaric acid, AK sugar, sodium chloride, potassium chloride, and sodium glutamate is much higher than that of human sensory organs. The detection sensitivity of electronic tongue to quinine sulfate is close to that of human sensory organs.

The above experiment uses a volt-ampere electronic tongue composed of noble metal bare electrodes, and uses the relaxation pulse as the excitation signal to collect the current response signal of the sample, extract effective eigenvalues by mathematical analysis methods, and finally analyze it in combination with pattern recognition methods . It can be used for authenticity identification of liquid food such as alcohol, beverages, tea, etc., product quality control and shelf life of brand enterprises, rapid detection of pesticide residues, rapid detection of pathogenic microorganisms, etc.