Study On The Application Of Voltammetric Electronic Tongue To The Distinction Of Tea Quality

The voltammetric electronic tongue is an effective and frequently-used analytical method , which mensurate the change of voltage, under the additional current environment, to reflect the information of the detected object. The character of its application on tea, have embodied in which the experimental material was mainly prepared in brewing; the research targets was just a sort of or kinds of in one category, not focusing on an systemic investigation into six varieties ever. Moreover, it never thinks over the relation to the physio-chemical measuring and sensory tests.In order to develop an novel way that its estimate have more objectivity and dependability, to assist or partly substitute the organoleptic evaluation, the paper take into account on the researchers as followings:1. The taste sensor test six tea samples (taking from six category respectively), which prepare according to extraction and brewing, where in the repeatability, the means of extraction was outstanding excellence to the infusion in that when taking the RSD(Relative Standard Deviation) refer to 3% as dividing line, the electronic tongue's sensor in the infusion have four times over this data, but the extraction have one times; while refers to 1%,the outcome is eleven and five.2. Employing the electronic tongue's seven sensor test the 27 tea samples which prepare according to extraction. The result is as below:1) While regard 27 tea samples as individual, the electronic tongue have a discrimination index of 87.51 to them, which suggest a favorable distinguish effect. And , in selective sensors, when take 3% as refer, the proportion to under is 95.67%, which imply an excellent accuracy;2) While regard 27 teas samples as six basic variety, the sensor's detecting data processed by PCA (principal component analysis), which the result, in the PCA diagram, show that, in virtue of different degree of fermentation, all category have a preferable division;3) While in the analysis of the green teas, the electronic tongue have a good identify to different processing (baking, roasting, sunning and bake-roasting),and have a good division to the ZhaoGuanCuiXu for different picking time, beside, there have a distinct boundary of Tomb Sweeping Day in the PCA diagram;4) While in analysis of the black teas, the discrimination index is 89.37; the black tea of different area also have a fine partition in the PCA diagram; And, the correlation coefficient have gotten 0.99 , when study the different grading Yunnan Red. 5) While in analysis of the Oolong teas, the discrimination index is 98.3. Compared between the result of PCA for the voltammetric electronic tongue and the chemical measuring, there are not only shearing some same feature, which the green and the white tea have a well partition to others; but also shearing some differentia ,which in the chemistry detection ,the dark have better distinction to the Oolong , but exist intercross with the yellow and the black ;whereas in the taste sensor ,the black and the yellow have good discrimination to the others, but the dark and the Oolong have a cross.The reasons accounting for the results, there maybe have same and different substance between the electronic tongue and the chemical analysis.4. There have a good consistency trend between the sensory evaluation and taste sensor.