| In this research,49 sample locations in south Sichuan tobacco area were chosen for gathering tobacco leaves of local main cultivars, respectively, and firstly for the tobacco leaves obtained, the upper leaves (B), middle leaves (C) and lower leaves (X) were selected (with each 49 copies selected respectively) to evaluate the appearance quality, chemical composition and sensory quality. The current tobacco leaf evaluation system used by Sichuan Province Tobacco Company and DTOPSIS analytical method based on grey correlation degree were adopted for the evaluation and analysis of the appearance quality, chemical composition and sensory quality of tobacco leaves from south Sichuan tobacco area, and finally the quality of flue-cured tobacco from south Sichuan tobacco area was evaluated, with the following main conclusions obtained:1. For the appearance quality of the tobacco leaves from south Sichuan tobacco area in 2011:most of the tobacco leaf samples were orange and a few of them were lemon yellow. The maturity of the tobacco leaves was relatively good, with loose middle leaves and relatively loose upper leaves and lower leaves for the structure of the tobacco leaves; the samples were rich in oil and the leaf surfaces had relatively good elasticity and a oil feeling; most of the leaves had strong chromaticity and a few had medium chromaticity; the color of tobacco leaves was relatively even. According to the results of the chemical composition measurement of the flue-cured tobacco leaves, the reducing sugar, total nitrogen, potassium, starch, sugar alkali ratio, and the average values of nitrogen alkali ratio and potassium chloride ratio of the upper leaves were basically in the appropriate range, but the total content of nitrogen was relatively high; the reducing sugar, total nitrogen, potassium, starch, sugar alkali ratio, and the average values of nitrogen alkali ratio and potassium chloride ratio of the middle leaves were basically in the appropriate range; the reducing sugar, total nitrogen, potassium, starch, sugar alkali ratio, and the average values of nitrogen alkali ratio and potassium chloride ratio of the lower leaves were basically in the appropriate range. However, the smell of the tobacco leaf samples was not obvious or less obvious; a few samples from Yibing had a tar sweet smell, but most of the samples had no obvious smell style; the smell quality was medium; there were a few samples having sufficient volume of aroma; the samples had relatively strong offensive smell, and the withered smell, earth smell, saw green smell and local offensive smell were found in the lower leaves; the smell of the upper leaves were relatively more concentrated and the smell concentration of middle leaves and lower leaves was medium; the taste of upper leaves and lower leaves was strong and that of the middle leaves was medium; the samples could irritate throat, with small sweetness for the upper leaves and relatively more sweetness for the middle leaves and lower leaves; the aftertaste would remain on the tone.2. The quality of tobacco leaves from South Sichuan tobacco area was comprehensively evaluated by adopting the current tobacco leaf evaluation system of Sichuan Tobacco Company and the DTOPSIS method based on grey correlation degree, and the similarities and differences of these two methods were compared. (1) The differences on weighting the indexes that determine the appearance quality, chemical composition and sensory quality of the two comprehensive methods evaluating the tobacco leaf quality resulted in the different outcomes on appearance quality, chemical composition and sensory quality. (2) In the comprehensive evaluation system for tobacco leaves used by the Tobacco Company, the weights of appearance quality, chemical composition and sensory quality were obtained by using subjective weighting method. While in the DTOPSIS evaluation method based on grey correlation degree, they were obtained by using analytic hierarchy process. However, the results of these two evaluation methods were the same due to lack of physical properties. (3) In the comprehensive evaluation system for tobacco leaves used by the Tobacco Company, the standard for evaluating different part was different and the grading system with full score of 100 was finally adopted for all parts. The grading principle of the comprehensive evaluation method for tobacco leaf constructed by using DTOPSIS method based on grey correlation degree is the data ordering based on the most ideal values and the negative ideal values, which means that the final results cannot be simply compared by using scores due to the different principles used by these two evaluation methods.3. The advantage of DTOPSIS method based on grey correlation degree for evaluating the tobacco leaf quality is rely on the weighting method, which adopts grey correlation degree for determining or improving the weights, and weighting by using grey correlation degree is an objective weighting method. While the subjective weighting method was used in the current evaluation method of Sichuan Tobacco Company. On the other hand, the gap between scores would be widened by using C, evaluating the tobacco leaf quality in the DTOPSIS analytical method based on grey correlation degree, which can make the final result looks more direct and clear and can avoid the similar or same scores that happened in the current evaluation method used by Sichuan Tobacco Company.4. In this research project, the DTOPSIS analytical method based on grey correlation degree was adopted for comprehensively evaluating the appearance quality, chemical composition and sensory quality of tobacco leaves, and finally the comprehensive evaluation of quality of flue-cured tobacco leaves from south Sichuan tobacco area was obtained. For the upper leaves, samples from the 8th group, Daqi village, Shuanghe town, Changning county, Yibing City got the best results; and for the middle leaves, from the 5th group, Qunyu village, Xianfeng town, Xingwen county, Yibing city; and for the lower leaves, from Laping village, Luohai town, Gong county, Yibing city. |
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