| In order to make clear the quality characteristics of tobacco leaves in Zunyi, according to the representative principle of sampling, in 2012 and 2013, the acquisition of tobacco samples was finished, including the upper and middle leaves in 10 counties in Zunyi, and then, the appearance identification, chemical composition test, sensory quality evaluation and aroma substance detection were completed. By analyzing and discussing the results of the above four aspects, the quality characteristics of tobacco leaves in Zunyi was cleared. And then the difference of chemical composition between Zunyi and other typical areas were analysed. The evaluation indexes of Zunyi tobacco leaves quality were discussed for the first time. The result laid the foundation for coordinating chemical composition, supporting cultivation and modulation in accordance with the requirement of quality indicators, and then improving the quality of tobacco. Specific results were as follows:(1) Quality characteristics of tobacco leaves in ZunyiThe quality of appearance: the upper leaves were all ripe; color intenssity was strong; body was fleshy; leaf structure was firm; oil was oily; grade was B2 F. The middle leaves were all ripe; color intenssity was moderate; body was medium; leaf structure was open; oil was oily; grade was C3 F.Routine chemical components: routine chemical components between the upper and middle tobacco leaves were obviously different in Zunyi area. The contents of total sugar, reducing sugar in middle leaves were significantly higher than those in upper leaves; the contents of total alkaloids, total nitrogen, chlorine and volatile alkali in middle leaves were significantly lower than those in upper leaves; the contents of potassium and starch in middle leaves were slightly higher than those in upper leaves.Sensory quality: the flavor of Zunyi tobacco leaves was intermediate flavor; momentum ranged from moderate to moderate+, and in the upper leaves, it was higher than that in the middle leaves; smoke density was mainly ranged from thicker- to thicker, and in the upper leaves, it was slightly higher than that in the middle; aroma permeability was mainly in range from medium+ to stronger, and aroma permeability in middle leaves was slightly stronger than that in upper leaves; the quality grade of tobacco was ranged from moderate+ to good-, the quality of middle leaves was significantly better than that of upper leaves. Comprehensive evaluation, the sensory quality of middle tobacco leaves was better than that of upper leaves in Zunyi.Aroma: 65 kinds of aroma substances were checked out in Zunyi tobacco leaves and 11 kinds of compounds including megastigmatrienone-2, megastigmatrienone-4, β-damascenone, furfural, furfural alcohol, benzene acetaldehyde, benzene methanol, solanone, neophytadiene, methyl palmitate, linolenic acid methyl ester were higher, accounting for 94.81% of the total substances. In addition, neophytadiene accounted for 81.52% of the total substances, highest percentage.(2)Differences of chemical components between Zunyi and other typical tobacco areasThere was a great difference of chemical components between Zunyi and other areas. The starch content was higher, total nitrogen and K2 O content was lower, and the other chemical components contents were in the middle level. The contents of carotenoid degradation products, maillard reaction products, aromatic amino acid degradation products were all the highest, while the content of chlorophyll degradation products was the lowest.(3) Preliminary study on the evaluation index of Zunyi tobacco leaf.In upper leaves, the total sugar, reducing sugar, total alkaloids, total nitrogen, chlorine, starch, volatile alkali, the ratio of sugar to alkali, Schmuck value and ratio of sugar to nitrogen had very significant impacts on smoking quality, the content of potassium and the ratio of potassium to chlorin had significant impacts on smoking quality. In middle leaves, the total sugar, total nitrogen, potassium, chloride, and the ratio of reducing sugar to total sugar, Schmuck value and sugar-nitrogen ratio had very significant impacts on smoking quality, volatile alkali, reducing sugar, total alkaloids and sugar-alkali ratio had significant impacts on smoking quality. The difference between total sugar and reducing sugar, the ratio of reducing sugar to total sugar and alkali-nitrogen ratio had a little impact on the upper’s smoking quality. Starch, potassium-chloride ratio and alkali-nitrogen ratio had a little impact on the middle’s smoking quality. Extracted representative evaluation index through factor analysis, there were the total sugar, total nitrogen, total alkaloids, potassium, chloride and starch in the upper leaves, and total sugar, total nitrogen, total alkaloids, the ratio of reducing sugar to total sugar, potassium and chlorine in the middle leaves. Then we established the membership function of above indexes. The aroma mainly affected aroma quality, after taste and irritancy. Key word: Zunyi, Flue-cured tobacco, Characteristics, Analysis... |
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