Study On Quality Evaluation Of Flue-cured Tobacco In Henan Province And Prediction Model Establishment Of Key Indexes Based On Near Infrared Spectroscopy

Tobacco is a raw material of cigarette manufacturing enterprises, Quality differences among tobacco products originated from tabacco with different quality couldn’t be compensated by perfuming-feeding or any subsequent processing procedure. How to evaluate the quality of tobacco scientifically and objectively is the focus and hot sissues in the tobacco industry, the evaluation results can not only be used to guide tobacco agriculture, control the quality of tobacco and improve their application value, but also provide basis for the tobacco production, and maintain stability of tobacco products quality.Flue-cured tobacco, produced in Henan province, that is, major tobacco planting area with long history, is provided with unique characteristic and prominent advantage, and applicated widely in so many cigarette products from some domestic cigarrete manufacturers. In this paper, 174 tobacco samples in Henan province were selected, and their physical characteristics, chemical components and sensory quality indexes were mensurated or evaluated by those traditional classical methods. 169flue-cured tobacco samples were preserved as a sample set of statistical analysis through outlier detection and elimination. The overall situation of quality indexes of flue-cured tobacco in Henan province was analysed. The key indexes of each quality module were selected. Comprehensive quality equilibrium and difference were studied based on factor analysis and regularity research of each quality module of flue-cured tobacco. Similarity evaluation method of comprehensive quality of the flue-cured tobacco samples was studied based on the similarity degree statistical variable. Prediction model of physical characteristics and discriminant model of sensory quality of flue-cured tobacco were established based on near infrared spectroscopy technology. The main conclusions are as follows:(1)The quality of flue-cured tobacco in Henan province was generally expressed as leaf thickness was relatively thick, the moisture absorption is good, the structurewas relatively loose, the fillibility and combustion was medium, and the processing tolerance was medium and slightly high. Total alkaloid, total sugar and reducing sugar content were high, total nitrogen content was relatively appropriate, chlorine,starch and the ratio sugar to alkaloid were relatively high, the ratio of nitrogen to nicotine, ratio of potassium to chlorine and potassium content were relatively low.Aroma quality and aroma volume were above average, miscellaneous gases and stimulation were mediocre, aftertaste was medium and slightly clean, concentration was between medium and high, physiological strength was relatively strong.(2) Based on relationship among quality indexes and special characteristic of quality indexes, we selected leaf thickness, leaf density, filling value, tensile strength,equilibrium moisture content and smoldering time as key physical indexes; we selected total sugar, total nitrogen, totao alkaloids, reducing sugar, potassium,chlorine, the ratio of sugar to alkaloids as key chemical indexes; we selected aroma quality, aroma volume, miscellaneous gases, stimulation, aftertaste, concentration and physiological strength as key sensory quality indexes.(3) Equilibrium and difference evaluation method of comprehensive quality of flue-cured tobacco was proposed based on comprehensive factor score. Based on key indexes of quality module, comprehensive factor mathematical model of sensory quality, chemical components and physical characteristics of flue-cured tobacco in Henan province were respectively as follows: Fs=0.367X1+0.370X2+0.424X3+0.440X4++0.441X5+0.304X6+0.108X7-14.572, Fc=-0.282X1+0.020X2+0.038X3-0.458X4+0.223X5+0.223X6+0.031X7-0.825,Fp=-0.188X1+7.064X2+0.005X3+0.055X4+0.394X5-0.043X6-6.692.Comprehensive factor score range of sensory quality, chemical components and physical characteristics of 169 samples were respectively-1.942~1.916 、-1.714~1.710、-1.243~1.771, and their average were all zero. Every index value of the quality module was closer to the overall average level with comprehensive factor score of quality module closer to zero; On the contrary, indexes equilibrium of the quality module was worse, which indicated that the sample had obvious advantages or disadvantages. Overall difference between samples increased with the increase of comprehensive factor score difference in the quality module. Cluster analysis resultbased on comprehensive factor score of each quality module had some guidance on tobacco group processing or formulation maintenance. In group processing, samples from the different subgroups of the same main group or the same subgroup could be divided into the same group, and samples from different main groups couldn’t be divided into the same group based on sensory quality or chemical component of tobacco, samples from the same subgroup could provide reference for formulation maintenance. Tobacco growing part was adequately considered based on physical characteristics in group processing.(4) A new statistical variable, that is, similarity degree(S) was constructed based on simple correlation coefficient and Euclidean distance, evaluation results of tobacco comprehensive quality between every two samples based on similarity degree was better than simple correlation coefficient and Euclidean distance separately.Similarity evaluation standard of comprehensive quality of flue-cured tobacco in Henan province was established, the principle and method of validating evaluation standard were established too. Comprehensive physical characteristics similarity evaluation standard for flue-cured tobacco samples in Henan province was weak(S<1.2), relatively weak(1.2≤S<2.5), medium(2.5≤S<5.0), relatively strong(5.0≤S<9.5) and strong(S≥9.5); comprehensive chemical component similarity evaluation standard for flue-cured tobacco samples was identified, that is,weak(S<1.5), relatively weak(1.5≤S<4.5), medium(4.5≤S<9.5), relatively strong(9.5≤S<17.5) and strong(S≥17.5); and comprehensive sensory quality similarity evaluation standard for flue-cured tobacco samples was identified, that is, relatively weak(S<27.5), medium(27.5≤S<50.0), relatively strong(50.0≤S<83.5) and strong(83.5≤S<127.5), very strong(S≥127.5). Sample grouping results based on different similarity degree(Sα) according to the grouping principle and method all showed that similarity degree could indicate similarity of tobacco comprehensive quality, and similarity degree evaluation standard was reasonable.(5) Prediction model of main physical indexes of flue-cured tobacco(leaf density,leaf thickness, filling value, smoldering time, equilibrium moisture content and tensile strength) were established based on near infrared spectroscopy technology,fast determination of key physical indexes were achieved. For the first time, the cluster results of every sensory quality index score of flue-cured tobacco were discriminated by near infrared spectroscopy technology, the overall average accuracy rate of the discrimination was more than 75%, the highest prediction accuracy was more than 70%. It can provide the basis for the fast detection of the key quality indexes of flue-cured tobacco and lay the foundation for the popularization and application of the comprehensive quality evaluation model.