The Quality Difference of Tobacco Leaves Between Different Flue

Lina YANG Xinwei JI Folin LI Bingbing LYU Kun HUANG Enping PU Zelin CHEN Junhong CHEN Xiaolin YANG Jungang DUAN Rui LI

Abstract [Objectives] This study was conducted to compare the effects of different curing processes， in order to optimize the local supporting intensive flue-curing process.

[Methods] A comparative experiment was carried out in Mile， Luxi and Jianshui on the four-layer tobacco-packed intensive curing process （K1） and the eight-point precise and intensive curing process （ K2 ）.

[Results] The results showed that according to the appearance evaluation of the tobacco leaves， K1 was higher than  K2  in respective scores of color， maturity， leaf structure and defects and the total score， while K1 equaled  K2  in the scores of identity， oil content， chroma and length. The differences in respective scores of the two processes were not significant. According to the results of sensory evaluation， the two tobacco enterprises got different evaluation results of  unblended cigarettes made of the middle leaves due to different raw material requirements of the enterprises by different processes. K1 was higher than  K2  in the sensory evaluation of China Tobacco Yunnan Industrial Co.， Ltd.， while it was lower than  K2  in that of China Tobacco Zhejiang Industrial Co.， Ltd.， and the difference in the total score between the two processes was significant. From the content of chemical components， in the conventional chemical component contents including total sugar， reducing sugar， chlorine and starch， K1 was higher than  K2 ， while in the contents of potassium， total phytonine， total nitrogen and petroleum ether extract， K1 was lower than  K2 ， but the differences were not significant. K1 was lower than  K2  in the contents of neutral aroma components including ketones， alcohols， aldehydes， heterocyclics， neophytadiene and total content， while K1 was higher than  K2  in the contents of esters， phenols， but the respective differences were not significant. Except the significant difference in the total score in the sensory evaluation of China Tobacco Zhejiang Industrial Co.， Ltd.， there were no significant differences in other items in the appearance evaluation， sensory evaluation and chemical composition of tobacco leaves between K1 and  K2 .

[Conclusions] The supporting intensive curing process can be further optimized on the basis of this study.

Key words Flue-cured tobacco; Flue-curing technology; Quality of tobacco leaves

Honghe tobacco-growing area is an important raw material base for various China tobacco companies including China Tobacco Yunnan Industrial Co.， Ltd and Zhejiang Industrial Co.， Ltd. However， in recent years， due to the abnormal climate in the area during the transplanting period with drought and the mature period with much rain， low temperature and insufficient illumination， the difficulty of curing has been increased， thereby reducing the quality of tobacco. Tobacco curing is an important link in the production of flue-cured tobacco leaves， which is of great significance to compensating for the defects in the quality of tobacco leaves and to consolidating the inherent quality of the tobacco leaves[1]. At present， there have been some studies on the effects of different curing processes on the quality of tobacco leaves[2-5]. However， no studies have been reported on the tobacco leaves formed under the abnormal climate conditions in Honghe area. In this study， the differences in the quality of flue-cured tobacco leaves between different curing processes in Honghe tobacco producing area were studied， so as to provide reference for optimizing the local intensive curing process.

Materials and Methods

Experiential locations

The experiment was carried out in Qinglong Town of Jianshui County， Xiangyang Town of Luxi County， and Miyang of Mile City in Hani-Yi Autonomous Prefecture of Honghe.

Experiential materials

The tested variety was Yunyan 87. Tobacco leaves in the middle （8-9 leaf positions in the stem）  part were selected.

Experiential design

The tobacco leaves of suitable maturity with the same quality were picked， 2 leaves/plant. Twelve poles of tobacco leaves were weaved for each part at each sampling point and numbered. The tobacco poles were placed the middle of the middle layer of the baking barn， and a four-layer tobacco-packed intensive curing process （K1） and an eight-point precise and intensive baking process （ K2 ） were set up as two treatments. Whole-furnace baking of tobacco leaves weaved on poles was adopted， and the baking barn met the quality and performance requirements of the national intensive baking room technical specifications.

Determination items and methods

Appearance evaluation

According to the color， maturity， leaf structure， body， oil， color intensity， length and waste and injury， referring to the tobacco leaf appearance quality scoring standards of Hongyun Honghe Group， the middle and upper leaves were scored for appearance quality according to the 100-point system.

Sensory evaluation

The samples were cut into shreds， subjected to water balance treatment and made into cigarettes， which were then sent to Technology Center of China Tobacco Yunnan Industrial Co.， Ltd  and Zhejiang Industrial Co.， Ltd for evaluation. Yunnan Technology Center evaluated the cigarettes according to the 9-point scale value method for unblended cigarettes （YC/T 138-1998）.

Chemical components

The conventional chemical components of leaves samples were detected according to the Chinese national standard method， and the aroma components were analyzed by "Simultaneous Distillation Extraction and Gas Chromatography-Mass Spectrometry"[6].

Data processing

Statistics and graphing of the detection results were performed with Microsoft Excel 2010， and the significance of the difference was analyzed with SPSS 20.

Results and Analysis

Appearance evaluation

It can be known from Table 5 that the scores of color， maturity， leaf structure and damage and total score of tobacco leaves in the K1 process were higher than those in the  K2  process， while the scores of the body， oil， color intensity and length in the K1 process were equal that in the  K2  process. There were no significant differences of leaf appearance evaluation in the scores of various items and total score between K1 and  K2 .

Sensory evaluation

It can be known from Table 6 that the evaluation results of Yunnan Industrial Co.， Ltd. were as follows： the scores of the aroma quality， aroma quantity， concentration， offensive odor， impact， ash color and use value and the total score with the K1 process were all lower than those with the  K2  process， and the scores of the irritancy， aftertaste and combustibility with the K1 process were all higher than those with the  K2  process. There were no significant differences in the scores of the various items and total score between K1 and  K2  in the sensory evaluation.

It can be known from table 7 that the evaluation results from Zhejiang Industrial Co.， Ltd. were as follows： the scores of the quality of aroma， volume of aroma， diffusivenes， offensive taste， fineness， mellow， irritancy， dryness， aftertaste score and the total score in the K1 process leaves were all higher than those in the  K2  process leaves， and the score of the softness of the K1 process leaves was equal to that of the  K2  process leaves. The differences in quality of aroma， volume of aroma， diffusiveness， offensive taste， fineness， softness， mellow， irritancy， dryness and aftertaste between K1 and  K2  were all non-significant， and there was a significant difference in the total score.

Chemical components

Conventional chemical components

It can be known from table 8 that the total sugar， reducing sugar， chlorine and starch contents of the K1 leaves were higher than those of the  K2  leaves， while the contents of potassium， total hytonine， total nitrogen and petroleum ether extract of the K1 leaves were lower than those of  the K2  leaves. There were no significant differences in the contents between K1 and  K2.

Neutral aroma components

It can be known from table 9 that the differences in neutral aroma components between different processes were as follows： in the contents of ketones， alcohols， aldehydes， heterocyclics and neophytadiene and the total content of the leaves， K1 was lower than  K2 ， while in the contents of esters and phenols， K1 was higher than the  K2 . However， the differences in the contents of neutral aroma components were all not significant between K1 and  K2 .

Conclusions and Discussion

The four-layer tobacco-packed intensive curing process is currently used in Honghe Prefecture. The characteristic of the eight-point precise and intensive curing process is that the temperature-holding time in each key period is appropriately extended， especially in the late stage of color fixing[7-9]. The study by Ye et al.[10 ]has shown that appropriately extending the temperature-stabilizing period in the late stage of color fixing can effectively promote the full conversion of chemical substances in tobacco leaves and increase the content of Aromatic precursor， which accords with the result that the contents of ketones， alcohols， aldehydes， heterocyclics and neophytadiene and the total content all followed K1

In the appearance evaluation of tobacco leaves， for the scores of leaf color， maturity， leaf structure and damage and total score， K1 was higher than  K2 ， while for the scores of body， oil content， color intensity and length， K1 equaled  K2 . However， the differences in respective scores were not significant between the two processes.

K1 was lower than  K2  in the sensory evaluation of Yunnan Industrial Co.， Ltd.; and K1 was higher than  K2  in the sensory evaluation of Zhejiang Industrial Co.， Ltd. and the difference between the total scores of K1 and  K2  was significant.

From the point of view of chemical component contents， in the conventional chemical component contents including total sugar， reducing sugar， chlorine and starch， K1 was higher than  K2 ， while in the contents of potassium， total plant alkaloids， total nitrogen and petroleum ether extract， K1 was lower than  K2 ， but the respective differences were not significant.

K1 was lower than  K2  in the contents of neutral aroma components including ketones， alcohols， aldehydes， heterocyclics， neophytadiene and the total content， while K1 was higher than  K2  in the contents of esters， phenols， but the respective differences were not significant.

In general， except the significant difference in the total score in the sensory evaluation of Zhejiang Industrial Co.， Ltd， there were no significant differences in other items in the appearance evaluation， sensory evaluation and chemical composition of leaves between K1 and  K2 .

References

[1] YU J， WU Y， CHEN ZP. Effects of different temperature and relative humidity on smoking quality of tobacco in baking period[J]. Guizhou Agricultural Sciences， 2007（4）： 50-51， 55. （in Chinese）

[2] YANG XD. Effects of different flue-curing processes on tobacco quality of Yunyan 87[J]. Jiangxi Agriculture， 2018（10）： 24-25. （in Chinese）

[3] WANG HC， GAO Q， TANG HY， et al. Effect of baking with medium temperature and humidity on  tobacco quality of Yunyan 87[J]. Mod Agric Sci Technol， 2017（3）： 235， 237. （in Chinese）

[4] CUI GM， HUANG W， ZHAO GK， et al. Effect of different flue-curing techniques on smoking quality and aroma substances of flue-cured tobacco leaves[J]. Journal of Anhui Agricultural Sciences， 2013， 41（24）： 10125-10128. （in Chinese）

[5] CUI GM， HUANG W， ZHAO GK， et al. Effect of different flue-curing technologies on appearance grade quality and key chemical components of crude tobacco leaves[J]. Horticulture & Seed， 2013（9）： 52-56， 62. （in Chinese）

[6] WU LJ， DUAN J， LI CY， et al. Analysis of volatile components in tobacco by simultaneous distillation extraction and gas chromatography-mass spectrometry[J]. Journal of Analytical Science， 2012， 28（6）： 807-810. （in Chinese）

[7] ZHOU YL， SUN SB. Effects of eight-point intensive curing technology on quality of Yunyan 87 leaves[J]. Journal of Anhui Agricultural Sciences， 2015， 43（32）： 190-192， 237. （in Chinese）

[8] HAN S， WU F. Study on 8-point precision baking process of tobacco[J]. Mod Agric Sci Technol， 2013（13）： 218， 226. （in Chinese）

[9] XU XH， WANG CY， LIU CN， et al. Foundation and application of eight-point curing technology[J]. Chinese Tobacco Science， 2012， 33（5）： 68-73. （in Chinese）

[10] YE WM， LI SF， HU NJ， et al. Effect of stable time at 54 degree on quality and output value of flue-cured tobacco leaves[J]. Chinese Tobacco Science， 2014， 35（1）： 61-66. （in Chinese）

[11] LIU Y， YE WM， WANG YS， et al. Effects of different flue-curing processes on tobacco quality on Yunyan 87[J]. Chinese Tobacco Science， 2016， 37（1）： 56-60. （in Chinese）