Xu Yue-qi, Wang Peng-ze, Tao Tao, Dang Xia, Li Yan-zhou, Wei Hui-qin, Ma Wen-hui, and Yang Nan*

1 Pingdingshan Branch of Henan Province Tobacco Company, Pingdingshan 467000, Henan, China

2 Tianchang International Tobacco Co., Ltd., Tianchang Redrying Factory, Xuchang 461000, Henan, China

3 College of Tobacco Science, Henan Agricultural University, Zhengzhou 450002, China

4 Tianchang International Tobacco Co., Ltd., Xuchang 461000, Henan, China

Abstract: To study the regional distribution features of aroma characteristics, the regional distribution maps of aroma characteristics of 225 tobacco leaf samples from Henan Province were drawn by Kriging interpolation method in ArcGIS. The results showed that: (1) the aroma quality of flue-cured tobacco from Henan Province tobacco-growing areas ranged from better to slightly better and aroma quantity ranged from just a little to much. The ability of diffusiveness expressed slight to a little strong and the raw green odour, immature odour and ligneous odour were tiny; (2) there were significant differences between the aroma quality and scorched odour and no statistical differences among the aroma quantity, diffusiveness, raw green odour, ligneous odour and immature odour from different counties; (3) there were trends that scale of aroma quality increased from southwest to both north and east, aroma quantity showed a patchy distribution in space, diffusiveness decreased from east to west, scorched odour increased from west to both north and south, ligneous odour increased from north to south and green odour increased from south to north.

Key words: tobacco leaf, sensory evaluation, aroma characteristic, regional distribution characteristic

Introduction

Sensory evaluation includes the evaluation of style and quality characteristics (Tang, 2008; Qiao et al., 2014).Among them, the quality characteristic evaluation includes aroma, taste and smoke characteristics,and the sensory evaluation of aroma characteristic indexes consists of aroma quality, aroma quantity,diffusiveness and miscellaneous odour (Wang et al.,2015; Zhou et al., 2013; Zhou, 2009). To study the quality style characteristic of tobacco leaves, quality of tobacco leaves should be evaluatedfirstly. In order to develop high-quality tobacco leaves, the new evaluation method named quality style characteristic sensory evaluation method of tobacco leaf is gradually formed (Qiao et al., 2014). The quality style of tobacco leaf is the basis for the selection and use for Chinese style cigarette (Tang, 2004; Wang et al., 2014 Tang,2007). Flavor style characteristic and sensory quality are core of studying high-quality tobacco leaves (Du et al., 2010; Tang et al., 2011; Deng, 2013; Chen,2009). Most researches emphasize on laws of style indexes. However, distribution laws of aroma charac-teristic were rarely reported before, especially for Henan Province tobacco leaves (Wang et al., 2011;Wang et al., 2015; Chen, 2010). Therefore, relatively scientific and reasonable sensory evaluation and quantitative analysis of aroma characteristic of tobacco from Henan Province were studied to identify aroma regional distribution features, which had important significance to propel development of high-quality tobacco from Henan Province, promote the whole quality level and supply ability of tobacco and meet the needs of high-quality tobacco leaves for Chinese style cigarette and smoothly implement strategy of"big market, large enterprises and big brand".

Materials and Methods

Area descriptions

The study was conducted in Henan Province (31°23'N-36°22'N, 110°21'E-116°39'E ) (Fig. 1), which was located on the middle east of China and in the lower reaches of the Yellow River and extended 580 km from east to west, 550 km from south to north. Henan Province belonged to warm temperate to the subtropical zone and had humid and semi-humid monsoon climate with annual average temperature 12-16℃ and 24-29℃in July. There were abundant rain in summer, enough sunshine in autumn and long frostless period. The soil types were mainly yellow brown soil, cinnamon soil and red clay. Soil layers with appropriate soil pH were deep and loose. Thus, Henan Province had excellent natural conditions to product high quality tobacco. And it was one of the important provinces in Chinese to produce representative tobacco with strong aroma features.

Materials

A total of 225 C3F samples were collected from 27 full flavor tobacco growing prefectures of Henan Province from year 2014 to year 2016, including Xuchang, Pingdingshan, Nanyang, Luoyang, Sanmenxia,Zhumadian, Luohe cities, et al. Five sample points,three sample points and one sample point were selected from A, B and C three class points, respectively.Samples were selected according to flue-cured tobacco(GB/T2635-92). Main cultivated varieties in the largest cultivars acreage of tobacco prefectures were Zhongyan100, Yunyan87 and Qinyan97.

Fig. 1 Location of the study area

Sample pretreatment methods

Cut tobacco of 0.9-1.0 mm was obtined by QS-1 type slicer (produced by Zhengzhou Tobacco Research Institute) after moisture regain of tobacco leaves.Unblended cigarettes were balanced under constant temperature and humidity conditions with temperature of (22±1)℃ and air relative humidity of 60%±2% for 48 h before sensory evaluation.

Sensory evaluation method of aroma characteristic

Aroma characteristics were evaluated quantitatively according to 0-5 mark isometric scaling method in sensory evaluation method of tobacco quality style characteristic. The evaluating committee consisted of more than 10 experts from the major projects of high-quality tobacco (Table 1). Miscellaneous odour included immature odour, raw green odour, scorched odour, ligneous odour, earthy odour, rosin odour,pollen odour, herbal odour and metallic odour. The scaling data referred to the common assessment of sensory quality by more than two thirds experts were valid. Then, valid scaling data of the same odour were added up and their means were obtained by Σ valid scaling value/Σ effective population. All the mean results were kept two decimal places.

Data processing

Data were analyzed by Excel and SPSS 20.0. Spatial distribution maps of aroma characteristic of full flavor tobacco (C3F) from Henan Province were drawn by Kriging interpolation method (Mujere and Kanji,2015; Das et al., 2014; Chang et al., 2014) in ArcGIS.

Table 1 Aroma characteristic indexes of tobacco leaves

Results

Aroma statistical indexes of flue-cured tobacco with strong aroma features from Henan Province

As shown in Table 2, mean of aroma quality,aroma quantity and diffusiveness were 2.88 points,2.82 points and 2.86 points, respectively. Behaviors of aroma quality and diffusiveness were both from slightly good to less and aroma quantity was from a litte to much. Variability coefficients of aroma quality and aroma quantity were both 7%, but diffusiveness was 6%. However, the variability coefficients of them belonged to the low intensity. In the nine kinds of miscellaneous odour, immature odour, green odour,ligneous odour and scorched odour were all a little.There was no earthy odour, rosin odour, pollen odour,herbal odour and metallic odour.

Regional features of aroma characteristic indexes of flue-cured tobacco from Henan Province

Aroma characteristic radar maps of flue-cured tobacco from Henan Province are shown in Fig. 1, which was drawn on the basis of the results of sensory evaluation scores. Aroma characteristics of flue-cured tobacco from different areas in Henan Province were diverse.Aroma quality and diffusiveness of flue-cured tobacco from Xuchang City (Fig. 2-1) were good. And aroma quantity was from more adequate to less. There were a little immature odour, raw green odour, ligneous odour and earthy odour. However, scorched odour was a little more and there was no pollen odour, herbal odour and metallic odour.

Aroma quality of flue-cured tobacco from Pingdingshan City (Fig. 2-2) was from slightly good to less. Aroma quantity was much and the characteristic of diffusiveness was less good. There was a little immature odour, raw green odour and ligneous odour.Scorched odour was from a little to much and there was no rosin odour, pollen odour, herbal odour and metallic odour. Flue-cured tobacco from Luoyang(Fig. 2-3) and Sanmenxia cities (Fig. 2-4) had the same aroma characteristics with less good to good aroma qualities. Their aroma quantity and diffusiveness were much and less good, respectively. Immature odour,raw green odour, ligneous odour and scorched odour were a little and there was no earthy odour, rosin odour, pollen odour, herbal odour and metallic odour.

Table 2 Aroma characteristic indexes of flue-cured tobacco with strong aroma features from Henan Province

Fig. 2 Aroma characteristic radar maps of flue-cured tobacco in Henan Province tobacco-growing areas

Aroma quality of flue-cured tobacco from Luohe City (Fig. 2-5) was less. Aroma quantity, diffusiveness and nine kinds of miscellaneous odour were totally same as aroma characteristics of flue-cured tobacco from Luoyang City.

Aroma quality and diffusiveness of flue-cured tobacco from Zhumadian City (Fig. 2-6) were same to Pingdingshan City. Aroma quantity was from a litte to much. And behaviors of nine kinds of miscellaneous odour were totally same as Xuchang City.

Behaviors of aroma quality, aroma quantity and diffusiveness of flue-cured tobacco from Nanyang City (Fig. 2-7) were same to Luohe City. Nine kinds of miscellaneous odour were totally same as Xuchang and Zhumadian cities.

Regional differences of flue-cured tobacco aroma characteristic from Henan Province tobacco-growing areas

Aroma characteristic indexes are shown in Table 3.The results indicated that there were immature odour,green odour, scorched odour and ligneous odour in all seven different areas in Henan Province. But there was no rosin odour, pollen odour, herbal odour and metallic odour. Earthy odour was only in some areas.Aroma quality means of flue-cured tobacco from Henan Province tobacco-growing areas were from 2.65 to 3.06 points. Aroma quality showed a trend of decrease from Zhumadian, Nanyang, Xuchang, Luoyang, Sanmenxia, Pingdingshan to Luohe cities. And there were significant differences among aroma quality from different regions in Henan Province. Besides,aroma quality of flue-cured tobacco from Zhumadian City was significantly better than Luohe. Aroma quantity means were from 2.70 to 3.03 points in Henan Province tobacco-growing areas. Aroma quantities generally decreased from Xuchang, Luoyang, Sanmenxia, Zhumadian and Pingdingshan cities, Nanyang City to Luohe City and there were no statistical differences among those areas.

Table 3 Comparison on aroma characteristics of flue-cured tobacco from different prefectures in Henan Province tobaccogrowing areas

Means of diffusiveness with no statistical differences among different areas were from 2.69 to 2.96 points.Immature odour means were from 1.21 to 1.33 points.There was a tendency of decrease of immature odour means with no statistical differences from Nanyang,Xuchang, Zhumadian, Sanmenxia, Luoyang, Pingdingshan to Luohe cities. Raw green odour means were from 1.13 to 1.35 points, which were non-significant differencee among different areas and decreased from Sanmenxia, Luoyang, Zhumadian, Pingdingshan,Nanyang, Luohe to Xuchang cities. Scorched odour means were significant differences among different areas from 1.27 to 1.92 points with a tendency of decrease from Luohe, Sanmenxia, Xuchang, Luoyang,Nanyang, Pingdingshan to Zhumadian cities. Meanwhile, scorched odour means of Zhumadian City were significantly better than Luohe City. Ligneous odour means were from 1.21 to 1.37 points. It generally decreased from Sanmenxia, Pingdingshan, Luohe,Xuchang, Luoyang, Zhumadian to Nanyang cities and there were no statistical differences among these areas.

Spatial distribution features of aroma characteristic indexes of flue-cured tobacco from Henan Province tobacco-growing areas

Spatial distribution maps about six kinds of aroma characteristic indexes (Including aroma quality, aroma quantity, diffusiveness, scorched odour, ligneous odour and immature odour ) are shown in Fig. 3, which were drawn by Kriging interpolation method in ArcGIS.Scale of aroma quality (Fig. 3-1) of flue-cured tobacco from Henan Province tobacco-growing areas mainly located in the range of 2.72-3.26 on the map. It increased from southwest to both north and east and there were high value regions in spatial distribution maps of Luoyang, Zhumadian and Sanmenxia cities.Scale of aroma quantity (Fig. 3-2) mainly located in the range of 2.72-3.26 on the map and was in the way of patchy distribution. Besides, Zhumadian and Nanyang cities both had a high value area. Scale of diffusiveness(Fig. 3-3) was from 2.54 to 3.31 in the space and there was a tendency of decrease from east to west. In addition, there were three high value areas in Zhumadian,Xuchang and Luohe cities. Scale of scorched odour(Fig. 3-4) mainly located in the range of 1.22-2.22 and increased from west to north and south. There were two high value areas in spatial distribution maps of Nanyang and Zhumadian cities. Scale of ligneous odour(Fig. 3-5) was mainly located in 1.22-1.50 and there was a trend that increased from north to south. Ligneous odour of flue-cured tobacco from Nanyang cities had a high value area. Scale of immature odour (Fig. 3-6) was from 1.20 to 1.60 in the space and it increased in the opposite trend of ligneous odour from south to north.

Fig. 3 Spatial distribution of aroma quality characteristic indexes of flue-cured tobacco from Henan Province tobaccogrowing areas

Discussion

Sensory evaluations of three consecutive years were studied to characterize aroma of flue-cured tobacco from Henan Province tobacco-growing areas.

The results showed that aroma quality and diffusiveness were from slightly good to less and aroma quantity was from a litte to much. There was a little scorched odour and more immature odour, raw green odour and ligneous odour (Wang et al., 2014).Aroma characteristic was one of an important quality characteristics and inherent quality of tobacco, which had a direct impact on the overall quality (Song et al.,2014). Therefore, more researches should be emphasized on inherent quality of tobacco.

According to tobacco planting regionalization,Sanmenxia and Luoyang were divided into tobaccogrowing areas of western Henan Province. Xuchang,Pingdingshan and Luohe cities were divided into tobacco-growing areas of central Henan Province.And Nanyang and Zhumadian cities were divided into tobacco-growing areas of southern Henan Province.Besides, aroma qualities of tobacco from Luohe and Pingdingshan cities were different from Nanyang and Zhumadian cities. While, Luohe and Pingdingshan cities were not in the same planting regionalization with Nanyang and Zhumadian. Obviously, there were some correlations between aroma characteristics and ecological conditions. Under different ecological conditions, inherent qualities of tobacco were different.And aroma characteristic was one of important aspact of them (Yu et al., 2008). Therefore, ecological factors should be paid more attention, which could significantly influence inherent qualities of tobacco from Henan Province.

The ecological factors, such as light hours, temperature, rainfall, soil and other ecological factors had great influence on material metabolism of tobacco leaves. And material metabolism affected the aroma characteristic of tobacco leaves. Flue-cured tobacco with strong aroma features from Henan Province,both aroma quantity and quality was positively correlated with the average daily temperature in the mature period. And the effect of temperature on the aroma quantity of tobacco leaves was greater than that of aroma quality in the period of vigorous growth. Diffusiveness had a very significant negative correlation with the temperature difference and light hours in various periods. In miscellaneous odour,there was a significant positive correlation among immature odour and green odour and precipitation in various periods. Tobacco smoke concentration and ligneous odour and the whole growth period＞10℃ accumulated temperature reached extremely significant positive correlation. With the decrease in light hours, carotenoids degradation products of tobacco leaves, chlorophyll content of degradation products and the total aroma substances decreased significantly. Thus, aroma quantity and quality decreased and immature odour aggravated of tobacco.In particular, the decrease of light hours in the mature period was not conducive to the improvement of aroma quality and characteristics of tobacco leaves.The style and quality of tobacco leaves on sandy soil and loam were most prominent. However, the tobacco leaf style and quality characteristics of heavy clay were the least obvious. Degree and aroma quality of flue-cured tobacco with strong aroma features were positively correlated with the content of soil sand grains, and had a significant negative correlation with the content of clay. Obviously, mode-rate amount of light, temperature, rainfall, high sand grain and low clay content were conducive to the formation and characteristic of quality and flavor quality.

In the present work, aroma characteristics of tobacco from Henan Province were studied, which mainly included aroma quality, aroma quantity, diffusiveness and odour (Immature odour, ligneous odour, raw green odour and immature odour). Spatial distribution maps of aroma characteristic were drawn by Kriging interpolation method in ArcGIS, which could be conducive to get a better understanding of regional distribution of tobacco aroma characteristics from Henan Province and predicted aroma characteristics of tobacco samples from some locations. Spatial distribution maps would have guiding significances in developing tobacco base unit and helping industrial brand select raw materials.

Conclusions

Aroma characteristics of flue-cured tobacco from Henan Province were studied. Mean of aroma quality,aroma quantity and diffusiveness were from 2.65 to 3.06, 2.70 to 3.03 and 2.69 to 2.96 points, respectively.Immature odour, raw green odour and ligneous odour were all a little, while scorched odour was from a little to much. However, there was no earthy odour, rosin odour, pollen odour, herbal odour and metallic odour. The results indicated that there were significant differences between the aroma quality and the scorched odour from different prefectures, while there was no statistical differences among aroma quantity, diffusiveness, immature odour, raw green odour and ligneous odour. The spatial distribution maps indicated that the scale of aroma quality decreased from southwest to both north and east,diffusiveness decreased from east to west, scorched odour decreased from west to both north and south,ligneous odour increased from north to south, and immature odour increased from south to north. Aroma quantity was in the way of patchy distribution.