Preparation method of tobacco extract based on scenting pretreatment

Abstract

The invention discloses a preparation method of a tobacco extract based on scenting pretreatment. Comprising the following steps: step 1, performing loosening and moisture regaining on lamina tobacco leaves, and then shredding and drying the lamina tobacco leaves; 2, firstly picking fresh flowers, stacking until scenting requirements are met, and scenting twice to enable the tobacco shreds to adsorb the fragrance of the fresh flowers; and 3, carrying out supercritical CO2 extraction on the scented tobacco shreds to obtain the tobacco extract. When the prepared tobacco extract is applied to cigarettes, the cigarettes are endowed with characteristic aroma characteristics while the original tobacco aroma is supplemented and modified, richness, aroma quality and layering sense can be effectively improved, and compared with single use of traditional tobacco extracts and flower aroma raw materials, the tobacco extract is high in aroma naturalness and good in coordination, and aroma emitting and pressing conditions are not prone to occurring. The whole preparation method is green, safe, high in environmental protection degree, simple to operate, easy to control and suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural flavor development, and particularly relates to a preparation method of a tobacco extract using scenting technology as a pretreatment. Background Art

[0002] The flavoring and flavor addition technology is one of the core technologies affecting the style characteristics and sensory quality of cigarettes. Among many tobacco flavor raw materials, the importance of tobacco extracts is unparalleled. According to the requirements of the cigarette leaf group formula and the cigarette design goal, adding an appropriate amount of tobacco extract to the liquid flavor and surface flavor formula of cigarettes can make up for the dull flavor and lack of satisfaction caused by tar reduction. The raw material source of tobacco extract is tobacco itself, and there is basically no problem of disharmony with the whole cigarette during the application process. Therefore, as a tobacco flavor raw material, tobacco extract has inherent advantages.

[0003] With the development of the times and the progress of technology, consumers' concepts are constantly upgraded, and the consumption level is gradually improved. The development of natural tobacco flavors represented by tobacco extracts needs to adapt to the changes in the market pattern and consumption trends. It is necessary to not only strengthen the quality and stability of tobacco flavors in terms of quality control, but also continuously innovate and upgrade in terms of application effects and technical levels.

[0004] To a certain extent, tobacco leaves and tea leaves are similar. Both are consumer goods with certain flavor characteristics and physiological effects formed by the leaves of natural plants through a certain modulation process. After different modulation processes, both tobacco leaves and tea leaves have relatively dry properties and are easy to absorb flavors. Then, the tobacco leaves are given certain aroma style characteristics by spraying liquid flavor and surface flavor. In the case of scented tea, usually the tea leaves are mixed with fresh flowers, and the method of fresh flowers emitting fragrance and tea leaves absorbing fragrance is used to make the tea leaves have the natural fragrance characteristics of both tea leaves and fresh flowers.

[0005] The scented tea scenting process fully uses natural plant raw materials to achieve the effect of flavoring tea leaves. The naturalness and reduction degree of the aroma of scented tea are relatively high, and the whole process is safe, green and environmentally friendly; while the tobacco flavor raw materials used in the tobacco flavoring and flavor addition technology of tobacco leaves are divided into natural and synthetic. Some natural flavor raw materials cause loss or distortion of aroma due to the use of certain extraction, separation and concentration means, and are prone to problems of being difficult to coordinate with tobacco aroma during application. In order to improve the naturalness, safety and natural degree of tobacco flavor raw materials, the development of natural flavor raw materials can fully draw on the traditional scented tea scenting process. Summary of the Invention

[0006] The present invention draws on the traditional scented tea scenting technology, screens appropriate natural flower plant raw materials before extracting the tobacco leaf raw materials, performs scenting and flavoring treatment on the tobacco leaf raw materials, and then performs supercritical CO on the scented tobacco leaf raw materials 2Extraction enables the prepared tobacco extract to enhance the natural aroma and satisfaction of tobacco in cigarette applications, while possessing new fragrance characteristics or style features, meeting different flavoring application requirements, and conforming to the continuous upgrading of flavoring and dosing technologies and the development trend of market consumption.

[0007] The present invention is achieved through the following technical solutions: A method for preparing a tobacco extract based on scenting and flavoring, characterized in that the method comprises the following steps: I. Preparation of tobacco leaf raw materials: (1) Cutting: Using re-dried flue-cured tobacco cut tobacco as raw materials, after loose moisture regain, use a cutting machine to cut into shreds; (2) Drying: Hot air drying is carried out on the cut tobacco shreds.

[0008] II. Scenting: (1) Fresh flower treatment: Pick fresh flower buds, then stack them until the opening rate of the buds ≥ 80%, remove the buds to obtain the fresh flowers to be scented; or pick fresh flowers for stacking, break off the flower stalks and stamens, and only take the petals as the fresh flowers to be scented; (2) First scenting: Stack one layer of fresh flowers and one layer of tobacco shreds for scenting. When the stack temperature exceeds 40 °C, carry out ventilation treatment; (3) Spreading and drying: Spread out the tobacco shreds after the first scenting under normal temperature, cool and ventilated conditions, and wait until the temperature drops to about room temperature for the next operation; (4) Second scenting: Stack the spread and dried tobacco shreds again with one layer of fresh flowers and one layer of tobacco shreds for scenting. When the stack temperature exceeds 40 °C, carry out ventilation treatment. (5) Removing flowers and drying: Separate the tobacco shreds from the fresh flowers after scenting is completed, remove the flower residues, and carry out hot air drying.

[0009] III. Supercritical CO 2 Extraction: The specific process of supercritical CO 2 extraction using tobacco as raw materials is well-known to those skilled in the art and will not be elaborated here. However, considering a higher extraction rate and according to the model and parameter conditions of the supercritical CO 2 extraction equipment applied in the present invention, preferably, the temperature for supercritical CO 2 extracting the scented tobacco shreds is set at 30 - 40 °C; the extraction pressure is set at 20 - 40 MPa; the extraction time is set at 1.5 - 3.5 h; the extraction flow rate is set at 2 - 4 L / min; the entrainer used is ethanol, and the ethanol dosage is 12% of the mass of the tobacco shreds charged.

[0010] Further, I. Preparation of tobacco leaf raw materials: Step (1) Cutting: The moisture content of the loose and redried flue-cured tobacco slices is controlled at 18-25 wt%. The specifications of the cut tobacco after cutting are: width 0.8-1.2 mm, length range 1.0-2.0 mm; specifically, the purpose of loosening and redrying the sliced tobacco leaves before cutting is to reduce the breakage rate; the cutting process is to increase the contact area between the cut tobacco and the fresh flowers, so as to better adsorb the aroma substances in the fresh flowers in the scenting process, and also increase the contact area with the supercritical fluid in the subsequent extraction process, achieving the effect of improving efficiency and extraction rate.

[0011] Further, I. Preparation of tobacco leaf raw materials: Step (2) Drying: The baking temperature is set at 65-85 °C, and the moisture content of the final cut tobacco is controlled at 6-9 wt%. Specifically, drying by baking can make the cut tobacco have a relatively low moisture content, which is more conducive to improving the adsorption of the natural aroma in the fresh flowers during the scenting process; Further, II. Scenting: Step (1) Fresh flower treatment: Different types of fresh flowers are treated differently. There are two treatment methods in the present invention. The fresh flowers are harvested according to the best time for different fresh flowers to bloom and pick. The first is to moderately stack the harvested fresh flower buds until the opening rate of the flower buds ≥ 80%, and then remove the flower buds to obtain the fresh flower raw materials for scenting; the second is to remove the flower stalks and stamens after stacking the harvested flowers, and select the petals as the fresh flower raw materials for scenting. Specifically, different fresh flowers have different best times on the day of harvest due to different flowering seasons, and they must be treated differently to achieve the best effect of fresh flowers in the scenting process; Further, II. Scenting: Step (2) First scenting: Stack the cut tobacco and fresh flowers layer by layer, with the weight ratio of tobacco to flowers being 100:(60-100), and scent for 12-16 hours. When the stack temperature exceeds 40 °C, ventilation treatment is carried out. Specifically, the purpose of ventilation is to reduce the stack temperature, increase oxygen, and make the cut tobacco and fresh flowers contact more evenly, so that the cut tobacco fully absorbs the aroma of the fresh flowers. Otherwise, it is easy to cause the fresh flowers to produce unpleasant off-flavors due to rising temperature and stuffiness, affecting the naturalness and freshness of the final aroma; secondly, the development and design goal of the tobacco extract prepared in the present invention, which is mainly based on the original tobacco aroma, remains unchanged. Through fresh flower scenting, the fresh, sweet, fresh, and secluded aromas in the floral fragrance are imparted to the tobacco extract as auxiliary aromas, and are applied in the liquid material and surface aroma formulas to fit the cigarette style and aroma design goal. The parameters can be flexibly adjusted according to actual application needs to better meet the overall aroma characteristics and aroma harmony requirements of the preparation of tobacco extracts; Further, II. Scenting: Step (3) Spreading and drying: Spread the cut tobacco after the first scenting in a cool and ventilated place at room temperature. This process can be carried out for 24-36 h. Specifically, in case of high temperature and high humidity weather, a dehumidifier can be used to accelerate the spreading process. This step can reduce the stack temperature while improving the efficiency of the second scenting; Furthermore, second, scenting: Step (4) Secondary scenting: Stack the cooled tobacco leaves layer by layer with fresh flowers, with the weight ratio of fresh flowers being 100:(20 - 50), scent for 8 - 12 hours, and perform ventilation treatment when the stack temperature exceeds 40°C. Specifically, the reduction in the amount of fresh flowers used and the scenting time in secondary scenting is because the main characteristic of the tobacco extract prepared in the present invention is still the original tobacco fragrance. Through scenting with fresh flowers, the main aroma is enriched and has a partial natural floral fragrance. This is still somewhat different from the purpose of scented tea scenting. Therefore, it is not necessary to achieve an ideal state of fragrance absorption saturation for the tobacco leaves during the fresh flower scenting process, and the weight ratio of fresh flowers and the scenting time can be adjusted according to actual needs; Furthermore, second, scenting: Step (5) Flower removal and drying: After scenting is completed, separate the tobacco leaves from the flower residues through flower removal, and dry the scented tobacco leaves. The baking temperature is set at 35 - 45°C, and the moisture content of the tobacco leaves is controlled at 9 - 12 wt%. Specifically, the scented tobacco leaves are not baked and dried at a relatively high temperature, and the moisture content of the baked tobacco leaves is controlled at a suitable level, which is beneficial for the effective extraction of aroma components in subsequent supercritical CO 2 extraction and improves the extraction rate.

[0012] Furthermore, third, supercritical CO 2 extraction: In the field of natural tobacco flavor raw materials, supercritical CO 2 extraction technology has been studied more deeply and is widely applied. In the present invention, reasonable process parameters are optimized and designed to extract the effective aroma components in the scented tobacco leaves to the greatest extent. Specifically, the supercritical CO 2 extraction form has the advantages of low temperature and no need to use organic solvents. Coupled with the use of green solvent - edible ethanol as an entrainer in the present invention, on the basis of green and environmental protection of the process, it not only does not damage the thermosensitive aroma components in the scented tobacco leaves, but also greatly improves the effective extraction of aroma components with different polarities, making the prepared tobacco extract have the advantages of natural and complete aroma.

[0013] Preferably, the tobacco leaf raw materials described in Step 1 are flue-cured tobacco leaves from different regions, different parts, and different grades in China, including single-variety tobacco leaves, blended tobacco leaves, and formulated leaf group tobacco leaves; Preferably, the fresh flowers described in Step 2 are natural plant fresh flowers suitable for the scenting process, and their plant raw materials or related flavor raw material products are included in the enterprise standard of China National Tobacco Corporation, "List of Additives Permitted for Use in Tobacco Products (YQ52 - 2015)". Specifically, it includes one or several of jasmine flowers, rose flowers, (bitter) orange flowers, acacia flowers, lavender flowers, turmeric flowers, and ylang-ylang flowers.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention firstly performs fresh flower scenting on domestic flue-cured tobacco shreds, and appropriately adjusts the moisture content of the shredded tobacco in the process to increase the adsorption of the effective aroma components of the fresh flowers by the shredded tobacco. The weight ratio of the fresh flowers to the shredded tobacco and the scenting time in the scenting process can be flexibly changed according to the design and application target of the tobacco extract finally obtained, and then uses supercritical CO 2 Extraction is performed on the tobacco shreds after the scenting. The entire extraction process is beneficial to the effective extraction of volatile and semi-volatile aroma components, thereby achieving the preparation of tobacco extracts with new characteristic aromas or styles. The raw materials of the present invention are all natural plant raw materials. 2 Edible ethanol is used as an entrainer in the extraction process, which is green and highly environmentally friendly.

[0015] 2. The novel tobacco extract prepared in the present invention does not change its main function of supplementing and enhancing the original aroma of tobacco, as well as modifying and coordinating the main aroma of the tobacco leaf group formula. The tobacco extract prepared after different fresh flowers can be selected for application according to the cigarette style or aroma design goals to achieve the effect of enriching the aroma layering and improving the aroma quality, and to achieve the design goals of the aroma and style characteristics of the cigarette. Compared with the use of traditional tobacco extracts and flower fragrance raw materials alone in the process of flavoring and adding, the aroma performance is more natural, integrated and balanced, and it is not easy to have inharmonious situations such as fragrance emitting and fragrance suppression. Implementation

[0016] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0017] A method for preparing a tobacco extract based on pre-scenting treatment comprises the following steps: 1. Preparation of tobacco raw materials: (1) Cutting into shreds: taking redried Yunnan Yuxi upper mixed tobacco leaves as raw materials, loosening and rehumidifying them to control the moisture content of the tobacco leaves to 18wt%, and then cutting them into shreds, setting the shred width to 1.2mm, so that the length of the shredded tobacco is within the range of 1.0-2.0mm; (2) Drying: Place the tobacco in a hot air circulation drying room and set the temperature to 75°C so that the moisture content of the tobacco after drying is 8%.

[0018] 2. Scenting: (1)Fresh flower treatment: Pick the plump, semi-open, snow-white and crystal-clear jasmine flower buds with green stalks in the afternoon on a sunny day during the dog days. Then stack them, controlling the stack height and temperature of the fresh flowers. When the opening rate of the jasmine flowers is ≥ 80%, remove the flower buds to obtain the fresh jasmine flowers to be scented; (2)First scenting: Stack the materials layer by layer with one layer of jasmine flowers and one layer of cut tobacco. The weight ratio of cut tobacco to fresh flowers is 100:60. Scent for 14 hours. When the stack temperature exceeds 40 °C, conduct ventilation treatment to reduce the temperature and dissipate the heat in time; (3)Spreading and drying: Spread the cut tobacco after the first scenting in a cool and well-ventilated place at room temperature until it reaches room temperature and then let it stand still. This step lasts for 36 hours in total; (4)Second scenting: Mix the cut tobacco after spreading and drying with fresh jasmine flowers according to the weight ratio of 100:50, and then stack them layer by layer with one layer of fresh flowers and one layer of cut tobacco. Scent for 12 hours, and control the stack temperature below 40 °C during the scenting process; (5)Removing flowers and drying: Sieve the cut tobacco and fresh flowers after scenting twice. Remove the flowers for the first time and the flower residues for the second time. Then transfer the scented cut tobacco to a hot air circulation drying room. Set the drying room temperature at 35 °C, and the moisture content of the dried cut tobacco is 9 wt%;

[0019] III. Supercritical CO 2 Extraction: Conduct supercritical extraction on the scented cut tobacco, adding 95 vol% ethanol accounting for 12% of the weight of the fed cut tobacco as the entrainer. The extraction conditions are: extraction temperature 40 °C, pressure 35 MPa, flow rate 2 - 4 L / min, and extraction time 2.5 hours to obtain the tobacco extract. Example

[0020] A preparation method of tobacco extract based on pre-treatment before scenting, comprising the following steps: I. Preparation of tobacco leaf raw materials: (1)Cutting: Take the re-dried middle and upper mixed cut tobacco leaves from Zunyi, Guizhou as raw materials. After loose re-moistening, control the moisture content of the cut tobacco leaves at 25 wt%. Then cut them, set the cutting width at 1.0 mm, and make the length of the cut tobacco after cutting within the range of 1.0 - 2.0 mm; (2)Drying: Place the cut tobacco in a hot air circulation drying room, set the temperature at 85 °C, and make the moisture content of the dried cut tobacco 6%;

[0021] II. Scenting: (1)Fresh flower treatment: During the rose blooming period, select the large, plump and newly blooming flowers for picking. Then stack them, controlling the stack height and temperature of the fresh flowers. Then remove the flower stalks and stamens to obtain the fresh rose petals to be scented; (2) First scenting: Stack the tobacco leaves and rose petals layer by layer. The weight ratio of tobacco leaves to petals is 100:100. Scent for 16 hours. When the stack temperature exceeds 40 °C, perform ventilation treatment to reduce the temperature and dissipate the heat in time; (3) Spreading and drying: Spread the tobacco leaves after the first scenting in a cool and ventilated place at room temperature until they reach room temperature and then let them stand still. This step takes a total of 30 hours; (4) Second scenting: Mix the tobacco leaves after spreading and drying with fresh rose petals at a weight ratio of 100:30, and stack them layer by layer of petals and layer by layer of tobacco leaves. Scent for 10 hours, and control the stack temperature below 40 °C during the scenting process; (5) Removing flowers and drying: Screen the tobacco leaves and fresh flowers twice after scenting. Remove the petals for the first time and remove the flower residues for the second time. Then transfer the scented tobacco leaves to a hot air circulation drying room. Set the drying room temperature to 45 °C. The moisture content of the dried tobacco leaves is 12 wt%.

[0022] Three, supercritical CO 2 Extraction: Perform supercritical extraction on the scented tobacco leaves, add 95 vol% ethanol accounting for 12% of the weight of the fed tobacco leaves as an entrainer. The extraction conditions are: extraction temperature 35 °C, pressure 20 MPa, flow rate 2 - 4 L / min, extraction time 3.5 hours to obtain tobacco extracts. Example

[0023] A preparation method of tobacco extracts based on pre-treatment by scenting, comprising the following steps: I. Preparation of tobacco leaf raw materials: (1) Cutting: Take the re-dried middle orange-colored grade 4 (CF) single-leaf cut tobacco leaves from Shiyan, Hubei as raw materials. After loose reconditioning, control the moisture content of the cut tobacco leaves at 20 wt%, and then cut them. Set the cutting width to 0.8 mm so that the length of the cut tobacco leaves after cutting is in the range of 1.0 - 2.0 mm; 4 (2) Drying: Place the cut tobacco leaves in a hot air circulation drying room, set the temperature to 65 °C, and make the moisture content of the dried cut tobacco leaves 9 wt%. (2) Drying: Place the cut tobacco leaves in a hot air circulation drying room, set the temperature to 65 °C, and make the moisture content of the dried cut tobacco leaves 9 wt%.

[0024] II. Scenting: (1) Fresh flower treatment: During the full bloom period of navel orange flowers, pick the plump and semi-open bitter orange flower buds with green stalks, then stack them, control the stack height and temperature of the fresh flowers. Wait until the opening rate of the orange flowers ≥ 80%, and remove the unopened flower buds to obtain the fresh orange flowers to be scented; (2) First scenting: Stack the orange flowers and tobacco leaves layer by layer. The weight ratio of tobacco leaves to orange flowers is 100:90. Scent for 12 hours. When the stack temperature exceeds 40 °C, perform ventilation treatment to reduce the temperature and dissipate the heat in time; (3)Cooling and drying: The tobacco leaves after the first scenting are cooled to room temperature under normal temperature, in a cool and well-ventilated condition, and then left standing. This step lasts for 24 hours in total. (4)Second scenting: The tobacco leaves after cooling and drying are mixed with fresh orange blossoms according to a weight ratio of 100:20, and then stacked layer by layer with one layer of fresh flowers and one layer of tobacco leaves. The scenting process lasts for 8 hours, and the temperature inside the stack is controlled below 40°C during the scenting process. (5)Removing flowers and drying: The tobacco leaves and fresh flowers after scenting are screened twice. The first screening removes the flowers, and the second screening removes the flower residues. Then the scented tobacco leaves are transferred to a hot air circulation drying room, where the temperature of the drying room is set at 40°C, and the moisture content of the dried tobacco leaves is 10 wt%.

[0025] III. Supercritical CO 2 Extraction: The scented tobacco leaves are subjected to supercritical extraction, and 95 vol% ethanol accounting for 12% of the weight of the charged tobacco leaves is added as an entrainer. The extraction conditions are as follows: extraction temperature 30°C, pressure 40 MPa, flow rate 2 - 4 L / min, and extraction time 1.5 h, to obtain a tobacco extract.

[0026] The three kinds of tobacco extracts prepared in Examples 1 - 3 are added to the blank leaf group of the test cigarettes in the form of flavoring at a ratio of 0.05%, and cigarette products are made using the laboratory process of the cigarette industry. Then, sensory evaluation is carried out in accordance with the "YC / T 415 - 2011 Sensory Evaluation Method for Tobacco In-Process Products". The results are shown in Table 1 and Table 2.

[0027] Table 1 Sensory Evaluation Table Table 2 Sensory Evaluation Table (National Standard Scoring) Group Luster (5) Aroma (32) Harmony (6) Off-odor (12) Irritation (20) Aftertaste (25) Total Blank 5 24.12 4.98 7.55 15.89 18.23 75.77 Example 1 5 28.37 5.44 9.31 18.54 21.13 87.79 Example 2 5 28.85 5.63 9.27 18.49 21.52 88.76 Example 3 5 27.93 5.51 9.63 17.96 21.36 87.39 It can be seen from the sensory evaluation results that adding the prepared tobacco extract products can effectively improve the quality and quantity of the cigarette aroma. On the basis of enhancing and coordinating the tobacco aroma, it can play the role of enriching the aroma and strengthening the aroma characteristics, and the taste and aftertaste of the cigarettes have also been improved.

Claims

1. A preparation method of tobacco extract based on pretreatment before scenting, characterized in that, the method comprises the following steps: I. Preparation of tobacco leaf raw materials: (1) Cutting into shreds: Using the flue-cured tobacco cut tobacco after re-drying as raw materials, after loose re-damping, use a cutting machine to cut into shreds; (2) Drying: Hot air drying is carried out on the cut tobacco shreds. II. Scenting: (1) Fresh flower treatment: Pick fresh flower buds, then stack them until the opening rate of the buds ≥ 80%, remove the buds to obtain the fresh flowers to be scented; or pick fresh flowers and stack them, break off the flower stalks and stamens, and only take the petals as the fresh flowers to be scented; (2) Primary scenting: Stack one layer of fresh flowers and one layer of tobacco shreds for scenting. When the stack temperature exceeds 40°C, carry out ventilation treatment; (3) Spreading and drying: Spread out the tobacco shreds after primary scenting under normal temperature, cool and ventilated conditions, and wait until the temperature drops to about room temperature for the next operation; (4) Secondary scenting: Stack the tobacco shreds after spreading and drying again with one layer of fresh flowers and one layer of tobacco shreds for scenting. When the stack temperature exceeds 40°C, carry out ventilation treatment; (5) Removing flowers and drying: Separate the tobacco shreds from the fresh flowers after scenting is completed, remove the flower residues, and carry out hot air drying. III. Supercritical CO 2 Extraction: Subject the scented cut tobacco to supercritical CO 2 extraction to obtain a tobacco extract.

2. The preparation method of a tobacco extract based on pretreatment before scenting according to claim 1, characterized in that, I. Preparation of tobacco leaf raw materials: The tobacco leaf raw materials described include flue-cured tobacco leaves from different regions, different parts and different grades in China, including single-variety tobacco leaves, mixed-cut tobacco leaves and formulated leaf group tobacco leaves.

3. The preparation method of a tobacco extract based on pretreatment before scenting according to claim 1, characterized in that, I. Preparation of tobacco leaf raw materials: Step (1) Cutting into shreds: After loose re-damping, the moisture content of the cut tobacco is controlled at 18-25wt%; the specifications of the cut tobacco shreds are: the width is 0.8-1.2mm, and the length range is 1.0-2.0mm.

4. The preparation method of a tobacco extract based on pretreatment before scenting according to claim 1, characterized in that, I. Preparation of tobacco leaf raw materials: Step (2) Drying: Carry out drying on the tobacco shreds in a hot air circulation drying room, and the drying temperature is set at 65-85°C. The moisture content of the dried tobacco shreds is controlled at 6-9wt%.

5. The preparation method of a tobacco extract based on pretreatment before scenting according to claim 1, characterized in that, II. Scenting: Step (1) Fresh flower treatment: The fresh flowers are natural plant fresh flowers suitable for the scenting process, and their plant raw materials or related fragrance raw material products are included in the enterprise standard of China National Tobacco Corporation "List of Additives Permitted for Use in Tobacco Products (YQ52-2015)". Specifically include one or several of jasmine flowers, rose flowers, (bitter) orange flowers, acacia flowers, lavender flowers, turmeric flowers, ylang-ylang flowers; the fresh flower treatment methods include two types. The first is to pick fresh flowers and stack them moderately until the opening rate of the buds ≥ 80%, remove the buds to obtain the fresh flower raw materials for scenting; the second is to remove the flower stalks and stamens after stacking the picked fresh flowers, and select the petals as the fresh flower raw materials for scenting.

6. The preparation method of a tobacco extract based on pretreatment before scenting according to claim 1, characterized in that, II. scenting: Step (2) primary scenting: The weight ratio of tobacco shreds to fresh flowers is 100:(60 - 100), scenting for 12 - 16 hours, and when the stack temperature exceeds 40°C, ventilation treatment is carried out.

7. A method for preparing a tobacco extract based on pre-treatment before scenting according to claim 1, characterized in that II. scenting: Step (3) spreading and drying: The tobacco shreds after primary scenting are spread in a cool, ventilated condition at room temperature for 24 - 36 h.

8. A method for preparing a tobacco extract based on pre-treatment before scenting according to claim 1, characterized in that II. scenting: Step (4) secondary scenting: The weight ratio of tobacco shreds to fresh flowers is 100:(20 - 50), scenting for 8 - 12 hours, and when the stack temperature exceeds 40°C, ventilation treatment is carried out.

9. A method for preparing a tobacco extract based on pre-treatment before scenting according to claim 1, characterized in that II. scenting: Step (5) flower removal and drying: The tobacco shreds are separated from the flower residues by flower removal, and the scented tobacco shreds are dried in a hot air circulation drying room, the drying temperature is set at 35 - 45°C, and the moisture content of the tobacco shreds is controlled at 9 - 12 wt%.

10. A method for preparing a tobacco extract based on pre-treatment before scenting according to claim 1, characterized in that III. Supercritical CO 2 Extraction: Supercritical CO 2 The extraction process parameters include: the temperature is set at 30 - 40°C; the extraction pressure is set at 20 - 40 MPa; the extraction time is set at 1.5 - 3.5 h; the extraction flow rate is set at 2 - 4 L / min; the entrainer used is ethanol, and the ethanol dosage is 12% of the mass of the charged cut tobacco.