Method for improving quality of microwave expanded cut rolled tobacco

Abstract

The application provides a method for improving the quality of microwave-expanded cut stem for cigarettes, and belongs to the technical field of tobacco processes. The method makes full use of the internal changes of tobacco stems and products thereof after enzymolysis, re-cutting and microwave expansion, and improves the internal quality of the cut stem. Specifically, the method increases the content of Maillard reaction products in the drying process and the content of flavor components in the cut stem, increases the processing resistance of the cut stem, improves the softness of the cut stem and the compatibility with leaf tobacco, reduces the tar content, harmful component content such as carbon monoxide, offensive odor and irritancy in the mainstream smoke of the cigarette, and reduces the breakage of the cut stem, thereby improving the internal quality of the cut stem, increasing the proportion of the cut stem in the cigarette, and making the mainstream smoke of the cigarette full and delicate in aroma. The method has a certain popularization and application value in the industrial production of cigarettes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of tobacco processing, and particularly relates to a method for improving the quality of microwave-expanded re-cut stem. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and does not necessarily constitute an acknowledgement or a suggestion that this information forms part of the prior art already known to a person of ordinary skill in the art.

[0003] Tobacco stem is the hard and tough vein part of tobacco leaf, accounting for about 25% of the total mass of tobacco leaf. It is abundant in source. The tobacco stem contains abundant pore structure, vessel structure and fiber air chamber, and is an ideal material for preparing high-filling material. In addition, the chemical components of tobacco stem are similar to those of tobacco leaf. The stem prepared from tobacco stem is an important component of cigarette formula. The stem has stronger physical support and can improve the specific physical and chemical properties of cigarette, reduce the consumption of tobacco raw materials, improve the utilization rate of raw materials, reduce the amount of smoke tar, and play an important role in reducing harm and tar, reducing cost and consumption in cigarette.

[0004] The traditional preparation process of stem generally includes feeding, screening, washing stem, storing stem, steaming and pressing stem, cutting stem, adding material, expanding, air selection and storage. Since the stem prepared by the traditional process is only cut once, the final stem is mostly in the form of sheet, which is obviously different from the shape of tobacco cut filler, and the compatibility between the two is not high, which limits the application of stem in cigarette, especially in the current popular slim cigarette. In addition, the traditional stem process passes through the pressing stem process, which reduces the expansion degree of the stem and the filling value of the stem.

[0005] The chemical components contained in tobacco stem are basically similar to those in tobacco leaf, but there are great differences in content, especially in the content of flavor components. Therefore, the smoke produced by burning tobacco stem has insufficient aroma and dull taste. At the same time, tobacco stem contains abundant lignin, pectin, protein, hemicellulose and other substances, and has poor thermal cracking performance. After thermal cracking, substances such as phenol, o-diphenol and alkyl catechol are produced. These compounds not only cause astringency, produce woody odor, green odor, burnt feather odor and other irritating gases, which affect the sensory quality of cigarette, but also are harmful to health. In addition, a large amount of pectin contained in stem has high hygroscopicity, which can firmly adsorb moisture in the environment. This brings additional energy consumption for removing moisture in raw materials in the processing process, and also puts higher requirements on the relative humidity of the storage environment. These factors directly or indirectly lead to the fact that tobacco stem and its products cannot be used as a large amount of cigarette formula component, resulting in low utilization rate of tobacco stem.

[0006] Studies have shown that microwave expansion treatment of stem can effectively tear the cell wall, make the chemical composition of stem change obviously, and have a positive effect on improving the smoking quality of stem, and the inside of the stem after microwave expansion is porous, the adsorption capacity of external material liquid and spices is greatly enhanced, and the operation of adding spices is facilitated. However, the microwave expansion has strict requirements on the moisture content of the raw material, and uneven moisture content of the raw material will lead to insufficient expansion or heavy stem stem dryness, and the whole stem rate is low when the microwave expansion tobacco stem is cut.

[0007] The chemical composition contained in the stem prepared by the traditional method is basically similar to that of tobacco leaf, but there is a big difference in content, especially in the content of flavoring ingredients, so the smoke produced by burning tobacco stem is short of aroma, and the taste is flat. At the same time, tobacco stem contains rich lignin, pectin, protein, hemicellulose and other substances, and has poor thermal cracking performance, and after thermal cracking, phenol, o-diphenol, alkyl catechol and other substances will be produced. These compounds not only cause astringency, produce woodiness, greenness, burnt feather smell and other irritating gases to affect the sensory quality of cigarettes, but also are harmful to health. SUMMARY

[0008] In order to solve the above problems, the present application provides a tobacco stem expansion process, which combines biological enzyme treatment, re-cutting stem and microwave expansion to improve the quality of tobacco stem and its products, reduce the impurities and irritation in the mainstream smoke of stem, increase the aroma and aftertaste of cigarettes, and improve the compatibility of stem and leaf in cigarettes. The process includes the following steps: tobacco stem screening, stem washing, stem steaming, stem storage, stem cutting, re-cutting stem, microwave expansion, and air selection, and the stem is subjected to temperature increasing and constant temperature treatment before microwave expansion.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0010] In a first aspect of the present application, a method for improving the quality of microwave-expanded re-cutting stem for tobacco is provided, comprising:

[0011] Screening, washing and steaming the tobacco stem to obtain pretreated tobacco stem;

[0012] Spraying a composite enzyme solution on the pretreated tobacco stem for primary storage to obtain composite enzyme tobacco stem;

[0013] Spraying a protease on the composite enzyme tobacco stem for secondary storage to obtain protease-composite enzyme tobacco stem;

[0014] Cutting the protease-composite enzyme tobacco stem to obtain stem;

[0015] Adding material and cutting the stem to obtain re-cutting stem;

[0016] The cut stem is sequentially subjected to temperature increasing and constant temperature treatment, so that the Maillard reaction is fully carried out and the moisture and temperature of the stem are balanced, and the enzyme-treated stem is obtained.

[0017] The enzyme-treated stem is subjected to microwave expansion, and the stem is obtained.

[0018] The present application overcomes the shortcomings in the prior art, and provides a method for improving the compatibility of stem and leaf, reducing the bad flavor of stem smoke, increasing the aroma of cigarette mainstream smoke, and having higher filling value and combustibility, thereby promoting the application of stem in medium and high-grade cigarettes.

[0019] In some embodiments, the water temperature for washing the stem is 40-70℃, the water flow rate is 0.65-0.70m / s, the washing time is 20-50s, and the circulating water is replaced every 3h;

[0020] In some embodiments, the specific parameters for filtering the washed stem are as follows: the number of filter screens is 20 meshes, the angle of the filter screen is 25°, and the filtering time is 4-10s;

[0021] In some embodiments, the cooled stem after filtering is cooled to room temperature before the next step;

[0022] In some embodiments, the saturated water vapor pressure is 0.2-0.4MPa, the steaming time is 6-10s, and the water content of the cooled stem is 35-40%;

[0023] In some embodiments, the complex enzyme is composed of hemicellulase, laccase and pectinase;

[0024] In some embodiments, the concentration of the complex enzyme solution is 4wt%, wherein the total activity ratio of hemicellulase:laccase:pectinase is 3-300:3-300:2-200, the total activity of hemicellulase in each kilogram of complex enzyme is 30-3000 million U, the total activity of laccase is about 30-3000 million U, and the total activity of pectinase is 20-2000 million U;

[0025] The enzyme is added to the stem at the inlet end of the drum, and the complex enzyme solution is atomized by compressed air at room temperature at a pressure of 0.08-0.12MPa to uniformly spray on the surface of the stem, and the drum rotates at a speed of 6-10rpm / min to uniformly mix the stem and the enzyme solution;

[0026] In some embodiments, the environmental temperature for once storing the stem is 30-40℃, and the time is 2-8h;

[0027] In some embodiments, the total activity of protease enzyme in each kilogram of protease solution is 160-300 million U;

[0028] In some embodiments, after the tobacco stems have finished storing, they are taken out of the cabinet and then returned to the drum in step 3) to add enzyme. The enzyme solution is atomized with room temperature compressed air at 0.08-0.12 MPa and sprayed evenly on the surface of the tobacco stems. The drum speed is 6-10 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly.

[0029] In some embodiments, the ambient temperature for secondary stalk storage is 30-40°C, and the time is 2-8 hours;

[0030] In some embodiments, the thickness of the cut stem is 0.12-0.18 mm;

[0031] In some embodiments, the width of the cut stem is 0.7-1.2 mm;

[0032] In some embodiments, the heating process includes: heating the tobacco stems to 70-80°C and maintaining the temperature of the tobacco stems for at least 3-4 minutes;

[0033] In some embodiments, the obtained recut tobacco stems are subjected to heating and moisture regulation treatment in a screw conveyor to ensure that the moisture content of the tobacco stems is 20-22 wt% while ensuring that the temperature of the tobacco stems is qualified.

[0034] In some implementations, the microwave power is 60 kW, and the moisture content of the tobacco stems after expansion and drying is 11-12 wt%.

[0035] More specifically, it includes the following steps:

[0036] 1) Screen the tobacco stems to remove stems and broken stems that are less than 10mm in length and less than 3mm in diameter. Place the screened tobacco stems in a stem washing machine for washing and filtration.

[0037] 2) The tobacco stems after washing are subjected to HT steaming, and then cooled to room temperature;

[0038] 3) Prepare a compound enzyme solution by adding water to hemicellulase, laccase and pectinase, and spray it evenly on the surface of the tobacco stems in step 2). Then place the tobacco stems sprayed with the biological enzyme solution in a covered stem cabinet for storage for a certain period of time.

[0039] 4) Prepare an enzyme solution with 2% by mass by adding water to the protease, and then spray it evenly on the surface of the tobacco stems after the storage in step 3). Then store it in a covered stem cabinet for a period of time. The covered stem cabinet can reduce the moisture loss of the tobacco stems during storage.

[0040] 5) Cut the tobacco stems that have finished storing them into stem strips using a stem strip cutter;

[0041] 6) Add the above-mentioned shredded stems to the spices, with the total mass percentage of spices to shredded stems being 0.5-2.5%;

[0042] 7) The above-mentioned stem shreds are cut again using a leaf shredder to obtain double-cut stem shreds;

[0043] 8) The above-mentioned double-cut stems are subjected to heating and constant temperature treatment to fully induce the Maillard reaction and balance the moisture and temperature of the stems;

[0044] 9) The enzymatically hydrolyzed stems were microwave-expanded to obtain double-cut stems with high filling capacity, high whole-strand rate, and higher aroma components.

[0045] In a second aspect, the present invention provides microwave-expanded double-cut tobacco stems prepared by the above-described method, wherein the whole stem content of the double-cut stems is ≥74%, and the filling value is ≥5.6 cm. 3 / g.

[0046] A third aspect of the present invention provides the application of the above-described double-cut stem strands in the preparation of cigarettes.

[0047] Beneficial effects of the present invention

[0048] 1) The method for enzymatic treatment of tobacco stems according to this application effectively degrades components in tobacco stems that are detrimental to cigarette quality by optimizing the activity of the compound enzyme and protease, the time of the enzymatic reaction, and the order of adding enzyme solution, thereby reducing the off-gas produced by tobacco stem combustion and avoiding the severe breakage of stem strands caused by excessive pectin degradation.

[0049] 2) The method of preheating and heat-preserving the stems before microwave expansion according to this application allows the enzymatic reaction products, polysaccharides and polypeptides, to fully undergo Maillard reactions, generating special aroma products, effectively compensating for the insufficient aroma of stems produced by traditional processes. Simultaneously, the preheating and heat-preserving treatment ensures uniform temperature and humidity of the stems entering the microwave expansion process, effectively avoiding insufficient expansion or scorching caused by uneven moisture loss during microwave expansion. The higher temperature of the stems after the preheating treatment also effectively reduces the power and energy loss during microwave expansion.

[0050] 3) The method for double-cutting stems according to this application does not employ the pressing step in the traditional stem-cutting process, thus further increasing the filling capacity and combustibility of the stems. In addition, by performing double-cutting treatment on the tobacco stems, the physical form of the double-cut stems is filamentous, which has better compatibility with the leaf filaments.

[0051] 4) This invention patent utilizes an enzyme-treated tobacco stem method. By optimizing the activity of compound enzymes and proteases, the time of the enzymatic reaction, and the order of adding enzyme solutions, it effectively converts components in tobacco stems that are detrimental to cigarette quality into low molecular weight compounds. The subsequent heating and heat preservation treatment causes the enzymatically catalyzed low molecular weight compounds to undergo a Maillard reaction, generating special aroma products, effectively compensating for the insufficient aroma of tobacco stems produced by traditional processes.

[0052] 5) The equipment required for this invention patent is currently widely used in the tobacco industry, and the research on Maillard reaction is also relatively mature. At the same time, the heating and heat preservation treatment will make the temperature and humidity of the stems uniform, effectively avoiding the phenomenon of insufficient expansion or scorching caused by uneven moisture loss of the stems during microwave expansion. The higher temperature of the stems after the heating treatment also effectively reduces the energy loss of the drying process. Detailed Implementation

[0053] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0054] This invention discloses a method for preparing microwave-expanded tobacco stems. The invention is described in detail below with reference to specific embodiments. These embodiments are merely illustrative and intended to facilitate understanding, implementation, or use of the invention by those skilled in the art, and do not limit the scope of protection of the invention. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Where there is no conflict, the embodiments and features in the embodiments of this invention can be combined with each other. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0055] In this invention, unless otherwise specified, all materials and equipment used are commercially available or commonly used in the art. The hemicellulase, laccase, pectinase, and protease in the following examples are all in powder form and are commercially available. Unless otherwise specified, the methods in the following examples are conventional methods in the art.

[0056] Example 1:

[0057] A method for preparing microwave-expanded tobacco stems, the specific steps of which are as follows:

[0058] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0059] (2) Remove tobacco stems and broken stems with a length of less than 10 mm and a diameter of less than 3 mm from the raw tobacco stems. Wash the stems with warm water at 65℃ (water flow rate is 0.65 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0060] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.3 MPa for 8 seconds. Then, they were cooled to room temperature. The moisture content of the tobacco stems after cooling was 35%.

[0061] (4) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. The compound enzyme solution is atomized with compressed air at room temperature using 0.08 MPa to spray it evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of the compound enzyme solution is 3% of the weight of the tobacco stems. The total activity of hemicellulase in each kilogram of compound enzyme solution is 120 million U, the total activity of laccase is 180 million U, and the total activity of pectinase is 90 million U. Then, the tobacco stems sprayed with the compound enzyme solution are stored in a covered stem cabinet at 34°C for 3 hours. The covered stem cabinet can keep the tobacco stems moist during storage. The optimal temperature for the compound enzyme is explored through preliminary experiments, and 34°C is preferred as the optimal temperature.

[0062] (5) After the tobacco stems from the previous storage step are removed from the cabinet, they are returned to the drum in step (4). The protease solution is atomized with room temperature compressed air at 0.08 MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of protease solution used is 1.5% of the weight of the tobacco stems, and the total activity of the protease in each kilogram of protease solution is 160 million U. Then, the tobacco stems sprayed with protease are stored in a covered stem cabinet at 34°C for 4 hours.

[0063] (6) Cut the tobacco stems obtained in the previous step using a stem cutter. The width of the cut stems is 0.15mm, which gives the stems with a thickness of 0.15mm. Then, add the spices. The amount of spices added is 1% of the stems. Store in a buffer cabinet for 2 hours.

[0064] (7) Use a shredder to recut the stem slices obtained in the previous step. The width of the cut stem is 1.0 mm, which gives you recut stem shreds with a width of 1.0 mm.

[0065] (8) The stems obtained in the previous step are subjected to a heating treatment. The stems are heated and kept at a constant temperature in a two-stage spiral conveyor device. At the end of the heating stage, the temperature of the stems reaches 70-80℃, and this temperature is maintained for 3-4 minutes in the constant temperature stage. At the end of the constant temperature stage, the moisture content of the stems is 16-17 wt%. During the heating and constant temperature process, a large amount of reducing sugars, peptides, and small molecule proteins generated by enzymatic hydrolysis on the surface and inside of the stems undergo Maillard reaction, producing Maillard reaction products with rich aroma and bright yellow color. At the same time, the spiral conveyor device ensures that the stems are heated evenly during the heating process, and the moisture distribution is relatively uniform. After entering the microwave expansion equipment, they can be dehydrated quickly, synchronously, and uniformly, effectively saving energy and avoiding carbonization caused by local excessive or insufficient moisture in the stems.

[0066] (9) Add the above-mentioned stems to the microwave expansion device, use a belt conveyor, microwave power of 60kw, and convey the stems forward so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the stems is controlled to be 11-12wt%.

[0067] (10) The microwave-expanded filaments were sieved by air separation to remove impurities and then rapidly cooled. After air separation, the whole filament rate of the expanded filaments was 88%, and the filling value was 8.1 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0068] Example 2:

[0069] A method for preparing microwave-expanded tobacco stems, the specific steps of which are as follows:

[0070] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0071] (2) Remove stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the tobacco stem raw material. Wash the stems with warm water at 55℃ (water flow rate is 0.6 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0072] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.4 MPa for 10 seconds, and then cooled to room temperature.

[0073] (4) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. The compound enzyme solution is atomized with compressed air at room temperature (0.08 MPa) to spray it evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of the compound enzyme solution is 5% of the weight of the tobacco stems. The total activity of hemicellulase in each kilogram of compound enzyme solution is 200 million U, the total activity of laccase is 240 million U, and the total activity of pectinase is 120 million U. Then, the tobacco stems sprayed with the compound enzyme solution are stored in a covered stem cabinet at 34°C for 3 hours.

[0074] (5) After the tobacco stems from the previous storage step are removed from the cabinet, they are returned to the drum in step (4). The protease solution is atomized with room temperature compressed air at 0.08 MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of protease solution used is 2.5% of the weight of the tobacco stems, and the total activity of the protease in each kilogram of protease solution is 270 million U. Then, the tobacco stems sprayed with protease are stored in a covered stem cabinet at 34°C for 6 hours.

[0075] (6) Cut the tobacco stems obtained in the previous step using a stem cutter. The width of the cut stems is 0.12 mm, which is to obtain stem shreds with a thickness of 0.12 mm. Then, add the flavoring. The amount of flavoring added is 1.5% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0076] (7) Use a shredder to shred the stem slices obtained in the previous step. The width of the shreds is 1.1 mm, thus obtaining stem shreds with a width of 1.1 mm.

[0077] (8) The stems obtained in the previous step are heated. The stems are heated and kept at a constant temperature in a two-stage screw conveyor. The temperature of the stems reaches 70-80℃ at the end of the heating stage, and is maintained at this temperature for 3-4 minutes in the constant temperature stage. At the end of the constant temperature stage, the moisture content of the stems is 19-21wt%.

[0078] (9) Place the above-mentioned filaments into a microwave expansion device, use a belt conveyor, and convey the filaments forward with a microwave power of 80kw so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the filaments is controlled to be 11-12wt%.

[0079] (10) The above-mentioned microwave-expanded filaments were sieved by air separation to remove impurities and then rapidly cooled. The air separation parameters were as follows: the whole filament rate of the expanded filaments after air separation was 74%, and the filling value was 6.0 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0080] Example 3:

[0081] A method for preparing microwave-expanded tobacco stems, the specific steps of which are as follows:

[0082] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0083] (2) Remove stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the tobacco stem raw material, and wash the stems with warm water at 60℃ (water flow rate is 0.8 m / s, bottom belt frequency is 24 Hz, and the circulating water is replaced every 3 hours).

[0084] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.2 MPa for 7 seconds, and then cooled to room temperature.

[0085] (4) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. The compound enzyme solution is atomized with compressed air at room temperature (0.08 MPa) to spray it evenly onto the surface of the tobacco stems. The drum speed is 10 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of the compound enzyme solution is 4% of the weight of the tobacco stems. The total activity of hemicellulase, laccase, and pectinase in each kilogram of compound enzyme solution is 200 million U, 200 million U, and 150 million U. The tobacco stems sprayed with the compound enzyme solution are then stored in a covered stem cabinet at 34°C for 5 hours.

[0086] (5) After the tobacco stems from the previous storage step are removed from the cabinet, they are returned to the drum in step (4). The protease solution is atomized with room temperature compressed air at 0.08 MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 10 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of protease solution used is 3% of the mass of the tobacco stems, and the total activity of the protease in each kilogram of protease solution is 300 million U. Then, the tobacco stems sprayed with protease are stored in a covered stem cabinet at 34°C for 5 hours.

[0087] (6) Cut the tobacco stems obtained in the previous step into stems using a stem cutter. The width of the cut stems is 0.10 mm, which is to obtain stem shreds with a thickness of 0.10 mm. Then, add the spices. The amount of spices added is 0.5% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0088] (7) Use a shredder to shred the stem slices obtained in the previous step. The width of the shredded stem is 0.7 mm, which gives you double-cut stem shreds with a width of 0.7 mm.

[0089] (8) The stems obtained in the previous step are heated. The stems are heated and kept at a constant temperature in a two-stage screw conveyor. The temperature of the stems reaches 60-70℃ at the end of the heating stage and is maintained at this temperature for 5-6 minutes in the constant temperature stage. At the end of the constant temperature stage, the moisture content of the stems is 16-17wt%.

[0090] (9) Place the above-mentioned filaments into a microwave expansion device, use a belt conveyor, and use a microwave power of 50kw to convey the filaments forward so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the filaments is controlled to be 12-13wt%.

[0091] (10) The microwave-expanded filaments were sieved by air separation to remove impurities and then rapidly cooled. After air separation, the whole filament rate of the expanded filaments was 75%, and the filling value was 6.4 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0092] Example 4:

[0093] A method for preparing microwave-expanded tobacco stems, the specific steps of which are as follows:

[0094] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0095] (2) Remove stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the tobacco stem raw material. Wash the stems with warm water at 50℃ (water flow rate is 0.65 m / s, bottom belt frequency is 18 Hz, and the circulating water is replaced every 3 hours).

[0096] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.4 MPa for 6 seconds, and then cooled to room temperature.

[0097] (4) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. The compound enzyme solution is atomized with compressed air at room temperature using 0.12 MPa to spray it evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of the compound enzyme solution is 3% of the weight of the tobacco stems. The total activity of hemicellulase in each kilogram of compound enzyme solution is 120 million U, the total activity of laccase is 180 million U, and the total activity of pectinase is 90 million U. Then, the tobacco stems sprayed with the compound enzyme solution are stored in a covered stem cabinet at 34°C for 4 hours.

[0098] (5) Cut the tobacco stems obtained in the previous step into stems using a stem cutter. The thickness of the cut stems is 0.12 mm, which is to obtain stem shreds with a width of 0.12 mm. Then, add the spices. The amount of spices added is 1% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0099] (6) Use a shredder to shred the stem slices obtained in the previous step. The width of the shredded stem is 1.2 mm, which gives you double-cut stem shreds with a width of 1.2 mm.

[0100] (7) The stems obtained in the previous step are heated. The stems are heated and kept at a constant temperature in a two-stage screw conveyor. The temperature of the stems reaches 70-80℃ at the end of the heating stage and is maintained at this temperature for 3-4 minutes in the constant temperature stage.

[0101] (8) Place the above-mentioned filaments into a microwave expansion device, use a belt conveyor, and convey the filaments forward with a microwave power of 80kw so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the filaments is controlled to be 11-12wt%.

[0102] (9) The microwave-expanded filaments were then sieved through an air classifier to remove impurities and rapidly cooled. After air classification, the whole filament rate was 76%, and the filling value was 6.3 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0103] Example 5:

[0104] A method for preparing microwave-expanded tobacco stems, the specific steps of which are as follows:

[0105] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0106] (2) Remove tobacco stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the raw tobacco stems. Wash the stems with warm water at 70℃ (water flow rate is 0.65 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0107] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.3 MPa for 10 seconds, and then cooled to room temperature.

[0108] (4) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. A composite enzyme solution is atomized using 0.10 MPa room temperature compressed air to spray it evenly onto the surface of the tobacco stems. The drum speed is 10 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The atomized composite enzyme solution is sprayed evenly on the tobacco stems obtained in the previous step during their transport to the stem cabinet. The amount of the composite enzyme solution is 3% of the weight of the tobacco stems. The total activity of hemicellulase in each kilogram of the composite enzyme solution is 120 million U, the total activity of laccase is 180 million U, and the total activity of pectinase is 90 million U. The tobacco stems are then sprayed with atomized protease solution. The amount of the protease solution is 1.5% of the weight of the tobacco stems. The total activity of protease in each kilogram of the protease solution is 160 million U. The tobacco stems sprayed with protease are then stored in an environment of 34°C and 80% relative humidity for 8 hours.

[0109] (5) Cut the tobacco stems obtained in the previous step into stems using a stem cutter. The thickness of the cut stems is 0.12 mm, which is to obtain stem shreds with a thickness of 0.12 mm. Then, add the flavoring. The amount of flavoring added is 2.5% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0110] (6) Use a shredder to shred the stem slices obtained in the previous step. The width of the shredded stem is 1.0 mm, which gives you double-cut stem shreds with a width of 1.0 mm.

[0111] (7) The stems obtained in the previous step are heated. The stems are heated and kept at a constant temperature in a two-stage screw conveyor. The temperature of the stems reaches 70-80℃ at the end of the heating stage, and is maintained at this temperature for 3-4 minutes in the constant temperature stage. At the end of the constant temperature stage, the moisture content of the stems is 16-17wt%.

[0112] (8) Place the above-mentioned filaments into a microwave expansion device, use a belt conveyor, and convey the filaments forward with a microwave power of 90kw so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the filaments is controlled to be 11-12wt%.

[0113] (9) The microwave-expanded filaments were then sieved through an air classifier to remove impurities and rapidly cooled. After air classification, the whole filament rate was 85%, and the filling value was 7.7 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0114] Comparative Example 1: The traditional method for preparing expanded stem fibers specifically includes the following steps:

[0115] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0116] (2) Remove tobacco stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the raw tobacco stems. Wash the stems with warm water at 55℃ (water flow rate is 0.65 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0117] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.3 MPa for 8 seconds. Then the stems were cooled to room temperature. The moisture content of the tobacco stems after cooling was 35-40%.

[0118] (4) Press the tobacco stems after the previous moistening step to a thickness of 1.5 mm and cut them to a width of 0.12 mm.

[0119] (5) Add the atomized filaments obtained in the previous step, with the amount of fragrance added being 2% of the filaments, and store in a buffer cabinet for 2 hours;

[0120] (6) The filaments obtained in the previous step are dried using a drum dryer. The hot air temperature is 160℃, the hot air flow rate is [missing value], the outlet temperature is 60℃, and the drum rotation speed is 4πrad / s. The moisture content of the dried filaments is 12-13wt%. Then, impurities are removed by air separation and the temperature is rapidly reduced. After air separation, the whole filament rate of the expanded filaments is 75%, and the filling value is 5.4cm. 3 / g, and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0121] Comparative Example 2: A method for preparing microwave-expanded tobacco stems, specifically including the following steps:

[0122] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0123] (2) Remove tobacco stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the raw tobacco stems. Wash the stems with warm water at 55℃ (water flow rate is 0.65 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0124] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.3 MPa for 8 seconds. Then, they were cooled to room temperature. The moisture content of the tobacco stems after cooling was about 35%.

[0125] (3) The tobacco stems obtained in the previous step are conveyed into a drum. Enzymes are added to the tobacco stems at the drum inlet. The compound enzyme solution is atomized with compressed air at room temperature (0.08 MPa) to spray it evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of the compound enzyme solution is 3% of the weight of the tobacco stems. The total activity of hemicellulase in each kilogram of compound enzyme solution is 120 million U, the total activity of laccase is 180 million U, and the total activity of pectinase is 90 million U. Then, the tobacco stems sprayed with the compound enzyme solution are stored in a covered stem cabinet at 34°C for 4 hours.

[0126] (4) After the tobacco stems from the previous storage step are removed from the cabinet, they are returned to the drum in step (4). The protease solution is atomized with room temperature compressed air at 0.08 MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 7 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly. The amount of protease solution used is 1.5% of the weight of the tobacco stems, and the total activity of the protease in each kilogram of protease solution is 160 million U. Then, the tobacco stems sprayed with protease are stored in a covered stem cabinet at 34°C for 6 hours.

[0127] (5) Cut the tobacco stems obtained in the previous step into stems using a stem cutting machine. The thickness of the cut stems is 0.12 mm, which is to obtain stem slices with a thickness of 0.12 mm. Then, add the spices. The amount of spices added is 2% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0128] (6) Use a shredder to shred the stem slices obtained in the previous step. The width of the shredded stem is 1.0 mm, which gives you double-cut stem shreds with a width of 1.0 mm.

[0129] (7) Place the above-mentioned filaments into a microwave expansion device, using a belt conveyor with a microwave power of 60kw, and convey the filaments forward to dry and expand them.

[0130] (9) The microwave-expanded filaments were then sieved through an air classifier to remove impurities and rapidly cooled. After air classification, the whole filament rate was 77%, and the filling value was 5.8 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0131] Comparative Example 3: A method for preparing microwave-expanded tobacco stems, specifically including the following steps:

[0132] (1) Prepare materials according to the formula requirements and the manufacturing capacity of the process.

[0133] (2) Remove tobacco stems and broken stems with a length of less than 10 mm and a diameter of less than 2 mm from the raw tobacco stems. Wash the stems with warm water at 55℃ (water flow rate is 0.65 m / s, bottom belt frequency is 21 Hz, and the circulating water is replaced every 3 hours).

[0134] (3) The tobacco stems after washing were subjected to HT steaming at a saturated steam pressure of 0.2 MPa for 7 seconds, and then cooled to room temperature.

[0135] (3) Cut the tobacco stems obtained in the previous step using a stem cutter. The width of the cut stems is 0.10 mm, which results in stem shreds with a thickness of 0.10 mm. Then, add the spices. The amount of spices added is 3% of the stem shreds. Store in a buffer cabinet for 2 hours.

[0136] (4) Use a shredder to shred the stem slices obtained in the previous step. The width of the shredded stem is 1.0 mm, which gives you double-cut stem shreds with a width of 1.0 mm.

[0137] (5) The stems obtained in the previous step are heated. The stems are heated and kept at a constant temperature in a two-stage screw conveyor. The temperature of the stems reaches 70-80℃ at the end of the heating stage and is maintained at this temperature for 3-4 minutes in the constant temperature stage.

[0138] (6) The above-mentioned filaments are placed in a microwave expansion device and conveyed forward using a belt conveyor with a microwave power of 90kw, so that they absorb an equal amount of energy. After microwave expansion, the moisture content of the filaments is controlled to be 11-12wt%.

[0139] (7) The microwave-expanded filaments were sieved by air separation to remove impurities and then rapidly cooled. After air separation, the whole filament rate of the expanded filaments was 81%, and the filling value was 5.6 cm. 3 / g; and store the stems in an open-type stem storage cabinet (temperature 26℃, relative humidity 60%) for ≥4h to obtain the product.

[0140] Test Example 1: Physical Shape Detection of Expanded Tobacco Stems

[0141] The detection method is as follows:

[0142] The filling value of the expanded tobacco stems provided by this invention was tested in accordance with the People's Republic of China Tobacco Industry Standard YC / T163-2003;

[0143] The whole-strand rate of the expanded tobacco stems provided by this invention was tested in accordance with the People's Republic of China Tobacco Industry Standard YC / T178-2003.

[0144] The physical morphology and degree of carbonization of the tobacco stems obtained in Examples 1-5 were compared with those obtained in Comparative Examples 1-3. The comparison results are shown in Table 1.

[0145] Table 1. Results of Physical Morphology and Degree of Carbonization Detection

[0146]

[0147] The above experimental results show that, in terms of physical properties, the filling value and whole-shred rate of the tobacco stems prepared by this invention are superior to those of traditional tobacco stems (Comparative Example 1). This is because the pressing process of traditional tobacco stems is omitted in this invention. The whole-shred rate of Example 1 is higher because the enzymatic hydrolysis degrades certain substances in the tobacco stems, improving the physical structure of the tobacco stems. The whole-shred rate of Examples 2 and 3 is lower because the sprayed enzyme activity is too high, resulting in excessive degradation and destruction of the physical structure of the tobacco stems. The whole-shred rate of Example 4 is lower because the complex enzyme solution was not sprayed with protease to inactivate it, leading to excessive enzymatic hydrolysis of the complex enzyme and destruction of the tobacco stem structure.

[0148] As shown in Table 1, no carbonization was observed in Examples 1-5, while Comparative Examples 1-3 showed varying degrees of carbonization. Regarding the stem filling value, the stem filling values ​​in Examples 1-5 were also higher than those in Comparative Examples 1-3, demonstrating that the stem expansion process of the present invention can produce expanded tobacco stems that are less prone to carbonization and have a high filling rate.

[0149] Test Example 2: Detection of aroma components in expanded tobacco stems

[0150] The detection method is as follows:

[0151] (1) Grind the sample to pass through a 60-mesh sieve and equilibrate at 22°C and 60% relative humidity for 24 hours;

[0152] (2) Weigh 25.00g of the sample powder after the previous step of equilibration, place it in a simultaneous distillation extraction device, add 350mL of saturated sodium chloride solution, add 40mL of dichloromethane extract to the other end, and perform simultaneous distillation extraction for 2.5h.

[0153] (3) The distilled extract from the previous step was distilled at 45°C to 1 mL of concentrated solution. Anhydrous sodium sulfate was added to remove water, and the solution was analyzed by gas chromatography / mass spectrometry (GC / MS).

[0154] (4) GC conditions were as follows: HP-5MS (30m×0.25mm×0.25μm) capillary column; injection port temperature 240℃; carrier gas: He, 1.0mL / min; split ratio: 30:1; injection volume: 1μL; injection port temperature: 250℃; temperature program: initial temperature 50℃, hold for 1min, increase to 170℃ at 8℃ / min, hold for 2min, then increase to 250℃ at 8℃ / min, hold for 15min. MS conditions were as follows: transfer line temperature 260℃; ion source temperature 230℃; quadrupole temperature 150℃; ionization voltage 70eV; mass number range: 50-550amu; MS library: Wiley05+Nist08 tandem search; quantification was performed using the internal standard method, with phenylethyl propionate as the internal standard.

[0155] Table 2. Results of aroma component detection (μg / g)

[0156]

[0157]

[0158]

[0159]

[0160]

[0161] As shown in Table 2, compared with Comparative Examples 1-3, the total amount of aroma substances in Experiments 1-5 was increased. Among them, the total amount of aroma substances in Examples 1, 2, and 3 was increased by 28.05%, 38.16%, and 33.76% respectively compared with the traditional stems (Comparative Example 1). This is because the complex enzyme and protease decomposed the macromolecules such as hemicellulose, lignin, pectin, and protein in the stems, generating some aroma precursors, sugars, and amino acids. The latter two underwent Maillard reaction under high temperature conditions.

[0162] As shown in Table 2, the content of neophytadiene in Examples 1-5 was increased to varying degrees compared with Comparative Examples 1-3. Neophytadiene is one of the degradation products of chlorophyll in tobacco, which can enhance the taste and aroma of flue-cured tobacco, and can also be degraded and transformed into aroma components. The content of Mérald reaction products and carotenoid degradation products of aroma components in Examples 1-5 was increased compared with Comparative Example 1 (traditional tobacco stems), with increases of up to 247% and 91%, respectively.

[0163] Experimental Example 3: Sensory Quality Evaluation of Expanded Tobacco Straw

[0164] The evaluation method is as follows:

[0165] The tobacco stems obtained in Examples 1-5 and the expanded tobacco stems obtained in Comparative Examples 1-3 were mixed with "Taishan" tobacco from Qingdao Cigarette Factory of Shandong China Tobacco Industry Co., Ltd. at a mass ratio of 1:4, and rolled into cigarettes as control samples. Cigarette evaluation experts conducted blind tastings according to the methods provided in GB5606.4-2005 and GB5606.5-2004, evaluating a total of 6 indicators. The evaluation criteria are shown in Table 3.

[0166] Table 3 Sensory quality evaluation results

[0167]

[0168]

[0169] The results in Table 3 show that cigarettes prepared using the stems provided in Examples 1, 2, 3, and 5 of this invention have improved gloss, a richer aroma, reduced impurities and irritation, a more pleasant aftertaste, and higher overall sensory evaluation scores. Furthermore, the cigarettes prepared using the stems provided in Examples 1, 2, 3, and 5 of this invention have lower tar and carbon monoxide levels in the mainstream smoke, demonstrating greater harm reduction and tar reduction.

[0170] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the quality of microwave-expanded and double-cut tobacco stems, characterized in that, include: The tobacco stems are sieved, washed, and steamed to obtain pretreated tobacco stems. The compound enzyme solution is sprayed onto the pretreated tobacco stems and stored once to obtain compound enzyme tobacco stems; the compound enzyme is composed of hemicellulase, laccase and pectinase. The protease was sprayed onto the compound enzyme tobacco stems and stored for a second time to obtain the protease-compound enzyme tobacco stems. The protease-complex enzyme was used to cut the tobacco stems to obtain stem filaments; The stem shreds are added to the feed and cut into shreds to obtain double-cut stem shreds; The recut tobacco stems were sequentially subjected to heating and isothermal treatments to ensure the Maillard reaction proceeded fully and to balance the moisture and temperature of the stems, resulting in enzyme-treated stems. The heating process included heating the tobacco stems to 70-80°C and maintaining the temperature for at least 3-4 minutes. After isothermal treatment, the moisture content of the tobacco stems was 20-22 wt%. The enzyme-treated tobacco stems are expanded by microwave; the microwave power is 50-90kw, and the moisture content of the tobacco stems after expansion and drying is 11-12wt%.

2. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The water temperature for washing stems is 40-70℃, the water flow rate is 0.5-1.5m / s, the bottom band frequency is 15-27Hz, the washing time is 20-50s, and the circulating water is changed every 2-6 hours.

3. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The saturated steam pressure of the tobacco stems is 0.2-0.4 MPa, the steaming time is 6-10 s, and the moisture content of the tobacco stems after cooling is 35-38%.

4. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The concentration of the complex enzyme solution is 2-8 wt%.

5. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that... The ratio of total activity of hemicellulase:laccase:pectinase is 3-300:3-300:2-200. The total activity of hemicellulase in each kilogram of the complex enzyme is 3 million to 300 million U, the total activity of laccase is 3 million to 300 million U, and the total activity of pectinase is 2 million to 200 million U.

6. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, Enzymes are added to the tobacco stems at the inlet end of the drum. The compound enzyme solution is atomized with room temperature compressed air at 0.08-0.12MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 6-10 rpm / min.

7. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The ambient temperature for storing stalks is 30-40℃, and the time is 2-8 hours.

8. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The total activity of the protease in each kilogram of protease solution is 160 million to 300 million U.

9. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, After the tobacco stems have finished their storage, enzymes are added again at the inlet of the drum. The enzyme solution is atomized with room temperature compressed air at 0.08-0.12 MPa and sprayed evenly onto the surface of the tobacco stems. The drum speed is 6-10 rpm / min to ensure that the tobacco stems and enzyme solution are mixed evenly.

10. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The ambient temperature for secondary storage of stalks is 30-40℃, and the time is 2-8 hours.

11. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The thickness of the cut stem is 0.12-0.18 mm.

12. The method for improving the quality of microwave-expanded and double-cut tobacco stems as described in claim 1, characterized in that, The width of the shredded part is 0.7-1.2mm.

13. The microwave-expanded and double-cut tobacco stems prepared by the method according to any one of claims 1-12, characterized in that, The whole filament rate of the double-cut stem filaments is ≥74%, and the filling value is ≥5.6cm. 3 / g.

14. The application of the double-cut stem strands as described in claim 13 in the preparation of cigarettes.

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