Online pretreatment process for reducing substance content of cell walls of tobacco stems

Abstract

The invention discloses an online pretreatment process for reducing the content of cell wall substances of tobacco stems, which comprises the following steps: (1) cleaned tobacco stems are added into high-pressure stem moistening equipment for steam explosion, and the steam explosion pressure is not greater than 2bar; (2) pressing and cutting the tobacco stems subjected to steam explosion to form cut stems; (3) adding a biological compound preparation into the cut stems for fermentation treatment; the biological compound preparation at least comprises cellulase, pectinase, laccase and ligninase. According to the method, the tobacco stems are subjected to steam explosion pretreatment under specific conditions, so that the structure of the tobacco stems is looser, meanwhile, the content of cell wall substances such as lignin is obviously reduced, the wood gas and irritation of the tobacco stems are reduced in combination with a specific fermentation process, and the cigarette product modified by adding the cut stems is free of irritation and offensive odor, smooth in smoke and high in smoking evaluation quality.

Description

Technical Field

[0001] The present application relates to an online pretreatment process for reducing the content of tobacco stem cell wall substances, and belongs to the technical field of tobacco product processing. Background Art

[0002] Tobacco stems account for 25% to 30% of the weight of tobacco leaves. Since tobacco stems have similar components to tobacco leaves and have the functions of improving the structure of cigarettes, reducing costs, and reducing harm and tar, they are an important component of cigarette raw materials. However, the content of cell wall substances in tobacco stems is higher in tobacco stems, accounting for more than 40%. Cell wall substances include cellulose, hemicellulose, pectin, lignin and other substances. After pyrolysis and combustion, pectin will produce pyrolysis products such as methanol, formaldehyde and formic acid. These products not only bring irritation to the smoke and cover up the aroma of cigarettes themselves, but also have certain harm to the human body; lignin is the main cause of the heavy woody smell in the smoke, resulting in strong coughing and burning throat during combustion, interfering with the aroma of the smoke, and pyrolysis of lignin will produce catechol and alkylcatechol, causing astringency and carcinogenic activity, affecting the quality and safety of cigarettes. The presence of tobacco stem cell wall substances will cause irritating coughs and strong woody miscellaneous gases when burning, which will have an adverse effect on the quality of tobacco smoking.

[0003] Steam explosion treatment is a process in which biomass is treated with pressurized steam for a few seconds to a few minutes and then the pressure is suddenly reduced, so that the water that penetrates into the biomass is instantly converted into steam, destroying the structure of lignocellulose, degrading hemicellulose and lignin, and separating cellulose. Chinese patent CN101912149A-Method of improving tobacco stem quality by combining steam explosion with enzyme treatment technology, which uses steam explosion + enzyme treatment to treat tobacco stems, but its sensory evaluation shows that after the amount of stems processed by steam explosion and enzyme treatment is increased by 5%, the sensory quality of cigarettes is consistent with the original formula cigarettes. Its process can only achieve a slight increase in the content of tobacco stems and keep it consistent with the quality of the original cigarettes. With the innovation of technology and consumers' pursuit of quality, its process can no longer meet the evaluation needs of existing cigarette products. Summary of the invention

[0004] In order to solve the above problems, an online pretreatment process for reducing the content of cell wall substances in tobacco stems is provided. By pretreating the tobacco stems with steam explosion under specific conditions, the structure of the tobacco stems is made looser and the content of cell wall substances such as lignin is significantly reduced. Combined with a specific fermentation process, the woody smell and irritation of the tobacco stems are reduced. The cigarette products modified by adding stem shreds are non-irritating, free of impurities, with smooth smoke and high smoking quality.

[0005] According to one aspect of the present application, an online pretreatment process for reducing the content of tobacco stem cell wall substances is provided, comprising the following steps:

[0006] (1) adding the cleaned tobacco stems into a high-pressure stem moistening device for steam explosion, with the steam explosion pressure being no greater than 2 bar;

[0007] (2) pressing and cutting the steam-exploded tobacco stems into shredded stems;

[0008] (3) adding the biocomposite preparation to the shredded stems for fermentation treatment;

[0009] The biocomposite preparation at least comprises cellulase, pectinase, laccase and ligninase.

[0010] Optionally, the steam explosion pressure in step (1) is 1.6-1.75 bar.

[0011] Optionally, the spiral frequency in step (1) is 20-25 Hz.

[0012] Optionally, the steam temperature in step (1) is 140-150°C.

[0013] Preferably, in step (1), the steam explosion pressure is 1.7 bar, the spiral frequency is 22 Hz, and the steam temperature is 145°C.

[0014] Optionally, the steam explosion time in step (1) is 55-65 s; preferably, the steam explosion time in step (1) is 60 s.

[0015] Optionally, the steam explosion time includes a cooking time and an explosion time, the cooking time is 56-58 s, and the explosion time is 2-4 s.

[0016] Preferably, the steam explosion time includes a cooking time and an explosion time, the cooking time is 58 seconds, and the explosion time is 2 seconds.

[0017] Optionally, the moisture content of the tobacco stems after washing in step (1) is 12-14%, and the moisture content of the tobacco stems after steam explosion is increased by 3-5%.

[0018] Optionally, in step (2), the thickness of the pressed stems is 0.8±0.05 mm, and the thickness of the cut stems is 0.14±0.03 mm.

[0019] Optionally, in step (3), the moisture content of the shredded stems after fermentation is 34-38%, the fermentation temperature is 45-50° C., the fermentation humidity is 70-80%, and the fermentation time is 20-30 hours.

[0020] Preferably, in step (3), the moisture content of the shredded stems after fermentation is 38%, the fermentation temperature is 48° C., the fermentation humidity is 75%, and the fermentation time is 24 hours.

[0021] Optionally, the biocomposite preparation includes xylanase, pectinase, pectin lyase, pectinesterase, glucanase, laccase, ligninase, cellulase and glucosidase, and the added weight ratio is (2-3): (1-2): (0.1-0.3): (0.1-0.3): (0.4-0.6): (4-6): (1-2): (1-2): (0.4-0.6).

[0022] Preferably, the addition weight ratio is 3:2:0.2:0.2:0.5:5:1:1:0.5.

[0023] The beneficial effects of this application include but are not limited to:

[0024] 1. According to the online pretreatment process for reducing the content of cell wall substances in tobacco stems of the present application, by using steam explosion pretreatment under specific conditions combined with a specific fermentation process, the tobacco stem structure is first made looser and the content of cell wall substances such as lignin is significantly reduced, which is beneficial to the fermentation effect of subsequent biological fermentation stem shreds, and also significantly reduces the woodiness of the tobacco stem shreds, improves the aroma quality, and increases the aroma quantity.

[0025] 2. According to the online pretreatment process for reducing the content of cell wall substances in tobacco stems of the present application, by limiting the pressure, temperature and time parameters in steam explosion, the tissue structure of the tobacco stems is loosened to the point of being damaged, while the vascular bundles and other cavity tissues expand, the pore gaps increase and increase, the thin-walled tissue dissociates, and at the same time the cell vascular bundles are broken and damaged, the content of cell wall substances in the tobacco stems is reduced, and the components of the treated tobacco stems tend to be hydrolyzed into more small molecular aroma components, and the total amount of aroma components increases. The aroma volume and smoke concentration of the treated tobacco stems are slightly lost, but the aroma is permeable, and the woody smell, irritation, dryness in the mouth and residue are reduced, accompanied by a burnt sweet flavor.

[0026] 3. According to the online pretreatment process for reducing the content of cell wall substances in tobacco stems of the present application, by limiting the temperature, time and other parameters in the fermentation process, the shredded stems are fully fermented, the woody smell is significantly reduced, and the irritation is reduced. After treatment, the shredded stems are closer to the shape of tobacco leaves and have a good appearance. The product cigarettes modified by adding shredded stems are non-irritating, free of impurities, and have smooth smoke.

[0027] 4. According to the online pretreatment process for reducing the content of tobacco stem cell wall substances in the present application, by adding specific biological composite preparations, cellulose and pectin can be degraded and converted into sugar substances, reducing the addition of sugar in the process stage. At the same time, it can reduce the discomfort caused by cellulose and pectin to cigarettes, increase the blending ratio in cigarettes, and reduce the production cost of cigarettes while improving the smoking quality of cigarettes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 The invention is to analyze the effect of steam explosion pressure on tobacco stem lignin involved in the examples and comparative examples of the present application;

[0030] Figure 2 The effect of the steam explosion spiral frequency on tobacco stem lignin involved in the examples and comparative examples of the present application is analyzed;

[0031] Figure 3 The effect of steam explosion steam temperature on tobacco stem lignin in the examples and comparative examples of the present application is analyzed;

[0032] Figure 4 This is a cross-section image of A1 (original) tobacco stems scanned by electron microscopy;

[0033] Figure 5 This is the cross-section of A2 (sample) tobacco stems scanned by electron microscope;

[0034] Figure 6 This is the surface image of tobacco stems of B1 (original) scanned by electron microscope;

[0035] Figure 7 This is the surface image of tobacco stem of B2 (sample) scanned by electron microscope;

[0036] Figure 8 This is a longitudinal section of C1 (original) tobacco stems scanned by electron microscopy;

[0037] Fig. 9 This is a longitudinal section of C2 (sample) tobacco stem scanned by electron microscope. DETAILED DESCRIPTION

[0038] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0039] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention. The preferred implementation methods and materials described in this patent are for demonstration purposes only.

[0040] Materials and Apparatus: Materials: Experimental tobacco stems from the same batch of the applicant company.

[0041] instrument:

[0042] Multifunctional food grinder (Shenzhen Baijie Co., Ltd.);

[0043] WQ25 steam-pressurized tobacco stem conditioning machine (Zhisi Holding Group Co., Ltd.);

[0044] Simultaneous distillation and extraction device (homemade); AA3 continuous flow analyzer (Seal, Germany);

[0045] 7890-5975 gas chromatograph-mass spectrometer (Agilent, USA);

[0046] Constant temperature and humidity chamber (Binder, Germany);

[0047] 1290Ⅱ, 1290 ultra-high performance liquid chromatograph (Agilent, USA);

[0048] ICS 5000 ion chromatograph (Thermo Fisher Scientific, USA);

[0049] 7890B gas chromatograph (Agilent, USA);

[0050] Steam distillation apparatus (Dalian Yeda Technology Co., Ltd.);

[0051] Analytical balance (Mettler Toledo, Switzerland);

[0052] CNC ultrasonic cleaner (Kunshan Hechuang Ultrasonic Instrument Co., Ltd.);

[0053] UV-visible spectrophotometer (Shanghai Meipuda Instrument Co., Ltd.);

[0054] Soxhlet extractor (Qingdao Jingcheng Instrument Co., Ltd.);

[0055] Some glass instruments.

[0056] Example 1

[0057] The online pretreatment process for reducing the content of tobacco stem cell wall substances comprises the following steps:

[0058] (1) adding the washed tobacco stems to a high-pressure stem moistening device for steam explosion, the steam explosion pressure is 1.7 bar, the spiral frequency is 22 Hz, the steam temperature is 145° C., the steam explosion time is 60 s, the steam explosion time includes the steaming time and the explosion time, the steaming time is 58 s, and the explosion time is 2 s; the moisture content of the washed tobacco stems is 13%, and the moisture content of the tobacco stems after steam explosion is increased by 4%;

[0059] (2) pressing and cutting the steam-exploded tobacco stems to form stem shreds, wherein the thickness of the pressed stems is 0.8 mm and the thickness of the cut stems is 0.14 mm;

[0060] (3) A biological composite preparation is added to the shredded stems for fermentation treatment. The biological composite preparation includes xylanase, pectinase, pectin lyase, pectinesterase, glucanase, laccase, ligninase, cellulase and glucosidase. The weight ratio of addition is 3:2:0.2:0.2:0.5:5:1:1:0.5. After fermentation, the moisture content of the shredded stems is 38%, the fermentation temperature is 48°C, the fermentation humidity is 75%, and the fermentation time is 24 hours.

[0061] Example 2

[0062] The online pretreatment process for reducing the content of tobacco stem cell wall substances comprises the following steps:

[0063] (1) adding the washed tobacco stems to a high-pressure stem moistening device for steam explosion, the steam explosion pressure is 1.6 bar, the spiral frequency is 20 Hz, the steam temperature is 140° C., the steam explosion time is 55 s, the steam explosion time includes the steaming time and the explosion time, the steaming time is 53 s, and the explosion time is 2 s; the moisture content of the washed tobacco stems is 12%, and the moisture content of the tobacco stems after steam explosion is increased by 3%;

[0064] (2) pressing and cutting the steam-exploded tobacco stems to form stem shreds, wherein the thickness of the pressed stems is 0.85 mm and the thickness of the cut stems is 0.17 mm;

[0065] (3) A biological composite preparation is added to the shredded stems for fermentation treatment. The biological composite preparation includes xylanase, pectinase, pectin lyase, pectinesterase, glucanase, laccase, ligninase, cellulase and glucosidase. The weight ratios of addition are 2:1:0.1:0.1:0.4:6:1.5:1:0.4, respectively. After fermentation, the moisture content of the shredded stems is 34%, the fermentation temperature is 45°C, the fermentation humidity is 70%, and the fermentation time is 24 hours.

[0066] Example 3

[0067] The online pretreatment process for reducing the content of tobacco stem cell wall substances comprises the following steps:

[0068] (1) adding the washed tobacco stems to a high-pressure stem moistening device for steam explosion, the steam explosion pressure is 1.75 bar, the spiral frequency is 25 Hz, the steam temperature is 150° C., the steam explosion time is 65 s, the steam explosion time includes the steaming time and the explosion time, the steaming time is 63 s, and the explosion time is 2 s; the moisture content of the washed tobacco stems is 14%, and the moisture content of the tobacco stems after steam explosion is increased by 5%;

[0069] (2) pressing and cutting the steam-exploded tobacco stems to form stem shreds, wherein the thickness of the pressed stems is 0.75 mm and the thickness of the cut stems is 0.11 mm;

[0070] (3) A biological composite preparation is added to the shredded stems for fermentation treatment. The biological composite preparation includes xylanase, pectinase, pectin lyase, pectinesterase, glucanase, laccase, ligninase, cellulase and glucosidase. The weight ratios of addition are 3:2:0.3:0.2:0.6:4:1:1.5:0.6. After fermentation, the moisture content of the shredded stems is 36%, the fermentation temperature is 50°C, the fermentation humidity is 80%, and the fermentation time is 30 hours.

[0071] Comparison of pressure, spiral frequency and temperature parameters in comparative steam explosion

[0072] Three batches of 3000kg tobacco stems of brand A of our company were selected for test, and the parameters of high-pressure stem lubrication were adjusted online. Single-factor experimental tests were carried out, and the pressure of the steam-boosted tobacco stem conditioning machine was fixed at 2bar, the spiral frequency was 25Hz, and the steam temperature was 165℃. The different process parameters of the steam-boosted tobacco stem conditioning machine were adjusted respectively, and the parameters were adjusted to pressure (1.5bar, 2bar, 2.5bar, 3bar), spiral frequency (20Hz, 25Hz, 30Hz, 35Hz), and steam temperature (145℃, 155℃, 165℃, 175℃). Other process parameters of each batch of materials were strictly fixed and implemented according to unified standards. After the test, samples were retained for physical properties, chemical and sensory quality testing.

[0073] Experimental Example 1: Analysis of single factor experimental results

[0074] 1.1 Analysis of the effect of steam explosion pressure on tobacco stem lignin

[0075] For specific changes, see Figure 1 As shown by Figure 1 The results show that the effect of steam explosion pressure on tobacco stem lignin first increases and then decreases, with 2.5 bar being the inflection point.

[0076] 1.2 Analysis of the influence of steam explosion spiral frequency on tobacco stem lignin

[0077] For specific changes, see Figure 2 As shown by Figure 2 The results showed that the tobacco stem lignin content decreased with the increase of steam explosion spiral frequency.

[0078] 1.3 Analysis of the effect of steam explosion steam temperature on tobacco stem lignin

[0079] For specific changes, see Figure 3 As shown by Figure 3 The results show that the effect of steam explosion steam temperature on tobacco stem lignin is first increased and then decreased, with a turning point of about 165℃.

[0080] Experimental Example 2 Uniform design experiment and tobacco stem cell wall composition, aroma components, microstructure changes and sensory evaluation

[0081] 1. Experimental Parts

[0082] 1. Uniform Experimental Design

[0083] The same batch of tobacco stems as the control example were taken to design a uniform experiment. The experimental parameters of steam explosion treatment were set through experimental design, and the effects of different reaction conditions on the changes in tobacco stem lignin were detected. The effects of steam explosion treatment parameters on tobacco stem lignin were determined and evaluated through mathematical regression equations, and the degree of influence of each steam explosion treatment parameter on the change of tobacco stem lignin was determined by significance analysis.

[0084] According to the design principles of uniformity experiment, the following experimental plan was formulated. The uniformity experimental factors are shown in Table 1, and the uniformity experimental design table is shown in Table 2.

[0085] Table 1 Uniform experimental factors

[0086] Factor / Level Pressure bar Spiral frequency Hz Steam temperature℃ Level 1 1.5 20 145 Level 2 2 25 155 Level 3 2.5 30 165 Level 4 3 35 175

[0087] Table 2 Uniform experimental design table

[0088] factor Pressure bar Spiral frequency Hz Steam temperature℃ N1 3 20 155 N2 1.5 25 165 N3 2 30 145 N4 2.5 35 175

[0089] 2. Experiment on determination of main chemical components of tobacco stems

[0090] The main chemical components of tobacco leaves are tested according to industry standards. The specific methods include: "Continuous Flow Method for Determination of Water-soluble Sugar in Tobacco and Tobacco Products" (YC / T 159-2002); "Continuous Flow Method for Determination of Total Alkaloids in Tobacco and Tobacco Products" (YC / T 160-2002); "Continuous Flow Method for Determination of Total Nitrogen in Tobacco and Tobacco Products" (YC / T 161-2002); "Continuous Flow Method for Determination of Chlorine in Tobacco and Tobacco Products" (YC / T162-2002); "Determination of Chlorogenic Acid, Scopolamine and Rutin in Tobacco and Tobacco Products" (YC / T 202-2006); "Continuous Flow Method for Determination of Potassium in Tobacco and Tobacco Products" (YC / T217-2006); "Determination of Starch in Tobacco and Tobacco Products by Enzymatic Hydrolysis-Ion Chromatography" (YC / T283-2008); "Determination of Pectin in Tobacco and Tobacco Products by Ion Chromatography" (YC / T "Tobacco and tobacco products - Determination of neutral detergent fiber, acid detergent fiber, acid washed lignin - Detergent method" (YC / T 347-2010); "Tobacco and tobacco products - Determination of total volatile alkali" (YC / T 35-1996).

[0091] 3. Determination of cell wall materials

[0092] Through two extractions with organic solvents and hot water, water-soluble sugars, organic acids, inorganic salts, phenols, proteins, pigments, starch, lipids, waxes and other substances are removed from the tobacco leaf powder, and the remaining substances are the cell wall substances.

[0093] (1) Extraction with ethanol-benzene mixture: Accurately weigh 7g of smoke sample, put it into a filter paper bag, place it in a Soxhlet extractor, and add 600ml of ethanol-benzene (1:2) mixture into a round-bottom flask connected to the Soxhlet extractor, heat it with an electric heating mantle, and continue to extract for about 24 hours until the extract is colorless. Put the extraction residue into a G-3 glass sand funnel for suction filtration, and rinse it with ethanol and acetone three times respectively.

[0094] (2) Hot water extraction: Add about 100 times the weight of water to the smoke residue after extraction with ethanol-benzene mixed solution, install a reflux device, heat in a boiling water bath for 1 hour, and repeat the operation 3-4 times until there is no sugar in the extract. Put the residue after hot water extraction into a G-3 glass sand funnel of known weight for suction filtration, and rinse with water, ethanol, and acetone in turn. Dry at 60±1℃ for 4 hours and then weigh it, which is the weight of the cell wall material.

[0095] 4. Determination of aroma components

[0096] Before the experiment, 350 mL of pH distilled water and 60 mL of CH2Cl2 were added to both ends of the simultaneous distillation extraction and distilled simultaneously for 2 h to clean the simultaneous distillation extraction device and ensure the cleanliness of the instrument.

[0097] Weigh 30 g (accurate to 0.1 mg) of cigarette dust sample and put it into a 1000 mL round-bottom flask at one end of the simultaneous distillation extraction device, add 30 g of sodium chloride and 350 mL of distilled water, and heat it with a temperature-controlled electric heating mantle. The other end of the device is a concentration bottle containing 60 mL of CH2Cl2, which is heated in a water bath and simultaneously distilled and extracted for 2.5 hours. After the end, add 1 mL of internal standard phenylethyl acetate solution (0.4237 mg / mL), concentrate it to 1.0 mL, transfer it to a chromatographic bottle, and perform GC-MS analysis.

[0098] Chromatographic conditions: chromatographic column: HP-5MS (60m×0.25mm×0.25μm); injection port temperature: 280℃; injection volume: 1μL; split ratio: 5:1; carrier gas: He, 1.0mL / min; heating program: 50℃ for 2min, increase the temperature to 200℃ at a rate of 4℃ / min, maintain for 30min, and then increase the temperature to 280℃ at a rate of 4℃ / min and maintain for 20min.

[0099] Mass spectrometry conditions: transfer line temperature: 280°C; EI source electron energy: 70 eV; electron multiplier voltage: 1635 V; mass scanning range: 30-550 amu; ion source temperature: 230°C; quadrupole temperature: 150°C.

[0100] 5. Methods for determining microstructural changes

[0101] Preparation of electron microscope samples: Select the control sample and the tobacco stem treated with steam explosion at a pressure of 0.8 MPa and a pressure maintenance time of 20 s from the same part, drop a few drops of cold (0-4 ℃) 4% glutaraldehyde fixative on a precooled (0-4 ℃) slide, and cut a 1mm×3mm sample with a sharp blade. The sample was processed in the following order: pre-fixed with 4% glutaraldehyde, washed with 0.1 mol / L phosphate buffer for 3 times, post-fixed with 1% osmium acid, dehydrated once in ethanol series, transitioned with propylene oxide, embedded with Epon812 epoxy resin embedding agent, polymerized at 60 ℃ for 24 hours, then sliced ​​on an LKB ultrathin slicer, double stained with uranyl acetate and lead citrate, and finally observed and photographed under an electron microscope. The samples before and after steam explosion were first glued to the stage, gold-plated with an ion sputtering instrument, and then the cross-section, longitudinal section and tobacco stem surface of the sample were observed and photographed by SEM.

[0102] 2. Experimental Results Analysis

[0103] 1.1 Analysis of uniform experimental results

[0104] On the basis of single factor test, uniform test design was conducted for three factors: steam booster tobacco stem conditioning machine pressure (X1), spiral frequency (X2), and steam temperature (X3). 3 ) Uniform experimental table, the experimental design and results are shown in Table 3 below.

[0105] Table 3 Uniform test results

[0106] factor Pressure bar Spiral frequency Hz Steam temperature℃ Lignin% N1 3 20 155 3.58 N2 1.5 25 165 3.81 N3 2 30 145 2.73 N4 2.5 35 175 3.32

[0107] Table 4. Correlation analysis results of uniform experiment

[0108] Correlation coefficient Y Significant level P X1 -0.0277 0.9723 X2 -0.5161 0.4839 X3 0.555 0.445 X1*X1 0.0546 0.9454 X2*X2 -0.4963 0.5037 X3*X3 0.5315 0.4685 X1*X2 -0.393 0.607 X1*X3 0.0899 0.9101 X2*X3 -0.2549 0.7451

[0109] According to the correlation of each factor in Table 3, it can be inferred that the influence of each factor of tobacco stem steam explosion on lignin content is steam temperature (X3)> spiral frequency (X2)> pressure (X1). A uniform experimental partial correlation test was performed.

[0110] Table 5. Correlation analysis results of uniform experiment

[0111] Partial Correlation t-test value F-number p-value r(y,X3)= 0.9995 30.5104 0.0011 r(y,X3*X3)= -0.9994 29.9633 0.0011 Partial Correlation t-test value p-value

[0112] The influence of each parameter of tobacco stem steam explosion (including the interaction between each parameter) on tobacco stem lignin can be judged by the relative size of the partial correlation t test value between each parameter of tobacco stem steam explosion and lignin in the regression model. The partial correlation t test values ​​of each parameter and lignin are shown in Table 5. The confidence probability p-values ​​of each partial correlation test shown in Table 5 are very small, indicating that the regression test results are acceptable at the confidence level = 0.05, the regression results are credible, and the regression model can be applied.

[0113] The multi-factor quadratic regression analysis was performed using the data processing software DPS, and the quadratic regression equation was obtained as follows:

[0114] Y=-85.181250+1.092000000*X3-0.00335000000*X3*X3

[0115] (x1-1.5)*(x1-3) / 3<0

[0116] (x2-20)*(x2-35) / 35<0

[0117] (x3-145)*(x3-175) / 175<0

[0118] Correlation coefficient R = 0.9996, adjusted correlation coefficient Ra = 0.9999, determination coefficient R 2 =0.9988; F = 648.9> Df = (2, 1); significant level p = 0.0277; residual standard deviation S = 0.0224; determination coefficient = 0.99923; residual path coefficient = 0.00695. At the same time, the quadratic regression equation is optimized by the nonlinear programming method to obtain the minimum combination of tobacco stem lignin, that is, the steam booster tobacco stem rehumidifier pressure (X1) = 1.7046bar, H spiral frequency (X2) = 22.5866Hz, steam temperature (X3) = 145.00℃, which is substituted into the above regression equation to obtain the minimum prediction value of Y (tobacco stem lignin) of 2.7250%.

[0119] The best solution is: steam-pressurized tobacco stem rehumidification machine pressure (X1) = 1.7046 bar, H spiral frequency (X2) = 22.5866 Hz, steam temperature (X3) = 145.00°C, which is Example 1 of the present application.

[0120] 1.2 Verification Experiment

[0121] After the steam explosion parameters were adjusted according to Example 1, the lignin content was 2.87%, which was significantly lower than that of the original tobacco stems.

[0122] 2. Analysis of the effects of steam explosion on the chemical composition of tobacco stems

[0123] According to the steam explosion conditions of Example 1, the changes in the content of tobacco stem cell wall substances and the changes in the content of tobacco stem chemical components before and after steam explosion were investigated as shown in Tables 6 and 7.

[0124] Table 6 Results of changes in cell wall material content after steam explosion

[0125] Sample Information Full Fiber Pectin Lignin Cell wall material Tobacco stems as is 28.7 5.8 3.96 38.46 Example 1 26.5 5.3 2.87 34.67

[0126] Table 7 Chemical composition changes after steam explosion

[0127] Sample Information As is High pressure stem lubrication Total sugar (%) 18.8 18.6 Total plant alkaloids (%) 0.34 0.50 chlorine(%) 3.80 1.90 Reducing sugar (%) 13.0 11.7 Potassium (%) 4.83 5.83 Total nitrogen (%) 1.49 1.31 protein 8.92 8.54 PH 4.95 4.83 Chlorogenic acid 0.98 1.46 Scopolamine 0.25 0.30 Rutin 0.00 0.00 Total volatile alkali 0.13 0.08 starch 1.6 1.5

[0128] From the above analysis results, it can be seen that the total cellulose of the tobacco stems treated with steam explosion in Example 1 is reduced by 7.67%, pectin is reduced by 8.62%, lignin is reduced by 27.53%, and the cell wall material content of the tobacco stems treated with steam explosion is reduced by 9.85%. Steam explosion treatment has a significant removal effect on the total cellulose in the tobacco stems. This change is mainly due to the high temperature and high pressure environment of steam explosion, which damages the cellulose and hemicellulose structures in the leaves, and chemical transformation of small molecular polymers formed by partial chain breakage. The change in lignin is due to the fact that steam explosion destroys the stability of the cyclophenylpropane structure of lignin, and steam explosion has a reducing effect on the content of lignin in tobacco stems.

[0129] Due to the instantaneous expansion of steam explosion, the chemical composition of tobacco stems has changed significantly, among which the total sugar content of steam explosion is reduced by 1.09%, the reducing sugar content is reduced by 9.83%, the total nitrogen content is reduced by 11.3%, and the total volatile alkali content is reduced by 38.46%. The reduction of total sugar and reducing sugar is due to the fact that steam explosion is a high-temperature and high-pressure treatment method in a closed state. The total sugar and reducing sugar in the tobacco stems participate in caramelization and other reactions during the explosion process. The reduction of total nitrogen and total volatile alkali is related to the high-temperature volatilization and transformation of the tobacco stems.

[0130] 3. Results of the changes in aroma components in steam explosion treatment of Example 1

[0131] Table 8 shows the changes in the content of tobacco stem aroma components before and after steam explosion treatment in Example 1.

[0132] Table 8 Changes in aroma components in tobacco stems before and after steam explosion

[0133]

[0134]

[0135]

[0136]

[0137] The results of aroma component analysis show that 73 aroma components were detected in the original sample before steam explosion treatment in Example 1, while 88 aroma components were detected after steam explosion treatment. After steam explosion treatment, the components of tobacco stems tended to be hydrolyzed into more small molecule aroma components, including increased 2,3-pentanedione, 3-furfural, methylcyclopentenol ketone, 3-phenylpyridine, 4,7,9-megatriene-3-one, 5-methyl-2-phenylindoleazine, 3-furfural, 2'-hydroxy-5'-methylbenzene ... 53 new aroma components such as acetone, the total amount of aroma components increased from 93.2899μg / g to 107.6061μg / g, some flavor components such as isovaleraldehyde, 2-methyltetrahydrofuran-3-one, furfuryl alcohol, cyclopent-4-ene-1,3-dione, 2-acetylfuran, 5-methylfurfural, phenylacetaldehyde, 2-acetylpyrrole, etc. have a large increase, these substances will have a positive effect on the formation of the aroma of tobacco stems, thereby further increasing the aroma and taste of the stems.

[0138] This shows that under the conditions of pressure explosion defined in the present application, some precursor aroma substances degrade themselves or react with other substances in a high-temperature and closed explosion environment to generate small-molecule aroma substances, and impurities can be removed better. From the results, it can be seen that the total amount of Maillard reaction products, carotenoid degradation products, cypermethrin degradation products, fatty acids and their degradation products, chlorophyll degradation products and aroma substances are almost increased, the aroma volume and smoke concentration are slightly lost, but the aroma is permeable, woody smell, irritation, dry mouth feeling and residue are reduced, accompanied by a burnt sweet rhyme. This shows that steam pressurization and rehumidification is beneficial to reducing the pectin content in tobacco stems, promoting complex Maillard, caramelization and other reactions to increase the total amount of aroma components, balancing the coordination of intrinsic quality, increasing aroma permeability and burnt sweet rhyme, and improving the overall quality of tobacco stem processing. After the tobacco stem samples were treated with different steam explosion pressures, the content of phenylacetaldehyde, furfural, furfuryl alcohol and 2-acetylfuran aroma substances increased. This is because the steam explosion treatment of tobacco stems is carried out in a high temperature, high pressure and closed environment. The special treatment environment can degrade substances such as sugars in the tobacco stems or cause them to participate in complex chemical reactions, thereby increasing the content of such aroma substances.

[0139] 4. Effect of steam explosion treatment on the physical structure of tobacco stems

[0140] Example 1 Scanning electron microscope photos of control tobacco stems before and after steam explosion treatment and conventional alkali treatment are shown below Figure 4-Figure 9 Alkali treatment experiment: 50 g of tobacco stems were weighed, and 500 ml of 10% sodium carbonate solution was added, the temperature was 60° C., and the reaction time was 30 s.

[0141] Example 1 The effect of steam explosion on lignocellulose is mainly manifested in the destruction of cell wall morphology, spatial structure and molecular composition. As can be seen from the figures, the control tobacco stems are dense, the cells are neatly arranged, the thin-walled tissues in the longitudinal and cross sections are tightly and firmly embedded, the dredge tissues are arranged in an orderly manner, and the pore gaps are small, and the stem epidermal cells are smooth and complete; the tobacco stems treated with steam explosion have loose and damaged tissue structures, while the vascular bundles and other cavity tissues expand, the pore gaps increase and increase, the thin-walled tissues are dissociated, and the cell vascular bundles are broken and damaged.

[0142] As can be seen from the figures, the cell wall structure of the control tobacco stems is tight, the morphology is complete, the intercellular space is obvious, and the organelles are regularly distributed; while the cell wall of the tobacco stems treated with steam explosion is irregularly torn, and some of them are obviously broken, and the intercellular space disappears, and the organelles disappear. Since the cell wall materials such as cellulose, hemicellulose and pectin, which are the main components of sugar substances, and lignin, which is the main component of phenolic substances, are the main components of tobacco stems, after the tobacco stems are treated with steam explosion, the cell wall structure breaks and decomposes, and the substances in the organelles are degraded and transformed. The products of degradation and transformation, such as sugars, will participate in a series of complex chemical reactions under high temperature, high pressure and closed environment, thereby promoting the increase in the content of aromatic and browning reaction products in the tobacco stems.

[0143] Experimental Example 3 Evaluation of the indicators of shredded stems in Example 1 (steam explosion + fermentation)

[0144] 1. Physical indicators of stems

[0145] The samples were tested twice and the results are shown in Table 9.

[0146] Table 9 Physical index data of shredded stems

[0147] Thready stems The first set of samples The second set of samples average value Filament weight (g) 272 274 273 Medium yarn weight (g) 532 539.5 535.8 Short yarn amount (g) 190 181 185.5 Amount of broken silk (g) 6 5.5 5.8 Whole yarn rate (%) 80.4 81.4 80.9 Broken silk rate (%) 0.6 0.55 0.6 <![CDATA[Filling value (cm 3 / g)]]> 6.93 6.91 6.92 Moisture content (%) 13 12.79 12.90

[0148] As shown in Table 9, the whole-stem rate of the traditional shredded stems was 81.2%, and the whole-stem rate of the fermented shredded stems in Example 1 was 80.9%, which was slightly lower, and the filling value was 6.92 cm 3 / g, maintaining a good level and able to meet the quality requirements of large-scale production process.

[0149] 2. Online consumption of shredded stems

[0150] The specific data are shown in Table 10.

[0151] Table 10 Online consumption of shredded stems

[0152] project Total amount (kg) Material cumulative amount 3631 Offline processing and screening of tobacco dust 67.6 Addition residue 13.3 Residue of container 2.5 Coming out residual 20 Total Consumable Materials 103.4 Loss rate 2.8％

[0153] It can be seen from the table that the consumption loss rate of the shredded stems after fermentation in Example 1 is 2.8%, and the shredded stems have good processing resistance.

[0154] 3. Sensory quality evaluation of shredded stems

[0155] (1) Evaluation method

[0156] The sample of Example 1 was rolled into cigarettes and placed in a constant temperature and humidity chamber for 48 hours at a temperature of (22±1)°C and a relative humidity of (60±2)%. Seven members of the tobacco evaluation committee were organized to conduct sensory quality evaluation.

[0157] (2) Evaluation results: After high-pressure pretreatment of tobacco stems with moistening and bio-fermentation, the woody smell and irritation of the tobacco stems were slightly reduced compared with those before treatment. The treated shredded stems were closer to the shape of tobacco leaves and had a good appearance. The cigarettes modified by adding shredded stems were non-irritating, free of impurities, and had smooth smoke. The average sensory quality score was 48.1 points, and the sensory evaluation quality was stable.

[0158] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. An online pretreatment process for reducing the content of tobacco stem cell wall substances, characterized in that: The following steps are involved: (1) adding the cleaned tobacco stems into a high-pressure stem moistening device for steam explosion, with the steam explosion pressure being no greater than 2 bar; (2) pressing and cutting the steam-exploded tobacco stems into shredded stems; (3) adding the biocomposite preparation to the shredded stems for fermentation treatment; The biocomposite preparation at least comprises cellulase, pectinase, laccase and ligninase.

2. The online pretreatment process according to claim 1, characterized in that: The steam explosion pressure in step (1) is 1.6-1.75 bar.

3. The online pretreatment process according to claim 1, characterized in that: The spiral frequency in step (1) is 20-25 Hz.

4. The online pretreatment process according to claim 1, characterized in that: The steam temperature in step (1) is 140-150°C.

5. The online pretreatment process according to claim 1, characterized in that: The steam explosion time in step (1) is 55-65s.

6. The online pretreatment process according to claim 5, characterized in that: The steam explosion time includes cooking time and explosion time. The cooking time is 56-58s, and the explosion time is 2-4s.

7. The online pretreatment process according to claim 1, characterized in that: The moisture content of the tobacco stems after washing in step (1) is 12-14%, and the moisture content of the tobacco stems after steam explosion is increased by 3-5%.

8. The online pretreatment process according to claim 1, characterized in that: In step (2), the thickness of the pressed stems is 0.8±0.05 mm, and the thickness of the cut stems is 0.14±0.03 mm.

9. The online pretreatment process according to claim 1, characterized in that: After fermentation in step (3), the moisture content of the shredded stems is 34-38%, the fermentation temperature is 45-50° C., the fermentation humidity is 70-80%, and the fermentation time is 20-30 hours.

10. The online pretreatment process according to claim 1, characterized in that: The biological composite preparation comprises xylanase, pectinase, pectin lyase, pectinesterase, glucanase, laccase, ligninase, cellulase and glucosidase, and the added weight ratio is (2-3): (1-2): (0.1-0.3): (0.1-0.3): (0.4-0.6): (4-6): (1-2): (1-2): (0.4-0.6).

Images