A method for preparing a tobacco extract

Abstract

This invention provides a method for preparing a tobacco extract, comprising the following steps: S1) under the condition of introducing a protective gas, drying tobacco is heated to undergo pyrolysis treatment, and the volatiles generated by the pyrolysis treatment are collected by low-temperature condensation to obtain a condensate; S2) the condensate is subjected to electrochemical upgrading treatment to obtain the tobacco extract. Compared with the prior art, this invention first releases the volatile aroma components in the tobacco raw material through pyrolysis treatment, and then uses electrochemical upgrading treatment to directionally modulate the obtained volatile aroma components, thereby obtaining a tobacco extract with a high content of carboxylic acid and ester aroma substances. Adding it to sheet raw materials to prepare heated cigarettes can effectively enhance the tobacco aroma of the product.

Description

Technical Field

[0001] This invention belongs to the field of tobacco technology, and particularly relates to a method for preparing tobacco extract. Background Technology

[0002] Heated cigarettes, also known as heated non-combustible tobacco, heat tobacco without burning it at temperatures below 500℃ (generally in the range of 250℃ to 350℃), but can still deliver satisfaction and some tobacco aroma to consumers, with virtually no sideflow smoke.

[0003] Heated non-combustible tobacco products, by heating tobacco or tobacco extracts instead of burning tobacco, reduce the harmful components produced by the high-temperature combustion and decomposition of tobacco, thus significantly lowering the release of mainstream smoke chemical components. Furthermore, unlike the smoldering of conventional cigarettes, the tobacco is in a non-combustible / non-heated state during smoking intervals, thereby greatly reducing sidestream smoke and ambient smoke.

[0004] However, heated cigarettes release smoke at a significantly lower temperature than traditional cigarettes, resulting in insufficient release of tobacco flavor compounds and a weaker "tobacco flavor" compared to traditional cigarettes. To improve the smoking experience of heated cigarettes, tobacco extracts are usually added to compensate for the lack of "tobacco flavor."

[0005] Currently, technicians have developed a technology to prepare tobacco extracts with highly replicated tobacco flavor using high-temperature pyrolysis by simulating the release conditions of aroma substances in traditional cigarettes. However, due to the extremely complex reaction network and numerous reaction products during tobacco pyrolysis, the resulting extracts contain not only tobacco aroma components but also components detrimental to the smoking experience. Furthermore, existing technologies for preparing extracts through tobacco pyrolysis have not yet disclosed techniques for regulating the composition of tobacco pyrolysis products based on smoking experience, making it difficult to selectively reduce components detrimental to the smoking experience or enhance components beneficial to the taste. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing a tobacco extract with a high content of carboxylic acid and ester flavor substances.

[0007] This invention provides a method for preparing a tobacco extract, comprising the following steps:

[0008] S1) Under the condition of introducing a protective gas, the dry tobacco is heated to carry out thermal pyrolysis treatment, and the volatiles produced by thermal pyrolysis treatment are collected by low-temperature condensation to obtain condensate.

[0009] S2) The condensate is subjected to electrochemical upgrading treatment to obtain tobacco extract.

[0010] Preferably, the dried tobacco is obtained by drying the tobacco; the drying temperature is 60℃ to 100℃; the drying time is 1 to 24 hours; and the moisture content of the dried tobacco is 4 to 10 wt%.

[0011] Preferably, the heating rate in step S1) is 10-50℃ / min; the temperature of the pyrolysis treatment is 500℃-800℃; and the temperature is maintained for 0-20min after reaching the pyrolysis treatment temperature.

[0012] Preferably, the heating rate in step S1) is 20-30℃ / min; the temperature of the pyrolysis treatment is 550℃-650℃; and the temperature is maintained for 10-20 minutes after reaching the pyrolysis treatment temperature.

[0013] Preferably, the flow rate of the protective gas is such that the residence time of the volatiles released during the pyrolysis treatment at the pyrolysis treatment temperature is 2 to 10 seconds; and the temperature of the low-temperature condensation is -5°C to 20°C.

[0014] Preferably, step S2) specifically comprises:

[0015] The condensate, solvent, and conductive salt are mixed to obtain an electrochemical reaction solution;

[0016] Under conditions where a carbonic acid solution and / or carbon dioxide are bubbled into the electrochemical reaction solution, the electrochemical reaction solution is subjected to an electrochemical reaction to obtain a tobacco extract.

[0017] Preferably, the solvent is selected from one or more of ethylene glycol, propylene glycol and glycerol; the mass ratio of the condensate to the solvent is 1:(3-10);

[0018] The conductive salt is a potassium salt; the mass ratio of the condensate to the conductive salt is 1:(0.5-2).

[0019] Preferably, the amount of carbonate solution and / or carbon dioxide introduced is 2 to 10 mmol / min per gram of condensate;

[0020] The current density of the electrochemical reaction is 5–25 mA / cm². 2 The temperature of the electrochemical reaction is 0℃~30℃; the time of the electrochemical reaction is 2~4h.

[0021] Preferably, the electrochemical reaction solution undergoes an electrochemical reaction in an electrolytic cell; the anode of the electrolytic cell is an active metal electrode; the cathode of the electrolytic cell is a metal with electrochemical CO2 reduction activity; and the carbonic acid solution and / or carbon dioxide are introduced near the cathode.

[0022] The present invention also provides a tobacco extract prepared by the above preparation method.

[0023] This invention provides a method for preparing a tobacco extract, comprising the following steps: S1) under the condition of introducing a protective gas, drying tobacco is heated to undergo pyrolysis treatment, and the volatiles generated by the pyrolysis treatment are collected by low-temperature condensation to obtain a condensate; S2) the condensate is subjected to electrochemical upgrading treatment to obtain the tobacco extract. Compared with the prior art, this invention first releases the volatile aroma components in the tobacco raw material through pyrolysis treatment, and then uses electrochemical upgrading treatment to directionally modulate the obtained volatile aroma components, thereby obtaining a tobacco extract with a high content of carboxylic acid and ester aroma substances. Adding it to sheet raw materials to prepare heated cigarettes can effectively enhance the tobacco aroma of the product. Attached Figure Description

[0024] Figure 1 The graph shows the detection results of the content of carboxylic acid and ester flavor substances in the tobacco extracts obtained in Examples 1-4 and Comparative Example 1 of this invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a method for preparing a tobacco extract, comprising the following steps: S1) under the condition of introducing a protective gas, heating dry tobacco for thermal pyrolysis treatment, and collecting the volatiles generated by the thermal pyrolysis treatment by low-temperature condensation to obtain a condensate; S2) subjecting the condensate to electrochemical upgrading treatment to obtain a tobacco extract.

[0027] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0028] In this invention, tobacco is first dried to obtain dried tobacco. The drying temperature is preferably 60℃~100℃, more preferably 70℃~90℃, and even more preferably 80℃. The drying time is preferably 1~24h, more preferably 5~20h, even more preferably 10~15h, and most preferably 12h. The moisture content of the dried tobacco is preferably 4~10wt%, more preferably 4~8wt%. Using dried tobacco as raw material for pyrolysis can reduce the moisture content in the product.

[0029] Dry tobacco is subjected to pyrolysis under the condition of a protective gas. The protective gas can be any gas known to those skilled in the art and is not particularly limited; nitrogen is preferred in this invention. Pyrolysis under the condition of a protective gas purges the volatiles generated during the pyrolysis process out of the reactor, thereby promoting the full release of aroma components in the tobacco raw material at the minimum temperature required for release, achieving optimal aroma component yield and composition, and minimizing the loss of aroma components due to secondary pyrolysis at high temperatures and the generation of harmful components such as tar. The flow rate of the protective gas is preferably such that the volatiles released during the pyrolysis process are released within the optimal temperature range. The residence time at the thermal decomposition temperature is 2–10 s, more preferably 2–8 s, and even more preferably 2–5 s; the heating rate is preferably 10–50 °C / min, more preferably 20–50 °C / min, and even more preferably 20–30 °C / min; the thermal decomposition temperature is preferably 500 °C–800 °C, where most of the volatile aroma components can be fully released. Further increasing the temperature will lead to an increase in tar release. In this invention, it is more preferably 550 °C–800 °C, and even more preferably 550 °C–650 °C; after reaching the thermal decomposition temperature, it is preferably held for 0–20 min, and even more preferably for 10–20 min.

[0030] The volatiles generated by thermal decomposition are collected by low-temperature condensation to obtain condensate. By collecting the volatiles through low-temperature condensation rather than solvent dissolution, a condensate free of exogenous impurities can be obtained. The temperature of the low-temperature condensation is preferably -5℃ to 20℃, more preferably 0℃ to 15℃, and even more preferably 5℃ to 10℃. In this invention, the low-temperature condensation is preferably carried out by a condenser. The condenser is preferably cooled by ice water.

[0031] The condensate is subjected to electrochemical upgrading treatment; in this invention, the electrochemical upgrading treatment preferably specifically involves: mixing the condensate, solvent, and conductive salt to obtain an electrochemical reaction solution; and subjecting the electrochemical reaction solution to an electrochemical reaction under the condition of passing a carbonic acid solution and / or carbon dioxide to obtain a tobacco extract.

[0032] The condensate, solvent, and conductive salt are mixed to obtain an electrochemical reaction solution. The solvent can be any solvent well-known to those skilled in the art that can be used as an atomizing agent for heated cigarettes and has strong dissolving power for small molecule organic compounds; there are no special limitations. In this invention, the solvent is preferably a small molecule polyol solvent, more preferably one or more of ethylene glycol, propylene glycol, and glycerol. These solvents can simultaneously serve as both solvents and atomizing agents for heated cigarettes, thus eliminating the need for solvent removal in subsequent processes and allowing direct use in the production of flavored sheets. The mass ratio of the condensate to the solvent is preferably 1:(3-10), more preferably 1:1. The ratio of the conductive salt to the conductive salt is preferably 1:(0.5-2), more preferably 1:(0.5-1.5), even more preferably 1:(0.5-1), even more preferably 1:(0.5-0.8), and most preferably 1:(0.5-0.6).

[0033] The electrochemical reaction solution is subjected to an electrochemical reaction under the condition of introducing a carbonic acid solution and / or carbon dioxide; the amount of carbonic acid solution and / or carbon dioxide introduced per gram of condensate is preferably 2-10 mmol / min, more preferably 3-8 mmol / min, even more preferably 3-7 mmol / min, and most preferably 3.5-6.7 mmol / min; in some embodiments provided by the present invention, the amount of carbonic acid solution and / or carbon dioxide introduced per gram of condensate is specifically 5 mmol / min, 3.57 mmol / min, or 6.67 mmol / min; the electrochemical reaction is preferably carried out in an electrolytic cell. The electrolytic cell is preferably an active metal electrode, more preferably iron or magnesium; the oxidation activity of the active metal electrode needs to be stronger than that of most tobacco extract components to avoid the formation of substrate polymerization and precipitation during the electrochemical reaction; the cathode of the electrolytic cell is preferably a metal with electrochemical CO2 reduction activity, more preferably platinum; using a metal with electrochemical CO2 reduction activity as the cathode helps CO2 react with the active components in the extract to convert into carboxylic acids; the carbonic acid solution and / or carbon dioxide are preferably introduced near the cathode; the electrochemical reaction is preferably carried out under constant current conditions; the current density of the electrochemical reaction is preferably 5-25 mA / cm². 2 In some embodiments provided by this invention, the current density of the electrochemical reaction is specifically 10 mA / cm². 2 25mA / cm 2 or 5mA / cm 2The preferred temperature for the electrochemical reaction is 0°C to 30°C, more preferably 10°C to 30°C. In some embodiments provided by the present invention, the specific temperature for the electrochemical reaction is 20°C, 30°C, or 10°C. The preferred time for the electrochemical reaction is 2 to 4 hours.

[0034] After the electrochemical reaction is completed, it is preferable to perform a purification process to remove insoluble impurities generated during the electrochemical reaction, thereby obtaining the tobacco extract. The purification process can be any method known to those skilled in the art and is not particularly limited. In this invention, filtration or centrifugation is preferred to remove solid impurities.

[0035] This invention first releases volatile aroma components from tobacco raw materials through thermal decomposition, and then uses electrochemical upgrading to directionally modulate the obtained volatile aroma components, thereby obtaining a tobacco extract with a high content of carboxylic acid and ester aroma substances. Adding this extract to sheet raw materials to prepare heated cigarettes can effectively enhance the tobacco aroma of the product.

[0036] The present invention also provides a tobacco extract prepared by the above preparation method.

[0037] The present invention also provides a heated cigarette, comprising the tobacco extract prepared by the above preparation method.

[0038] To further illustrate the present invention, the following describes in detail a method for preparing a tobacco extract, in conjunction with specific embodiments.

[0039] All reagents used in the following examples are commercially available.

[0040] Example 1

[0041] (a) Take 10 kg of tobacco stems and dry them in an oven at 80°C for 12 hours to obtain a dry raw material with a moisture content of 8.0%.

[0042] (b) The obtained dry raw material was placed in a fixed-bed pyrolysis reactor and purged using high-purity nitrogen as a protective gas. The heating program of the pyrolysis reactor was set to increase the temperature to 550°C at a rate of 20°C / min and continue the reaction for 20 min. The flow rate of high-purity nitrogen was controlled to ensure that the residence time of volatiles in the pyrolysis reactor was 2 s.

[0043] (c) The volatiles enter the shell-and-tube condenser for condensation and enrichment. The condenser is cooled by ice water and operates at a temperature of 5°C.

[0044] (d) Collect 4.2 kg of the crude extract obtained in step (c) and mix it thoroughly with 21 kg of propylene glycol and 2.1 kg of potassium chloride to obtain an electrochemical reaction solution.

[0045] (e) The electrochemical reaction solution is placed in a one-chamber electrolytic cell, with magnesium as the anode and platinum as the cathode. CO2 gas is continuously introduced near the cathode at a flow rate of 21 mol / min. The electrochemical reaction is operated in constant current mode, with a preferred current density of 10 mA / cm². 2 The electrolysis time was 4 hours, and the electrolyte was continuously stirred by a stirrer. The electrolytic cell was cooled with cold water to maintain a constant temperature of 20°C.

[0046] (f) Filter the electrolyte after the reaction in step (e) to obtain a clear solution, which is the tobacco extract solution.

[0047] Example 2

[0048] (a) Take 10 kg of tobacco stems and dry them in an oven at 80°C for 12 hours to obtain a dry raw material with a moisture content of 8.0%.

[0049] (b) The obtained dry raw material was placed in a fixed-bed pyrolysis reactor and purged using high-purity nitrogen as a protective gas. The heating program of the pyrolysis reactor was set to increase the temperature to 800°C at a rate of 50°C / min and continue the reaction for 20 min. The flow rate of high-purity nitrogen was controlled to ensure that the residence time of volatiles in the pyrolysis reactor was 2 s.

[0050] (c) The volatiles enter the shell-and-tube condenser for condensation and enrichment. The condenser is cooled by ice water and operates at a temperature of 5°C.

[0051] (d) Collect 3.6 kg of the crude extract obtained in step (c) and mix it thoroughly with 18 kg of propylene glycol and 2.0 kg of potassium chloride to obtain an electrochemical reaction solution.

[0052] (e) The electrochemical reaction solution is placed in a one-chamber electrolytic cell, with magnesium as the anode and platinum as the cathode. CO2 gas is continuously introduced near the cathode at a flow rate of 18 mol / min. The electrochemical reaction is operated in constant current mode, with a preferred current density of 10 mA / cm². 2 The electrolysis time was 4 hours, and the electrolyte was continuously stirred by a stirrer. The electrolytic cell was cooled with cold water to maintain a constant temperature of 20°C.

[0053] (f) Filter the electrolyte after the reaction in step (e) to obtain a clear solution, which is the tobacco extract solution.

[0054] Example 3

[0055] (a) Take 10 kg of tobacco stems and dry them in an oven at 80°C for 12 hours to obtain a dry raw material with a moisture content of 8.0%.

[0056] (b) The obtained dry raw material was placed in a fixed-bed pyrolysis reactor and purged using high-purity nitrogen as a protective gas. The heating program of the pyrolysis reactor was set to increase the temperature to 550°C at a rate of 20°C / min and continue the reaction for 20 min. The flow rate of high-purity nitrogen was controlled to ensure that the residence time of volatiles in the pyrolysis reactor was 2 s.

[0057] (c) The volatiles enter the shell-and-tube condenser for condensation and enrichment. The condenser is cooled by ice water and operates at a temperature of 5°C.

[0058] (d) Collect 4.2 kg of the crude extract obtained in step (c) and mix it thoroughly with 21 kg of propylene glycol and 2.1 kg of potassium chloride to obtain an electrochemical reaction solution.

[0059] (e) The electrochemical reaction solution is placed in a one-chamber electrolytic cell, with magnesium as the anode and platinum as the cathode. CO2 gas is continuously introduced near the cathode at a flow rate of 28 mol / min. The electrochemical reaction is operated in constant current mode, with a preferred current density of 25 mA / cm². 2 The electrolysis time was 4 hours, and the electrolyte was continuously stirred by a stirrer. The electrolytic cell was cooled with cold water to maintain a constant temperature of 30°C.

[0060] (f) Filter the electrolyte after the reaction in step (e) to obtain a clear solution, which is the tobacco extract solution.

[0061] Example 4

[0062] (a) Take 10 kg of tobacco stems and dry them in an oven at 80°C for 12 hours to obtain a dry raw material with a moisture content of 8.0%.

[0063] (b) The obtained dry raw material is placed in a fixed-bed pyrolysis reactor and purged using high-purity nitrogen as a protective gas. The heating program of the pyrolysis reactor is set to increase the temperature to 550°C at a rate of 20°C / min and continue the reaction for 20 min. The flow rate of high-purity nitrogen is controlled to ensure that the residence time of volatiles in the pyrolysis reactor is 2 s.

[0064] (c) The volatiles enter the shell-and-tube condenser for condensation and enrichment. The condenser is cooled by ice water and operates at a temperature of 5°C.

[0065] (d) Collect 4.2 kg of the crude extract obtained in step (c) and mix it thoroughly with 21 kg of propylene glycol and 2.1 kg of potassium chloride to obtain an electrochemical reaction solution.

[0066] (e) The electrochemical reaction solution is placed in a one-chamber electrolytic cell, with magnesium as the anode and platinum as the cathode. CO2 gas is continuously introduced near the cathode at a flow rate of 15 mol / min. The electrochemical reaction is operated in constant current mode, with a preferred current density of 5 mA / cm². 2 The electrolysis time was 2 hours, and the electrolyte was continuously stirred by a stirrer. The electrolytic cell was cooled with cold water to maintain a constant temperature of 10°C.

[0067] (f) Filter the electrolyte after the reaction in step (e) to obtain a clear solution, which is the tobacco extract solution.

[0068] Comparative Example 1

[0069] (a) Take 10 kg of tobacco stems and dry them in an oven at 80°C for 12 hours to obtain a dry raw material with a moisture content of 8.0%.

[0070] (b) The obtained dry raw material was placed in a fixed-bed pyrolysis reactor and purged using high-purity nitrogen as a protective gas. The heating program of the pyrolysis reactor was set to increase the temperature to 800°C at a rate of 50°C / min and continue the reaction for 20 min. The flow rate of high-purity nitrogen was controlled to ensure that the residence time of volatiles in the pyrolysis reactor was 2 s.

[0071] (c) The volatiles enter the shell-and-tube condenser for condensation and enrichment. The condenser is cooled by ice water and operates at a temperature of 5°C.

[0072] (d) Collect 3.6 kg of the crude extract obtained in step (c) and mix it thoroughly with 18 kg of propylene glycol and 2.0 kg of potassium chloride to obtain an electrochemical reaction solution.

[0073] (e) The electrochemical reaction solution is placed in a one-chamber electrolytic cell, with magnesium as the anode and platinum as the cathode. No CO2 gas is introduced. The electrochemical reaction is operated in constant current mode, with a preferred current density of 10 mA / cm². 2 The electrolysis time was 4 hours, and the electrolyte was continuously stirred by a stirrer. The electrolytic cell was cooled with cold water to maintain a constant temperature of 20°C.

[0074] (f) Filter the electrolyte after the reaction in step (e) to obtain a clear solution, which is the tobacco extract solution.

[0075] The contents of carboxylic acids and esters of aroma compounds in the tobacco extracts obtained in Examples 1-4 and Comparative Example 1 were detected using the detection standards in "Determination of Volatile Organic Acids in Tobacco and Tobacco Products by Gas Chromatography-Mass Spectrometry (YC / T500-2014)". The results are as follows: Figure 1As shown in the figure, the relative content is the sum of the peak areas of the chromatograms of various substances. Among them, the quantitative data of the typical characteristic components formic acid and formic acid 2,3-dimethylphenyl ester are shown in Table 1.

[0076] Table 1 Content of typical characteristic components

[0077]

[0078] The tobacco extracts obtained in Examples 1-4 and Comparative Example 1 were added to thickened sheet tobacco at a ratio of 0.1 wt% using methods well-known to those skilled in the art, and produced as heated cigarettes. The cigarettes exhibited a mellow flavor, strong strength, rich and abundant aroma, smooth smoke, good smoke retention, a sweet and refreshing aftertaste, significant masking of impurities, and a relatively comfortable and clean finish. Professional smokers conducted sensory quality evaluations according to the national standard (sensory technical requirements) GB5606.4-2005, and the results are shown in Table 2 below.

[0079] Table 2 Sensory Quality Scores

[0080]

Claims

1. A method for preparing a tobacco extract, characterized in that, Includes the following steps: S1) Under the condition of introducing a protective gas, the dry tobacco is heated to carry out thermal pyrolysis treatment, and the volatiles generated by the thermal pyrolysis treatment are collected by low-temperature condensation to obtain condensate; the temperature of the low-temperature condensation is -5℃~20℃. S2) The condensate is subjected to electrochemical upgrading treatment to obtain a tobacco extract; The heating rate in step S1) is 10~50℃ / min; the temperature of the thermal decomposition treatment is 500℃~800℃; and the temperature is maintained for 0~20 min after reaching the thermal decomposition treatment temperature. Step S2) specifically involves: The condensate, solvent, and conductive salt are mixed to obtain an electrochemical reaction solution; Under the condition of passing a carbonic acid solution and / or carbon dioxide into the electrochemical reaction solution, the electrochemical reaction solution is subjected to an electrochemical reaction to obtain a tobacco extract; The electrochemical reaction solution undergoes an electrochemical reaction in an electrolytic cell; the anode of the electrolytic cell is an active metal electrode; the cathode of the electrolytic cell is a metal with electrochemical CO2 reduction activity; the carbonic acid solution and / or carbon dioxide are introduced near the cathode.

2. The preparation method according to claim 1, characterized in that, The dried tobacco is obtained by drying the tobacco; the drying temperature is 60℃~100℃; the drying time is 1~24 h; and the moisture content of the dried tobacco is 4~10 wt%.

3. The preparation method according to claim 1, characterized in that, The heating rate in step S1) is 20~30℃ / min; the temperature of the thermal decomposition treatment is 550℃~650℃; and the temperature is maintained for 10~20 min after reaching the thermal decomposition treatment temperature.

4. The preparation method according to claim 1, characterized in that, The flow rate of the protective gas is such that the residence time of the volatiles released during the pyrolysis treatment at the pyrolysis treatment temperature is 2-10 s.

5. The preparation method according to claim 1, characterized in that, The solvent is selected from one or more of ethylene glycol, propylene glycol and glycerol; the mass ratio of the condensate to the solvent is 1:(3~10). The conductive salt is a potassium salt; the mass ratio of the condensate to the conductive salt is 1:(0.5~2).

6. The preparation method according to claim 1, characterized in that, The amount of carbonic acid solution and / or carbon dioxide introduced per gram of condensate is 2 to 10 mmol / min; The current density of the electrochemical reaction is 5~25 mA / cm². 2 The temperature of the electrochemical reaction is 0℃~30℃; the time of the electrochemical reaction is 2~4 h.

7. The tobacco extract prepared by any one of claims 1 to 6.

Images