A method for improving tobacco essential oil yield and nicotine content by using solid base

Abstract

This invention discloses a method for synergistically improving the yield and nicotine content of tobacco essential oils using solid alkali. Addressing the problem of inefficient extraction in existing superheated steam distillation-dry distillation integrated technologies where nicotine exists in a salt state due to the acidity of the system, this invention mixes solid alkali with tobacco raw materials at a specific mass ratio before extraction. The alkaline environment promotes the conversion of nicotine from a salt state to a free state, and optimizes the pyrolysis pathway of aroma precursors. This method is simple, requires no equipment modification, and significantly improves extraction efficiency: the nicotine content in tobacco essential oils increases from 11.16% to 11.94–54.95%, and the essential oil yield increases from 10% to 10.38–14.59%. This invention achieves a synergistic improvement in nicotine content and essential oil yield, resulting in products with excellent aroma quality and significant industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of tobacco essential oil technology, and more specifically, relates to a method for improving the yield of tobacco essential oil and nicotine content by utilizing solid alkali. Background Technology

[0002] In the field of tobacco deep processing and essential oil extraction, the extraction and application of tobacco essential oils are key steps in improving the sensory quality of cigarettes and increasing product added value. Traditional steam distillation, while gentle, suffers from drawbacks such as low essential oil yield (typically below 0.2%), easy destruction of heat-sensitive components, and a limited range of aromas. Dry distillation, while increasing the yield (typically by 1-3%) and producing characteristic aromas like caramel, suffers from unstable heating, easily leading to localized overheating and off-flavors such as burnt and bitter tastes. To overcome the limitations of these single technologies, the integrated superheated steam distillation-dry distillation technology has emerged. This technology combines the gentleness of steam distillation with the high efficiency of dry distillation, significantly increasing the essential oil yield to 10%, with a nicotine content as high as 11.16% in the product. Furthermore, the product is rich in characteristic aromas such as roasted and sweet caramel notes, representing a significant advancement in the field of tobacco essential oil extraction.

[0003] However, this integrated technology still has room for optimization. For example, the extraction process generates a large amount of organic acids, resulting in an acidic environment where nicotine often exists as salts, making it difficult to distill with steam. Even if distilled, it easily dissolves in the aqueous phase as salt, severely impacting the nicotine yield. Simultaneously, acidic conditions also affect the thermal reaction process, negatively impacting the yield, chemical composition, and aroma quality of tobacco essential oils. Therefore, addressing the chemical reaction environment, particularly by using additives to regulate the acidity or alkalinity of the extraction environment to directionally influence the reaction pathway, represents a new approach to further explore the process's potential.

[0004] Studies have shown that alkaline conditions facilitate the conversion of nicotine, existing in tobacco as salt, into a free state, thereby increasing its volatility and extraction rate. Simultaneously, an alkaline environment also affects the pyrolysis and transformation process of aroma precursors in tobacco, thus altering the yield, chemical composition, and aroma quality of tobacco essential oils. However, existing research on alkaline additives largely focuses on traditional methods such as steam distillation, lacking research on integrated processes of superheated steam distillation and dry distillation. Furthermore, the comprehensive impact of alkaline additives adapted to this process on essential oil yield, nicotine content, and aroma quality remains unclear. Therefore, developing a method adapted to the superheated steam distillation-dry distillation process, which precisely controls the acid-base environment of the system to synergistically improve both tobacco essential oil yield and nicotine content without altering the core process framework, has significant scientific research and industrial application value. Summary of the Invention

[0005] To address the technical problems of existing superheated steam distillation-dry distillation integrated technology, which generates a large amount of organic acids during extraction, resulting in an acidic system that causes nicotine to exist in a salt form, hindering efficient extraction, and also affecting the conversion of aroma precursors and limiting essential oil yield, this invention provides a method for synergistically improving tobacco essential oil yield and nicotine content using a solid alkali. This method introduces a solid alkali in situ to regulate the acid-base environment of the reaction system, achieving efficient nicotine release and extraction, while simultaneously optimizing the pyrolysis pathway to significantly improve essential oil yield.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the yield and nicotine content of tobacco essential oil by utilizing solid alkali in synergistic effect involves mixing tobacco raw materials with solid alkali and loading them into a superheated steam distillation-dry distillation apparatus; introducing a mixture of nitrogen and superheated steam, starting the apparatus, and gradually increasing the temperature to extract components from the tobacco; collecting the distillate; using an organic solvent to extract the distillate; dehydrating the extract; and recovering the solvent by rotary evaporation to obtain tobacco essential oil rich in nicotine.

[0008] Preferably, the solid alkali is any one of urea, ammonium carbonate, sodium carbonate, and sodium hydroxide.

[0009] Preferably, the tobacco and solid alkali are simultaneously loaded into the superheated steam distillation-dry distillation apparatus in a uniformly mixed manner.

[0010] Preferably, the total amount of solid alkali added during the extraction process accounts for 1 to 5% of the total amount of tobacco raw materials.

[0011] Preferably, when the solid alkali is ammonium carbonate, the temperature program of the superheated steam distillation-dry distillation apparatus is as follows: the temperature is increased from room temperature to 100°C at a rate of 20°C / min, and then increased to 350°C at a rate of 2°C / min.

[0012] Preferably, when the solid alkali is urea or sodium hydroxide, the temperature program of the superheated steam distillation-dry distillation apparatus is as follows: the temperature is increased from room temperature to 130°C at a rate of 20°C / min, and then increased to 350°C at a rate of 2°C / min.

[0013] Preferably, when the solid alkali is sodium carbonate, the temperature program of the superheated steam distillation-dry distillation apparatus is as follows: the temperature is increased from room temperature to 200°C at a rate of 20°C / min, and then increased to 350°C at a rate of 2°C / min.

[0014] Preferably, the nicotine content in the tobacco essential oil is 11.94% to 54.95%.

[0015] Preferably, the yield of the tobacco essential oil is 10.38–14.59%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention originates from the results of experiments conducted by the applicant to design a scheme to increase the nicotine content in tobacco essential oils. During literature review and experimentation, the applicant discovered that extracting tobacco essential oils in an alkaline environment converts nicotine, which exists in the form of salts in tobacco, into a free state, making it easier to be carried out by superheated steam. Therefore, this invention introduces a solid alkali to ensure an alkaline environment during the tobacco essential oil extraction process, increasing the nicotine content from 11.16% before addition to 11.94-54.95% after addition, and the tobacco essential oil yield from 10% before addition to 10.38-14.59% after addition, thus demonstrating the technical advantages and advancements of this invention in the field of tobacco essential oil extraction. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described below with reference to specific embodiments. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed.

[0019] In the following examples, the yield of tobacco essential oil (%) = mass of tobacco essential oil / mass of tobacco raw material × 100%, where the mass of tobacco raw material is the mass of oven-dried raw material.

[0020] Example 1

[0021] A method for synergistically increasing tobacco essential oil yield and nicotine content using solid alkali includes the following steps:

[0022] A mixture of flue-cured tobacco leaf fragments and solid alkali was added to a superheated steam distillation-retorting apparatus, containing 200g of tobacco and 3% of the total tobacco weight of solid alkali (using urea, ammonium carbonate, sodium carbonate, and sodium hydroxide as solid alkalis, respectively). The retorting vessel was heated at a corresponding rate using external electric heating, while a mixture of nitrogen and superheated steam was introduced. The flow rates of nitrogen and superheated steam in the retorting vessel were 100mL / min and 1200g / h, respectively. The mixture containing the extract was condensed as it passed through a condenser with circulating cooling water, and the distillate was collected at 100–350℃. The distillate was extracted three times with a 1:1 volume ratio of ethyl acetate and n-hexane. The solvent-to-distillate volume ratio was 1:1 for the first extraction and 1:5 for the second and third extractions. Anhydrous sodium sulfate was added to the extract, and the mixture was stirred to remove water. The solvent was recovered using a rotary evaporator at 45℃ to obtain tobacco essential oil.

[0023] Example 2

[0024] A method for synergistically increasing tobacco essential oil yield and nicotine content using solid alkali includes the following steps:

[0025] A mixture of flue-cured tobacco leaf fragments and urea (200g tobacco, urea content of 1%, 3%, or 5% of the total tobacco weight) was added to a superheated steam distillation-reduction apparatus. The reduction vessel was heated from room temperature to 130°C at a rate of 20°C / min via external electric heating, and then further heated to 350°C at a rate of 2°C / min. Simultaneously, a mixture of nitrogen and superheated steam was introduced, with flow rates of 100 mL / min and 1200 g / h, respectively. The mixture containing the extract was condensed as it passed through a condenser with circulating cooling water, and the distillate was collected at 100–350°C. The distillate was extracted three times with a 1:1 volume ratio of ethyl acetate and n-hexane. The solvent-to-distillate volume ratio was 1:1 for the first extraction and 1:5 for the second and third extractions. Anhydrous sodium sulfate was added to the extract, and the mixture was stirred to remove water. The solvent was recovered using a rotary evaporator at 45°C to obtain tobacco essential oil.

[0026] Comparative Example 1

[0027] A method for extracting tobacco essential oil from tobacco leaves includes the following steps:

[0028] 200g of flue-cured tobacco leaf fragments were added to a superheated steam distillation-retorting apparatus. The retort was heated from room temperature to 350℃ at a rate of 2℃ / min by electric heating of the outer wall. At the same time, a mixture of nitrogen and superheated steam was introduced, with nitrogen and superheated steam flow rates of 100mL / min and 1200g / h, respectively. The mixture containing the extract was condensed as it passed through a condenser with circulating cooling water, and the distillate was collected at 100-350℃. The distillate was extracted three times with a mixed solvent of ethyl acetate and n-hexane in a volume ratio of 1:1. The volume ratio of solvent to distillate was 1:1 in the first extraction and 1:5 in the second and third extractions. Anhydrous sodium sulfate was added to the extract, and the mixture was stirred to remove water. The solvent was recovered using a rotary evaporator at 45℃ to obtain tobacco essential oil.

[0029] The yield of tobacco essential oil and the relative nicotine content obtained by the methods of Examples 1-2 and Comparative Example 1 are shown in Table 1 below.

[0030] Table 1. Yield and relative nicotine content of tobacco essential oil extracted with different amounts of solid alkali.

[0031]

[0032] As shown in Table 1, introducing solid alkali into the superheated steam distillation-dry distillation process has a generally significant positive effect on improving the nicotine content and yield of tobacco essential oils. Compared with Comparative Example 1 (essential oil yield 10.00%, relative nicotine content 11.16%), which did not add any solid alkali, the key indicators of all example groups were clearly improved, which confirms that the technical approach of creating an alkaline environment to synergistically improve the two core indicators is effective.

[0033] Further analysis revealed significant differences in the effects of different types of solid alkalis, exhibiting a directional regulatory characteristic. Urea demonstrated particularly outstanding performance in promoting nicotine release, achieving a nicotine content of 39.81% at a 3% addition level, which jumped to 54.95% at 5%, while simultaneously increasing the essential oil yield to 11.80%. This indicates that urea has a unique advantage in increasing nicotine content. In contrast, sodium carbonate was most effective in increasing the total essential oil yield, suggesting it may be more conducive to the overall pyrolysis and volatilization of various macromolecules in tobacco; sodium hydroxide showed a similar trend. The differences in the nicotine release-promoting effects of different alkalis are related to their alkalinity under high-temperature hydrothermal conditions, the specificity of their decomposition products, and their interaction with tobacco components. Ammonium carbonate provided a more balanced enhancement effect, showing a slight increase in both essential oil yield and relative nicotine content, offering diversity in process selection. In addition, the amount of solid alkali added is a key controllable parameter. Taking urea, which has a significant increase in both yield and nicotine content, as an example, its nicotine content and essential oil yield both show a clear positive growth relationship with the increase of the amount added. This proves that by precisely controlling the addition ratio, the composition of the final product can be flexibly controlled.

[0034] In summary, this invention successfully improves both nicotine extraction efficiency and total essential oil yield by mixing specific solid alkalis (urea, ammonium carbonate, sodium carbonate, and sodium hydroxide) with tobacco raw materials at a ratio of 1-5% followed by superheated steam distillation-dry distillation. This method not only has a clear principle—utilizing an alkaline environment to efficiently convert nicotine in tobacco as salt—but also offers significant effects and flexible control. Experimental data fully demonstrate that this invention achieves a synergistic leap in nicotine content and essential oil yield without significantly altering existing core processes, exhibiting simplicity and outstanding cost-effectiveness. Therefore, this invention provides an innovative, efficient, and practical solution for producing high-value-added, customizable tobacco essential oil products, possessing significant industrial application value.

[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synergistically improving tobacco essential oil yield and nicotine content using solid alkali, characterized in that, Includes the following steps: (1) Raw material pretreatment: The tobacco raw material is mixed with solid alkali and loaded into the superheated steam distillation-dry distillation device; (2) Extraction reaction: A mixture of nitrogen and superheated steam is introduced into the reaction apparatus, and the heating program is started to increase the temperature in a programmed manner so that the tobacco components are extracted in an alkaline environment and the distillate is collected. (3) Post-processing: The distillate was extracted with an organic solvent, the extract was dehydrated, and the solvent was recovered by rotary evaporation to obtain tobacco essential oil rich in nicotine.

2. The method according to claim 1, characterized in that, The solid alkali is selected from any one of urea, ammonium carbonate, sodium carbonate, and sodium hydroxide.

3. The method according to claim 1, characterized in that, The amount of solid alkali added is 1 to 5% of the mass of the tobacco raw material.

4. The method according to claim 1, characterized in that, The programmed heating process in step (2) includes two stages: First stage: Increase the temperature from room temperature to the preset constant temperature T1 at a heating rate of 20℃ / min. Second stage: Increase the temperature to 350℃ at a rate of 2℃ / min. The preset constant temperature T1 is determined according to the type of solid alkali selected.

5. The method according to claim 4, characterized in that, When the solid alkali is ammonium carbonate, the preset constant temperature T1 is 100℃.

6. The method according to claim 4, characterized in that, When the solid alkali is urea or sodium hydroxide, the preset constant temperature T1 is 130°C.

7. The method according to claim 4, characterized in that, When the solid alkali is sodium carbonate, the preset constant temperature T1 is 200℃.

8. The method according to claim 1, characterized in that, The nicotine content in the tobacco essential oil is 11.94% to 54.95%.

9. The method according to claim 1, characterized in that, The yield of the tobacco essential oil was 10.38%–14.59%.

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