Method for detecting moisture diffusion activation energy of tobacco leaves and application of method

Abstract

The invention provides a tobacco leaf moisture diffusion activation energy detection method and application thereof, and the method comprises the following steps: (1) raising the humidity of to-be-detected tobacco leaves, then lowering the humidity to carry out a balance test, and detecting the moisture ratio of the to-be-detected tobacco leaves in each humidity interval; (2) fitting by taking the moisture ratio of the tobacco leaves to be detected as a dependent variable and time as an independent variable to obtain a moisture diffusion coefficient; (3) selecting moisture diffusion coefficients under different humidity intervals and calculating an average value as a moisture diffusion coefficient under the fixed temperature; (4) replacing the fixed temperature and repeating the steps (1)-(3); and (5) fitting the fixed temperature and the moisture diffusion coefficient, and calculating the moisture diffusion activation energy. The detection method provided by the invention can accurately and effectively detect the moisture diffusion activation energy of the tobacco leaves, overcomes the problem of difference of the moisture diffusion activation energy of the tobacco leaves under different conditions, is accurate and reliable in result, and can be effectively used for comparing the moisture diffusion activation energy of different tobacco leaves.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco detection, and in particular relates to a method for detecting tobacco leaf moisture diffusion activation energy and an application thereof. Background Art

[0002] Moisture is one of the important factors affecting the quality of cigarettes. During the processing and storage of cigarettes, moisture will absorb and dehumidify as the temperature and humidity change. In order to study the changes in tobacco moisture, dynamic moisture adsorption method and moisture isothermal adsorption model have been widely used, and a series of evaluation methods have been developed. Existing literature also reports the application of dynamic moisture adsorption method to analyze the moisture retention mechanism of different cigarette raw materials such as leaf shreds and expanded shreds. However, the sample amount required by the dynamic moisture adsorption instrument in the above studies is tens of milligrams in some cases and several grams in others, which is quite different from the weight of shredded tobacco in conventional cigarettes. Therefore, errors may occur when analyzing the moisture change process of shredded tobacco in cigarettes. The sample amount required for the SPSx dynamic moisture adsorption analyzer test varies widely, which can cover the weight of a single cigarette. At present, the SPSx dynamic moisture adsorption analysis method has been successfully applied to many related fields such as pharmaceuticals, food, and materials, but there are few reports on its application in tobacco.

[0003] In addition, the current methods for evaluating the activation energy of water diffusion in tobacco and tobacco products are still traditional, mainly using different instruments and equipment and different real-time recording methods to measure the change of water content in tobacco at different temperatures over time, calculate the diffusion coefficient of water content in tobacco based on the change curve, and finally calculate the activation energy based on the Arrhenius equation. However, there are differences in the humidity ranges selected by the above methods, and the differences in the diffusion coefficients of water content in different humidity ranges are not consistent. Sometimes in a range, the activation energy of A# tobacco leaves is higher than that of B# tobacco leaves, and sometimes in a range, the activation energy of B# tobacco leaves is higher than that of A# tobacco leaves. Therefore, how to accurately measure the water diffusion coefficient of tobacco leaves and fit a reliable activation energy that is easy to compare the differences has become a difficult problem.

[0004] CN102221511B discloses a method for testing and evaluating the moisture absorption and dehumidification characteristics of tobacco leaves and the moisture retention performance of tobacco leaf preservatives. The invention uses a dynamic moisture adsorption analysis system to study the dynamic law of moisture loss in a dry environment after the tobacco leaves have reached moisture balance under high humidity conditions, and a linear fitting graph is made between the dry basis moisture content value Mt of the tobacco at time t and t0.5. The moisture loss rate constant k value is obtained from the slope of the obtained straight line, and the initial moisture content M0 of the tobacco leaves and the moisture loss rate constant k value are combined as the basis for evaluating the moisture absorption and dehumidification characteristics and moisture retention performance of the tobacco leaves.

[0005] CN102128763B discloses a method for testing the moisture retention performance of tobacco. The method uses a dynamic moisture adsorption analysis system to study the dynamics of moisture loss of tobacco in a dry environment, and finds that there is a good linear correlation between the dry basis moisture content of tobacco in the early stage of moisture loss and the square root of time. A straight line graph is drawn between the dry basis moisture content Mt value of tobacco at time t and t0.5, and the rate constant k value is obtained from the slope of the obtained straight line, which is used as the basis for testing the moisture retention performance of tobacco.

[0006] However, the above methods are all traditional methods in this field and cannot avoid the problem caused by the difference in water diffusion coefficient in different humidity ranges. Therefore, how to provide a method that can accurately detect and compare the difference in tobacco leaf water diffusion activation energy has become an urgent problem to be solved. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for detecting the water diffusion activation energy of tobacco leaves and its application. The detection method provided by the present invention can accurately and effectively detect the water diffusion activation energy of tobacco leaves, overcome the problem that there are differences in the water diffusion activation energy of tobacco leaves under different conditions, and the result is accurate and reliable, and can be effectively used for the comparison of water diffusion activation energy of different tobacco leaves.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In one aspect, the present invention provides a method for detecting the activation energy of tobacco leaf moisture diffusion, the detection method comprising the following steps:

[0010] (1) raising the humidity of the tobacco leaves to be tested to the highest humidity and then lowering it to the lowest humidity to conduct a balance test under fixed temperature and initial humidity conditions, and detecting the moisture ratio of the tobacco leaves to be tested in each humidity range;

[0011] (2) using the moisture ratio of the tobacco leaves to be tested in each humidity range obtained in step (1) as the dependent variable and time as the independent variable for fitting to obtain the moisture diffusion coefficient of the tobacco leaves to be tested in different humidity ranges;

[0012] (3) selecting the moisture diffusion coefficients of the tobacco leaves to be tested under different humidity ranges obtained in step (2) and calculating the average value as the moisture diffusion coefficient of the tobacco leaves to be tested under the fixed temperature;

[0013] (4) Repeating steps (1) to (3) at a fixed temperature to obtain the moisture diffusion coefficient of the tobacco leaves to be tested at different temperatures;

[0014] (5) Fitting the different fixed temperatures in steps (1)-(4) and their corresponding moisture diffusion coefficients of the tobacco leaves to be tested, and calculating the moisture diffusion activation energy of the tobacco leaves to be tested.

[0015] The above method obtains moisture changes by conducting moisture absorption and drying tests on tobacco leaf moisture ratio at different temperatures, and can determine the humidity range in which the moisture diffusion coefficient of tobacco leaves is relatively stable, and on this basis calculates the moisture diffusion coefficient of the tobacco leaves to be tested, and calculates the moisture diffusion activation energy of the tobacco leaves to be tested by fitting, thereby overcoming the problem of differences in the moisture diffusion activation energy of tobacco leaves detected under different conditions. The results are accurate and reliable, and can be effectively used for comparing the moisture diffusion activation energies of different tobacco leaves; and by first increasing the humidity and then reducing the humidity, the tobacco leaves can first fully absorb moisture and then dry, and accurate and reliable equilibrium experimental data can be effectively obtained, thereby improving the fitting accuracy of subsequent moisture diffusion coefficients and moisture diffusion activation energies.

[0016] Preferably, the initial humidity in step (1) is 58-62%, such as 58%, 59%, 60%, 61% or 62%, but is not limited to the above-listed values. Other values ​​not listed within the above-listed range are also applicable.

[0017] Preferably, the maximum humidity in step (1) is 78-82%, such as 78%, 79%, 80%, 81% or 82%, but is not limited to the above-listed values. Other values ​​not listed within the above-listed range are also applicable.

[0018] Preferably, the minimum humidity in step (1) is below 45%.

[0019] The above humidity selection can further improve the accuracy and reliability of the balance test results.

[0020] Preferably, the specific steps of increasing the humidity to the maximum humidity and then decreasing it to the minimum humidity for the equilibrium test in step (1) are to increase the humidity from the initial humidity to the maximum humidity in a fixed step size and then decrease it to the minimum humidity; each time the humidity changes by one step size, it is necessary to wait until the tobacco leaves to be tested are balanced before changing the humidity.

[0021] The above-mentioned specific operation steps can form humidity intervals during the equilibrium test, and study the moisture changes of tobacco leaves in units of humidity intervals, so that the experiment can effectively study and analyze the moisture change trends of tobacco leaves in different humidity change intervals at different temperatures, and then determine the humidity interval in which the moisture diffusion coefficient is relatively stable.

[0022] Preferably, the step size is 3-7%, such as 3%, 4%, 5%, 6% or 7%, etc., but is not limited to the above-listed values, and other values ​​not listed within the above-listed value range are also applicable.

[0023] Preferably, the fitting in step (2) is performed according to formula I and formula II:

[0024]

[0025] In the formula, MR represents the moisture content of the tobacco leaf to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0026] Compared with the existing formula, this formula has better fitting effect and can improve the determination coefficient of the fitting equation.

[0027] Preferably, the different humidity intervals in step (3) are in the range of 45-60%.

[0028] In the above-mentioned specific humidity range, the water diffusion coefficient is more stable than in other ranges, which can more effectively improve the accuracy of subsequent fitting.

[0029] Preferably, the different fixed temperatures in step (4) range from 5 to 60°C.

[0030] Preferably, the temperature difference between the different fixed temperatures in step (4) is greater than 2°C.

[0031] Preferably, the fixed temperature is changed at least twice in step (4).

[0032] Preferably, the fitting in step (5) is performed according to formula III:

[0033]

[0034] Where T is the fixed temperature, Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0035] On the other hand, the present invention also provides the application of the above-mentioned method for detecting the activation energy of tobacco leaf moisture diffusion in tobacco quality control.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The invention provides a method for detecting the water diffusion activation energy of tobacco leaves. By performing moisture absorption and drying tests on the water ratio of tobacco leaves at different temperatures to obtain water variation, the humidity range in which the water diffusion coefficient of tobacco leaves is relatively stable can be determined, and the water diffusion coefficient of tobacco leaves to be tested is measured and obtained based on the humidity range. The water diffusion activation energy of tobacco leaves to be tested is calculated by fitting, and the problem of differences in the water diffusion activation energy of tobacco leaves detected under different conditions is overcome. The result is accurate and reliable, and can be effectively used for comparing the water diffusion activation energies of different tobacco leaves. By first increasing the humidity and then reducing the humidity, the tobacco leaves can first fully absorb moisture and then be dried, and accurate and reliable equilibrium experimental data can be effectively obtained, and the fitting accuracy of subsequent water diffusion coefficient and water diffusion activation energy is improved. DETAILED DESCRIPTION

[0038] In order to further explain the technical means and effects adopted by the present invention, the technical solution of the present invention is further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0039] Example 1

[0040] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0041] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 22°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is increased from 60% to 80% in steps of 5%, and then decreased from 80% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0042] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 10°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is increased from 60% to 80% in steps of 5%, and then decreased from 80% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0043] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 35°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is increased from 60% to 80% in steps of 5%, and then decreased from 80% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0044] 4) Scatter plots of the moisture ratio of tobacco leaves after equilibrium at 10°C, 22°C, and 35°C over time in each humidity change range were established, and then the moisture diffusion coefficients of each tobacco leaf at the three temperatures were obtained by fitting using formulas I and II.

[0045]

[0046] In the formula, MR represents the moisture content of the tobacco leaves to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0047] Then, the average value of the water diffusion coefficient at each temperature in the three humidity intervals of "60-55%, 55-50%, 50-45%" is selected as the available diffusion coefficient at that temperature, and it is fitted with the temperature according to Formula III:

[0048]

[0049] Where, T is a fixed temperature (10℃, 22℃, 35℃), Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0050] The water diffusion activation energies of the three types of tobacco leaves were 73, 78, and 65 kJ / mol, respectively.

[0051] Example 2

[0052] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0053] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 20℃ and the relative humidity to 58%. After reaching equilibrium, the ambient humidity is increased from 58% to 82% in steps of 4%, and then decreased from 82% to 22% in steps of 4%. Each step of humidity change requires waiting for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0054] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 15°C and the relative humidity to 58%. After reaching equilibrium, the ambient humidity is increased from 58% to 82% in steps of 4%, and then decreased from 82% to 22% in steps of 4%. Each step of humidity change requires waiting for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0055] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 25°C and the relative humidity to 58%. After reaching equilibrium, the ambient humidity is increased from 58% to 82% in steps of 4%, and then decreased from 82% to 22% in steps of 4%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0056] 4) Scatter plots of the moisture ratio of tobacco leaves after equilibrium at 15°C, 20°C, and 25°C in each humidity change range over time were established, and then the moisture diffusion coefficients of each tobacco leaf at the three temperatures were obtained by fitting using formulas I and II.

[0057]

[0058] In the formula, MR represents the moisture content of the tobacco leaves to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0059] Then, the average value of the water diffusion coefficient at each temperature in the three humidity intervals of "58-54%, 54-50%, 50-46%" is selected as the available diffusion coefficient at that temperature, and it is fitted with the temperature according to Formula III:

[0060]

[0061] Where, T is a fixed temperature (10℃, 22℃, 35℃), Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0062] Example 3

[0063] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0064] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 23°C and the relative humidity to 62%. After reaching equilibrium, the ambient humidity is increased from 62% to 78% in steps of 4%, and then decreased from 78% to 10% in steps of 4%. Each step of humidity change requires waiting for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0065] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 12°C and the relative humidity to 62%. After reaching equilibrium, the ambient humidity is increased from 62% to 78% in steps of 4%, and then decreased from 78% to 10% in steps of 4%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0066] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 30°C and the relative humidity to 62%. After reaching equilibrium, the ambient humidity is increased from 62% to 78% in steps of 4%, and then decreased from 78% to 10% in steps of 4%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0067] 4) Scatter plots of the moisture ratio of tobacco leaves after equilibrium at 23°C, 12°C, and 30°C in each humidity change range over time were established, and then the moisture diffusion coefficients of each tobacco leaf at the three temperatures were obtained by fitting using formulas I and II.

[0068]

[0069] In the formula, MR represents the moisture content of the tobacco leaves to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0070] Then, the average value of the water diffusion coefficient at each temperature in the three humidity intervals of "58-54%, 54-50%, 50-46%" is selected as the available diffusion coefficient at that temperature, and it is fitted with the temperature according to Formula III:

[0071]

[0072] Where T is a fixed temperature (12°C, 23°C, 30°C), Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0073] Example 4

[0074] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0075] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 22°C and the relative humidity to 55%. After reaching equilibrium, the ambient humidity is increased from 55% to 75% in steps of 5%, and then decreased from 75% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0076] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 10°C and the relative humidity to 55%. After reaching equilibrium, the ambient humidity is increased from 55% to 75% in steps of 5%, and then decreased from 75% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0077] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 35°C and the relative humidity to 55%. After reaching equilibrium, the ambient humidity is increased from 55% to 75% in steps of 5%, and then decreased from 75% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0078] 4) Scatter plots of the moisture ratio of tobacco leaves after equilibrium at 10°C, 22°C, and 35°C over time in each humidity change range were established, and then the moisture diffusion coefficients of each tobacco leaf at the three temperatures were obtained by fitting using formulas I and II.

[0079]

[0080] In the formula, MR represents the moisture content of the tobacco leaves to be tested, Mt represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0081] Then, the average value of the water diffusion coefficient at each temperature in the three humidity intervals of "60-55%, 55-50%, 50-45%" is selected as the available diffusion coefficient at that temperature, and it is fitted with the temperature according to Formula III:

[0082]

[0083]

[0084] Where, T is a fixed temperature (10℃, 22℃, 35℃), Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0085] Example 5

[0086] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0087] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 22°C and the relative humidity to 65%. After reaching equilibrium, the ambient humidity is increased from 65% to 85% in steps of 5%, and then decreased from 85% to 10% in steps of 5%. Each step of humidity change requires waiting for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0088] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 10°C and the relative humidity to 65%. After reaching equilibrium, the ambient humidity is increased from 65% to 85% in steps of 5%, and then decreased from 85% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0089] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 35°C and the relative humidity to 65%. After reaching equilibrium, the ambient humidity is increased from 65% to 85% in steps of 5%, and then decreased from 85% to 10% in steps of 5%. After each step of humidity change, wait until the tobacco leaves to be tested are balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0090] 4) Scatter plots of the moisture ratio of tobacco leaves after equilibrium at 10°C, 22°C, and 35°C over time in each humidity change range were established, and then the moisture diffusion coefficients of each tobacco leaf at the three temperatures were obtained by fitting using formulas I and II.

[0091]

[0092] In the formula, MR represents the moisture content of the tobacco leaves to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

[0093] Then, the average value of the water diffusion coefficient at each temperature in the three humidity intervals of "60-55%, 55-50%, 50-45%" is selected as the available diffusion coefficient at that temperature, and it is fitted with the temperature according to Formula III:

[0094]

[0095] Where, T is a fixed temperature (10℃, 22℃, 35℃), Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor (m 2 / s), R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

[0096] Example 6

[0097] The present embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion. The specific steps are the same as those of Embodiment 1 except that in step 4), the average value of the moisture diffusion coefficient at each temperature in the three humidity ranges of "55-50%, 50-45%, 45-40%" is selected as the available diffusion coefficient at the temperature.

[0098] Example 7

[0099] This embodiment provides a method for detecting the activation energy of tobacco leaf moisture diffusion. The specific steps are the same as those of Embodiment 1 except that in step 4), the average value of the moisture diffusion coefficient at each temperature in the three humidity ranges of "65-60%, 60-55%, and 55-50%" is selected as the available diffusion coefficient at the temperature.

[0100] Example 8

[0101] This embodiment provides a method for detecting activation energy of tobacco leaf moisture diffusion. The specific steps are consistent with those of Embodiment 1 except that the following formula is used in step 4) instead of Formula II to fit the moisture diffusion coefficient of each tobacco leaf at three temperatures.

[0102]

[0103] Example 9

[0104] This embodiment provides a method for detecting activation energy of tobacco leaf moisture diffusion. The specific steps are consistent with those of Embodiment 1 except that the following formula is used in step 4) instead of Formula II to fit the moisture diffusion coefficient of each tobacco leaf at three temperatures.

[0105]

[0106] Comparative Example 1

[0107] This comparative example provides a method for detecting the activation energy of tobacco leaf moisture diffusion, and the specific steps are as follows:

[0108] 1) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, respectively, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 22°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is reduced from 60% to 10% in steps of 5%. After each step of humidity change, wait for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0109] 2) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 10°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is reduced from 60% to 10% in steps of 5%. After each step of humidity change, wait for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0110] 3) Weigh 0.7g of three tobacco leaf samples, X2F, C3F, and B2F, and place them in the SPSx dynamic moisture analyzer. Adjust the temperature of the SPSx dynamic moisture adsorption instrument to 35°C and the relative humidity to 60%. After reaching equilibrium, the ambient humidity is reduced from 60% to 10% in steps of 5%. After each step of humidity change, wait for the tobacco leaves to be tested to be balanced before changing the humidity. Record the moisture ratio of the tobacco leaves after each equilibrium.

[0111] 4) Same as Example 1.

[0112] Effect comparison:

[0113] X2F sample series A and series B were prepared by controlling the amount of propylene glycol applied to the surface of tobacco leaf samples, with five groups in each series. The water diffusion activation energy of each group of tobacco leaves in the A series samples was similar, and the water diffusion activation energy of each group of tobacco leaves in the B series samples increased in order from small to large. The A series and B series samples were tested using the methods of Examples 1-9 and Comparative Example 1, and the results were as follows:

[0114]

[0115]

[0116]

[0117] From the above data, it can be found that the method provided by the present invention can accurately detect the water diffusion activation energy of tobacco leaves, and can realize the effective comparison of water diffusion activation energy of different tobacco leaves. Comparing Examples 1-9, it can be found that the present invention can effectively improve the accuracy of detection calculation by controlling the equilibrium test humidity and selecting a specific humidity range and fitting formula; comparing Example 1 and Comparative Example 1, it can be found that the present invention can firstly increase the humidity and then reduce the humidity, so that the tobacco leaves can fully absorb moisture and then dry, and can effectively obtain accurate and reliable equilibrium experimental data, and improve the fitting accuracy of subsequent water diffusion coefficient and water diffusion activation energy.

[0118] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the detection method of tobacco leaf moisture diffusion activation energy and its application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0119] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0120] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for detecting the activation energy of tobacco leaf moisture diffusion, characterized in that: The detection method comprises the following steps: (1) raising the humidity of the tobacco leaves to be tested to the highest humidity and then lowering it to the lowest humidity to conduct a balance test under fixed temperature and initial humidity conditions, and detecting the moisture ratio of the tobacco leaves to be tested in each humidity range; (2) using the moisture ratio of the tobacco leaves to be tested in each humidity range obtained in step (1) as the dependent variable and time as the independent variable for fitting to obtain the moisture diffusion coefficient of the tobacco leaves to be tested in different humidity ranges; (3) selecting the moisture diffusion coefficients of the tobacco leaves to be tested under different humidity ranges obtained in step (2) and calculating the average value as the moisture diffusion coefficient of the tobacco leaves to be tested under the fixed temperature; (4) Repeating steps (1) to (3) at a fixed temperature to obtain the moisture diffusion coefficient of the tobacco leaves to be tested at different temperatures; (5) Fitting the different fixed temperatures in steps (1)-(4) and their corresponding moisture diffusion coefficients of the tobacco leaves to be tested, and calculating the moisture diffusion activation energy of the tobacco leaves to be tested.

2. The method for detecting the activation energy of tobacco leaf moisture diffusion according to claim 1, characterized in that: The initial humidity in step (1) is 58-62%; Preferably, the maximum humidity in step (1) is 78-82%; Preferably, the minimum humidity in step (1) is below 45%.

3. The method for detecting the activation energy of tobacco leaf moisture diffusion according to claim 1 or 2, characterized in that: The specific steps of increasing the humidity to the maximum humidity and then reducing it to the minimum humidity for the equilibrium test in step (1) are to increase the humidity from the initial humidity to the maximum humidity in a fixed step length and then reduce it to the minimum humidity; each time the humidity changes by one step length, it is necessary to wait until the tobacco leaves to be tested are balanced before changing the humidity.

4. The method for detecting the activation energy of tobacco leaf moisture diffusion according to claim 3, characterized in that: The step size is 3-7%.

5. The method for detecting the activation energy of tobacco leaf moisture diffusion according to any one of claims 1 to 4, characterized in that: The fitting in step (2) is performed according to formula I and formula II: In the formula, MR represents the moisture content of the tobacco leaf to be tested, M t represents the moisture content of the tobacco leaf to be tested at time t, M0 represents the moisture content of the tobacco leaf to be tested at the initial time, and M e represents the moisture content of the tobacco leaf under test at equilibrium, L is half the thickness of the tobacco leaf, and D eff represents the effective moisture diffusion coefficient, and t is the moisture diffusion time.

6. The method for detecting the tobacco leaf moisture diffusion activation energy according to any one of claims 1 to 5, characterized in that: The range of the different humidity intervals in step (3) is within 45-60%.

7. The method for detecting the activation energy of tobacco leaf moisture diffusion according to any one of claims 1 to 6, characterized in that: The range of the different fixed temperatures in step (4) is 5-60°C.

8. The method for detecting the activation energy of tobacco leaf moisture diffusion according to any one of claims 1 to 7, characterized in that: The temperature difference between the different fixed temperatures in step (4) is greater than 2°C; Preferably, the fixed temperature is changed at least twice in step (4).

9. The method for detecting the activation energy of tobacco leaf moisture diffusion according to any one of claims 1 to 8, characterized in that: The fitting in step (5) is performed according to formula III: Where T is the fixed temperature, Ln(D eff ) is the natural logarithm of the water diffusion coefficient of the tobacco leaf to be tested at the fixed temperature, D0 is the pre-exponential factor, R is the universal gas constant, E a is the water diffusion activation energy of the tobacco leaf to be tested.

10. Use of the method for detecting tobacco leaf moisture diffusion activation energy according to any one of claims 1 to 9 in tobacco quality control.

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