The difference between rapid moisture measurement and oven moisture measurement is compared. The results show that, under the same temperature condition, the rapid moisture determination method increases the moisture content of the tobacco leaf samples with the increase of the baking time. The comprehensive temperature test and. In the time test, the rapid moisture measurement method has a measurement temperature of 106 ° C and a measurement time of 7 minutes, which is close to the measurement value of the oven moisture measurement method.
[Key words] moisture content; fast method; oven method
The moisture content of tobacco leaves is a very important process parameter in the process of leaf-throwing and re-curing. It directly affects the separation effect of stem leaves and the quality of leaf-throwing. At the same time. The moisture content of tobacco leaves is also directly related to the storage quality of the finished tobacco leaves after re-curing. Because the tobacco leaf samples adopt different moisture content detection methods, the detection results are different, so the choice of moisture content inspection method directly affects the tobacco leaf moisture content during the processing. At present, there are two main methods for tobacco leaf re-curing enterprises to determine the moisture content of tobacco leaves, one is the moisture content inspection method prescribed in the national tobacco industry standard-the oven method, and the other is the rapid moisture measurement method, these two This test was conducted for any differences in the actual measurement results of the method.
1 Test materials and methods
The test tobacco variety is k326, and the tobacco leaf grade is middle orange three. The test method uses the oven method and the rapid determination method for comparison.
(1) Temperature test: The measurement time of the fixed rapid determination method is 7 minutes, and it is compared with the standard oven method after being treated with 6 different temperatures. The data of each experiment is shown in Table 1.
(2) Time test: The measurement temperature of the fixed rapid determination method is 106 ° C, 3min, 4min,…, 9min. There are 7 different treatment times compared with the standard oven method (take three samples). The experimental data is shown in Table 2.
2 Analysis and determination
(1) Oven method
During the inspection, first turn on the power of the oven, set the temperature at 100 ℃, start preheating, and wait for the temperature to rise to 100 ℃ and stabilize before testing. The specific steps of the detection are: Weigh 5 ~ 10g of the crushed sample with a sample box of known dry mass, record the weight of the weighed sample, put it in the oven, the sample box must be placed evenly, when the oven temperature rises to 100 ℃ Start timing, bake the sample for 2h, take the sample into the desiccator and equilibrate it for 15min to room temperature, weigh and record the result, and then calculate the water content by substituting the formula. The formula for calculating the water content is:
(2) Quick method
Turn on the power of the moisture analyzer. When the display shows 0,000, open the instrument cover. 1. Open the right door of the instrument and adjust the instrument parameters. The setting of each parameter is as follows. The temperature is 105 ℃, and the judgment time is 40 seconds.
2. Tare the sample tray and add about 2-3g of sample.
3. Press the "↑" key and then the test key to start the moisture determination process.
4. The results show the moisture content of tobacco leaves.
2. Tare the sample tray and add about 2-3g of sample.
3. Press the "↑" key and then the test key to start the moisture determination process.
4. The results show the moisture content of tobacco leaves.
3 Results and analysis
(1) The effect of the same measurement time and different measurement temperatures on the moisture content of tobacco leaves
It can be seen from Table 1 and Figure 1 that with the same measurement time and different temperature treatments, as the temperature increases, the measurement value of the fast method also increases, with a measurement time of 7min and a measurement temperature of 106 ° C: closer to the oven law. If the temperature is increased, the measured value will exceed the oven method, which may be caused by the evaporation of other substances. The samples with different water contents in Figure 1 show similar patterns.
(2) The effect of the same measurement temperature and different measurement time on the moisture content of tobacco leaves
As can be seen from Table 2 and Figure 2, the same measurement temperature and different time processing, as the time increases, the value measured by the fast method also increases, with the measurement temperature of 106 ℃, the measurement time of 7min is close to the oven method . After 7 minutes, the water content changes slowly, and the change is less than 0.1% / min, which has little effect on the results. Therefore, in the production practice, in order to save time, the measured temperature is 106 ° C and the measured time is 7min to represent the moisture content of the measured sample. The production workshop can adjust the process parameters in time according to the change of the measured moisture content to ensure the product quality. The samples with different water contents in Fig. 2 showed a similar pattern.
4 Conclusion and discussion
In the process of tobacco re-curing process, in order to achieve the ideal leafing effect, each process parameter must be optimized, and the moisture content of the tobacco leaf is one of the key factors, so it must be fast, accurate, convenient, simple, and can save a lot Human and material detection methods quickly feedback the measured moisture of tobacco leaves to the production workshop to guide production. The rapid method takes advantage of its rapid heating of the heat source to detect quickly and save time. Therefore, it is used in the moisture detection process of re-cured tobacco leaves. It plays an irreplaceable role in the rapid determination of the moisture content of re-cured tobacco leaves.
After experimental research, it was shown that the rapid method should set the corresponding measurement parameters according to different tobacco leaves in the process of detecting the moisture of tobacco leaves. Under the same temperature condition, with the extension of the baking time, the measured moisture content of the tobacco leaves increased, at the measurement temperature of 106 ℃, the measured value of 7min is close to the oven method. At the same baking time, with the increase of the baking temperature, the moisture content of tobacco leaves increased. When the measurement time was 7 min, the measured value at 106 ° C was close to the value of the oven method. If the temperature is increased, the measured value will exceed the value of the oven method, which may be caused by the evaporation of other substances.
There are many reasons for errors in the moisture detection process. There are environmental errors, such as errors caused by the time exposed to space and the influence of environmental humidity; there are errors caused by instruments and equipment, such as errors of dryers, aluminum boxes, and drying boxes; and errors of detection methods. When using different detection methods, in order to reduce the error as much as possible, the oven method should be used for calibration, and the oven method should be used as the benchmark to adjust the baking time and temperature in time to ensure the accuracy of the results of the rapid method. The adjustment of process parameters provides a basis to ensure the quality of products.
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