CN103558115A - Method for measuring content of free water in tobacco and tobacco product - Google Patents

Abstract

The invention discloses a method for measuring the free water content of tobacco and tobacco products. The method establishes a constant temperature drying environment with an absolute humidity of zero by using an SPSx moisture analyzer, so that the free water in the tobacco leaves is continuously exchanged until the quality is constant. The weightlessness of tobacco leaves represents the content of free water in tobacco leaves. This method can not only investigate the volatilization process of free water, but also improve the extraction efficiency of free water, reduce experimental errors, and improve the accuracy and reliability of test results.

Description

A method for measuring free water content of tobacco and tobacco products

technical field

The invention relates to the technical field of tobacco, in particular to a method for measuring the free water content of tobacco and tobacco products.

Background technique

The moisture content of tobacco and tobacco products is one of the important physical and chemical indicators of tobacco. The moisture content of tobacco directly affects the mechanical properties, combustion rate, chemical composition and sensory quality of tobacco leaves. Moisture in tobacco exists in two forms: free water and bound water. Free water, also known as bulk water, is stagnant water, which is not adsorbed by colloidal particles or macromolecules in plant cells, can move freely, and acts as a solvent. Free water and bound water have different characteristics due to their different states of existence, so they play different roles in cells. The different ratios of the two will affect the physical properties of the protoplasm, thereby affecting the intensity of metabolism. The larger the proportion of free water in the total water content, the smaller the viscosity of the protoplasm, and it is in a sol state, and the metabolism is more vigorous. The biological metabolism is strong, and the bound water can be converted into free water, so that the ratio of bound water to free water is reduced. When the metabolism of organisms is slow, free water can be converted into bound water, increasing the ratio of bound water to free water. The more free water, the stronger the metabolism. The more water combined, the stronger the drought resistance.

Most of the water in tobacco cells exists in the form of free water and can flow freely, so it is necessary to determine the free water content in tobacco. However, there are still relatively few methods for measuring the free water content in tobacco, mainly some methods for measuring the total water content. The determination methods of total water content mainly include direct method and indirect method. Direct method includes: thermal drying method, distillation method, Karl Fischer method, microwave method, gas chromatography and vacuum drying method. Indirect method includes differential calorimetry and near Infrared measurement method, etc. The thermal drying method mainly refers to the oven drying method, in which the cut tobacco is dried at a high temperature above 100°C, and the change in the quality of the cut tobacco represents the moisture content in the cut tobacco. The distillation method puts the water-insoluble organic solvent and the sample into the distillation type moisture measuring device to heat, the moisture in the sample is condensed in the condenser tube, and the moisture content of the sample is obtained from the capacity of the moisture. The Karl Fischer method uses water and Karl Fischer reagents to produce redox reactions to determine the water content in samples. The microwave method to measure the moisture content is to use the microwave to pass through the substance containing moisture during the transmission, part of the electromagnetic energy is absorbed by the water molecules, so that the microwave intensity is attenuated.

The vacuum drying method uses a lower temperature to dry and remove moisture under reduced pressure, and the reduced moisture is the moisture content of the sample. Gas chromatography uses an organic solvent to extract the moisture in the sample and separates and quantifies it through a packed column. Differential calorimetry is a technique to measure the relationship between the energy difference and temperature between the sample and the reference substance under programmed temperature control. When the sample contains moisture, an endothermic peak will appear to analyze the moisture content. The near-infrared method to determine moisture is to analyze the moisture content in the sample by establishing a model of moisture under near-infrared. Among the above methods, gas chromatography, microwave method, NIR method, differential calorimetry and Karl Fischer method utilize the physical and chemical properties of water for quantification. In several other determination methods, the moisture is separated from the sample to be tested first, and then the moisture content is obtained by weighing the moisture or the mass of the dry matrix.

The methods for determining the free water content in tobacco mainly include Abbe refractometer method, weighing method and gas chromatography. The Abbe refractometer method is a general method for determining the free water content in plant cells. In this method, the tobacco leaves are soaked in a high-concentration sugar solution to replace the free water in the tobacco leaves. The change in concentration before and after measures the content of free water. The weighing method also soaks the tobacco leaves in a high-concentration sugar solution to replace the free water in the tobacco leaves, then directly weighs the mass of the leaves before and after soaking, and expresses the content of free water by the difference in mass. Gas chromatography extracts the moisture in the sample by selecting a suitable organic solvent and separates and quantifies it through a packed column. Although these methods are commonly used, there are still some problems, such as relatively complicated measurement process, slightly poor repeatability, many factors affecting the extraction efficiency of free water, and large experimental errors.

The patent application number is 201110048801.1 discloses a method for measuring the free water content in tobacco, which uses gas chromatography analysis method to simply and quickly measure the free water content of tobacco samples, and fully wets the tobacco samples through the selection of extractants , the free water in the tobacco sample that can move freely is dissolved in the extractant, and the influence of the volatile components in the tobacco is excluded. The patent application number 201010235301.4 discloses a method for measuring the moisture retention performance of cigarettes and a specific constant temperature and humidity tester. The invention is to put the sample and the weighing device in the constant temperature and humidity box, and through the sealed inner sleeve Type operating gloves to operate samples and weighing instruments, obtain the water retention rate of the samples to be tested under different conditions in different time periods, and then judge the moisture retention performance of cigarettes. However, this method uses sealed inner sleeve type operating gloves, which is inconvenient to operate.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for measuring the free water content of tobacco and tobacco products by using an SPSx moisture analyzer.

This method establishes a constant temperature drying environment with an absolute humidity of zero, so that the free water in the tobacco leaves is continuously exchanged until the quality of the tobacco leaves remains constant, and the free water content of the tobacco leaves is expressed by the difference in the quality of the tobacco leaves. The volatilization process improves the extraction efficiency of free water, reduces experimental errors, and improves the accuracy and reliability of test results.

The present invention adopts following technical scheme:

A method for measuring the free water content of tobacco and tobacco products, the determination steps are as follows:

1) Adjust the humidity of the SPSx moisture analyzer to 0%, and keep the temperature constant;

2) Put the weighing pan containing the sample, and put another same weighing pan as a blank reference pan, and then weigh the tare;

3) Weigh the sample and place it in the weighing pan, and weigh the initial sample mass;

4) Automatically weigh the quality of the sample at regular intervals, and when the quality is constant and reaches equilibrium, the measurement ends;

5) Calculate the change value of mass to obtain the content of free water in the sample.

Further, the temperature range described in step 1) is 5-60°C.

Further, the mass of the sample taken in step 2) is 0.10-1.50 g.

Further, the time interval described in step 4) ranges from 1 to 10 minutes; the minimum time for a single cycle is 120 minutes; the maximum time for a single cycle is 100 hours.

The SPSx moisture analyzer includes an adjustable constant temperature and humidity box, a porous sample rack, a weighing pan and a sample chamber; the porous sample is set up in the constant temperature and humidity box; the weighing pan is placed on the porous sample rack; Controller and humidity controller; the lower cavity of the constant temperature and humidity box is equipped with a built-in high-precision analytical balance, temperature sensor, and automatic sampler; the high-precision analytical balance, temperature sensor, and automatic sampler are connected to the computer to achieve real-time monitor.

Beneficial effects of the present invention:

The invention can realize the online real-time monitoring of the free water content of the sample, reflecting the change process of the free water. The method can be used to measure the free water content of tobacco and tobacco products, and is simple, accurate and convenient to operate.

Description of drawings

Figure 1 is a schematic diagram of the operation of the SPSx moisture analyzer used in the present invention. Among them, 1 constant temperature and humidity chamber, 2 porous sample holder, 3 weighing pan, 4 sample chamber, 5 temperature controller, 6 humidity controller, 7 high-precision analytical balance, 8 temperature sensor, 9 automatic sampler and 10 computer .

Detailed ways

Example 1

Instrument used: SPSx moisture analyzer includes adjustable constant temperature and humidity box 1, porous sample rack 2, weighing pan 3 and sample chamber 4; porous sample rack 2 is set in the constant temperature and humidity box 1; weighing pan 3 is placed On the porous sample rack 2; the sample chamber is provided with a temperature controller 5 and a humidity controller 6; the lower cavity of the constant temperature and humidity box 1 is provided with a built-in high-precision analytical balance 7, a temperature sensor 8, and an automatic sampler 9; High-precision analytical balance 7, temperature sensor 8, and automatic sample injector 9 are connected with computer 10 to realize real-time monitoring.

Take 0.40 g of C ₃ F tobacco leaf sample and place it in the aluminum weighing pan of the SPSx moisture analyzer whose tare weight has been measured. When the temperature of the instrument is set at 20°C and the relative humidity is 0%, the mass is measured every 5 minutes. Wait for the mass change rate to be less than 0.01% for 2 hours, then end the measurement. Based on the initial mass and final mass of the sample, the free water content of the sample was calculated to be 8.026%.

$\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; \%</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

In the formula: W free water moisture content, %

G Weigh the mass of the pan after adding the sample (g);

G ₀ weighing pan mass (g);

G _n final sample and weighing pan mass (g);

For verifying the precision of this new method, measure in parallel 5 times, the result is shown in Table 1, carries out precision analysis to the data in Table 1 and obtains Table 2, and the result shows that the precision of the inventive method is better.

Table 15 parallel determination results

n (number of times) 1 2 3 4 5 Free water content (%) 8.026 8.031 8.013 8.021 8.018

Table 25 parallel determination precision analysis results

average value(%) 8.022 standard deviation(%) 0.007 Coefficient of variation C.V.% 0.087 variance 0.0000487

Example 2

Take 0.50 g of C ₃ F tobacco leaf sample and place it in the aluminum weighing pan of the SPSx moisture analyzer whose tare weight has been measured. When the temperature of the instrument is set at 20°C and the relative humidity is 0%, the mass is measured every 3 minutes. Wait for the mass change rate to be less than 0.01% for 2 hours, then end the measurement. According to the initial mass and final mass of the sample, the free water content of the sample can be calculated to be 8.017%.

Example 3

Take 1.00 g of C ₃ F tobacco leaf sample and place it in the weighing pan of the SPSx moisture analyzer whose tare weight has been measured. The mass change rate is less than 0.01% within 4 hours, and the measurement is terminated. According to the initial mass and final mass of the sample, the free water content of the sample can be calculated to be 8.020%.

Example 4

Take 0.80 g of B ₃ F tobacco leaf sample and place it in the aluminum weighing pan of the SPSx moisture analyzer whose tare weight has been measured. When the temperature of the instrument is set at 10°C and the relative humidity is 0%, the mass is measured every 3 minutes. Wait for the mass change rate to be less than 0.01% within 3 hours, then finish the measurement. According to the initial mass and final mass of the sample, the free water content of the sample can be calculated to be 8.160%.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. All the implementation manners cannot be exhaustively listed here. All obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (4)

1. a method for measuring tobacco and tobacco product free water content, is characterized in that, measuring step is as follows: 1) Adjust the humidity of the SPSx moisture analyzer to 0%, and keep the temperature constant; 2) Put the weighing pan containing the sample, and put another same weighing pan as a blank reference pan, and then weigh the tare; 3) Weigh the sample and place it in the weighing pan, and weigh the initial sample mass; 4) Automatically weigh the quality of the sample at regular intervals, and when the quality is constant and reaches equilibrium, the measurement ends; 5) Calculate the change value of mass to obtain the content of free water in the sample. 2. A method for measuring the free water content of tobacco and tobacco products according to claim 1, characterized in that the temperature range in step 1) is 5-60°C. 3. A method for measuring the free water content of tobacco and tobacco products according to claim 1, characterized in that the mass of the sample taken in step 2) is 0.10-1.50 g. 4. A method for measuring the free water content of tobacco and tobacco products according to claim 1, characterized in that: the time interval range in step 4) is 1-10 minutes; the minimum time for a single cycle is 120 minutes; the maximum The time taken for a single cycle is 100 hours.

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