CN110608968A - Water activity detection device and water activity detection method - Google Patents
Water activity detection device and water activity detection method Download PDFInfo
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- CN110608968A CN110608968A CN201911070135.4A CN201911070135A CN110608968A CN 110608968 A CN110608968 A CN 110608968A CN 201911070135 A CN201911070135 A CN 201911070135A CN 110608968 A CN110608968 A CN 110608968A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 155
- 230000000694 effects Effects 0.000 title claims abstract description 103
- 238000001514 detection method Methods 0.000 title claims abstract description 52
- 238000005303 weighing Methods 0.000 claims abstract description 45
- 241000208125 Nicotiana Species 0.000 claims abstract description 32
- 235000002637 Nicotiana tabacum Nutrition 0.000 claims abstract description 32
- 238000003795 desorption Methods 0.000 claims description 54
- 238000001179 sorption measurement Methods 0.000 claims description 52
- 239000000126 substance Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 30
- 239000000463 material Substances 0.000 description 21
- 238000012360 testing method Methods 0.000 description 8
- 230000001276 controlling effect Effects 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 238000009434 installation Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 4
- 238000002336 sorption--desorption measurement Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000004308 accommodation Effects 0.000 description 2
- 235000019504 cigarettes Nutrition 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 238000003908 quality control method Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 235000019505 tobacco product Nutrition 0.000 description 2
- 239000012491 analyte Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007791 dehumidification Methods 0.000 description 1
- 238000004925 denaturation Methods 0.000 description 1
- 230000036425 denaturation Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000011067 equilibration Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/02—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content
- G01N5/025—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content for determining moisture content
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Pathology (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
The invention discloses a water activity detection device and a water activity detection method, relates to the field of tobacco manufacturing, and is used for detecting the water activity of an object to be detected. The water activity detection device comprises a box body, a bearing part, a weighing component and a parameter control component. The box body comprises an accommodating cavity. The parameter control assembly is used for controlling the humidity and the temperature in the accommodating cavity. The bearing part is arranged in the accommodating cavity and is used for bearing the object to be detected. The weighing component is connected with the bearing part and is used for weighing the object to be detected. According to the technical scheme, the water activity of the object to be detected can be detected, and the quality of the object to be detected is accurately controlled.
Description
Technical Field
The invention relates to the field of tobacco manufacturing, in particular to a water activity detection device and a water activity detection method.
Background
The cut tobacco in the cigarette product is a porous medium consisting of complex organic substances. In the tobacco processing process, the moisture control of tobacco leaves (or cut tobacco) is an important content of processing quality control. The moisture regaining, absorbing and drying and moisture releasing processes of the tobacco directly influence the quality of the product. In addition, cigarette auxiliary materials such as: paper, filter sticks and the like have different performances under different temperature and humidity environments.
The inventor finds that at least the following problems exist in the prior art: in the prior art, whether the tobacco products are deteriorated or not can not be judged in advance, which is not beneficial to controlling the quality of the tobacco products.
Disclosure of Invention
The invention provides a water activity detection device and a water activity detection method, which are used for detecting the water activity of an object to be detected.
The invention provides a water activity detection device, which comprises:
the box body comprises an accommodating cavity;
the bearing part is arranged in the accommodating cavity and is used for bearing the object to be detected;
the weighing component is connected with the bearing part and is used for weighing the object to be detected; and
a parameter control assembly configured to control humidity and temperature within the receiving chamber.
In some embodiments, the water activity detection apparatus further comprises:
and the first controller is electrically connected with the parameter control assembly so as to control the temperature and the humidity inside the accommodating cavity to be constant.
In some embodiments, the water activity detection apparatus further comprises:
and the second controller is electrically connected with the weighing component and is used for acquiring the weight information of the object to be detected, which is acquired by the weighing component.
In some embodiments, the minimum scale of the weighing assembly is one thousandth of the maximum weighing capacity.
In some embodiments, the case further comprises:
the installation cavity is hermetically isolated from the containing cavity, and the weighing component is installed in the installation cavity and supports the bearing part through a supporting piece.
In some embodiments, the parameter control assembly comprises:
the temperature control assembly is arranged in the accommodating cavity and is used for controlling the temperature in the accommodating cavity; and
and the humidity control assembly is arranged in the accommodating cavity and is used for controlling the humidity in the accommodating cavity.
In some embodiments, the water activity detection apparatus further comprises:
and the calculating component is electrically connected with the parameter control component and the weighing component and is used for calculating the initial water activity of the object to be detected according to the humidity set by the parameter control component and the weight information of the object to be detected, which is acquired by the weighing component.
In some embodiments, the analyte to be detected comprises at least one of: tobacco shreds, cut stems and expanded tobacco shreds.
The embodiment of the invention also provides a water activity detection method, which is realized by adopting the water activity detection device provided by any technical scheme of the invention, and the method comprises the following steps:
setting the temperature and humidity in the accommodating cavity;
placing an object to be detected in the accommodating cavity;
periodically collecting the weight of the object to be detected;
when the variation of the weight of the object to be detected in a set time is less than a, calculating the equilibrium water content of the object to be detected according to the humidity in the accommodating cavity and the adsorption and desorption characteristic curve of the object to be detected;
calculating the initial water content of the object to be detected according to the equilibrium water content of the object to be detected;
and calculating the initial humidity of the object to be detected according to the initial water content of the object to be detected, so as to obtain the initial water activity of the object to be detected.
In some embodiments, the set time comprises at least five acquisition cycles.
In some embodiments, a is less than or equal to one-thousandth of the maximum weighing capacity of the weighing assembly.
In some embodiments, the calculating the equilibrium water content of the object to be detected according to the humidity in the accommodating cavity and the adsorption and desorption characteristic curve of the object to be detected includes:
if the collected weight of the object to be detected is gradually reduced, calculating the equilibrium moisture content of the object to be detected according to the humidity in the accommodating cavity and the desorption characteristic curve of the object to be detected; and if the collected weight of the object to be detected is gradually increased, calculating the equilibrium moisture content of the object to be detected according to the humidity in the accommodating cavity and the adsorption characteristic curve of the object to be detected.
In some embodiments, the initial water content of the to-be-detected object is calculated according to the equilibrium water content of the to-be-detected object by using the following formula:
H1＝1-G2(1-H2)/G1
wherein H1The initial water content of the object to be detected is obtained; h2The water content of the object to be detected in the equilibrium state is determined; g1The initial weight of the object to be detected; g2Is the initial weight of the object to be detected.
The water activity detection device that above-mentioned technical scheme provided through setting up the box that can control temperature and humidity, realizes waiting to detect the thing and balance in the holding intracavity. Because the temperature and the humidity in the accommodating cavity are preset, the numerical value of the temperature and the humidity can be accurately known, and the humidity of the object to be detected when the object to be detected reaches the equilibrium state can be known. The object to be detected can adsorb, desorb the phenomenon in the holding intracavity equilibrium process, so the weight of the object to be detected can change. The moisture content of the object to be detected in the original state can be obtained by collecting the weight change of the object to be detected. The initial humidity of the object to be detected can be obtained through the adsorption and desorption curve of the object to be detected. Since the humidity is the same as the water activity in the equilibrium state, the initial water activity of the sample is obtained. According to the obtained initial water activity, the water activity of the object to be detected in the initial state can be obtained, and whether the quality of the object to be detected can be guaranteed in the subsequent storage, processing and manufacturing operation processes of the object to be detected is judged. Therefore, the water activity detection device provided by the technical scheme provides guarantee for accurately controlling the quality of the object to be detected.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a schematic structural diagram of a water activity detection apparatus according to some embodiments of the present invention;
FIG. 2 is a schematic flow chart of a water activity detection method according to another embodiment of the present invention;
FIG. 3 is a schematic flow chart of a method for detecting water activity of cut tobacco according to another embodiment of the present invention;
fig. 4 is a schematic diagram of an adsorption and desorption characteristic curve of cut tobacco according to another embodiment of the present invention.
Detailed Description
The technical solution provided by the present invention is explained in more detail with reference to fig. 1 to 4.
The names or terms used herein are explained as follows.
The isothermal adsorption and desorption performance reflects the adsorption and desorption amount of the material to the water under the specified temperature condition. The isothermal adsorption and desorption performance of the material can be used for quickly, simply and accurately testing and evaluating the moisture adsorption and desorption performance of the tobacco flakes or the tobacco shreds.
Water Activity (Water Activity) refers to the state of presence of Water in the system, i.e., the degree of binding (degree of freedom) of Water. The water activity is a measure of the energy of the water in the system, the higher the water activity value is, the lower the degree of binding is; the lower the water activity value, the higher the degree of binding. The water activity is equal to the humidity at which the material is in equilibrium under certain circumstances. The equilibrium state means a humidity at which the material is in a constant temperature and humidity environment and neither adsorption nor desorption occurs.
The water activity Aw refers to: the ratio of the water vapor pressure P displayed by the material at a certain temperature to the pure water vapor pressure Po at the same temperature is: aw is P/Po.
In the tobacco field, most denaturation reactions are difficult to occur if the water activity of the material is below 0.65. Therefore, the water activity of the tobacco can be controlled to increase quality control of the tobacco material.
Referring to fig. 1, an embodiment of the present invention provides a water activity detection apparatus, which includes a box 1, a bearing portion 2, a weighing component 3, and a parameter control component (not shown). The case 1 includes an accommodating chamber 11. The parameter control assembly is used for controlling the humidity and temperature in the accommodating chamber 11. The bearing part 2 is arranged in the accommodating cavity 11 and is used for bearing an object to be detected. The weighing component 3 is connected with the bearing part 2 and is used for weighing the object to be detected.
The containing cavity 11 of the box body 1 is closed, and in the process of testing by using the water activity detection device, the containing cavity 11 does not freely circulate gas with the external environment. The temperature and humidity control in the accommodating cavity 11 is realized by a parameter control assembly.
The size, shape and the like of the accommodating cavity 11 of the box body 1 are determined by test requirements, and the volume of the accommodating cavity 11 is large if more materials need to be tested; otherwise, it is smaller.
The material and structure of the box body 1 are suitable for meeting the requirement, and fig. 1 shows some optional structures.
The bearing part 2 is used for bearing the material to be detected which needs to be adjusted. The carrier 2 is, for example, a tray. And placing the object to be detected in a tray, and calculating the water content of the material to be detected by weighing the weight change of the material to be detected in a regulating and controlling process in real time.
In the tobacco field, the object to be detected is, for example, cut tobacco, cut stems, expanded cut tobacco, and the like. It is understood that the object to be detected may also be a material in the food field.
The parameter control assembly is used for controlling the temperature and humidity in the accommodating chamber 11.
The mode of realizing temperature control has the multiple, for example through setting up the heater block, realizes the heating to the interior air of holding chamber 11 to realize that the temperature is unchangeable all the time in the holding chamber 11, constant temperature promptly. In order to obtain temperature information in the accommodating chamber 11 in real time, a temperature sensor may be provided. According to the data collected by the temperature sensor, the temperature of the accommodating cavity 11 is controlled in real time so as to reach a constant temperature.
The humidity control can be realized in various ways, for example, by arranging a dehumidifying and humidifying component, the humidity in the accommodating chamber 11 can be dehumidified and humidified, so that the humidity in the accommodating chamber 11 is always constant, namely constant humidity. In order to obtain humidity information in the accommodating chamber 11 in real time, a humidity sensor may be provided. According to the data collected by the humidity sensor, the humidity of the accommodating cavity 11 is controlled in real time so as to achieve constant humidity.
In tobacco processing, the water activity of the material cannot be directly obtained. The water activity detection device can be used. Specifically, sampling the whole batch of materials to be detected, then putting the samples into the water activity detection device, carrying out test monitoring, and obtaining the initial water activity of the sampled samples through calculation, so as to obtain the water activity of the whole batch of samples. According to the water activity of the whole batch of samples, the control on the material performance can be realized in a targeted manner subsequently.
Foretell water activity detection device, owing to have the parameter control subassembly, the environment in the holding chamber 11 is constant temperature and humidity, waits to detect the thing and places back in this holding chamber 11, along with self absorption or desorption moisture go on, finally can reach the humidity that detects the thing and the same state of humidity in the holding chamber 11, equilibrium state promptly. According to the humidity parameter of the balance state, the weight information of the object to be detected collected by the weighing component 3 and the adsorption characteristic curve of the object to be detected are calculated to obtain the water activity of the object to be detected when the object to be detected is initially placed into the accommodating cavity 11, namely the initial water activity, so that the detection of the water activity of the sample is completed.
In some embodiments, the water activity detection apparatus further comprises a first controller 6, and the first controller 6 is electrically connected to the parameter control component to control the temperature and humidity inside the accommodating chamber 11 to be constant, i.e. the inside of the accommodating chamber 11 is constant temperature and constant humidity.
In light of the above, the parameter control assembly, for example, adopts a heating component to realize constant temperature of the accommodating chamber 11, and adopts a dehumidifying and humidifying component to realize constant humidity of the accommodating chamber 11. The first controller 6 controls parameters such as heating time and heating temperature of the heating member. Meanwhile, the first controller 6 controls the working time of the dehumidifying and humidifying part and the moisture content of the dehumidification and humidification.
Specifically, a plurality of first controllers 6 may be provided to control the heating unit and the dehumidifying and humidifying unit, respectively. Or a first controller 6 is adopted to simultaneously control the working state and the working time of the heating component and the dehumidifying and humidifying component.
The first controller 6 is, for example, a PLC programmable controller, or other controller.
In some embodiments, the water activity detection apparatus further comprises a second controller 7. The second controller 7 is electrically connected with the weighing component 3 and is used for acquiring the weight information of the object to be detected acquired by the weighing component 3.
The first controller 6 and the second controller 7 are integrated, for example, or each employs a separate controller. In fig. 1, the first controller 6 and the second controller 7 are integrated and are the same controller.
The second controller 7 is mainly used for acquiring the weight of the object to be detected weighed by the weighing component 3. Before the object to be detected is placed in the accommodating cavity 11, the water activity of the object to be detected is balanced under the environment of the object to be detected, and the state is called as an initial state. After being placed in the accommodating cavity 11, the object to be detected can be adsorbed or desorbed until a new equilibrium state is reached, which is called an equilibrium state.
If the object to be detected is adsorbed in the accommodating cavity 11, the weight is gradually increased. If the object to be detected is desorbed in the accommodating cavity 11, the weight is gradually reduced.
In the process that the object to be detected reaches the equilibrium state, due to the absorption and desorption phenomena, the moisture in the object to be detected can be increased or reduced, namely the weight of the object to be detected can be changed. By judging the change trend of the weight, whether the object to be detected is in the adsorption or desorption phenomenon can be judged. If the adsorption process is adopted, the adsorption characteristic curve is adopted to carry out relevant subsequent calculation; if the desorption process is adopted, the desorption characteristic curve is adopted to carry out relevant subsequent calculation.
In some embodiments, the measurement accuracy of the weighing assembly is determined by the maximum weighing capacity, and the minimum scale of the weighing assembly 3 is one thousandth of the maximum weighing capacity.
The weighing component adopts the tray to bear the object to be detected, so that the weighing component 3 is very compact in structure, the occupied space of the accommodating cavity 11 is small, the object to be detected can be spread in the accommodating cavity 11 as much as possible, and a sufficient space is provided for the phenomenon of adsorption and desorption of the object to be detected.
Referring to fig. 1, in some embodiments, the box body 1 further includes a mounting cavity 12, the mounting cavity 12 is hermetically isolated from the accommodating cavity 11, the weighing assembly 3 is mounted inside the mounting cavity 12, and the bearing part 2 is supported by the support 4.
The installation cavity 12 and the accommodating cavity 11 are two airtight isolated cavities, and the temperature and humidity adjustment in the accommodating cavity 11 does not affect the temperature and humidity change in the installation cavity 12.
As shown in fig. 1, the installation cavity 12 is located below the accommodation cavity 11, and the installation cavity and the accommodation cavity are separated by a partition plate, and the partition plate is provided with a through hole. The supporting piece 4 is arranged in the through hole, and one end of the supporting piece extends into the accommodating cavity 11 and is connected with the bearing part 2; the other end is located in the mounting cavity 12 and is connected to the carrier assembly.
In some embodiments, the water activity detection apparatus further includes a calculation component 5, the calculation component 5 is electrically connected to both the parameter control component and the weighing component 3, and the calculation component 5 is configured to calculate the initial water activity of the object to be detected according to the humidity set by the parameter control component and the weight information of the object to be detected collected by the weighing component 3.
The specific calculation process is as follows:
firstly, according to the temperature and humidity in the accommodating cavity 11 set by the parameter control assembly, the humidity of the object to be detected when the object to be detected reaches the equilibrium state in the accommodating cavity 11 is obtained.
Secondly, according to the weight change trend of the object to be detected, whether the object to be detected is in the adsorption process or the desorption process in the accommodating cavity 11 is judged. If the weight of the object to be detected is gradually increased, the adsorption process is performed; if the weight of the object to be detected is gradually reduced, the desorption process is performed.
And then, calculating the water content of the object to be detected when the object to be detected reaches the equilibrium state according to the humidity of the object to be detected when the object to be detected reaches the equilibrium state and the adsorption and desorption characteristic curve. Specifically, if the object to be detected is in the adsorption process in the accommodating cavity 11, the moisture content of the object to be detected in the equilibrium state is calculated according to the humidity and the adsorption characteristic curve of the object to be detected in the equilibrium state. If the object to be detected is in the desorption process in the accommodating cavity 11, the moisture content of the object to be detected in the equilibrium state is calculated according to the humidity of the object to be detected in the equilibrium state and the desorption characteristic curve of the object to be detected, and the moisture content is also called as the equilibrium moisture content.
And then, calculating the initial water content of the object to be detected in the initial state by adopting a formula (1) according to the water content of the object to be detected in the equilibrium state and the characteristic that the weight of the solid is not changed before and after the adsorption and desorption of the object to be detected.
The specific formula (1) is as follows:
H1＝1-G2(1-H2)/G1
wherein H1The initial water content of the object to be detected; h2The water content of the object to be detected in the equilibrium state is shown; g1Is the initial weight of the object to be detected; g2Is the initial weight of the object to be detected.
And then, calculating to obtain the initial humidity of the object to be detected according to the initial water content of the object to be detected obtained through calculation and the adsorption and desorption curve of the object to be detected. If the object to be detected is in the adsorption process in the accommodating cavity 11, the initial moisture content of the object to be detected and the adsorption curve of the object to be detected are calculated to obtain the initial humidity of the object to be detected. If the object to be detected is in the desorption process in the accommodating cavity 11, the initial moisture content of the object to be detected and the desorption curve of the object to be detected are calculated to obtain the initial humidity of the object to be detected.
And finally, calculating the initial water content of the object to be detected. The initial water content of the object to be detected is equal to the initial humidity of the object to be detected.
And finishing the measurement of the initial water content of the object to be detected.
Another embodiment of the present invention provides a water activity detection method, which is implemented by using the water activity detection device provided in any one of the technical solutions of the present invention. For a detailed description of the water activity detection device, see above, it is not described herein.
The method comprises the following steps:
step S10, setting the temperature and humidity in the accommodating chamber 11.
The humidity in the accommodating cavity 11 is the humidity in the accommodating cavity 11, and the temperature in the accommodating cavity 11 is the humidity in the accommodating cavity 11. For example, the temperature and humidity in the accommodating chamber 11 are set by the parameter control assembly, so as to realize constant temperature and constant humidity in the accommodating chamber 11.
In the process of testing the object to be detected in the accommodating cavity 11, the accommodating cavity 11 is in a closed state and is not opened. In the whole test process, the temperature and the humidity of the accommodating cavity 11 depend on set parameters, and the gas in the accommodating cavity 11 is not exchanged with the external environment.
Step S20, placing the object to be detected inside the accommodating cavity 11.
The above steps S10 and S20 do not limit the sequence, and the temperature and humidity in the accommodating chamber 11 may be set first, and then the object to be detected is placed in the accommodating chamber 11; or vice versa. The technical solution of the embodiment of the present invention is not limited to this.
And step S30, periodically collecting the weight of the object to be detected.
The period for acquiring data can be set as required, if the whole adsorption and desorption time is A hours, the A hours are divided into 100 parts for example, and the A hours are acquired every A/100 time length.
Step S40, when the variation of the weight of the object to be detected in the set time is smaller than a, calculating the equilibrium moisture content of the object to be detected according to the humidity in the accommodating cavity 11 and the adsorption and desorption characteristic curve of the object to be detected.
In the above-described step S40, the set time includes at least five acquisition cycles.
Specifically, if the data are collected 5 times in a row, but the maximum difference between the five data is less than a, the mass of the object to be detected is determined to be substantially unchanged. Namely, the object to be detected reaches the equilibrium state in the accommodating cavity 11.
The value of a is related to the measurement accuracy. In step S40, a is 0.0001g or less.
The adsorption and desorption characteristic curve of the object to be detected comprises an adsorption characteristic curve and a desorption characteristic curve. Both the adsorption characteristic curve and the desorption characteristic curve satisfy the following formula (2), but constants are different.
y＝f(T℃,x)＝ax3-bx2+cx+d (2)
Wherein, y is the water content of the object to be detected, and x is the relative humidity of the object to be detected.
And if the collected weight of the object to be detected is gradually reduced, calculating the equilibrium water content of the object to be detected according to the humidity in the accommodating cavity and the desorption characteristic curve formula (1) of the object to be detected. If the object to be detected is in the adsorption process in the accommodating cavity 11, namely the weight of the object to be detected is heavier and heavier, the adsorption characteristic curve is adopted, and the equilibrium water content of the object to be detected is calculated.
And if the weight of the collected object to be detected is gradually increased, calculating the equilibrium water content of the object to be detected according to the humidity in the accommodating cavity and the adsorption characteristic curve formula (1) of the object to be detected. If the object to be detected is in the desorption process in the accommodating cavity 11, namely the weight of the object to be detected is lighter and lighter, the desorption characteristic curve is adopted, and the equilibrium water content of the object to be detected is calculated.
The adsorption characteristic curve and the desorption characteristic curve of the object to be detected are embedded in the calculation component 5, and the calculation component 5 adopts a PC computer for example. The calculation component 5 automatically judges whether the object to be detected is in the adsorption or desorption process according to a built-in command and the collected weight data of the object to be detected, and then calls one of the corresponding adsorption and desorption characteristic curves to calculate.
And step S50, calculating the initial water content of the object to be detected according to the equilibrium water content of the object to be detected.
The object to be detected includes a solid substance and moisture. Whether the material to be detected is adsorbed or desorbed or not is determined, and the weight of the solid in the material to be detected is unchanged in an initial state and an equilibrium state.
Specifically, the initial water content of the sample can be calculated by the following formula (1):
H1＝1-G2(1-H2)/G1
wherein H1The initial water content of the object to be detected; h2The water content of the object to be detected in the equilibrium state is shown; g1Is the initial weight of the object to be detected; g2Is the initial weight of the object to be detected.
And step S60, calculating the initial humidity of the object to be detected according to the initial water content of the object to be detected, so as to obtain the initial water activity of the object to be detected.
Because moisture content and humidity satisfy the adsorption and desorption characteristic curve, so according to the initial moisture content of waiting to detect the thing to and wait to detect the thing and be in the absorption or desorption process in holding chamber 11, can call corresponding adsorption/desorption characteristic curve, with the initial humidity that obtains waiting to detect the thing. The initial humidity of the test object is equal to the initial water activity of the test object. Thus, the initial water activity of the substance to be detected is obtained.
According to the initial water activity of the object to be detected, the initial water activity of the batch of materials in which the object to be detected is located can be known. According to the initial water activity of the whole batch of materials, the tobacco bale can be controlled and processed in a targeted manner subsequently, so that the quality of the finally obtained tobacco bale product is improved.
Some specific embodiments are described below.
1. The temperature and the relative humidity in the accommodating cavity 11 of the water activity detection device are set, the weight change of the object to be detected is monitored in real time, and the weight information of the object to be detected in the adsorption and desorption processes is collected.
Specifically, the object to be detected is placed in the accommodating cavity 11 of the water activity detection device, and the temperature and the relative humidity of the device are set according to the water activity value of the sample at a certain temperature. For example, if the water activity of the substance to be detected reaches 0.4 at 26 ℃, the temperature and relative humidity of the accommodating chamber 11 are set at 26 ℃ and 40%.
The water activity detection device comprises a weighing component 3, wherein the weighing component 3 detects the weight change of an object to be detected in real time and collects weight data.
2. The isothermal adsorption and desorption curve of the object to be detected is obtained, isothermal adsorption and desorption characteristic formulas of the object to be detected are established, and the characteristic formulas are stored to the calculation component 5 to serve as a water activity control database to be detected. If the objects to be detected are various, such as cut tobacco, cut stems and expanded cut tobacco, respective isothermal adsorption and desorption curves and isothermal adsorption and desorption characteristic formulas are respectively established.
3. And placing the object to be detected into the accommodating cavity 11 of the water activity detection device, selecting the type of the object to be detected in the computer, and selecting a corresponding isothermal adsorption and desorption characteristic equation from the water activity control database by the computer for subsequent calculation.
The weighing component 3 of the water activity detection device detects and records the weight of the object to be detected in real time. And the computer judges whether the state change of the sample belongs to an adsorption process or a desorption process according to the weight change of the object to be detected.
According to the judgment, the computer automatically selects the adsorption characteristic control mode or the desorption characteristic control mode of the sample.
When the change of the sample is less than a certain range (i.e., a described above) within a certain time, the computer judges that the water activity of the sample has reached the preset value.
Computer communicationInitial weight G of the sample1And the weight of the sample after equilibration G2And obtaining the weight change value of the sample. According to the adsorption characteristic model or the desorption characteristic model, the water content value H of the sample in the equilibrium state can be known2. The initial water content H of the sample can be obtained by calculating the following formula (1)1And the initial water activity value of the sample.
H1＝1-G2(1-H2)/G1 (1)
Wherein H1The initial water content of the object to be detected; h2The water content of the object to be detected in the equilibrium state is shown; g1Is the initial weight of the object to be detected; g2Is the initial weight of the object to be detected.
And obtaining the initial water activity of the sample according to the initial water content of the sample obtained by calculation and the adsorption characteristic model or the desorption characteristic model.
Some specific embodiments are described below.
The water activity of a certain grade of finished cut tobacco is regulated to 0.55, firstly, an isothermal adsorption characteristic curve formula (3) and an isothermal desorption characteristic curve formula (4) of the cut tobacco are obtained by fitting an isothermal adsorption desorption curve of the grade of cut tobacco at 26 ℃:
y1＝f(26℃,x)＝88.846x3-58.581x2+17.649x+2.0418
y1‘＝f(26℃,x)＝82.948x3-52.588x2+18.825x+1.4427
wherein y1 and y 1' are the moisture content of the cut tobacco, and x is the relative humidity of the cut tobacco. The isothermal adsorption characteristic curve formula (3) and the isothermal desorption characteristic curve formula (4) of the tobacco shreds both satisfy the structure of the formula (2).
First, the fitting equations (3) and (4) and the equation (1) described above are imported into computer software.
Then, the object to be detected is placed in a sample tray of the water activity adjusting device, the temperature in the accommodating cavity 11 is set to be 26 ℃, and the relative humidity in the accommodating cavity 11 is set to be 55%.
The water activity adjusting device starts to work, the balance transmits weight data to the computer through the data collector, and computer software records the initial weight and the real-time weight.
And judging that the sample is in an adsorption/desorption state according to the weight change (increase or decrease), and calling a corresponding equation. And (3) setting a judgment condition of weight balance in computer software, judging that the sample reaches balance and reaches a preset water activity value if the weight change is less than +/-1 mg within a certain time.
Next, the calculation component 5 calculates an initial moisture value and an initial water activity according to the initial weight, the equilibrium time moisture content obtained by the adsorption/desorption equation, and the initial moisture content calculation formula.
According to the technical scheme, the water activity adjusting device adjusts the temperature and the humidity of the set environment and detects the weight change of the sample in real time according to the temperature and humidity balance principle, combines the isothermal adsorption and desorption characteristics of the sample, obtains the initial water content and the water activity of the sample through scientific calculation, adjusts the sample to the target water activity, and calculates the water content under the target water activity.
In the description of the present invention, it is to be understood that the terms "central", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the scope of the present invention.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some of the technical features thereof, but such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (13)
1. A water activity detection device, comprising:
the box body (1) comprises an accommodating cavity (11);
the bearing part (2) is arranged in the accommodating cavity (11) and is used for bearing the object to be detected;
the weighing component (3) is connected with the bearing part (2) and is used for weighing the object to be detected; and
a parameter control assembly configured to control humidity and temperature within the housing chamber (11).
2. The water activity detection apparatus according to claim 1, further comprising:
a first controller (6) electrically connected with the parameter control assembly to control the temperature and humidity inside the accommodating chamber (11) to be constant.
3. The water activity detection apparatus according to claim 1, further comprising:
and the second controller (7) is electrically connected with the weighing component (3) and is used for acquiring the weight information of the object to be detected, which is acquired by the weighing component (3).
4. A water activity detection device according to claim 1, wherein the smallest scale of the weighing assembly (3) is one thousandth of the maximum weighing capacity.
5. The water activity detection apparatus according to claim 1, wherein the tank (1) further comprises:
a mounting chamber (12) hermetically isolated from the housing chamber (11); the weighing component (3) is arranged in the mounting cavity (12) and supports the bearing part (2) through a support part (4).
6. The water activity detection apparatus according to claim 5, wherein the parameter control assembly comprises:
the temperature control assembly is arranged in the accommodating cavity (11) and is used for controlling the temperature in the accommodating cavity (11); and
and the humidity control assembly is arranged in the accommodating cavity (11) and is used for controlling the humidity in the accommodating cavity (11).
7. The water activity detection apparatus according to claim 1, further comprising:
and the calculating component (5) is electrically connected with the parameter control component and the weighing component (3), and the calculating component (5) is used for calculating the initial water activity of the object to be detected according to the humidity set by the parameter control component and the weight information of the object to be detected, which is acquired by the weighing component (3).
8. The water activity detection apparatus according to claim 1, wherein the substance to be detected comprises at least one of: tobacco shreds, cut stems and expanded tobacco shreds.
9. A water activity detection method, which is realized by the water activity detection device of any one of claims 1 to 8, and comprises the following steps:
setting the temperature and humidity in the accommodating cavity;
placing an object to be detected in the accommodating cavity;
periodically collecting the weight of the object to be detected;
when the variation of the weight of the object to be detected in a set time is less than a, calculating the equilibrium water content of the object to be detected according to the humidity in the accommodating cavity and the adsorption and desorption characteristic curve of the object to be detected;
calculating the initial water content of the object to be detected according to the equilibrium water content of the object to be detected;
and calculating the initial humidity of the object to be detected according to the initial water content of the object to be detected, so as to obtain the initial water activity of the object to be detected.
10. The water activity detection method according to claim 9, wherein the set time comprises at least five collection cycles.
11. The water activity detection method according to claim 9, wherein a is less than or equal to one thousandth of the maximum weighing capacity of the weighing assembly.
12. The water activity detection method according to claim 9, wherein the calculating of the equilibrium water content of the substance to be detected according to the humidity in the accommodating chamber and the adsorption and desorption characteristic curve of the substance to be detected comprises:
if the collected weight of the object to be detected is gradually reduced, calculating the equilibrium moisture content of the object to be detected according to the humidity in the accommodating cavity and the desorption characteristic curve of the object to be detected; and if the collected weight of the object to be detected is gradually increased, calculating the equilibrium moisture content of the object to be detected according to the humidity in the accommodating cavity and the adsorption characteristic curve of the object to be detected.
13. The water activity detection method according to claim 9, wherein the initial water content of the substance to be detected is calculated from the equilibrium water content of the substance to be detected by using the following formula:
H1＝1-G2(1-H2)/G1
wherein H1The initial water content of the object to be detected is obtained; h2The water content of the object to be detected in the equilibrium state is determined; g1The initial weight of the object to be detected; g2Is the initial weight of the object to be detected.
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| CN114428029A (en) * | 2022-01-14 | 2022-05-03 | 南京师范大学 | Method and device for measuring liquid moisture absorption capacity |
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