An efficient water activity testing device

Abstract

The present invention discloses an efficient water activity testing device, which includes a temperature and humidity sensor, and also includes a box body and a box cover. A separated sample accommodating cavity and a sensor accommodating cavity are arranged on the upper end surface of the box body. A first annular groove is arranged on the upper end surface of the box body. The sample accommodating cavity and the sensor accommodating cavity are both located in the first annular groove. A first sealing ring is arranged in the first annular groove. The box cover and the box body are connected by a plurality of bolts. After tightening the bolts, the first sealing ring is pressed, and there is a certain gap between the box body and the box cover. The temperature and humidity sensor is arranged at the position of the box cover corresponding to the sensor accommodating cavity, and a sealing structure is arranged between the temperature and humidity sensor and the box cover. In the present invention, the sample accommodating cavity and the sensor accommodating cavity are separately arranged, effectively reducing the headspace, thus shortening the time for the sample to be measured to reach equilibrium with the headspace, improving the testing efficiency and shortening the testing time.

Description

Technical Field

[0001] The present invention belongs to the technical field of water activity testing, and particularly relates to an efficient water activity testing device. Background Art

[0002] Water activity is the ratio of the vapor pressure of water in a sample at a specific temperature to the saturated vapor pressure of pure water at the same temperature. The regulation of water activity is achieved by controlling the interaction between water molecules in food and other food components. Water activity has a wide range of applications in fields such as food shelf life prediction, control of foodborne pathogenic bacteria, and battery research and development.

[0003] Currently, the most mainstream testing method is the headspace relative humidity measurement method. This method indirectly calculates the water activity value at a given temperature by measuring the temperature and relative humidity in the headspace where the sensor is located after reaching equilibrium (equilibrium means that the vapor pressure in the sample and the headspace reaches equilibrium).

[0004] The water activity testing device used in this method during measurement is as Figure 1 shown. The high-precision sensor used in this kind of water activity testing device has a relatively large inherent volume, resulting in a large headspace volume. The larger the headspace volume, the longer the time required for the sample and the headspace to reach equilibrium. Therefore, the large headspace volume leads to a long testing time for the relevant testing device. In addition, after the sample and the headspace reach equilibrium, there is a large difference between the original vapor pressure of the sample and the vapor pressure of the sample after equilibrium, resulting in a relatively low testing accuracy of the headspace relative humidity measurement method.

[0005] The difference in water activity at different temperatures is very large. A slight change in water activity can cause the heat resistance of some foodborne pathogenic microorganisms to increase exponentially, resulting in incomplete sterilization and endangering consumer safety. Therefore, the measurement of water activity at a wide range of temperatures, especially at sterilization temperatures, is crucial, but this has not been taken seriously in China at present. At the same time, the research on methods for efficiently and accurately measuring isothermal water activity is still in its infancy.

[0006] Based on this, this patent designs an efficient water activity testing device. By separating the sample space and the headspace and converting the up-and-down structure into a left-and-right structure, the volume of the headspace is significantly reduced, effectively improving the testing speed and accuracy. Summary of the Invention

[0007] The purpose of the present invention is to provide an efficient water activity testing device, aiming to improve the problem that the high-precision sensor used in the existing water activity testing device has a relatively large inherent volume, resulting in a large headspace volume and thus a long testing time.

[0008] To achieve the purpose of the present invention, the present application provides the following technical solutions:

[0009] An efficient water activity testing device includes a temperature and humidity sensor, and also includes a box body and a box cover. A separated sample accommodating cavity and a sensor accommodating cavity are arranged on the upper end surface of the box body. A first annular groove is arranged on the upper end surface of the box body. Both the sample accommodating cavity and the sensor accommodating cavity are located in the first annular groove. A first sealing ring is arranged in the first annular groove. The box cover and the box body are connected by a plurality of bolts. After the bolts are tightened, the first sealing ring is compressed, and there is a certain gap between the box body and the box cover. The temperature and humidity sensor is arranged at the position of the box cover corresponding to the sensor accommodating cavity, and a sealing structure is arranged between the temperature and humidity sensor and the box cover.

[0010] Preferably, the temperature and humidity sensor (7) is arranged at the position of the box cover (2) corresponding to the sensor accommodating cavity (12), and a sealing structure is arranged between the temperature and humidity sensor (7) and the box cover (2).

[0011] Preferably, the sensor accommodating cavity includes an upper rectangular hole part and a lower rectangular hole part. The length and width of the upper rectangular hole part are respectively greater than those of the lower rectangular hole part. The upper rectangular hole part and the lower rectangular hole part are respectively used for accommodating the head and the rod part of the temperature and humidity sensor.

[0012] Preferably, the whole box body is cylindrical, the box body is made of aluminum alloy, and the box body is an integrally formed structure.

[0013] Preferably, the whole box cover is disc-shaped, the box cover and the box body are made of aluminum alloy, and the diameter of the box cover is the same as that of the box body.

[0014] Preferably, the first annular groove is a circular annular groove, and the first annular groove is arranged concentrically with the box body.

[0015] Preferably, at least four threaded mounting holes are evenly arranged on the upper end surface of the box body along its circumferential direction, and each threaded mounting hole is located outside the first annular groove. Mounting through holes corresponding to the threaded mounting holes one by one are arranged on the box cover. The rod part of the bolt passes through the mounting through hole and is screwed into the threaded mounting hole.

[0016] Preferably, a weight reduction cavity is arranged below the sample accommodating cavity, and the lower end of the weight reduction cavity is open.

[0017] Preferably, a filling piece is further included. The shape of the filling piece is adapted to the shape of the sample accommodating cavity. The filling piece can be put into the sample accommodating cavity or taken out of the sample accommodating cavity.

[0018] Preferably, the filling piece is made of a metal material, preferably aluminum alloy.

[0019] Preferably, the filling sheet and the sample accommodating cavity are semi-circular in shape.

[0020] Preferably, the box cover is provided with a hole for installing the head of the temperature and humidity sensor, and a second annular groove is provided on the hole wall of the hole, and a second sealing ring is provided in the second annular groove.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. In the present invention, the sample accommodating cavity and the sensor accommodating cavity are separately arranged, effectively reducing the headspace. In this way, the time for the sample to be measured to reach equilibrium with the headspace is shortened, the test efficiency is improved, and the test time is shortened.

[0023] 2. The sensor accommodating cavity of the present invention includes an upper rectangular hole portion and a lower rectangular hole portion, and the sizes of the upper rectangular hole portion and the lower rectangular hole portion are respectively adapted to the head and the rod of the temperature and humidity sensor, achieving the effect of further reducing the headspace.

[0024] 3. The present invention is provided with a filling sheet, which is made of aluminum alloy. It not only has good heat transfer performance, but also can be used to adjust the usage amount of the sample to be measured. Appropriately reducing the sample usage amount can still accurately measure its water activity, and the speed is faster.

[0025] 4. The present invention has the advantages of high measurement accuracy, good sealing performance, and at the same time takes into account the cost performance and low manufacturing difficulty, and has great prospects for industrial application and promotion. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the existing water activity test equipment;

[0027] Figure 2 is a schematic structural diagram of the present invention;

[0028] Figure 3 is a cross-sectional schematic diagram of the box body of the present invention;

[0029] Figure 4 is a bottom view of the box body of the present invention;

[0030] Figure 5 is a schematic structural diagram of the box cover of the present invention;

[0031] Figure 6 is a schematic structural diagram of the filling sheet of the present invention;

[0032] Figure 7 is a comparative diagram of the change in the water activity values measured by the present invention and the traditional test equipment for egg white powder (a), egg powder (b), and egg yolk powder (c);

[0033] Figure 8It is a direct comparison diagram of the color change of the discolored silica gel of the present invention (a) and the traditional test equipment (b) under high temperature and high humidity environment.

[0034] In the figure: 1. Box body; 11. Sample accommodation cavity; 12. Sensor accommodation cavity; 121. Upper rectangular hole part; 122. Lower rectangular hole part; 13. First annular groove; 14. Weight reduction cavity; 15. Threaded mounting hole; 2. Box cover; 21. Mounting through hole; 3. Filling piece; 36. Fixing hole; 4. First sealing ring; 5. Bolt; 6. Second sealing ring; 7. Temperature and humidity sensor. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] Please refer to Figure 2 、 Figure 3 and Figure 4 , an efficient water activity test device, including a temperature and humidity sensor 7, a box body 1 and a box cover 2. The box body 1 is generally cylindrical, made of aluminum alloy, and has good thermal conductivity. A separated sample accommodation cavity 11 and a sensor accommodation cavity 12 are provided on the upper end surface of the box body 1. The shape of the sample accommodation cavity 11 is semi-circular, and the sample to be tested is placed in the sample accommodation cavity 11. The sensor accommodation cavity 12 includes an upper rectangular hole part 121 and a lower rectangular hole part 122. The length and width of the upper rectangular hole part 121 are respectively greater than the length and width of the lower rectangular hole part 122. The upper rectangular hole part 121 and the lower rectangular hole part 122 are respectively used to accommodate the head and the rod part of the temperature and humidity sensor 7. The box body 1 with the sample accommodation cavity 11 and the sensor accommodation cavity 12 is made of an aluminum alloy metal block through machining and electrochemical corrosion. The box body 1 is an integrally formed structure to ensure the sealing performance outside the upper ports of the sample accommodation cavity 11 and the sensor accommodation cavity 12 and ensure good heat transfer effect, so as to facilitate rapid heating to the specified temperature. The box cover 2 is generally disc-shaped, made of aluminum alloy, and has good thermal conductivity. The box cover 2 has the same diameter as the box body 1.

[0037] Please refer to Figure 2 、 Figure 3 and Figure 5, a first annular groove 13 is provided on the upper end surface of the box body 1. The sample accommodation cavity 11 and the sensor accommodation cavity 12 are both located in the first annular groove 13. The first annular groove 13 is an annular groove, and the first annular groove 13 is arranged concentrically with the box body 1. Four threaded mounting holes 15 are uniformly arranged on the upper end surface of the box body 1 along its circumferential direction, and each threaded mounting hole 15 is located outside the first annular groove 13. Mounting through holes 21 corresponding to the threaded mounting holes 15 one by one are provided on the box cover 2. The rod portion of the bolt 5 passes through the mounting through hole 21 and is screwed into the threaded mounting hole 15. A first sealing ring 4 is arranged in the first annular groove 13. The box cover 2 and the box body 1 are connected by a plurality of bolts 5. After the bolts 5 are tightened, the first sealing ring 4 is pressed, and there is a certain gap between the box body 1 and the box cover 2, and this gap is kept below 0.5 mm.

[0038] Please refer to Figure 2 , the temperature and humidity sensor 7 is arranged at the position of the box cover 2 corresponding to the sensor accommodation cavity 12, and a sealing structure is arranged between the temperature and humidity sensor 7 and the box cover 2. The box cover 2 is provided with a hole for mounting the head of the temperature and humidity sensor 7. The sealing structure between the temperature and humidity sensor 7 and the box cover 2 includes a second annular groove provided on the hole wall of this hole and a second sealing ring 6 arranged in the second annular groove.

[0039] Please refer to Figure 2 , Figure 4 and Figure 6 , and in addition, a filling piece 3 is also included. The shape of the filling piece 3 is adapted to the shape of the sample accommodation cavity 11, and it is also semi-circular in shape. The size of the filling piece 3 is slightly smaller than the size of the sample accommodation cavity 11, so that the filling piece 3 can be put into the sample accommodation cavity 11 and can also be taken out from the sample accommodation cavity 11, and not too much sample to be measured will enter the gap between the filling piece 3 and the cavity wall of the sample accommodation cavity 11. The filling piece 3 is made of aluminum alloy and has good heat transfer effect. The filling piece 3 can be used to adjust the usage amount of the sample to be measured. The ratio of the sample space to the sensor space needs to be kept above a specific ratio to be considered capable of accurately measuring the water activity of the sample. This calculation process is obtained under extreme conditions (high temperature, extremely low water activity). For most samples to be measured, appropriately reducing the sample usage amount can still accurately measure its water activity and at a faster speed.

[0040] Please refer to Figure 2 and Figure 3, a weight reduction cavity 14 is provided below the sample accommodation cavity 11. The lower end of the weight reduction cavity 14 is open, and the weight reduction cavity 14 is provided on the lower end surface of the box body 1. The weight reduction cavity 14 can be made by machining and electrochemical etching. By providing the weight reduction cavity 14, firstly, the weight of the entire device can be reduced, improving the portability of the present invention; secondly, since the temperature and humidity sensor 7 has a certain height, by providing the weight reduction cavity 14, the height of the sample accommodation cavity 11 can be reduced, and the amount of the filling sheet 3 used during testing can be reduced, which can not only simplify the operation but also effectively ensure the heat transfer effect.

[0041] Working principle of the present invention: In the present invention, the sample accommodation cavity 11 and the sensor accommodation cavity 12 are separately provided, effectively reducing the headspace. In this way, the time for the sample to be measured to reach equilibrium with the headspace is shortened, the testing efficiency is improved, and the testing time is reduced. Taking egg powder with a water activity (25 °C) of 0.529 as an example, when heating from 30 °C to 90 °C and reaching equilibrium at 90 °C, a traditional testing device requires 83 min, while the present invention only requires 30 min.

[0042] As Figure 7 shown, taking egg white powder, egg powder, and egg yolk powder with a water activity (25 °C) of 0.529 as examples, the changes in water activity at 25 - 75 °C are tested, and each group of tests is repeated 3 times. From Figure 7 this, it can be seen that the error bars of the present invention are almost smaller than those of the traditional testing device in all tests. Therefore, the present invention also has the advantage of higher testing accuracy.

[0043] As Figure 8 shown, after placing discolored silica gel in the present invention ( Figure 8 a) and the traditional testing device ( Figure 8 b), and respectively testing for 1 h and 5 h in a high-temperature and high-humidity environment (100 °C, relative humidity of about 82%), it can be observed that the color of the discolored silica gel in the traditional testing device changes from dark blue to light purple (this change process represents water adsorption), while the color of the discolored silica gel in the testing device of this patent hardly changes. Therefore, the sealing performance of the present invention is greatly improved compared to the traditional testing device.

[0044] In addition, compared with manufacturing an inverted T-shaped box body to reduce the sensor accommodation cavity 12, the manufacturing process difficulty of the present invention is very low. Because to ensure good sealing performance, the testing device is all made by integral molding rather than welding. The processing difficulty of the inverted T-shaped box body is relatively large, and the waste of raw materials is also large. Therefore, the present invention also has the advantage of low manufacturing difficulty. The upper rectangular hole portion 121 and the lower rectangular hole portion 122 of the present invention are respectively adapted to the head and the rod of the temperature and humidity sensor 7, achieving the effect of further reducing the headspace.

[0045] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An efficient water activity testing device, comprising a temperature and humidity sensor (7), characterized in that: The box body (1) further comprises a box body (1) and a box cover (2), wherein the upper end surface of the box body (1) is provided with a sample accommodating chamber (11) and a sensor accommodating chamber (12) which are separated from each other, and the upper end surface of the box body (1) is provided with a first annular groove (13), wherein the sample accommodating chamber (11) and the sensor accommodating chamber (12) are both located in the first annular groove (13), and a first sealing ring (4) is provided in the first annular groove (13), and the box cover (2) and the box body (1) are connected by a plurality of bolts (5), and after the bolts (5) are tightened, the first sealing ring (4) is compressed, and a certain gap is provided between the box body (1) and the box cover (2); The box cover (2) is provided with a hole for mounting the head of the temperature and humidity sensor (7), and a second annular groove is provided on the hole wall of the hole, and a second sealing ring (6) is provided in the second annular groove; The sensor accommodating cavity (12) comprises an upper rectangular hole portion (121) and a lower rectangular hole portion (122); the length and width of the upper rectangular hole portion (121) are respectively greater than the length and width of the lower rectangular hole portion (122); the upper rectangular hole portion (121) and the lower rectangular hole portion (122) are respectively used to accommodate the head portion and the rod portion of the temperature and humidity sensor (7); It also includes a filling sheet (3), the shape of the filling sheet (3) being compatible with the shape of the sample accommodating cavity (11), and the filling sheet (3) can be placed in the sample accommodating cavity (11) and can also be taken out of the sample accommodating cavity (11); A weight-reducing chamber (14) is provided below the sample accommodating chamber (11), and the lower end of the weight-reducing chamber (14) is open; The sample accommodating chamber (11) and the sensor accommodating chamber (12) are arranged separately, thereby reducing the headspace and shortening the time for the sample to be tested and the headspace to reach equilibrium.

2. The efficient water activity testing device according to claim 1, characterized in that: The box body (1) is cylindrical in shape as a whole, is made of aluminum alloy, and is an integrally formed structure.

3. The efficient water activity testing device according to claim 2, characterized in that: The box cover (2) is in the shape of a disk as a whole. The box body and the box cover (2) are made of aluminum alloy. The box cover (2) and the box body (1) have the same diameter.

4. The efficient water activity testing device according to claim 3 is characterized in that: The first annular groove (13) is a circular annular groove, and the first annular groove (13) and the box body (1) are arranged coaxially.

5. The efficient water activity testing device according to claim 4, characterized in that: The upper end surface of the box body (1) is evenly provided with at least four threaded mounting holes (15) along its circumferential direction, and each threaded mounting hole (15) is located outside the first annular groove (13); the box cover (2) is provided with mounting through holes (21) corresponding to each threaded mounting hole (15) one by one; the shank of the bolt (5) passes through the mounting through holes (21) and is screwed into the threaded mounting hole (15).

6. The efficient water activity testing device according to claim 5, characterized in that: The filling sheet (3) is made of an aluminum alloy material, and the filling sheet (3) and the sample containing cavity (11) are quasi-semicircular in shape.

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