Efficient water activity testing equipment

Abstract

The invention discloses efficient water activity testing equipment which comprises a temperature and humidity sensor and further comprises a box body and a box cover, a sample containing cavity and a sensor containing cavity which are separated are formed in the upper end face of the box body, a first annular groove is formed in the upper end face of the box body, and a second annular groove is formed in the lower end face of the box body. A first annular groove is formed in the box body, the sample containing cavity and the sensor containing 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 through a plurality of bolts, after the bolts are screwed down, the first sealing ring is pressed, and a certain gap is formed between the box body and the box cover; the temperature and humidity sensor is arranged at the position, corresponding to the sensor containing cavity, of the box cover, and a sealing structure is arranged between the temperature and humidity sensor and the box cover. According to the invention, the sample accommodating cavity and the sensor accommodating cavity are separately arranged, so that the headspace space is effectively reduced, the balance time of the to-be-tested sample and the headspace is shortened, the test efficiency is improved, and the test time is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of water activity testing, and in particular 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 food shelf life prediction, foodborne pathogen control, 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 that temperature by measuring the temperature and relative humidity of the headspace where the sensor is located after equilibrium (equilibrium means that the vapor pressure of the sample and the headspace has reached equilibrium).

[0004] The water activity test equipment used in this method is as follows: Figure 1 As shown in the figure, the high-precision sensor used in this water activity test equipment has a large inherent volume, resulting in a larger headspace volume. The larger the headspace volume, the longer it takes for the sample to reach equilibrium with the headspace. Therefore, the larger headspace volume leads to a long test time for the relevant test equipment. In addition, after the sample and the headspace are in equilibrium, there is a large difference between the original vapor pressure of the sample and the vapor pressure after the sample is in equilibrium, resulting in a low test accuracy of the headspace relative humidity measurement method.

[0005] Water activity varies greatly at different temperatures. Slight changes in water activity can cause the heat resistance of some foodborne pathogens to increase exponentially, resulting in incomplete sterilization and endangering consumer safety. Therefore, the measurement of water activity is crucial at a wide range of temperatures, especially at sterilization temperatures, which has not yet attracted much attention in China. At the same time, research on methods for efficiently and accurately measuring isothermal water activity is still in the early stages.

[0006] Based on this, this patent designs an efficient water activity testing equipment, which greatly reduces the volume of the headspace by separating the sample space and the headspace, and converts the top-bottom structure into the left-right structure, thereby effectively improving the test speed and accuracy. Summary of the invention

[0007] The object 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 large inherent volume, resulting in a large headspace volume, which in turn leads to a long testing time.

[0008] To achieve the purpose of the present invention, this application provides the following technical solutions: An efficient water activity testing device comprises a temperature and humidity sensor, a box body and a box cover, wherein the upper end surface of the box body is provided with a sample accommodating cavity and a sensor accommodating cavity separated from each other, the upper end surface of the box body is provided with a first annular groove, the sample accommodating cavity and the sensor accommodating cavity are both located in the first annular groove, a first sealing ring is provided 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 a certain gap is provided between the box body and the box cover; the temperature and humidity sensor is provided at a position of the box cover corresponding to the sensor accommodating cavity, and a sealing structure is provided between the temperature and humidity sensor and the box cover.

[0009] Preferably, the temperature and humidity sensor (7) is arranged at a position of the box cover (2) corresponding to the sensor accommodating cavity (12), and a sealing structure is provided between the temperature and humidity sensor (7) and the box cover (2).

[0010] Preferably, the sensor accommodating cavity includes an upper rectangular hole portion and a lower rectangular hole portion, the length and width of the upper rectangular hole portion are respectively larger than the length and width of the lower rectangular hole portion, and the upper rectangular hole portion and the lower rectangular hole portion are respectively used to accommodate the head and rod portion of the temperature and humidity sensor.

[0011] Preferably, the box body is cylindrical as a whole, is made of aluminum alloy, and is an integrally formed structure.

[0012] Preferably, the box cover is disc-shaped as a whole, and the box body and the box cover are made of aluminum alloy, and the box cover has the same diameter as the box body.

[0013] Preferably, the first annular groove is a circular annular groove, and the first annular groove and the box body are arranged coaxially.

[0014] Preferably, the upper end surface of the box body is evenly provided with at least four threaded mounting holes along its circumferential direction, and each threaded mounting hole is located on the outside of the first annular groove, and the box cover is provided with mounting through holes corresponding to each threaded mounting hole one by one, and the rod of the bolt passes through the mounting through hole and is screwed into the threaded mounting hole.

[0015] Preferably, a weight-reducing cavity is provided below the sample accommodating cavity, and the lower end of the weight-reducing cavity is open.

[0016] Preferably, a filling sheet is further included, the shape of which matches the shape of the sample accommodating cavity, and the filling sheet can be put into the sample accommodating cavity and can also be taken out of the sample accommodating cavity.

[0017] Preferably, the filling piece is made of metal material, preferably aluminum alloy.

[0018] Preferably, the filling sheet and the sample accommodating cavity are semicircular in shape.

[0019] 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.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention sets the sample accommodating chamber and the sensor accommodating chamber separately, which effectively reduces the headspace, thus shortening the time for the sample to be tested to reach equilibrium with the headspace, improving the test efficiency and shortening the test time.

[0021] 2. The sensor accommodating cavity of the present invention includes an upper rectangular hole portion and a lower rectangular hole portion, the sizes of which are respectively matched with the head portion and the rod portion of the temperature and humidity sensor, thereby achieving the effect of further reducing the headspace.

[0022] 3. The present invention is provided with a filling piece, which is made of aluminum alloy and not only has good heat transfer properties, but can also be used to adjust the amount of the sample to be tested. The water activity can still be accurately measured by appropriately reducing the amount of sample used, and the speed is faster.

[0023] 4. The present invention has the advantages of high measurement accuracy and good sealing, while also taking into account the advantages of cost performance and low manufacturing difficulty, and has great prospects for industrial application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the existing water activity testing equipment; Figure 2 It is a schematic diagram of the structure of the present invention; Figure 3 is a schematic cross-sectional view of a box body of the present invention; Figure 4 is a bottom view of the box body of the present invention; Figure 5 It is a structural schematic diagram of the box cover of the present invention; Figure 6 It is a schematic diagram of the structure of the filling piece of the present invention; Figure 7 It is a comparison chart of the changes in water activity values ​​in egg white powder (a), egg powder (b) and egg yolk powder (c) measured by the present invention and the traditional testing equipment; Figure 8 It is a visual comparison chart of the color change of the color-changing silica gel of the present invention (a) and the traditional testing equipment (b) under high temperature and high humidity environment.

[0025] In the figure: 1. box body; 11. sample accommodating chamber; 12. sensor accommodating chamber; 121. upper rectangular hole portion; 122. lower rectangular hole portion; 13. first annular groove; 14. weight reduction chamber; 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 DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 2 , Figure 3 and Figure 4 , an efficient water activity testing device, includes a temperature and humidity sensor 7, a box body 1 and a box cover 2. The box body 1 is cylindrical as a whole, and the box body 1 is made of aluminum alloy and has good thermal conductivity. A separated sample accommodating chamber 11 and a sensor accommodating chamber 12 are provided on the upper end surface of the box body 1. The shape of the sample accommodating chamber 11 is semicircular, and the sample accommodating chamber 11 is used to place the sample to be tested. The sensor accommodating chamber 12 includes 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 used to accommodate the head and rod portion of the temperature and humidity sensor 7, respectively. The box body 1 with the sample accommodating cavity 11 and the sensor accommodating cavity 12 is made of an aluminum alloy metal block through mechanical processing and electrochemical corrosion. The box body 1 is an integrally formed structure to ensure the sealing of the sample accommodating cavity 11 and the sensor accommodating cavity 12 outside the upper port and to ensure a good heat transfer effect, so as to facilitate rapid heating to the specified temperature. The box cover 2 is disc-shaped as a whole. The box body and cover 2 are made of aluminum alloy with good thermal conductivity. The diameter of the box cover 2 is the same as that of the box body 1.

[0028] See also Figure 2 , Figure 3 and Figure 5The upper end surface of the box body 1 is provided with a first annular groove 13, and the sample accommodating cavity 11 and the sensor accommodating 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 coaxially with the box body 1. The upper end surface of the box body 1 is evenly provided with 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, and the rod of the bolt 5 passes through the mounting through holes 21 and is screwed into the threaded mounting hole 15. The first annular groove 13 is provided with a first sealing ring 4, and the box cover 2 and the box body 1 are connected by a plurality of bolts 5. After tightening the bolts 5, the first sealing ring 4 is compressed, and there is a certain gap between the box body 1 and the box cover 2, and the gap is kept below 0.5mm.

[0029] See also Figure 2 The temperature and humidity sensor 7 is arranged at a 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. The box cover 2 is provided with a hole for installing the head of the temperature and humidity sensor 7, and the sealing structure between the temperature and humidity sensor 7 and the box cover 2 includes a second annular groove arranged on the hole wall of the hole and a second sealing ring 6 arranged in the second annular groove.

[0030] See also Figure 2 , Figure 4 and Figure 6 , and also includes a filling piece 3. The shape of the filling piece 3 is adapted to the shape of the sample accommodating cavity 11, and is also semicircular. The size of the filling piece 3 is slightly smaller than the size of the sample accommodating cavity 11, so that the filling piece 3 can be placed in the sample accommodating cavity 11, and can also be taken out of the sample accommodating cavity 11, and there will not be too much sample to be tested entering the gap between the filling piece 3 and the cavity wall of the sample accommodating cavity 11. The filling piece 3 is made of aluminum alloy and has a good heat transfer effect. The filling piece 3 can be used to adjust the amount of sample to be tested. The ratio of the sample space to the sensor space must be maintained above a specific ratio to be considered to accurately measure the water activity of the sample. The calculation process is calculated under extreme conditions (high temperature and extremely low water activity). For most samples to be tested, appropriately reducing the amount of sample used can still accurately measure their water activity, and at a faster speed.

[0031] See also Figure 2 and Figure 3A weight-reducing chamber 14 is provided below the sample accommodating chamber 11, the lower end of the weight-reducing chamber 14 is provided with an opening, and the weight-reducing chamber 14 is provided on the lower end surface of the box body 1, and the weight-reducing chamber 14 can be made by machining and electrochemical corrosion. By providing the weight-reducing chamber 14, firstly, the weight of the entire device can be reduced, thereby improving the portability of the present invention; secondly, since the temperature and humidity sensor 7 has a certain height, the height of the sample accommodating chamber 11 can be reduced by providing the weight-reducing chamber 14, and the amount of the filling sheet 3 used can be reduced during the test, which can not only simplify the operation, but also effectively ensure the heat transfer effect.

[0032] Working principle of the present invention: The present invention sets the sample accommodating chamber 11 and the sensor accommodating chamber 12 separately, effectively reducing the headspace, thus shortening the time for the sample to be tested to reach equilibrium with the headspace, improving the test efficiency and reducing the test time. Taking egg powder with a water activity (25°C) of 0.529 as an example, it takes 83 minutes for traditional testing equipment to heat from 30°C to 90°C and reach equilibrium at 90°C, while the present invention only takes 30 minutes.

[0033] like Figure 7 As shown in the figure, egg white powder, egg powder and egg yolk powder with a water activity (25°C) of 0.529 were used as examples to test the changes in water activity at 25-75°C, with each test repeated 3 times. Figure 7 It can be seen that the error bars of the present invention are smaller than those of the traditional testing equipment in almost all tests, so the present invention also has the advantage of higher testing accuracy.

[0034] like Figure 8 As shown, in the present invention ( Figure 8 a) and traditional test equipment ( Figure 8 b) After placing the color-changing silica gel, the test was conducted in a high temperature and high humidity environment (100°C, relative humidity of about 82%) for 1 h and 5 h respectively. It can be observed that the color of the color-changing silica gel in the traditional test equipment changed from dark blue to light purple (this change process represents the adsorption of moisture), while the color of the color-changing silica gel in the test equipment of the present invention hardly changed. Therefore, the sealing performance of the present invention is greatly improved compared with the traditional test equipment.

[0035] In addition, compared to manufacturing an "inverted T" shaped box body to reduce the sensor accommodating cavity 12, the process manufacturing difficulty of the present invention is very low. Because in order to ensure good sealing, the test equipment is formed in one piece rather than welded, 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 portion of the temperature and humidity sensor 7, achieving the effect of further reducing the head space.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that 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 invention also 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).

2. The efficient water activity testing device according to claim 1, characterized in that: 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 a head portion and a rod portion of a temperature and humidity sensor (7).

3. 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.

4. The efficient water activity testing device according to claim 3 is 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.

5. The efficient water activity testing device according to claim 3, 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.

6. The efficient water activity testing device according to claim 5, 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).

7. The efficient water activity testing device according to claim 1, characterized in that: 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.

8. The efficient water activity testing device according to claim 1, characterized in that: In addition, a filling sheet (3) is included. The shape of the filling sheet (3) is compatible with the shape of the sample accommodating cavity (11). 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).

9. The efficient water activity testing device according to claim 8, characterized in that: The filling sheet (3) is made of a metal material, preferably an aluminum alloy, and the filling sheet (3) and the sample containing cavity (11) are quasi-semicircular in shape.

10. The efficient water activity testing device according to claim 1, characterized in that: 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.

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