Device for measuring content of microorganisms in food

Abstract

The invention relates to the technical field of devices for measuring the content of microorganisms, in particular to a device for measuring the content of microorganisms in food. According to the technical scheme, the device comprises a rack and further comprises a mounting plate installed in the rack in a sliding mode, a lifting mechanism for driving the mounting plate to do lifting motion and a lifting mechanism installed on the mounting plate in a sliding mode are installed in the rack, and a pipettor for sucking samples and a power component are fixedly installed on the lifting mechanism. And the power part drives the lifting mechanism to lift and simultaneously enables the pipettor to generate suction force to the outside. According to the invention, it is helpful to ensure that the diluent is uniformly sucked at each depth, so that the problem of inaccurate detection data caused by different contents of microorganisms in the diluent is reduced, and the diluent can be uniformly discharged into the next test tube by reversely repeating the steps during discharging.

Description

Technical Field

[0001] The present invention relates to the technical field of devices for measuring the content of microorganisms, and particularly to a device for measuring the content of microorganisms in food. Background Art

[0002] A device for measuring the content of microorganisms is an instrument used to detect the number of microorganisms in environmental samples such as food, water, soil, and air. The types and quantities of microorganisms are of great significance in multiple fields such as food safety, environmental monitoring, and industrial fermentation processes. Therefore, accurately and quickly measuring the content of microorganisms is crucial for quality control and risk assessment in these fields. In the detection of the content of microorganisms in food, food samples need to be placed in a diluent, and then the diluent is extracted for subsequent microbial counting and identification.

[0003] Dilution is divided into primary dilution and serial dilution. Each time dilution is performed, a pipette is used to extract a specified amount of the diluent in the test tube and put it into the next test tube. After the sample is placed in the diluent, the content of microorganisms at different depths in the diluent may vary. This phenomenon is usually referred to as the non-uniform vertical distribution of microorganisms, and the reasons include: sample suspension, microbial activity, oxygen distribution, and sample physical properties. When the existing device samples, it often extracts at a specific depth in the test tube, which may result in the content of microorganisms in the extracted sample not representing the content of microorganisms in the entire test tube, ultimately leading to a certain error in the value obtained from the final test, and thus being unfavorable for improving the detection accuracy. Summary of the Invention

[0004] The purpose of the present invention is to propose a device for measuring the content of microorganisms in food in view of the problems in the background art.

[0005] The technical solution of the present invention: A device for measuring the content of microorganisms in food includes a frame, and further includes: A mounting plate slidably installed in the frame, and a lifting mechanism for driving the mounting plate to move up and down is installed in the frame; A lifting mechanism slidably installed on the mounting plate, and a pipette for sucking the sample is fixedly installed on the lifting plate mechanism; A power component, which drives the lifting mechanism to rise and simultaneously makes the pipette generate suction externally, and the power driving mechanism adjusts the speed of the pipette sucking externally while keeping the lifting speed of the lifting mechanism unchanged.

[0006] Optionally, a slide rail is fixedly installed on the frame, the mounting plate is fixedly installed on the slide rail, and a first push rod motor is fixedly installed on the frame, and the output shaft of the first push rod motor is fixedly connected to the mounting plate.

[0007] Optionally, the lifting mechanism includes a support rod fixedly installed on the mounting plate. A lifting plate is slidably installed on the support rod. A chute is provided on the lifting plate, and the chute is slidably connected to the support rod. A first lead screw is threadedly connected to the lifting plate.

[0008] Optionally, the pipette includes a body fixedly installed on the lifting plate. A piston is slidably installed in the body. A connecting rod is fixedly installed on the piston. A support block is fixedly installed on the connecting rod, and the support block is fixedly connected to the lifting plate. Two slide bars and a second lead screw are fixedly installed on the support block. A positioning block is fixedly installed on the lifting plate, and the slide bars are slidably connected to the positioning block. An internal lead screw is threadedly connected to the second lead screw, and a first telescopic rod is fixedly installed on the internal lead screw.

[0009] Optionally, the power component includes a first frustum and a second frustum rotatably installed on the mounting plate. The first frustum is coaxially and fixedly connected to the first lead screw, and the second frustum is coaxially and fixedly connected to the first telescopic rod. The upper bottom surface of the first frustum and the lower bottom surface of the second frustum are in the same plane, and the lower bottom surface of the first frustum and the upper bottom surface of the second frustum are in the same plane. A transmission belt is sleeved on the first frustum and the second frustum. A first motor is fixedly installed on the mounting plate, and the output shaft of the first motor is coaxially and fixedly connected to the first frustum. The power component further includes a speed change assembly for driving the transmission belt to perform lifting movement.

[0010] Optionally, the speed change assembly includes a plurality of adjusting rods slidably installed on the mounting plate. One ends of the plurality of adjusting rods are fixedly installed with a lifting ring, and the other ends of the plurality of adjusting rods are fixedly installed with a synchronous plate. A plurality of clamping seats are fixedly installed on the lifting ring. Spheres are rotatably installed on the upper and lower sides of the clamping seats. The transmission belt is located inside the plurality of clamping seats and abuts against the plurality of spheres. A second push rod motor is fixedly installed on the mounting plate, and the output shaft of the second push rod motor is fixedly connected to the synchronous plate.

[0011] Optionally, a second telescopic rod is fixedly installed on the lifting ring. One end of the second telescopic rod is fixedly installed with a wheel seat, and a tension pulley is rotatably installed on the wheel seat. A spring is fixedly installed inside the second telescopic rod.

[0012] Optionally, a plurality of test tube racks are circumferentially and arrayedly installed at the bottom of the frame. A transposition and mixing mechanism for driving the plurality of test tube racks to perform circular motion and rotate simultaneously is installed inside the frame.

[0013] Optionally, the transposition and mixing mechanism includes a first gear and a second gear rotatably mounted on the frame. A plurality of the test tube racks are rotatably mounted on the first gear. The first gear and the second gear mesh with each other. A second motor is fixedly mounted in the frame. The output shaft of the second motor is fixedly connected to the second gear coaxially. The first gear and the second gear mesh with each other. The test tube rack penetrates through the first gear and is fixedly mounted with a third gear. A fourth gear is fixedly mounted in the frame. The third gear and the fourth gear mesh with each other.

[0014] Optionally, a first protection plate and a second protection plate are fixedly mounted on the frame. The test tube rack is located between the first protection plate and the second protection plate. A plurality of sealing plates are rotatably mounted between the first protection plate and the second protection plate.

[0015] In summary, the present application includes at least one of the following beneficial technical effects: In the present invention, the method of the pipette gradually moving upward from the bottom of the diluent to aspirate the liquid helps to ensure uniform aspiration of each depth of the diluent, thereby reducing the problem of inaccurate detection data caused by different microbial contents in the diluent. This operation mode can ensure that the pipette aspirates the uniformly mixed part of the diluent, rather than a local area at a certain depth. By uniformly aspirating the diluent, the accuracy of the detection data can be improved because the microbial content in each sample is uniform.

[0016] Furthermore, since the pipette aspirates from the bottom, the error caused by surface microbial aggregation or bubbles can be reduced. This method helps to ensure that the microbial content in the aspirated liquid is consistent with the overall content of the diluent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The structural schematic diagram of the device for measuring the microbial content of the present invention is given; Figure 2 It is a position relationship diagram of the lifting mechanism and the pipette of the present invention; Figure 3 It is an installation schematic diagram of the pipette of the present invention; Figure 4 It is a structural schematic diagram of the pipette of the present invention; Figure 5 It is a structural schematic of the power component of the present invention Figure 1 ; Figure 6 It is a structural schematic of the power component of the present invention Figure 2 ; Figure 7 is Figure 6 a partial enlarged view of A in Figure 8 It is a structural schematic diagram of the card seat and the sphere of the present invention; Figure 9 Schematic structural diagram of the first protection plate and the second protection plate of the present invention; Figure 10 Schematic structure of the position-changing mixing mechanism of the present invention Figure 1 ; Figure 11 Schematic structure of the position-changing mixing mechanism of the present invention Figure 2 。

[0018] Reference numerals: 1, frame; 2, mounting plate; 201, slide rail; 202, first push rod motor; 3, lifting plate; 301, support rod; 302, chute; 303, first lead screw; 4, device body; 401, piston; 402, connecting rod; 403, support block; 404, slide bar; 405, positioning block; 406, second lead screw; 407, internal threaded rod; 408, first telescopic rod; 5, first frustum; 501, second frustum; 502, transmission belt; 503, lifting ring; 504, card seat; 505, sphere; 506, adjusting rod; 507, synchronous plate; 508, second push rod motor; 509, first motor; 6, second telescopic rod; 601, wheel seat; 602, tensioning wheel; 603, spring; 7, test tube rack; 701, first gear; 702, second gear; 703, second motor; 704, third gear; 705, fourth gear; 706, first protection plate; 707, second protection plate; 708, sealing plate. Detailed implementation manners

[0019] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] Embodiment 1 As Figures 1 to 4 shown, a device for measuring the microbial content in food proposed by the present invention includes a frame 1, and further includes a mounting plate 2 slidably installed in the frame 1, and a lifting mechanism for driving the mounting plate 2 to move up and down is installed in the frame 1. A slide rail 201 is fixedly installed on the frame 1, the mounting plate 2 is fixedly installed on the slide rail 201, and a first push rod motor 202 is fixedly installed on the frame 1. The output shaft of the first push rod motor 202 is fixedly connected to the mounting plate 2. The mounting plate 2 can be driven to move up and down along the slide rail 201 by the first push rod motor 202.

[0021] This embodiment further includes a lifting mechanism slidably mounted on the mounting plate 2. A pipette for sucking samples is fixedly mounted on the lifting plate mechanism. The lifting mechanism includes a support rod 301 fixedly mounted on the mounting plate 2. A lifting plate 3 is slidably mounted on the support rod 301. A chute 302 is provided on the lifting plate 3. The chute 302 is slidably connected to the support rod 301. A first lead screw 303 is threadedly connected to the lifting plate 3. When the first lead screw 303 rotates, driven by the guiding action of the support rod 301 and the chute 302, the lifting plate 3 can be driven to move up and down along the chute 302.

[0022] Furthermore, the pipette includes a body 4 fixedly mounted on the lifting plate 3. A piston 401 is slidably mounted in the body 4. A connecting rod 402 is fixedly mounted on the piston 401. A support block 403 is fixedly mounted on the connecting rod 402. The support block 403 is fixedly connected to the lifting plate 3. Two slide rods 404 and a second lead screw 406 are fixedly mounted on the support block 403. A positioning block 405 is fixedly mounted on the lifting plate 3. The slide rods 404 are slidably connected to the positioning block 405. An internally threaded rod 407 is threadedly connected to the second lead screw 406. A first telescopic rod 408 is fixedly mounted on the internally threaded rod 407. When the lifting plate 3 moves up and down, the first telescopic rod 408 will be driven to expand and contract. When the first telescopic rod 408 rotates, the internally threaded rod 407 will be driven to rotate. At this time, the rotating internally threaded rod 407 will drive the second lead screw 406 to move up and down. The support block 403 can be driven to move up and down through the second lead screw 406, so that the connecting rod 402 can drive the piston 401 to move up and down. By the piston 401 moving up and down, the body 4 can generate suction or thrust on the outside world, so that the diluent can be extracted or discharged.

[0023] It should be noted that during use, a disposable tip needs to be installed on the body 4. The diluent will be sucked into the tip. And to prevent cross-infection, when extracting the diluent in different test tubes, a disposable tip needs to be replaced each time. Here, the disposable tip is replaced manually. In the prior art, there are already mechanisms for automatically replacing tips, which can be directly applied here and will not be elaborated again.

[0024] Such as Figures 2 to 8As shown in the figure, this embodiment further includes a power component. While the power component drives the lifting mechanism to rise, it causes the pipette to generate suction externally. The power driving mechanism adjusts the speed at which the pipette sucks externally while keeping the lifting speed of the lifting mechanism unchanged. The power component includes a first frustum 5 and a second frustum 501 rotatably mounted on the mounting plate 2. The first frustum 5 is coaxially and fixedly connected to the first lead screw 303, and the second frustum 501 is coaxially and fixedly connected to the first telescopic rod 408. The upper bottom surface of the first frustum 5 and the lower bottom surface of the second frustum 501 are in the same plane, and the lower bottom surface of the first frustum 5 and the upper bottom surface of the second frustum 501 are in the same plane. A transmission belt 502 is sleeved on the first frustum 5 and the second frustum 501. A first motor 509 is fixedly mounted on the mounting plate 2, and the output shaft of the first motor 509 is coaxially and fixedly connected to the first frustum 5. When the first motor 509 rotates, it will drive the first frustum 5 to rotate. The rotating first frustum 5 will drive the transmission belt 502 to rotate through the friction between the first frustum 5 and the transmission belt 502, and drive the second frustum 501 to rotate through the transmission belt 502, so that the first frustum 5 and the second frustum 501 can rotate synchronously. Furthermore, the first frustum 5 can drive the first lead screw 303 to rotate, and the second frustum 501 can drive the first telescopic rod 408 to rotate.

[0025] Furthermore, the power component further includes a speed change component for driving the lifting movement of the transmission belt 502. The speed change component includes a plurality of adjusting rods 506 slidably mounted on the mounting plate 2. One end of the plurality of adjusting rods 506 is fixedly mounted with a lifting ring 503, and the other end of the plurality of adjusting rods 506 is fixedly mounted with a synchronous plate 507. A plurality of clamping seats 504 are fixedly mounted on the lifting ring 503. Spheres 505 are rotatably mounted on the upper and lower sides of the clamping seats 504. The transmission belt 502 is located inside the plurality of clamping seats 504 and abuts against the plurality of spheres 505. A second push rod motor 508 is fixedly mounted on the mounting plate 2, and the output shaft of the second push rod motor 508 is fixedly connected to the synchronous plate 507. When adjusting the mass of the diluent sucked during a single extraction, it is necessary to adjust the distance that the piston 401 moves per unit time. The number of turns that the second frustum 501 rotates per unit time can be adjusted through the transmission ratio between the first frustum 5 and the second frustum 501, so that the mass of the sucked diluent can be controlled. By driving the lifting ring 503 to move up and down through the second push rod motor 508, the clamping seats 504 can be driven to move up and down. The transmission belt 502 can be driven to move up and down through the clamping seats 504, so that the transmission belt 502 moves on the first frustum 5 and the second frustum 501. Since both the first frustum 5 and the second frustum 501 are frustum-shaped, that is, variable diameter, the transmission ratio between the first frustum 5 and the second frustum 501 can be changed, so that the number of turns that the second frustum 501 rotates can be changed without changing the number of turns that the first frustum 5 rotates.

[0026] Among them, a second telescopic rod 6 is fixedly installed on the lifting ring 503. One end of the second telescopic rod 6 is fixedly installed with a wheel seat 601. A tension pulley 602 is rotatably installed on the wheel seat 601. A spring 603 is fixedly installed inside the second telescopic rod 6. By applying pressure to the second telescopic rod 6 through the spring 603, it can ensure that the tension pulley 602 always abuts against the transmission belt 502. Furthermore, it can compensate for the deformation of the transmission belt 502, making the transmission belt 502 always maintain a tensioned state, and thus ensuring the transmission effect of the first frustum 5 on the second frustum 501.

[0027] Working principle: First, the first push rod motor 202 drives the mounting plate 2 to move downward along the slide rail 201, which can drive the device body 4 and the disposable suction head on the device body 4 to move downward, so that the suction head enters the bottom of the test tube. Then, the first motor 509 drives the first frustum 5 to rotate. The rotating first frustum 5 will drive the transmission belt 502 to rotate through the frictional force between the first frustum 5 and the transmission belt 502, and drive the second frustum 501 to rotate through the transmission belt 502, so that the first frustum 5 and the second frustum 501 can rotate synchronously. Furthermore, the first frustum 5 can drive the first lead screw 303 to rotate, and the second frustum 501 can drive the first telescopic rod 408 to rotate. At this time, through the guiding action of the support rod 301 and the chute 302, the lifting plate 3 can be driven to rise along the chute 302, and at the same time, the suction head can be driven to move upward from the bottom of the test tube. At the same time, the first telescopic rod 408 will drive the internal threaded rod 407 to rotate. At this time, the rotating internal threaded rod 407 will drive the piston 401 to rise. Through the rising piston 401, the device body 4 can generate suction on the outside world, so that the diluent can be extracted into the suction head. When the suction head moves 2 mm below the liquid level, the first motor 509 can be turned off to prevent air from being sucked into the suction head, and the suction head can be withdrawn from the diluent through the first push rod motor 202. Thus, the pipette can gradually move upward from the bottom of the diluent to suck the diluent, which helps to ensure uniform suction at various depths of the diluent, thereby reducing the problem of inaccurate test data caused by different microbial contents in the diluent. And when discharging, repeat the above steps in the reverse direction, and the diluent can be evenly discharged into the next test tube.

[0028] Furthermore, by driving the lifting ring 503 to move up and down through the second push rod motor 508, the clamping seat 504 can be driven to move up and down. The clamping seat 504 can drive the transmission belt 502 to move up and down, so that the transmission belt 502 moves on the first frustum 5 and the second frustum 501. Since both the first frustum 5 and the second frustum 501 are frustum-shaped, i.e., with variable diameters, the transmission ratio between the first frustum 5 and the second frustum 501 can be changed. Thus, the number of rotations of the second frustum 501 can be changed without changing the number of rotations of the first frustum 5, and then the moving distance of the piston can be changed, thereby adjusting the suction volume.

[0029] Embodiment 2 As Figures 9 to 11 shown, based on Embodiment 1, a plurality of test tube racks 7 are circumferentially and arrayedly installed at the bottom of the frame 1. A transposition and mixing mechanism is installed in the frame 1 to drive the plurality of test tube racks 7 to perform circular motion while rotating themselves. The transposition and mixing mechanism includes a first gear 701 and a second gear 702 rotatably installed on the frame 1. A plurality of test tube racks 7 are rotatably installed on the first gear 701. The first gear 701 and the second gear 702 are meshed with each other. A second motor 703 is fixedly installed in the frame 1. The output shaft of the second motor 703 is coaxially and fixedly connected to the second gear 702. The first gear 701 and the second gear 702 are meshed with each other. The test tube rack 7 penetrates through the first gear 701 and is fixedly installed with a third gear 704. A fourth gear 705 is fixedly installed in the frame 1. The third gear 704 and the fourth gear 705 are meshed with each other. When a plurality of test tubes filled with diluent are placed on the test tube racks 7, by starting the second motor 703, the second gear 702 can be driven to rotate. Through the second gear 702, the first gear 701 can be driven to rotate, so that a plurality of test tube racks 7 can be driven to rotate, and different test tubes can be moved to directly below the pipette tip. When the test tube rack 7 rotates with the first gear 701, the third gear 704 will be driven to rotate along the edge of the fourth gear 705 and the third gear 704 will rotate itself, so that the test tube rack 7 can be driven to rotate, and the test tubes inside the test tube rack 7 can be driven to rotate, and the diluent after sample addition can be evenly mixed.

[0030] A first protection plate 706 and a second protection plate 707 are fixedly installed on the frame 1. The test tube rack 7 is located between the first protection plate 706 and the second protection plate 707. A plurality of sealing plates 708 are rotatably installed between the first protection plate 706 and the second protection plate 707. The first protection plate 706 and the second protection plate 707 prevent the transposition and mixing mechanism from being exposed outside and prevent the transposition and mixing mechanism from pinching the operator during operation.

[0031] The working principle of this embodiment is as follows: Place multiple test tubes filled with diluent on the test tube rack 7. By starting the second motor 703, the second gear 702 can be driven to rotate. Through the second gear 702, the first gear 701 can be driven to rotate, thereby driving multiple test tube racks 7 to rotate, and different test tubes can be moved to directly below the pipette tip. When the test tube rack 7 rotates with the first gear 701, the third gear 704 will be driven to rotate along the edge of the fourth gear 705, and the third gear 704 will rotate itself, thereby driving the test tube rack 7 to rotate itself, and the test tubes inside the test tube rack 7 can be driven to rotate, so as to uniformly mix the diluent after sample addition is completed.

[0032] The above specific embodiments are only several alternative embodiments of the present invention. Based on the technical solution of the present invention and the relevant inspirations of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A device for determining the content of microorganisms in food, comprising a frame (1), characterized in that: Also includes: A mounting plate (2) slidably mounted in the frame (1), wherein a lifting mechanism for driving the mounting plate (2) to perform lifting movement is installed in the frame (1); A lifting mechanism slidably mounted on the mounting plate (2), wherein a pipette for aspirating the sample is fixedly mounted on the lifting plate mechanism; The power component drives the lifting mechanism to rise and at the same time causes the pipette to generate suction force to the outside. The power driving mechanism adjusts the speed of the pipette to absorb the outside while keeping the lifting speed of the lifting mechanism unchanged.

2. A device for determining the content of microorganisms in food according to claim 1, characterized in that: A slide rail (201) is fixedly mounted on the frame (1), the mounting plate (2) is fixedly mounted on the slide rail (201), a first push rod motor (202) is fixedly mounted on the frame (1), and an output shaft of the first push rod motor (202) is fixedly connected to the mounting plate (2).

3. A device for determining the content of microorganisms in food according to claim 2, characterized in that: The lifting mechanism comprises a support rod (301) fixedly mounted on the mounting plate (2), a lifting plate (3) being slidably mounted on the support rod (301), a sliding groove (302) being provided on the lifting plate (3), the sliding groove (302) being slidably connected to the support rod (301), and a first screw rod (303) being threadedly connected to the lifting plate (3).

4. A device for determining the content of microorganisms in food according to claim 3, characterized in that: The pipette comprises a body (4) fixedly mounted on a lifting plate (3), a piston (401) being slidably mounted in the body (4), a connecting rod (402) being fixedly mounted on the piston (401), a supporting block (403) being fixedly mounted on the connecting rod (402), the supporting block (403) being fixedly connected to the lifting plate (3), two sliding rods (404) and a second screw rod (406) being fixedly mounted on the supporting block (403), a positioning block (405) being fixedly mounted on the lifting plate (3), the sliding rod (404) being slidably connected to the positioning block (405), an internally threaded rod (407) being threadedly connected to the second screw rod (406), and a first telescopic rod (408) being fixedly mounted on the internally threaded rod (407).

5. A device for determining the content of microorganisms in food according to claim 4, characterized in that: The power component comprises a first truncated table (5) and a second truncated table (501) rotatably mounted on the mounting plate (2); the first truncated table (5) is coaxially fixedly connected to the first screw rod (303); the second truncated table (501) is coaxially fixedly connected to the first telescopic rod (408); the upper bottom surface of the first truncated table (5) and the lower bottom surface of the second truncated table (501) are in the same plane, and the lower bottom surface of the first truncated table (5) and the upper bottom surface of the second truncated table (501) are in the same plane; a transmission belt (502) is sleeved on the first truncated table (5) and the second truncated table (501); a first motor (509) is fixedly mounted on the mounting plate (2); an output shaft of the first motor (509) is coaxially fixedly connected to the first truncated table (5); and the power component further comprises a speed change assembly for driving the transmission belt (502) to perform lifting motion.

6. A device for determining the content of microorganisms in food according to claim 5, characterized in that: The speed change assembly comprises a plurality of adjustment rods (506) slidably mounted on the mounting plate (2), a lifting ring (503) being fixedly mounted on one end of the plurality of adjustment rods (506), a synchronization plate (507) being fixedly mounted on the other end of the plurality of adjustment rods (506), a plurality of clamping seats (504) being fixedly mounted on the lifting ring (503), balls (505) being rotatably mounted on the upper and lower sides of the clamping seats (504), the transmission belt (502) being located inside the plurality of clamping seats (504) and abutting against the plurality of balls (505), a second push rod motor (508) being fixedly mounted on the mounting plate (2), and an output shaft of the second push rod motor (508) being fixedly connected to the synchronization plate (507).

7. A device for determining the content of microorganisms in food according to claim 6, characterized in that: A second telescopic rod (6) is fixedly mounted on the lifting ring (503), a wheel seat (601) is fixedly mounted on one end of the second telescopic rod (6), a tensioning wheel (602) is rotatably mounted on the wheel seat (601), and a spring (603) is fixedly mounted inside the second telescopic rod (6).

8. The device for determining the content of microorganisms in food according to claim 1, characterized in that: A plurality of test tube racks (7) are installed in a circular array at the bottom of the frame (1), and a transposition mixing mechanism is installed in the frame (1) for driving the plurality of test tube racks (7) to perform circular motion and simultaneous rotation.

9. A device for determining the content of microorganisms in food according to claim 8, characterized in that: The transposition mixing mechanism comprises a first gear (701) and a second gear (702) rotatably mounted on a frame (1); a plurality of the test tube racks (7) are rotatably mounted on the first gear (701); the first gear (701) and the second gear (702) are meshed with each other; a second motor (703) is fixedly mounted inside the frame (1); an output shaft of the second motor (703) is coaxially fixedly connected to the second gear (702); the first gear (701) and the second gear (702) are meshed with each other; the test tube rack (7) passes through the first gear (701) and is fixedly mounted with a third gear (704); a fourth gear (705) is fixedly mounted inside the frame (1); the third gear (704) and the fourth gear (705) are meshed with each other.

10. A device for determining the content of microorganisms in food according to claim 9, characterized in that: A first protective plate (706) and a second protective plate (707) are fixedly mounted on the frame (1); the test tube rack (7) is located between the first protective plate (706) and the second protective plate (707); and a plurality of sealing plates (708) are rotatably mounted between the first protective plate (706) and the second protective plate (707).

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