A preparation process and a pressing device for a stage-pressed old bean curd

Abstract

The present application relates to the technical field of bean product processing, and in particular to a preparation process and a pressing device for old bean curd by stage pressing. The process includes five stages of pressure control, wherein the first three stages are slow and gradual pressing by the pressing device, with a pressure of less than or equal to 20 KPa, and the last two stages are fast and high-pressure pressing, with a pressure of greater than or equal to 30 KPa. The five stages of pressing time is 25±2 min. The pressing device includes a pressing box and a hydraulic assembly. The pressing box includes a box body (1) and a pressing plate. The hydraulic assembly is vertically connected to the upper side of the pressing plate. The pressing plate includes a connecting frame and a movable bottom surface. The movable bottom surface includes a plurality of adjacent strip plates. Spring support rods are connected between the connecting frame and the strip plates. The inside of the connecting frame is provided with a gradual extrusion assembly. The gradual extrusion assembly includes a connecting shaft and a plurality of extrusion pieces. The pressing process is slow at first and then fast, and the gradual drainage can effectively prevent the surface of the bean curd from premature skinning, and ensure efficient drainage and uniform distribution of moisture.

Description

Technical Field

[0001] This invention relates to the field of soybean product processing technology, specifically to a staged pressing process for preparing firm tofu and its pressing device. Background Technology

[0002] Traditional tofu pressing processes often involve single or simple multiple pressing, which results in problems such as inaccurate control of water content, loose internal structure, and poor surface formation.

[0003] Traditional tofu making processes typically employ a single pressing mode or a simple two-stage pressing method. The simple pressing method results in a relatively singular path for water to drain from the tofu, making it easy for water retention zones to form inside the tofu block. On the other hand, using high-pressure rapid pressing can cause the surface to form a skin too early, hindering the continued drainage of internal water and consequently extending the pressing time.

[0004] Therefore, this application provides a staged pressing process for making firm tofu and a pressing device thereof, which solves the problems of simple pressing mode and low pressing efficiency in the pressing process of firm tofu in the prior art. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a staged pressing process for preparing firm tofu and a pressing device thereof.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A process for preparing firm tofu using a phased pressing method includes five stages of pressure control. The first three stages employ a pressing device for slow, gradual pressing at a pressure ≤20 kPa, while the latter two stages employ rapid, high-pressure pressing at a pressure ≥30 kPa. The total pressing time for the five stages is 25 ± 2 min.

[0008] As an optimization, the third stage is a pulse suppression mode with a suppression / release time ratio of 4:1.

[0009] As an optimization, the specific details of the five-stage pressure control are as follows:

[0010] S1. First stage of pressing: During the first 0-5 minutes, the initial pressure is 5-10 kPa, the pressing plate descends at a speed of 0.5-1 cm / min, and the pressing is repeated 3 times with a 30-second interval between each pressing.

[0011] S2. Second stage of pressing: After 5-10 minutes, the pressure is increased to 15-20 kPa, and the pressing plate of the pressing device descends at a speed of 0.2-0.5 cm / min, with an interval of 1 minute;

[0012] S3. Third stage compression: At 10-15 min, maintain a pressure of 20 kPa and use pulse compression, with a cycle of 2 min compression and 30 s release.

[0013] S4. Fourth stage compression: At 15-20 min, rapidly increase the pressure to 30-35 kPa, increase the platen speed to 2 cm / min, and each compression lasts for 5 min;

[0014] S5. Fifth stage of pressing: At 20-25 minutes, the peak pressure is 40-45 kPa. With the assistance of surface hot air, the temperature is maintained at 50-60℃ to achieve rapid skin formation.

[0015] A pressing device includes a pressing box and a hydraulic assembly. The pressing box includes a box body (1) and a pressing plate. The hydraulic assembly is vertically connected to the upper side of the pressing plate. The pressing plate includes a connecting frame and a movable bottom surface. The movable bottom surface includes several adjacent strip plates. A spring support rod is connected between the connecting frame and the strip plates. A progressive extrusion assembly is provided inside the connecting frame. The progressive extrusion assembly is arranged along the length direction of the connecting frame. When the progressive extrusion assembly rotates, it can sequentially extrude several strip plates along the length direction of the connecting frame, extruding the water in the tofu downwards and towards the drainage side.

[0016] The progressive extrusion assembly includes a connecting shaft and several sets of extrusion components. Each set of extrusion components includes two parallel extrusion discs, which are respectively located on the upper side of the two long sides of the strip plate. When the connecting shaft rotates, the extrusion disc on the far drainage side contacts the strip plate first, and the extrusion disc on the near drainage side contacts the strip plate later.

[0017] As an optimization, the extrusion disc is fan-shaped, and the extrusion disc is coaxially arranged with the connecting shaft. The central angles of the two extrusion discs in each group of extrusion parts are different.

[0018] From the far drainage side to the near drainage side, the central angle of the extrusion disc gradually decreases.

[0019] As an optimization, one end of the connecting shaft is provided with a drive assembly, which includes a drive motor and a connecting belt. One end of the connecting shaft is provided with a connecting gear, the output shaft of the drive motor is provided with a drive gear, and the connecting belt is sleeved on the outside of the connecting gear and the drive gear.

[0020] As an optimization, each of the strip plates is equipped with at least 4 spring support rods, which are rotatably connected to the strip plate. The spring support rods near the drainage side can slide relative to the connecting frame.

[0021] When the strip plate is located above the bottom surface of the connecting frame, the spring support rod is in a shortened state.

[0022] As an optimization, a drain outlet is provided on one side of the bottom of the pressing box along its length, and the central angle of the extruder near the drain outlet is smaller than the central angle of the extruder away from the drain outlet.

[0023] As an optimization, several of the extruders have the same diameter, and the connecting shaft is arranged adjacent to the strip plate. When the tofu is extruded, the distance between the connecting shaft and the adjusting plate is less than the diameter of the extruder.

[0024] As an optimization, the hydraulic assembly includes a telescopic cylinder, which is vertically connected to the upper part of the connecting frame.

[0025] The beneficial effects of this plan are as follows:

[0026] The preparation process of this application achieves directional water removal through a five-stage gradient pressing system. During the pressing process, the water is removed gradually from a slow start to a fast start, which can effectively prevent premature skin formation on the surface of the tofu and ensure efficient water removal and uniform distribution. Finally, a dense structure is formed through rapid high-pressure pressing, which avoids the loose internal structure of the firm tofu and produces high-quality firm tofu with a skin thickness of ≥0.8mm and a central water content of 68-72%.

[0027] The pressing device of this application can press tofu from top to bottom along the length of the pressing device, thereby "draining" the water from the firm tofu and squeezing the water in the firm tofu toward the drainage side, thus preventing the water from being absorbed back after the pressing device is released.

[0028] The progressive extrusion assembly creates a track-like extrusion effect by setting extrusion discs with differentiated central angles. The fan-shaped extrusion discs ensure linear pressure transmission and avoid local stress concentration. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the pressing device of the present invention from the side.

[0030] Figure 2 This is a front view schematic diagram of the pressing device of the present invention.

[0031] Figure 3 This is a schematic diagram of the bottom axial side of the pressing device of the present invention.

[0032] Figure 4 This is an isometric view of the connection structure between the pressure plate and the hydraulic assembly of the present invention.

[0033] Figure 5 This is a front view schematic diagram of the connection structure between the pressure plate and the hydraulic component of the present invention.

[0034] Figure 6 For the present invention Figure 5 A schematic diagram of the AA cross-section structure.

[0035] Figure 7 This is an isometric view of the positional structure of the movable bottom surface and the progressive extrusion assembly of the present invention.

[0036] Figure 8 This is a schematic diagram of the back axis of the position structure of the active bottom surface and the progressive extrusion assembly of the present invention.

[0037] Figure 9 This is a schematic diagram of the overall structure of the progressive extrusion assembly of the present invention.

[0038] Figure 10 This is a schematic diagram of the progressive extrusion assembly of the present invention from the axial side.

[0039] The components are: 1. Box body, 2. Connecting frame, 3. Strip plate, 4. Spring support rod, 5. Connecting shaft, 6. Extrusion plate, 7. Drive motor, 8. Connecting belt, 9. Drain outlet, and 10. Telescopic cylinder. Detailed Implementation

[0040] A process for preparing firm tofu using a phased pressing method includes five stages of pressure control. The first three stages employ a pressing device for slow, gradual pressing at a pressure ≤20 kPa, while the latter two stages employ rapid, high-pressure pressing at a pressure ≥30 kPa. The total pressing time for the five stages is 25 ± 2 min.

[0041] The third stage is a pulsed suppression mode with a suppression / release time ratio of 4:1.

[0042] The five-stage pressure control process is detailed below:

[0043] S1. First stage of pressing: During the first 0-5 minutes, the initial pressure is 5-10 kPa, the pressing plate descends at a speed of 0.5-1 cm / min, and the pressing is repeated 3 times with a 30-second interval between each pressing.

[0044] S2. Second stage of pressing: After 5-10 minutes, the pressure is increased to 15-20 kPa, and the pressing plate of the pressing device descends at a speed of 0.2-0.5 cm / min, with an interval of 1 minute;

[0045] S3. Third stage compression: At 10-15 min, maintain a pressure of 20 kPa and use pulse compression, with a cycle of 2 min compression and 30 s release.

[0046] S4. Fourth stage compression: At 15-20 min, rapidly increase the pressure to 30-35 kPa, increase the platen speed to 2 cm / min, and each compression lasts for 5 min;

[0047] S5. Fifth stage of pressing: At 20-25 minutes, the peak pressure is 40-45 kPa. With the assistance of surface hot air, the temperature is maintained at 50-60℃ to achieve rapid skin formation.

[0048] The embodiments employ the above-described staged pressing process for preparing firm tofu and the pressing device of this application to prepare firm tofu. Comparative Example 1 uses the preparation process of this application and produces firm tofu using an existing one-time pressing device. Comparative Example 2 uses a one-time pressing method and an existing one-time pressing device to prepare firm tofu. Comparative Example 3 uses a two-stage pressing method and the pressing device of this application to produce dried tofu. The specific details and product testing results are as follows:

[0049]

[0050] In Examples 1-3, the pressing time was 25 minutes, with each of the five stages being pressed for 5 minutes. In Comparative Example 2, the pressing was performed at 35 kPa for 25 minutes, and in Comparative Example 3, the pressing was performed at 20 kPa for 15 minutes and at 45 kPa for 10 minutes.

[0051] As shown in the table above, the tofu skin obtained using the phased pressing process and pressing device of this application has a moderate thickness and a central moisture content of about 70%. In contrast, Comparative Example 2, using a traditional single-stage pressing method and ordinary pressing device, resulted in an excessively thick tofu skin with an excessively high central moisture content, exhibiting a dry exterior and a wet interior. Comparative Example 3, using the existing two-stage pressing method and the pressing device of this application, yielded a tofu skin with a relatively lower moisture content, significantly lower than that of Comparative Example 2.

[0052] Therefore, the phased pressing process and pressing device of this application can effectively reduce the water content of firm tofu and obtain firm tofu with a suitable skin thickness.

[0053] like Figures 1-10 As shown, the pressing device includes a pressing box and a hydraulic assembly. The pressing box includes a box body 1 and a pressure plate. The hydraulic assembly is vertically connected to the upper side of the pressure plate. The pressure plate includes a connecting frame 2 and a movable bottom surface. The movable bottom surface includes several adjacent strip plates 3. A spring support rod 4 connects the connecting frame 2 and the strip plates 3. A progressive extrusion assembly is provided inside the connecting frame 2. The progressive extrusion assembly is arranged along the length direction of the connecting frame 2. When the progressive extrusion assembly rotates, it can sequentially extrude the strip plates 3 along the length direction of the connecting frame 2, squeezing the water in the tofu downwards and towards the drainage side.

[0054] The progressive extrusion assembly includes a connecting shaft 5 and several sets of extrusion components. Each set of extrusion components includes two parallel extrusion discs 6. The two extrusion discs 6 are respectively located on the upper side of the two long sides of the strip plate 3. When the connecting shaft 5 rotates, the extrusion disc 6 on the far drainage side contacts the strip plate 3 first, and the extrusion disc 6 on the near drainage side contacts the strip plate 3 later.

[0055] The side furthest from the drain is the side away from the drain flow direction, and the side closest to the drain flow direction is the side closest to the drain flow direction. For example, if the water flows from left to right during the squeezing process, then the left side is the furthest from the drain and the right side is the inlet and outlet side.

[0056] The extrusion disc 6 can be fixedly sleeved on the connecting shaft 5, or it can be integrally formed with the connecting shaft 5. When the connecting shaft 5 rotates, it drives multiple extrusion discs 6 to rotate simultaneously. The extrusion disc 6 with a larger central angle can contact the strip plate 3 earlier and push the strip plate 3 downward to extrude the tofu.

[0057] To ensure that the strip plate 3 can be pressed downward stably, multiple parallel progressive extrusion components can be installed inside the connecting frame 2 to stably extrude the strip plate 3.

[0058] like Figure 9 and Figure 10 As shown, the extrusion disc 6 is fan-shaped and is coaxially arranged with the connecting shaft 5. The two extrusion discs 6 of each group of extrusion parts have different central angles.

[0059] From the far drainage side to the near drainage side, the central angle of the extrusion disc 6 gradually decreases.

[0060] Each extrusion disc 6 has a different central angle, and multiple extrusion discs 6 are aligned at one end, so that the other ends of the multiple extrusion discs 6 are arranged in a stepped distribution. When the connecting shaft 5 rotates, the stepped extrusion discs 6 come into contact with the strip plate 3 in sequence.

[0061] like Figure 10 As shown, a drive assembly is provided at one end of the connecting shaft 5. The drive assembly includes a drive motor 7 and a connecting belt 8. A connecting gear is provided at one end of the connecting shaft 5. A drive gear is provided on the output shaft of the drive motor 7. The connecting belt 8 is sleeved on the outside of the connecting gear and the drive gear.

[0062] The connecting belt 8 can mesh with the drive gear and the connecting gear, driving the connecting shaft 5 to rotate synchronously. Meanwhile, to ensure the stability of the rotation of the connecting shaft 5, a support seat should be provided inside the connecting frame 2, allowing the connecting shaft 5 to be rotatably connected to the support seat.

[0063] like Figure 3 and Figure 7 As shown, each of the strip plates 3 is equipped with at least 4 spring support rods 4, which are rotatably connected to the strip plate 3. The spring support rods 4 near the drainage side can slide relative to the connecting frame 2.

[0064] When the strip plate 3 is located on the upper side of the bottom surface of the connecting frame 2, the spring support rod 4 is in a shortened state.

[0065] The strip plate 3 can be pressed downward through the bottom of the connecting frame 2. Because the two pressing discs 6 corresponding to the strip plate 3 press downward at different times, the strip plate 3 will rotate during downward pressing. Therefore, the spring support rod 4 near the drainage side will have a certain amount of relative displacement with the strip plate 3. Correspondingly, the strip plate 3 should be provided with a sliding groove so that the lower end of the spring support rod 4 can slide relative to the sliding groove.

[0066] like Figure 1 As shown, a drain outlet 9 is provided at the bottom of one side of the pressing box along its length direction, and the central angle of the extruder near the drain outlet 9 is smaller than the central angle of the extruder away from the drain outlet 9.

[0067] like Figure 8 As shown, several of the extrusion pieces have the same diameter, and the connecting shaft 5 is arranged adjacent to the strip plate 3. When the tofu is extruded, the distance between the connecting shaft 5 and the adjusting plate is less than the diameter of the extrusion piece.

[0068] like Figure 1 As shown, the hydraulic assembly includes a telescopic cylinder 10, which is vertically connected to the upper part of the connecting frame 2.

[0069] How to use:

[0070] In practical use, the pressing device of this application first presses the pressing plate downward through the telescopic cylinder 10;

[0071] When the pressing plate is pressed tightly against the tofu, the strip plate 3 is stored inside the connecting frame 2;

[0072] The drive motor 7 drives the connecting shaft 5 to rotate, and the connecting shaft 5 drives the extrusion disc 6 to rotate. When the extrusion disc 6 contacts the strip plate 3, it pushes the strip plate 3 downward to squeeze, and the telescopic cylinder 10 extends synchronously to improve the extrusion effect on the tofu.

[0073] Since the size of the extrusion plate 6 corresponding to each strip plate 3 is different, and the extrusion plate 6 gradually decreases from the drain side to the water inlet side, multiple strip plates 3 are squeezed in sequence, thereby squeezing the water in the tofu toward the drain outlet 9 and promoting the discharge of water.

[0074] To ensure efficient operation of the device, a limiting groove or similar structure can be installed inside the connecting frame 2, allowing the strip plate 3 to move downwards along the limiting groove during pressing, preventing the strip plate 3 from shaking. Correspondingly, the bottom of the connecting frame 2 can be open, or it can be fitted with a high-density filter cloth or filter membrane with a certain degree of elasticity to limit the top of the tofu and prevent the tofu from being damaged by pressure.

[0075] The above-described specific embodiments are merely specific examples of the present invention. The patent protection scope of the present invention includes, but is not limited to, the product form and style of the above-described specific embodiments. Any staged pressing process for making firm tofu and its pressing device that conforms to the claims of the present invention, and any appropriate changes or modifications made by those skilled in the art, shall fall within the patent protection scope of the present invention.

Claims

1. A tofu pressing device, comprising a pressing box and a hydraulic assembly, wherein the pressing box comprises a box body (1) and a pressure plate, and the hydraulic assembly is vertically connected to the upper side of the pressure plate, characterized in that: The pressing plate includes a connecting frame (2) and a movable bottom surface. The movable bottom surface includes several adjacent strip plates (3). A spring support rod (4) is connected between the connecting frame (2) and the strip plates (3). A progressive extrusion assembly is provided inside the connecting frame (2). The progressive extrusion assembly is arranged along the length direction of the connecting frame (2). When the progressive extrusion assembly rotates, it can sequentially extrude several strip plates (3) along the length direction of the connecting frame (2), extruding the water in the tofu downwards and towards the drainage side. The progressive extrusion assembly includes a connecting shaft (5) and several sets of extrusion components. Each set of extrusion components includes two parallel extrusion discs (6). The two extrusion discs (6) are respectively located on the upper side of the two long sides of the strip plate (3). When the connecting shaft (5) rotates, the extrusion disc (6) on the far side of the drainage first contacts the strip plate (3), and the extrusion disc (6) on the near side of the drainage then contacts the strip plate (3). Each of the strip plates (3) is equipped with at least 4 spring support rods (4), which are rotatably connected to the strip plate (3). The spring support rods (4) near the drainage side can slide relative to the connecting frame (2). When the strip plate (3) is located above the bottom surface of the connecting frame (2), the spring support rod (4) is in a shortened state; The extrusion disc (6) is fan-shaped and is coaxial with the connecting shaft (5). The two extrusion discs (6) of each set of extrusion parts have different central angles. From the far drainage side to the near drainage side, the central angle of the extrusion disc (6) gradually decreases; Each extrusion disc (6) has a different central angle. One end of the multiple extrusion discs (6) is aligned, so that the other end of the multiple extrusion discs (6) is distributed in a stepped manner. When the connecting shaft (5) rotates, the stepped extrusion discs (6) come into contact with the strip plate (3) in sequence.

2. The tofu pressing device according to claim 1, characterized in that: One end of the connecting shaft (5) is provided with a drive assembly, which includes a drive motor (7) and a connecting belt (8). One end of the connecting shaft (5) is provided with a connecting gear, and the output shaft of the drive motor (7) is provided with a drive gear. The connecting belt (8) is sleeved on the outside of the connecting gear and the drive gear.

3. The tofu pressing device according to claim 1, characterized in that: A drain outlet (9) is provided at the bottom of one side of the pressing box along its length. The central angle of the extruder near the drain outlet (9) is smaller than that of the extruder away from the drain outlet (9).

4. The tofu pressing device according to claim 1, characterized in that: Several of the extrusion pieces have the same diameter. The connecting shaft (5) is arranged adjacent to the strip plate (3). When the tofu is extruded, the distance between the connecting shaft (5) and the adjusting plate is less than the diameter of the extrusion piece.

5. The tofu pressing device according to claim 1, characterized in that: The hydraulic assembly includes a telescopic cylinder (10), which is vertically connected to the upper part of the connecting frame (2).

6. A staged pressing process for preparing firm tofu, using the firm tofu pressing device according to any one of claims 1-5, characterized in that: It includes five stages of pressure control. The first three stages use a pressing device for slow, gradual pressing with a pressure ≤20 kPa, while the last two stages use rapid, high-pressure pressing with a pressure ≥30 kPa. The total pressing time for the five stages is 25 ± 2 min.

7. The process for preparing firm tofu through staged pressing according to claim 6, characterized in that: The third stage is a pulsed suppression mode with a suppression / release time ratio of 4:

1.

8. The process for preparing firm tofu through staged pressing according to claim 6, characterized in that: The five-stage pressure control process is detailed below: S1. First stage of pressing: During the first 0-5 minutes, the initial pressure is 5-10 kPa, the pressing plate descends at a speed of 0.5-1 cm / min, and the pressing is repeated 3 times with a 30-second interval between each pressing. S2. Second stage of pressing: After 5-10 minutes, the pressure is increased to 15-20 kPa, and the pressing plate of the pressing device descends at a speed of 0.2-0.5 cm / min, with an interval of 1 minute; S3. Third stage compression: At 10-15 min, maintain a pressure of 20 kPa and use pulse compression, with a cycle of 2 min compression and 30 s release. S4. Fourth stage compression: At 15-20 min, rapidly increase the pressure to 30-35 kPa, increase the platen speed to 2 cm / min, and each compression lasts for 5 min; S5. Fifth stage of pressing: At 20-25 minutes, the peak pressure is 40-45 kPa. With the assistance of surface hot air, the temperature is maintained at 50-60℃ to achieve rapid skin formation.

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