Storage technology of bean curd

Abstract

The invention discloses a storage process of bean curd. The storage process comprises the following steps: step 1, putting the bean curd into a container; 2, the container is filled with hot water so that air in the container and the bean curds can be completely exhausted; 3, sealing the container; 4, the sealed container is subjected to sterilization treatment; air in the container and tofu is completely exhausted through boiled water, and the preservation time of the tofu in the sealed container is prolonged; meanwhile, the pressure between the bean curds and between the bean curds and the container is reduced through buoyancy of water, and transportation and storage are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of food storage, and particularly relates to a storage process for tofu. Background Art

[0002] With the development of economy and society, people's living standards have been continuously improved, the pace of life has accelerated, and higher requirements have been put forward for food. People pursue convenient, fast, safe and healthy eating methods. To achieve the purpose of convenience and speed, people rely more on finished or semi-finished foods. Therefore, the food industry has developed rapidly and has become one of the three pillar industries of the national economy; foods are easily invaded by a series of microorganisms such as bacteria, molds, and yeasts during processing, preservation, and consumption, resulting in spoilage. Spoilage not only makes the food lose its nutritional value but also causes food poisoning. There are various storage methods for tofu in the prior art, including direct refrigeration, brine treatment, boiling or steaming, oil sealing, vacuum packaging, frozen storage, high-temperature disinfection, and the use of food preservatives, etc. However, most of them can only be stored for 5 - 10 days and cannot be stored for a long time. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a storage process for tofu, which extends the storage time of tofu.

[0004] The present invention adopts the following technical solutions:

[0005] A storage process for tofu, comprising:

[0006] Step 1: Place at least one piece of tofu in a container;

[0007] Step 2: Fill the container with hot water to expel the air in the container and the tofu;

[0008] Step 3: Seal the container;

[0009] Step 4: Sterilize the sealed container;

[0010] Through the combined process of filling with hot water to expel oxygen, sealing, and sterilization, oxygen is effectively isolated to inhibit the growth of microorganisms, the shelf life of tofu is extended, and at the same time, the preliminary inactivation of some bacteria can be achieved by the pretreatment with high-temperature hot water.

[0011] Preferably, Step 1 further includes: processing the tofu into the same shape as the container, so that the distance between the tofu and the container is small, and the shape of the tofu is adapted to the container to minimize the air remaining space, reduce the gas dead angle when injecting hot water, and ensure that the sterilization medium (hot water) can completely wet the surface of the tofu.

[0012] Preferably, the distance between the tofu and the container is at most 3 mm. This 3-mm distance limit not only ensures that the tofu is not mechanically damaged but also forms capillary channels to facilitate the penetration of hot water, while avoiding excessive voids that may cause air retention and affect the sterilization effect. At the same time, it can also prevent the tofu from being damaged due to collisions between the tofu and the container during transportation.

[0013] Preferably, the distance between the tofu and the container is 2 mm. The 2-mm gap design and buoyancy support reduce the impact force on the tofu during the thermal sterilization stage, avoiding the pore collapse caused by self-weight extrusion in the traditional process.

[0014] Preferably, multiple pieces of tofu are stacked or placed side by side in the container. The multi-layer / multi-piece three-dimensional arrangement improves the space utilization rate of the container. Through the design of the hot water circulation channel, it is ensured that each piece of tofu can be evenly heated, realizing large-scale storage for industrial production.

[0015] Preferably, the hot water in step two is at least water above 80 degrees Celsius. High-temperature water above 80 °C can fully dissolve the protein on the surface of the tofu to form a protective film.

[0016] Preferably, the hot water in step two is boiling water at 100 degrees Celsius. Instantaneous treatment with boiling water can destroy the activity of lipoxygenase inside the tofu and inhibit the generation of beany smell during storage.

[0017] Preferably, in step two, boiling water fills the space between adjacent pieces of tofu and between the tofu and the inner wall of the container. By reducing the pressure between the tofu pieces and between the tofu and the container through buoyancy, a hydrodynamic support layer is formed using the buoyancy of the boiling water, effectively dispersing the self-weight pressure of the tofu and preventing the tissue structure collapse caused by the traditional stacking method, and maintaining the honeycomb porosity.

[0018] Preferably, in step three, when the hot water fills the container, the container is sealed, or after the hot water fills the container, hot water is continuously injected into the container to keep the container always in a filled state and then sealed. The dynamic liquid sealing technology realizes the construction of a zero-oxygen environment, and by continuously injecting water under positive pressure, the cooling shrinkage effect is offset, eliminating the mechanical stress damage caused by traditional vacuum packaging to the surface of the tofu.

[0019] Preferably, the container is one of a stainless steel tank, a plastic box, or a plastic packaging bag; a cylindrical tank body can form rotational turbulence to enhance the sterilization effect, and the elastic modulus of food-grade plastic adapts to the thermal expansion and contraction coefficient of the tofu. The selection of multiple materials meets the requirements of different cold chain scenarios.

[0020] Preferably, the sterilization treatment in step four is the pasteurization method. The synergistic effect of pasteurization and the previous hot water treatment can inactivate pathogenic bacteria while retaining the characteristic lactic acid bacteria in tofu, achieving the dual goals of "directed sterilization" and beneficial flora regulation. The instantaneous boiling water treatment can increase the inactivation rate of lipoxygenase, control the content of bean odor substances (such as hexanal) below 0.02 μg / g, reaching the level that cannot be detected by the senses; at the same time, pasteurization (62-65 °C / 30 min) selectively retains characteristic flavor precursor substances (such as γ-aminobutyric acid). Analyzed by GC-MS, its content is 2.3 times higher than that of the high-temperature sterilization process.

[0021] Compared with the prior art, the present invention has the following advantages: The present invention provides a storage process for tofu. At least one piece of tofu is placed in a container, the container is filled with hot water to exhaust the air in the container and the tofu, the container is sealed, and the sealed container is sterilized. Through the combined process of hot water filling for oxygen exhaustion, sealing, and sterilization, oxygen can be effectively isolated to inhibit the growth of microorganisms, extend the shelf life of tofu, and at the same time, the preliminary inactivation of some bacteria can be achieved by high-temperature hot water pretreatment. Specific Embodiments

[0022] In order to facilitate the understanding of the technical solution of the present invention, the following will be described in detail with reference to specific embodiments.

[0023] Example 1

[0024] A storage process for tofu includes:

[0025] Step 1: Cut a piece of tofu into a cylindrical shape and place it in a cylindrical stainless steel tank. The distance between the cylindrical tofu and the annular side wall of the cylindrical stainless steel tank is 3 mm;

[0026] Step 2: Fill the container with 80-degree hot water to exhaust the air in the container and the tofu, so that the 80-degree hot water fills the space between the tofu and the cylindrical stainless steel tank;

[0027] Step 3: When the water fills the cylindrical stainless steel tank, cover the stainless steel upper cover on the cylindrical stainless steel tank through a capping machine for sealing to ensure that there is no air in the cylindrical stainless steel tank;

[0028] Step 4: Perform pasteurization treatment on the sealed container.

[0029] Among them, the tofu selected is the common old tofu on the market. After the above treatment, the entire cylindrical stainless steel tank can be stored in an environment of 0-5 for 50 days without bulging.

[0030] Example 2

[0031] A storage process for tofu includes:

[0032] Step 1: Cut three pieces of tofu into cylindrical shapes and stack them in a cylindrical stainless-steel tank. The distance between the cylindrical tofu and the annular side wall of the cylindrical stainless-steel tank is 2 mm;

[0033] Step 2: Fill the container with boiling water at 100 degrees Celsius to expel the air from the container and the tofu, so that the boiling water at 100 degrees Celsius fills the space between the tofu and the cylindrical stainless-steel tank;

[0034] Step 3: When the water fills the cylindrical stainless-steel tank, cover the cylindrical stainless-steel tank with a stainless-steel upper cover through a capping machine for sealing to ensure that there is no air in the cylindrical stainless-steel tank;

[0035] Step 4: Conduct pasteurization treatment on the sealed container.

[0036] Among them, the tofu used is the common old tofu on the market. After the above treatment, the entire cylindrical stainless-steel tank can be stored in a refrigerator at 0 - 5 degrees Celsius for 60 days without bulging.

[0037] Example 3

[0038] A storage process for tofu, including:

[0039] Step 1: Cut three pieces of tofu into cuboid shapes and place them side by side in a cuboid stainless-steel tank. The distance between the cuboid tofu and the side wall of the cuboid stainless-steel tank is 2.5 mm;

[0040] Step 2: Fill the container with boiling water at 100 degrees Celsius to expel the air from the container and the tofu, so that the boiling water at 100 degrees Celsius fills the space between the tofu and the cuboid stainless-steel tank;

[0041] Step 3: After the water fills the cuboid stainless-steel tank, continuously inject boiling water into the container to keep the container always full, and cover the cuboid stainless-steel tank with a stainless-steel upper cover through a capping machine for sealing to ensure that there is no air in the cuboid stainless-steel tank;

[0042] Step 4: Conduct pasteurization treatment on the sealed container.

[0043] Among them, the tofu used is the common old tofu on the market. After the above treatment, the entire cuboid stainless-steel tank can be stored in a refrigerator at 0 - 5 degrees Celsius for 60 days without bulging.

[0044] Example 4

[0045] A storage process for tofu, including:

[0046] Step 1: Cut three pieces of tofu into cuboid shapes and place them side by side in a cuboid plastic box. The distance between the cuboid tofu and the side wall of the cuboid plastic box is 1.5 mm;

[0047] Step 2: Fill the container with 90-degree hot water to expel the air in the container and the tofu, so that the 90-degree hot water fills the space between the tofu and the rectangular plastic box;

[0048] Step 3: When the water fills the rectangular plastic box, seal the plastic film on the rectangular plastic box through a plastic sealing machine to ensure that there is no air in the rectangular plastic box;

[0049] Step 4: Conduct pasteurization treatment on the sealed container.

[0050] Among them, the tofu used is the common old tofu on the market. After the above treatment, placing the entire rectangular plastic box in an environment of 0 - 5°C for refrigeration can keep it from bulging for 55 days.

[0051] Example 5

[0052] A storage process for tofu, including:

[0053] Step 1: Place a piece of tofu in a plastic packaging bag, with a spacing of 3 mm between the tofu and the plastic packaging bag;

[0054] Step 2: Fill the plastic packaging bag with 100-degree boiling water to expel the air in the container and the tofu, so that the 100-degree boiling water fills the space between the tofu and the plastic packaging bag;

[0055] Step 3: When the water fills the plastic packaging bag, seal the opening of the plastic packaging bag through a plastic sealing machine to ensure that there is no air in the plastic packaging bag;

[0056] Step 4: Conduct pasteurization treatment on the sealed container.

[0057] Among them, the tofu used is the common old tofu on the market. After the above treatment, placing the entire plastic packaging bag in an environment of 0 - 5°C for refrigeration can keep it from bulging for 55 days.

[0058] Example 6

[0059] A storage process for tofu, including:

[0060] Step 1: Cut three pieces of tofu into cylindrical shapes, soak them in a 0.5% sodium lactate solution at 40°C for 90 seconds to form an ion exchange layer (with a thickness of about 50 μm), enhance the anti-deformation ability during subsequent high-temperature treatment, and stack them in a cylindrical stainless steel tank, with a spacing of 2 mm between the cylindrical tofu and the annular side wall of the cylindrical stainless steel tank;

[0061] Step 2: Fill the container with 100-degree boiling water to expel the air in the container and the tofu, so that the 100-degree boiling water fills the space between the tofu and the cylindrical stainless steel tank;

[0062] Step 3: With the cylindrical stainless - steel tank filled with water, cover the stainless - steel upper cover on the cylindrical stainless - steel tank through a capping machine for sealing to ensure there is no air inside the cylindrical stainless - steel tank;

[0063] Step 4: Conduct pasteurization treatment on the sealed container.

[0064] Among them, step 2 also includes:

[0065] (1) Pre - filling stage: Inject 100 °C boiling water from the bottom of the container at a rate of 0.3 L / min to 1 / 3 of the height and maintain for 120 seconds to pre - gelatinize the protein on the surface of the tofu.

[0066] (2) Turbulent displacement stage: Switch to the pulsed water injection mode (pressure 0.15 MPa, frequency 2 Hz), inject 100 °C boiling water to 95% of the volume, and reduce the dissolved oxygen content to less than 0.8 mg / L.

[0067] (3) Dynamic sealing stage: When the liquid level is 5 mm from the port, start the synchronous suction device (vacuum degree - 0.02 MPa), and at the same time replenish boiling water at a rate of 0.1 L / min to achieve zero - bubble sealing.

[0068] Step 3 also includes:

[0069] Immediately after sealing, cool down to 85 °C at a rate of 1 °C / s, and maintain internal convection so that the tofu blocks are supported by buoyancy (the density difference is controlled at 0.05 g / cm 3 ).

[0070] Step 4 also includes:

[0071] (1) Pasteurization gradient: Maintain at 62 °C for 25 min → maintain at 68 °C for 8 min → maintain at 55 °C for 15 min, and the cumulative F value reaches 4.8 to ensure that the killing rate of Bacillus stearothermophilus is ≥ 95%.

[0072] (2) Electromagnetic assistance: Apply a 27 MHz high - frequency electric field (field strength 15 V / cm) to promote the dipole rotation of water molecules, and shorten the sterilization time by 40%.

[0073] The above is only the preferred embodiment of the present invention. The protection scope of the present invention is subject to the scope defined by the claims. Several improvements and refinements made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A storage process for tofu, characterized in that, Comprising: Step 1: Place at least one piece of tofu in a container; Step 2: Fill the container with hot water to expel the air in the container and the tofu; Step 3: Seal the container; Step 4: Perform sterilization treatment on the sealed container.

2. The storage process of tofu according to claim 1, characterized in that, Step 1 further includes: Processing the tofu into the same shape as the container so that the distance between the tofu and the container is small.

3. The storage process of tofu according to claim 2, characterized in that, The distance between the tofu and the container is at most 3 mm.

4. The storage process of tofu according to claim 1, characterized in that, Multiple pieces of tofu are stacked or placed side by side in the container.

5. The storage process of tofu according to claim 5, characterized in that, In Step 2, the hot water is at least above 80 degrees Celsius.

6. The storage process of tofu according to claim 5, characterized in that, In Step 2, the hot water is boiling water at 100 degrees Celsius.

7. The storage process of tofu according to claim 6, characterized in that, In Step 2, the boiling water fills the space between adjacent pieces of tofu and between the tofu and the inner wall of the container, reducing the pressure between the tofu and the pressure between the tofu and the container through buoyancy.

8. The storage process of tofu according to claim 1, characterized in that, In Step 3, when the hot water fills the container, seal the container, or after the hot water fills the container, continuously inject hot water into the container so that the container is always in a filled state and then seal the container.

9. The storage process of tofu according to claim 1, characterized in that, The container is one of a stainless steel tank, a plastic box, or a plastic packaging bag.

10. The storage process of tofu according to claim 1, characterized in that, In Step 4, the sterilization treatment is pasteurization.