Vertical temperature-variable pressure-difference quantitative puffed nut kernel crisp processing method and puffing equipment

Abstract

The application discloses a vertical variable-temperature pressure-difference quantitative puffed nut kernel crisp processing method and a puffing equipment, and relates to the field of food processing and treatment. The method comprises the following steps: after the nut kernel raw material is cleaned and soaked, standing and draining; the pretreated nut kernel is loaded into a hanging basket in a vertical puffing tank, steam is introduced into the vertical puffing tank, the nut kernel is subjected to steaming treatment, the vertical puffing tank is heated, the water in the nut kernel is vaporized, the pressure in the tank is increased and the tank is kept warm; the pressure relief valve between the vertical puffing tank and the vacuum tank is quickly opened, the pressure in the vertical puffing tank is instantaneously reduced, the water in the nut kernel is flash evaporated, the volume of the nut kernel is expanded, and a honeycomb structure is formed; the nut kernel is continuously heated and dehydrated under vacuum until the water content of the nut kernel is reduced; heating is stopped, and the nut kernel is cooled to room temperature; and the micro-puffed crisp nut kernel is obtained. Through the above steps, the quality problems of the existing nut kernel, such as hard taste, easy oxidation, great loss of nutrients, short shelf life and serious homogenization after high-temperature roasting and frying processing, can be solved.

Description

Technical Field

[0001] This invention relates to the field of food processing, and in particular to a vertical variable temperature and pressure differential quantitative puffing method and puffing equipment for making nuts crispy. Background Technology

[0002] Nuts are a popular snack among consumers. Currently, most nut products on the market are processed using high-temperature roasting or baking techniques, typically at temperatures between 120 and 180°C. This process dehydrates and cooks the nuts through heating, resulting in a specific aroma and crisp texture.

[0003] However, traditional high-temperature frying or baking processes have the following technical drawbacks: Nuts are rich in unsaturated fatty acids, which are chemically reactive and readily oxidize when in direct contact with air at high temperatures. Studies have shown that for every 10°C increase in temperature, the rate of oil oxidation approximately doubles. During oxidation, oils produce hydroperoxides, which further decompose to produce low-molecular-weight aldehydes, ketones, and other substances. Simultaneously, the peroxide value and acid value increase significantly, not only reducing the product's commercial value and shelf life but also posing potential health hazards.

[0004] Prolonged high-temperature roasting will destroy heat-sensitive nutrients in nuts, such as vitamin E and B vitamins, resulting in a decrease in the nutritional value of the product.

[0005] Some manufacturers add synthetic antioxidants to their products to inhibit oil oxidation and extend shelf life, which contradicts the current consumer trend of pursuing natural, healthy, and clean-label foods.

[0006] Therefore, developing a new processing technology that can maintain the good taste of nuts, reduce oil oxidation, retain nutrients, extend shelf life, and eliminate the need for added antioxidants is of great practical significance and market value. Summary of the Invention

[0007] This invention provides a vertical variable temperature and pressure differential quantitative puffing method and puffing equipment for making crispy nuts, which can solve the quality problems of existing nuts after high-temperature processing, such as hard texture, easy oxidation, large loss of nutrients, and serious homogenization.

[0008] To address the above problems, this invention provides a vertical variable temperature and pressure differential quantitative puffing method for processing crispy nuts, comprising: Step 1: Wash and soak the nuts, then let them drain. Step 2: Place the pre-treated nuts into the hanging basket inside the vertical puffing tank, layering them so that the layers are not squeezed together; Step 3: Steam is introduced into the vertical puffing tank to steam the nuts, so that the nuts are initially cooked and absorb moisture. Step 4: Heat the vertical puffing tank to vaporize and evaporate the moisture inside the nuts, and pressurize and keep the tank warm. Step 5: Quantitatively set the valve opening size according to the required puffing rate, so that the pressure inside the vertical puffing tank drops instantly, causing the internal moisture of the nuts to flash evaporate, expand in volume, and form a honeycomb structure; Step Six: Continue heating and dehydration under vacuum until the moisture content of the nuts decreases; Step 7: Stop heating, cool to room temperature, and remove to obtain slightly puffed and crispy nuts.

[0009] The present invention provides a vertical variable temperature and pressure difference quantitative puffing method for making crispy nuts, which, compared with the prior art, has the following beneficial effects, but is not limited to: By layering nuts in a vertical puffing tank and sequentially steaming, heating and pressurizing, instantaneous pressure release flash steaming, and vacuum dehydration, a uniform honeycomb-like porous structure can be formed inside the nuts without relying on high-temperature roasting or baking. This significantly improves the product's texture, making it crispy and easy to chew, and preventing it from hardening. At the same time, because the processing avoids prolonged direct contact with air at high temperatures, the oxidation of unsaturated fatty acids can be effectively inhibited, reducing peroxide value and acid value, minimizing the destruction of nutrients, and extending the product's shelf life without the need for added antioxidants. The final product is a micro-puffed crispy nut kernel with intact shape, high nutrient retention, and safe and healthy consumption.

[0010] Preferably, in step one, the moisture content of the raw materials is controlled to be 15% to 70%.

[0011] Preferably, in step one, the soaking is performed using purified water, and the soaking temperature is controlled at 25-30℃. Soaking time is 30-120 minutes.

[0012] Preferably, in step four, the vertical expansion tank is heated by steam, with a heating temperature of 100°C or higher and a heating rate maintained at 2–10°C / min.

[0013] Preferably, this application also provides a puffing device for performing the above-described vertical variable temperature and pressure differential quantitative puffing method for making nuts crispy, comprising: A vertical puffing tank with an internal hanging basket for holding nuts; The vacuum tank is connected to the vertical expansion tank via a pressure relief valve; A heating system for heating the vertical expansion tank; A vacuum system is used to evacuate the vacuum tank; A cooling system for cooling the vertical expansion tank; The control system is used to control temperature, pressure, time, and vacuum.

[0014] Preferably, the basket is driven by an overhead crane to achieve rapid feeding and discharging; the basket is equipped with layered partitions to prevent the nuts from being squeezed between layers and to ensure uniform expansion; the vertical expansion tank, the overhead crane, and the conveying device form a continuous production line operation system.

[0015] Preferably, a pressure relief valve is provided on the connecting pipeline between the vertical expansion tank and the vacuum tank, and the pressure relief valve is a metering solenoid valve.

[0016] Preferably, the suspended platform includes: Suspended basket frame; Layered partitions are horizontally installed inside the suspended basket frame, dividing the interior of the suspended basket frame into 2 to 8 layers. Each layer of partition is a perforated plate or woven mesh with a mesh diameter of 1 to 5 mm. The top of the basket is equipped with a lifting ring for connecting to the overhead crane hook; The bottom of the basket is equipped with positioning feet for engaging with positioning seats at the bottom of the vertical expansion tank.

[0017] Preferably, the heating system includes an electric heating tube or a steam heating jacket, which is located in the lower middle part of the outer wall of the vertical expansion tank, and the heating area covers 1 / 2 to 2 / 3 of the tank height.

[0018] Preferably, the cooling system includes a cooling water jacket disposed on the outer wall of the vertical expansion tank. The cooling water jacket and the heating jacket are the same jacket or are disposed in different height areas. The cooling water jacket is provided with an inlet and an outlet. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the vertical variable temperature and pressure difference quantitative puffing nut kernel crisping processing method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the vertical differential pressure expansion device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the overall structure of the suspended platform according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a vertical expansion tank according to an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 100. Vertical expansion tank; 110. Suspended basket; 111. Suspended basket frame; 112. Layered partition; 113. Lifting ring; 120. Pressure gauge; 130. Safety valve; 200. Vacuum tank; 300. Heating system; 400. Cooling system; 500. Pressure relief valve. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0023] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but not excluding the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0024] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.

[0027] like Figures 1 to 4 As shown in the embodiment of the present invention, a vertical variable temperature and pressure differential quantitative puffing method for making crispy nuts is provided, comprising: Step 1: Wash and soak the nuts, then let them drain. Step 2: Place the pre-treated nuts into the hanging basket 110 inside the vertical puffing tank 100, layering them so that the layers are not squeezed together; Step 3: Steam is introduced into the vertical puffing tank 100 to steam the nuts, so that the nuts are initially cooked and absorb moisture. Step 4: Heat the vertical puffing tank 100 to vaporize and evaporate the moisture inside the nuts, thereby pressurizing and keeping the tank warm. Step 5: Quantitatively set the valve opening size according to the required puffing rate, so that the pressure inside the vertical puffing tank drops instantly, causing the internal moisture of the nuts to flash evaporate, expand in volume, and form a honeycomb structure; Step Six: Continue heating and dehydration under vacuum until the moisture content of the nuts decreases; Step 7: Stop heating, cool to room temperature, and remove to obtain slightly puffed and crispy nuts.

[0028] In this application, firstly, the raw nuts are washed, soaked, and left to drain. Then, the pre-treated nuts are placed in the basket 110 inside the vertical puffing tank 100, arranged in layers without compression between the layers. Steam is then introduced into the vertical puffing tank 100 to steam the nuts, allowing them to preliminarily cook and absorb moisture. Next, the vertical puffing tank 100 is heated to vaporize the moisture inside the nuts and pressurize and keep the tank warm. Then, the pressure relief valve 500 between the vertical puffing tank 100 and the vacuum tank 200 is quickly opened to instantly reduce the pressure inside the vertical puffing tank 100. The moisture inside the nuts flashes, expands in volume, and forms a honeycomb structure. Then, heating continues under vacuum to dehydrate the nuts until the moisture content of the nuts decreases. Finally, heating is stopped and the nuts are cooled to room temperature. The resulting micro-puffed and crispy nuts are then obtained.

[0029] Meanwhile, in this embodiment, a pressure pipeline is provided on the vertical puffing tank 100. The pressure pipeline is used to transport steam or high-pressure air. The steam inlet is connected to a steam pipeline, which is used to introduce steam into the vertical puffing tank 100 for heating and steaming the nuts. The compressed air inlet is connected to a compressed air pipeline, and the outer end of the compressed air pipeline is provided with an interface for connecting an air compressor. A pressure-reducing valve is provided on the compressed air pipeline. When the steam supply pressure is insufficient, compressed air is supplied to the vertical puffing tank 100 through the compressed air pipeline by the air compressor to make the pressure inside the tank reach the process requirements.

[0030] In this embodiment of the application, in step one, the moisture content of the raw material is controlled to be 15% to 70%.

[0031] In actual production, the initial moisture content of different types and batches of nuts varies. To achieve a stable puffing effect, the moisture content of the raw materials needs to be adjusted to the range of 15% to 70% during the soaking and settling processes.

[0032] If the moisture content is less than 15%, there is insufficient free water available for vaporization inside the material, resulting in minimal volume expansion during puffing and a hard texture. If the moisture content is greater than 70%, the material is too wet and soft, leading to excessive moisture during depressurization, over-expansion, product breakage, and excessively long subsequent vacuum drying time, increasing energy consumption.

[0033] Therefore, controlling the moisture content of the raw materials between 15% and 70% is crucial to ensuring the micro-expansion effect. In this embodiment, the moisture content is preferably controlled between 25% and 40%.

[0034] In this embodiment of the application, in step one, the water is soaked in pure water at a temperature of 25-30 degrees Celsius for 30-120 minutes.

[0035] This soaking condition ensures that the nuts fully absorb water to reach the target moisture content while avoiding excessive soaking time that could lead to microbial growth, thus maintaining the freshness and hygienic quality of the raw materials.

[0036] In this embodiment of the application, in step four, the vertical expansion tank 100 is heated by steam, the heating temperature is above 100 degrees Celsius, and the heating rate is maintained at 2 to 10 degrees Celsius / min.

[0037] These processing conditions allow for a uniform increase in the internal temperature of the nuts, ensuring a stable rise in pressure within the container. This provides suitable preheating conditions for subsequent instantaneous flash puffing, preventing uneven heating that could lead to under- or over-puffing of some nuts.

[0038] In this embodiment of the application, a vertical differential pressure expansion device is provided. This device is used to perform the above-described method, and specifically, the device includes: A vertical puffing tank 100 has an internal hanging basket 110 for placing nuts; The vacuum tank 200 is connected to the vertical expansion tank 100 via the pressure relief valve 500; Heating system 300 is used to heat the vertical expansion tank 100; A vacuum system is used to evacuate the vacuum tank 200; Cooling system 400 is used to cool the vertical expansion tank 100; The control system is used to control temperature, pressure, time, and vacuum.

[0039] The basket 110 is driven by an overhead trolley, enabling rapid loading and unloading. The basket 110 is equipped with layered partitions 112, which allow the nuts to be placed in layers without being squeezed. The spaced upper and lower layers ensure convenient loading and unloading and ensure uniform puffing process. The vertical puffing tank 100 can be combined with an overhead trolley and conveying device to form a continuous production line system, which is suitable for large-scale industrial production.

[0040] A pressure relief valve 500 is also installed on the connecting pipeline between the vertical expansion tank 100 and the vacuum tank 200. The pressure relief valve 500 is an electromagnetic quick-opening valve, which can ensure that the pressure relief speed meets the pressure requirements of flash expansion and ensure the expansion effect.

[0041] The suspended basket 110 specifically includes a suspended basket frame 111 and horizontally arranged layered partitions 112 within the frame. The layered partitions 112 divide the interior of the suspended basket frame 111 into 2 to 8 layers. Each partition is made of perforated plate or woven mesh with a mesh diameter of 1 to 5 mm to ensure that steam and heat can pass through smoothly without leaking out the nuts. The top of the suspended basket 110 is equipped with a lifting ring 113 for connecting to the overhead crane hook, and the bottom is equipped with positioning feet that can cooperate with the positioning seats at the bottom of the vertical expansion tank 100 to achieve stable positioning of the suspended basket 110 within the vertical expansion tank 100.

[0042] The spaced upper and lower partitions 112 facilitate the loading and unloading of nuts. The overall basket 110 is square, and the spaced upper and lower partitions prevent the nuts from being squeezed, making it convenient to process the nuts in each layer individually.

[0043] The heating system 300 can use an electric heating tube or a steam heating jacket. The heating components are located in the lower middle part of the outer wall of the vertical puffing tank 100. The heating area covers 1 / 2 to 2 / 3 of the tank height, which can ensure uniform heating inside the tank and avoid local overheating that could affect the quality of the nuts.

[0044] The cooling system 400 includes a cooling water jacket installed on the outer wall of the vertical expansion tank 100. The cooling water jacket can be combined with the heating jacket into the same jacket, or it can be installed separately in different height areas of the tank. The cooling water jacket is provided with independent inlet and outlet, which can quickly cool the tank and the material.

[0045] The control system includes a pressure gauge, a thermometer, and a vacuum gauge. The pressure gauge is located at the top of the vertical expansion tank 100, and a safety valve 130 is also installed on the vertical expansion tank 100.

[0046] This processing method uses a variable-temperature pressure differential puffing process to process nut kernels. The entire process is carried out in a closed, oxygen-free environment, which avoids the oxidation of nut kernel oils when they come into contact with oxygen at high temperatures. This results in a longer shelf life without the need for artificial antioxidants, meeting the demand for natural and healthy products. At the same time, this process has a lower processing temperature, which can retain more of the heat-sensitive nutrients in the nuts, enhancing the nutritional value of the product. Flash puffing also allows the nuts to form a loose honeycomb structure, resulting in a crispier texture than traditional roasting processes and a better product flavor.

[0047] In this embodiment, the basket 110 is driven by an overhead trolley to achieve rapid feeding and discharging; the basket 110 is provided with layered partitions 112 to prevent the nuts from being squeezed between layers and to ensure uniform expansion; the vertical puffing tank 100, together with the overhead trolley and conveying device, forms a continuous production line system.

[0048] An I-beam track is erected above the vertical expansion tank 100, with the track length covering the feeding area, the vertical expansion tank 100 area, and the unloading area. The overhead crane's traveling mechanism is driven by a motor and can move along the track; the lifting mechanism is connected to the suspended basket 110 and lifting ring 113 via a steel wire rope and is driven by another motor. The traveling and lifting of the overhead crane are controlled by a PLC and are linked with other equipment on the production line.

[0049] Based on the above, the assembly line operation process is as follows: First, at the loading station, the operator lays the pre-treated nuts on the partitions of the hanging basket 110, and the hanging basket 110 is placed on the loading platform.

[0050] Then the gantry crane moves above the loading station, lowers the hook to hook the lifting ring 113 of the basket 110, lifts the basket 110, and then moves along the track to directly above the vertical expansion tank 100.

[0051] The gantry crane slowly lowers the basket 110 into the vertical expansion tank 100, so that the positioning feet at the bottom of the basket 110 automatically engage with the positioning seat at the bottom of the tank, and then the hook is released and the gantry crane moves away.

[0052] Close the can lid and puff the nuts. After processing, the overhead crane moves above the vertical puffing tank 100, hooks the hanging basket 110 and the lifting ring 113, and lifts the basket 110. The overhead crane moves the basket 110 above the unloading station, lowers the basket 110 to the unloading platform, and the operator takes out the product, cleans the basket 110 and reuses it.

[0053] In this embodiment of the application, a pressure relief valve 500 is provided on the connecting pipeline between the vertical expansion tank 100 and the vacuum tank 200, and the pressure relief valve 500 is a metering solenoid valve.

[0054] For quantitative solenoid valves, two-position, normally closed solenoid valves are preferred. The solenoid valves are directly controlled by the PLC to ensure that pressure relief is completed instantly and a sufficient pressure difference is formed.

[0055] In this application, the electromagnetic quick-opening valve is set as a quantitative switch. The electromagnetic quick-opening valve can achieve quantitative pressure difference puffing by controlling the system to preset the valve opening time and opening degree, adapting to the processing needs of different types of nuts with different moisture contents, and ensuring that the degree of puffing is stable and controllable.

[0056] Once the pressure inside the vertical puffing tank 100 reaches the set value and the heat preservation process is complete, the PLC outputs a signal to open the electromagnetic quick-opening valve. The high-pressure gas inside the vertical puffing tank 100, carrying water vapor, quickly enters the vacuum tank 200 through the pipeline. Due to the extremely rapid opening of the electromagnetic valve, the pressure inside the vertical puffing tank 100 drops from 0.3MPa to -0.1MPa within 0.5 seconds, resulting in a pressure difference of 0.4MPa, which is sufficient to cause the moisture inside the nut kernels to undergo violent flash evaporation and volume expansion.

[0057] In this embodiment, the vacuum tank 200 is provided with a buffer function.

[0058] In this embodiment of the application, the suspended platform 110 includes: Suspended basket frame 111; A layered partition 112 is horizontally set inside the suspended basket frame 111, dividing the interior of the suspended basket frame 111 into 2 to 8 layers. Each partition is a perforated plate or woven mesh with a mesh diameter of 1 to 5 mm. The top of the basket 110 is provided with a lifting ring 113 for connecting to the hook of the overhead crane; The bottom of the basket 110 is provided with positioning feet for engaging with the positioning seat at the bottom of the vertical expansion tank 100.

[0059] Perforated plates or woven mesh allow hot steam and high-pressure air to penetrate smoothly through each layer, ensuring even heating and consistent pressure distribution for each layer of nuts. This prevents some nuts from under- or over-expanding due to stacking and compression, guaranteeing uniform expansion throughout the entire batch. The hanging basket frame 111 is welded from stainless steel square tubing, providing a stable overall structure capable of withstanding the weight of a full load. It will not rust or deform even under long-term high temperature and humidity conditions, meeting the hygiene requirements for food production.

[0060] In this embodiment, the heating system 300 includes an electric heating tube or a steam heating jacket. The heating tube or jacket is located in the lower middle part of the outer wall of the vertical expansion tank 100, and the heating area covers 1 / 2 to 2 / 3 of the tank height.

[0061] Because the lower part of the tank is the main area where the hanging basket 110 is placed, containing the vast majority of the nuts to be processed, the heating zone only covers this part. This ensures that the materials receive sufficient heat while reducing heat waste and energy consumption. Simultaneously, it prevents excessive heating of the upper empty area of ​​the tank, reducing energy consumption in subsequent cooling processes. During heating, heat is transferred from the tank wall to the inside, raising the temperature of the air inside. Through convection heat transfer, the temperature of each layer of nuts inside the tank rises evenly, achieving uniform heating.

[0062] In this embodiment of the application, the cooling system 400 includes a cooling water jacket disposed on the outer wall of the vertical expansion tank 100. The cooling water jacket and the heating jacket are the same jacket or are disposed in different height areas. The cooling water jacket is provided with an inlet and an outlet.

[0063] When cooling is required after processing, low-temperature cooling water enters the jacket through the inlet, absorbs heat from the tank, and flows out through the outlet. This continuous flow of cooling water removes heat from the tank, rapidly lowering the internal temperature and preventing nuts from remaining in a high-temperature environment for extended periods. This further reduces oil oxidation and nutrient degradation, while also shortening the production cycle and improving processing efficiency. When the heating jacket and cooling water jacket are the same, steam is used for heating and cooling water for cooling, eliminating the need for an additional jacket, simplifying the equipment structure and reducing manufacturing costs. When the two are located at different heights, with the heating jacket positioned in the lower heating zone and the cooling water jacket covering the entire outer wall of the tank, cooling efficiency is even higher, making it suitable for large-scale processing equipment.

[0064] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A vertical variable temperature and pressure differential quantitative puffing method for making nut kernels crispy, characterized in that, include: Step 1: Wash and soak the nuts, then let them drain. Step 2: Place the pre-treated nuts into the hanging basket (110) inside the vertical puffing tank (100), layer by layer, ensuring that the layers are not squeezed together; Step 3: Steam is introduced into the vertical puffing tank (100) to steam the nuts, so that the nuts are initially cooked and absorb moisture; Step 4: Heat the vertical puffing tank (100) to vaporize and evaporate the moisture inside the nuts, thereby pressurizing and keeping the tank warm. Step 5: Quantitatively set the valve opening size according to the puffing rate requirement, so that the pressure inside the vertical puffing tank (100) drops instantly, the moisture inside the nut kernels flashes out, the volume expands, and a honeycomb structure is formed; Step Six: Continue heating and dehydration under vacuum until the moisture content of the nuts decreases; Step 7: Stop heating, cool to room temperature, and remove to obtain slightly puffed and crispy nuts.

2. The vertical variable temperature and pressure difference quantitative puffing method for making crispy nuts according to claim 1, characterized in that, In step one, the moisture content of the raw materials is controlled to be 15% to 70%.

3. The vertical variable temperature pressure difference quantitative puffing method for crisping nuts according to claim 2, characterized in that, In step one, the sample is soaked in purified water at a temperature of 25-30°C for 30-120 minutes.

4. The vertical variable temperature and pressure difference quantitative puffing method for crisping nuts according to claim 1, characterized in that, In step four, the vertical expansion tank (100) is heated by steam, with a heating temperature of 100°C or higher and a heating rate of 2 to 10°C / min.

5. An extrusion apparatus for implementing the method according to any one of claims 1 to 4, characterized in that, include: A vertical puffing tank (100) with an internal hanging basket (110) for placing nuts; The vacuum tank (200) is connected to the vertical expansion tank (100) via a pressure relief valve (500); A heating system (300) is used to heat the vertical expansion tank (100); A vacuum system for evacuating the vacuum container (200); A cooling system (400) is provided for cooling the vertical expansion tank (100); The control system is used to control temperature, pressure, time, and vacuum.

6. A vertical differential pressure expansion device according to claim 5, characterized in that, The basket (110) is driven by a crane to achieve rapid feeding and discharging; the basket (110) is equipped with a layered partition (112) to prevent the nuts from being squeezed between layers and to ensure uniform expansion.

7. A vertical differential pressure expansion device according to claim 5, characterized in that, A pressure relief valve (500) is provided on the connecting pipeline between the vertical expansion tank (100) and the vacuum tank (200), and the pressure relief valve (500) is a quantitative solenoid valve.

8. A vertical differential pressure expansion device according to claim 5, characterized in that, The suspended platform (110) includes: Suspended basket frame (111); A layered partition (112) is horizontally set inside the suspended basket frame (111) to divide the interior of the suspended basket frame (111) into 2 to 8 layers. Each partition is a perforated plate or woven mesh with a mesh diameter of 1 to 5 mm. The top of the basket (110) is provided with a lifting ring (113) for connecting to the hook of the crane; The bottom of the basket (110) is provided with positioning feet for cooperating with the positioning seat at the bottom of the vertical expansion tank (100).

9. A vertical differential pressure expansion device according to claim 5, characterized in that, The heating system (300) includes an electric heating tube or a steam heating jacket, which is located in the lower middle part of the outer wall of the vertical expansion tank (100), and the heating area covers 1 / 2 to 2 / 3 of the tank height.

10. A vertical differential pressure expansion device according to claim 5, characterized in that, The cooling system (400) includes a cooling water jacket disposed on the outer wall of the vertical expansion tank (100). The cooling water jacket and the heating jacket are the same jacket or are disposed in different height areas. The cooling water jacket is provided with an inlet and an outlet.

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