Vegetable blanching system based on vacuum deoxidation and nitrogen charging and use method thereof

Abstract

The invention relates to a vegetable blanching system based on vacuum deoxidation and nitrogen charging and a using method thereof, and belongs to the technical field of fruit and vegetable processing.The vegetable blanching system comprises a double-chamber blanching tank, a vacuum deoxidation unit, an inert gas protection unit, a cooling unit and an intelligent control system.The double-chamber blanching tank is provided with a sealing partition plate and is divided into a material chamber and a blanching liquid chamber through the sealing partition plate; and the material chamber is provided with a sealable material inlet and a drawable material basket. According to the vegetable blanching device, ultralow-oxygen protection of the vegetable blanching process is achieved, the product quality is greatly improved, oxidation is fundamentally inhibited, oxygen carried by the material chamber, the blanching liquid chamber and vegetables can be deeply removed through combination of vacuum pulsating deoxidation and inert gas replacement, oxidation reaction in the blanching process is fundamentally avoided, and the service life of the vegetable blanching device is prolonged. And heat treatment is carried out in a low-oxygen environment, so that the natural color, vitamins, antioxidant substances and other nutritional ingredients of the vegetables can be reserved to the greatest extent, and the blanching product is superior to a traditional blanching product.

Description

Technical Field

[0001] This invention relates to the field of fruit and vegetable processing technology, and in particular to a vegetable blanching system based on vacuum deoxygenation and nitrogen filling, and its application method. Background Technology

[0002] Blanching is an indispensable pretreatment process for vegetables before quick-freezing, dehydration, or canning. Its main purpose is to deactivate endogenous enzymes such as peroxidase and polyphenol oxidase in order to maintain color, flavor, and nutrition. However, traditional hot water or steam blanching processes are carried out in a high-temperature, aerobic environment, which leads to a large loss of heat-sensitive and easily oxidized components such as vitamin C and chlorophyll, resulting in severe browning of the product and a decline in quality.

[0003] To reduce oxidative damage, existing technologies have proposed blanching in an inert gas environment. For example, Chinese Patent Publication No. CN102429006B describes a method and equipment for separately vacuuming and nitrogen-filling the blanching liquid and materials before mixing and blanching. This technology reduces the oxygen content to some extent, but it still has the limitation of insufficient deoxygenation depth. For vegetables with complex tissue structures and abundant internal micropores, such as broccoli and spinach, a single vacuuming is not enough to effectively remove residual oxygen in the interstitial spaces. Incomplete deoxygenation becomes a bottleneck for color protection.

[0004] Therefore, a vegetable blanching system and process is proposed that is more thorough in deoxygenation, more intelligent in control, and can realize the full-process anaerobic connection of "deoxygenation-blanching-cooling". Through vacuum pulse technology, dissolved oxygen in the vegetable tissue and blanching solution is forcibly replaced, and the control system is used to realize the full-process automated and standardized anaerobic operation, thereby maximizing the preservation of the natural color and nutrients of vegetables. Summary of the Invention

[0005] This invention provides a vegetable blanching system based on vacuum deoxygenation and nitrogen filling, and its application method. It solves the problems of oxidation and deterioration, incomplete deoxygenation, and low efficiency in traditional vegetable blanching processes, which are usually carried out in an atmospheric pressure and aerobic environment.

[0006] The present invention provides the following solution to the above-mentioned technical problems: a vegetable blanching system based on vacuum deoxygenation and nitrogen filling and its usage method, comprising a double-chamber blanching tank, a vacuum deoxygenation unit, an inert gas protection unit, a cooling unit, and an intelligent control system. The double-chamber blanching tank is equipped with a sealing partition, which separates a material chamber and a blanching liquid chamber. The material chamber is equipped with a sealable inlet and a pull-out material basket. The blanching liquid chamber is equipped with an inlet and an outlet. The bottoms of the material chamber and the blanching liquid chamber are connected by one or more connecting pipes. Each connecting pipe is equipped with a controllable first valve. The heating unit is located in the blanching liquid chamber to heat and maintain the temperature of the blanching liquid.

[0007] The vacuum deoxygenation unit includes a vacuum pump set, and a first vacuum pipeline and a second vacuum pipeline connecting the vacuum pump set with the material chamber and the scalding liquid chamber. The first vacuum pipeline and the second vacuum pipeline are respectively equipped with a second valve and a third valve.

[0008] The inert gas protection unit includes an inert gas source, and a first gas pipeline and a second gas pipeline connecting the inert gas source to the material chamber and the scalding liquid chamber. The first gas pipeline and the second gas pipeline are respectively equipped with a fourth valve and a fifth valve.

[0009] The cooling unit is connected to the material chamber, and receives and quickly cools the blanched vegetables transferred from the material chamber.

[0010] The intelligent control system includes a PLC controller, a sensor group, and a human-machine interface. The sensor group includes a pressure sensor, a temperature sensor, and an oxygen concentration sensor. The intelligent control system is connected to the vacuum pump group, the first to fifth valves, the heating unit, and the cooling unit.

[0011] Based on the above technical solution, the present invention can be further improved as follows.

[0012] Furthermore, the vacuum deoxygenation unit includes a vacuum pump and a three-way valve. By switching the three-way valve, the material chamber and the scalding liquid chamber can be connected separately or simultaneously. According to process requirements, it is possible to freely choose to deoxygenate either chamber individually or both at the same time, which improves the flexibility of process adjustment.

[0013] Furthermore, the oxygen concentration sensor is located at the top of the material chamber. The intelligent control system receives feedback signals from the oxygen concentration sensor during the blanching process. When the oxygen concentration exceeds a set threshold, it triggers a supplementary vacuuming or inert gas filling operation. The intelligent control system is programmed to automatically control the second, third, fourth, and fifth valves according to a preset sequence to perform at least one cyclical operation on the material chamber and blanching liquid chamber, including "vacuuming to the target absolute pressure and holding the pressure for a first duration - filling inert gas to the target pressure and holding the pressure for a second duration".

[0014] An oxygen concentration sensor is installed at the top of the material chamber to continuously and directly monitor the oxygen content in the gaseous environment that comes into contact with the vegetables. Based on this feedback signal, the intelligent control system implements dynamic intervention during the blanching process. Once the oxygen concentration exceeds the safety threshold (e.g., 0.5%), remedial measures are immediately initiated (vacuuming or filling with inert gas) to ensure that the entire critical process stage is always in a strictly oxygen-free or low-oxygen state.

[0015] The dynamic monitoring and compensation mechanism fundamentally solves the problem of oxygen concentration rebound caused by system micro-leakage or material gas evolution, providing an unprecedentedly precise control method for vegetables to retain color, nutrition and flavor to the maximum extent during blanching. The pulsed circulation operation uses pressure difference changes to make oxygen in the material pores and liquid escape more fully and be replaced. Compared with single vacuuming and gas filling, deoxygenation is more thorough and the utilization rate of inert gas is higher.

[0016] Furthermore, the cooling unit includes a sealed cooling tank filled with a cooling medium. The sealed cooling tank is equipped with an inert gas covering pipe and a material basket transfer track, enabling oxygen-free connection and transfer with the material chamber. This achieves inert gas protection throughout the entire process from deoxygenation and blanching to cooling. The sealed cooling tank structure prevents air from entering during the cooling process, while the internal cooling medium (such as water or an ice-water mixture) provides an efficient heat exchange pathway, preventing the vegetables from oxidizing and deteriorating due to contact with oxygen during the critical stages after high-temperature blanching and in the initial cooling phase, thus locking in the blanching effect.

[0017] Furthermore, the heating unit in the scalding and bleaching liquid chamber is one of a coil-type electric heater, an external jacketed steam heater, or an electromagnetic induction heater; a perforated partition is provided above the heating unit inside the scalding and bleaching liquid chamber.

[0018] Coil-type electric heaters are suitable for applications with convenient power supply and precise control requirements; external jacketed steam heaters can utilize existing steam heat sources in the factory, resulting in lower operating costs; electromagnetic induction heaters have the advantages of high heating efficiency and fast response, preventing vegetables (or any loose debris) from directly contacting the surface of the heating unit, avoiding localized overheating and scorching. The holes in the partition allow the blanching liquid to flow freely, ensuring that heat is evenly distributed throughout the chamber, while preventing violent convection near the heating unit from directly impacting the material, making the heating gentler and more uniform. The partition is removable, facilitating cleaning and maintenance of the heating unit below.

[0019] A method for using a vegetable blanching system based on vacuum deoxygenation and nitrogen filling

[0020] S1. Filling and sealing: Place the vegetables in a material basket in a sealed material chamber, and inject the blanching solution into a sealed blanching solution chamber that is connected to the bottom of the material chamber through a pipe with a valve;

[0021] S2. Vacuum Pulsating Deoxygenation: Perform independent vacuum pulsating deoxygenation operations on the material chamber and the scalding liquid chamber; the vacuum pulsating deoxygenation operation includes at least one cycle, the cycle being: first, evacuate the chamber to a first absolute pressure of 5-20 kPa and maintain it for a first duration of 1-5 minutes, then fill the chamber with inert gas to atmospheric pressure or slightly positive pressure and maintain it for a second duration of 0.5-2 minutes;

[0022] The vacuum pulsed deoxygenation operation is repeated 2-4 times, and after the last cycle, the chamber is filled with inert gas until the pressure is 10-30 kPa higher than atmospheric pressure to form a micro-positive pressure protection.

[0023] The absolute pressure for vacuuming the material chamber and the scalding liquid chamber is independently controlled within the range of 5-15 kPa, and the pressure holding time is independently controlled within 2-4 minutes.

[0024] S3. Anaerobic blanching: Maintain an inert gas environment in the material chamber after deoxygenation; at the same time, heat the blanching liquid in the blanching liquid chamber to a set temperature of 90-100℃; then, open the connecting valve between the material chamber and the blanching liquid chamber to allow the blanching liquid to enter and submerge the vegetables in the material chamber, and blanch them under the protection of inert gas.

[0025] Throughout the blanching process in step S3, the oxygen concentration in the material chamber is monitored and maintained below 0.5%.

[0026] S4. Rapid Cooling: After blanching, the material basket along with the vegetables is quickly transferred to a cooling unit in an inert gas protected environment for rapid cooling. The cooling is carried out in a closed cooling tank filled with cooling medium and covered with inert gas until the core temperature of the vegetables drops below 15°C.

[0027] The beneficial effects of this invention are as follows: This invention provides a vegetable blanching system based on vacuum deoxygenation and nitrogen filling, and its method of use, which has the following advantages:

[0028] 1. It achieves ultra-low oxygen protection in the vegetable blanching process, greatly improving product quality and fundamentally inhibiting oxidation. By combining "vacuum pulsed deoxygenation" with "inert gas replacement", it can deeply remove oxygen from the material chamber, blanching liquid chamber, and the vegetables themselves, fundamentally avoiding oxidation reactions during the blanching process. Heat treatment in a low-oxygen environment can retain the natural color (such as chlorophyll), vitamins, antioxidants and other nutrients of vegetables to the greatest extent, which is superior to traditional blanching products.

[0029] 2. High deoxygenation depth and efficiency: It adopts a cyclic (pulsating) operation of "vacuuming-pressure holding-inert gas filling-pressure holding", which utilizes multiple drastic pressure changes to effectively "extract" and replace the oxygen dissolved in the micropores of vegetable tissue and blanching solution. The deoxygenation effect is far superior to single vacuuming or atmospheric pressure replacement, realizing the refinement and adaptability of the process.

[0030] 3. Convenient, safe and reliable operation: It achieves closed-loop control capability through online monitoring of oxygen concentration sensor. When the oxygen concentration rises unexpectedly, it can automatically trigger remedial measures to ensure the absolute stability of the process environment and solve the risks caused by micro-leakage or material gas evolution.

[0031] 4. The system has a high degree of integration, combining efficiency and practicality. It adopts a dual-chamber design, in which materials and blanching solution are treated independently in the early stage, avoiding premature contact between the undeoxygenated blanching solution and materials and introducing oxygen. It also facilitates separate temperature control and liquid replacement.

[0032] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0034] Figure 1 A flowchart illustrating a vegetable blanching system based on vacuum deoxygenation and nitrogen filling, and its usage method, provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a vegetable blanching system based on vacuum deoxygenation and nitrogen filling, and its usage method, provided in an embodiment of the present invention. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1-2 The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0037] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] like Figure 2 As shown, the present invention provides a vegetable blanching system based on vacuum deoxygenation and nitrogen filling and its usage method, including a double-chamber blanching tank, a vacuum deoxygenation unit, an inert gas protection unit, a cooling unit and an intelligent control system;

[0040] The double-chamber blanching tank is a sealed container with a pressure-resistant structure. Its interior is divided into two independent chambers by a vertical sealing partition: the left chamber is the material chamber and the right chamber is the blanching liquid chamber. The top of the material chamber is equipped with a feed inlet that can be quickly opened, closed and sealed. Inside, there is a material basket that can be pulled out along the guide rail. The upper part of the side wall of the blanching liquid chamber is equipped with a liquid inlet and the bottom is equipped with a liquid outlet. A heating unit is installed at the bottom of the blanching liquid chamber. In this embodiment, a coil-type electric heater is preferred. A perforated partition is installed above the heating unit to prevent vegetable scraps from directly contacting the heater and to promote uniform heating of the liquid. The bottom of the material chamber and the blanching liquid chamber are connected by two connecting pipes. Each pipe is equipped with a pneumatically controlled first valve.

[0041] The vacuum deoxygenation unit includes a vacuum pump and a three-way valve. The common end of the three-way valve is connected to the suction port of the vacuum pump through a pipeline. The other two working ends are connected to the top of the material chamber through the first vacuum pipeline and to the top of the scalding liquid chamber through the second vacuum pipeline. A second valve is installed on the first vacuum pipeline and a third valve is installed on the second vacuum pipeline. By controlling the switching of the three-way valve and the opening and closing of each valve, the material chamber or the scalding liquid chamber can be flexibly vacuumed individually or simultaneously.

[0042] The inert gas protection unit includes a nitrogen cylinder as the inert gas source. The main pipeline leading out of the nitrogen cylinder outlet is divided into two branches: the first gas pipeline leads to the top of the material chamber and is equipped with a fourth valve; the second gas pipeline leads to the top of the scalding liquid chamber and is equipped with a fifth valve.

[0043] The cooling unit is a closed cooling tank filled with an ice-water mixture as the cooling medium. An inert gas covering pipe is installed at the top of the cooling tank to continuously introduce nitrogen to maintain positive pressure and an oxygen-free environment inside the tank. One end of the cooling tank is connected to the material basket outlet of the material chamber through a closed transfer track to realize the oxygen-free and rapid transfer of the material basket after blanching.

[0044] The intelligent control system is a PLC controller. Sensor groups are arranged at key locations in the system: an oxygen concentration sensor is installed on the top of the material chamber to monitor the gas phase oxygen content in real time; pressure sensors and temperature sensors are installed in the material chamber and the scalding liquid chamber, respectively. All human-machine interaction is completed through the human-machine interface touch screen. The PLC controller is connected to the auxiliary equipment of the vacuum pump, the first to fifth valves, the heating unit and the cooling unit through electrical circuits. According to the preset program and sensor feedback, it automatically executes all process steps.

[0045] like Figure 1 As shown, the specific working principle and usage method of this invention are as follows:

[0046] S1, Filling and sealing;

[0047] Vegetable loading: Operators use the quick-opening feed inlet (using a sanitary quick-opening clamp structure) at the top of the material chamber to evenly load the vegetables to be processed (such as broccoli and spinach) into the pull-out material basket (made of 304 or 316L stainless steel mesh basket), and then close and lock the feed inlet to ensure a seal.

[0048] Blanching solution injection: Blanching solution (such as water or solution with added color protectant) with preset concentration and pH value is injected into the blanching solution chamber through the inlet (connected to a sanitary centrifugal pump) to the designated liquid level. The liquid level can be observed through a liquid level sensor or sight glass.

[0049] System sealing check: The intelligent control system uses a pressure sensor (PN series pressure transmitter) to conduct a preliminary pressure holding test on the two chambers to confirm the sealing performance of all sealing points such as the first valve, feed port, and liquid inlet;

[0050] S2, vacuum pulsed deoxygenation;

[0051] The PLC of the intelligent control system (S7-1200 series can be selected) automatically executes the program according to the preset program;

[0052] Start-up procedure: The operator selects the "pulsating deoxygenation" process on the human-machine interface and sets the key parameters: target absolute pressure (e.g., 8 kPa), pressure holding time (e.g., 3 minutes), number of cycles (e.g., 3 times), and final micro-positive pressure value (e.g., 20 kPa higher than atmospheric pressure).

[0053] Execute the pulsating loop:

[0054] Vacuuming stage: The PLC first controls the three-way valve (such as a pneumatic three-way valve) to connect the material chamber pipeline, and at the same time opens the second valve to start the vacuum pump (R5 series rotary vane vacuum pump). The system pumps the pressure in the material chamber to the set target absolute pressure (such as 8 kPa). This process uses a pressure sensor for closed-loop feedback control.

[0055] Pressure holding stage: After reaching the target pressure, close the second valve and maintain this vacuum state for a period of time (e.g., 3 minutes). This "pressure holding period" is crucial for the full escape of gases from the pores inside the vegetable tissue and the surface under the action of pressure difference.

[0056] Inert gas filling stage: After the pressure holding is completed, the PLC closes the passage between the three-way valve and the vacuum pump, opens the fourth valve leading to the material chamber, and fills the material chamber with high-purity nitrogen (purity ≥99.9%) from the inert gas source (such as an industrial nitrogen cylinder group equipped with a pressure reducing valve or a nitrogen generator) until the pressure returns to normal pressure or the set slight positive pressure.

[0057] Secondary pressure holding stage: Maintain pressure at normal or slightly positive pressure for a period of time to allow nitrogen to fully permeate and replace the residual air;

[0058] Cycle and switching: The above "vacuuming-pressure holding-nitrogen filling-pressure holding" constitutes a complete cycle. The PLC control program will repeat this cycle 2-4 times. Subsequently, the system executes the same or parameter-independent pulsating deoxygenation program on the scalding and bleaching liquid chamber by switching the three-way valve and the third valve to remove the oxygen dissolved in the scalding and bleaching liquid.

[0059] Final state protection: After the last cycle, the system will fill the two chambers with nitrogen to a stable micro-positive pressure state (such as +20kPa) to form a positive pressure protection barrier to prevent air from seeping in;

[0060] S3, oxygen-free perming and bleaching;

[0061] This phase is conducted in an established low-oxygen environment, with an oxygen concentration sensor (InPro6850i optical oxygen sensor) providing real-time monitoring.

[0062] Preheating and monitoring: During or after the deoxygenation process, the PLC starts the heating unit (using a coil-type electric heater) in the scalding and bleaching liquid chamber. Through the feedback of the temperature sensor (PT100 platinum resistance), the scalding and bleaching liquid is precisely heated and kept at the set temperature (e.g., 95℃).

[0063] Mixing and Blanching: When both chambers reach the deoxygenation state required by the process and the temperature of the blanching solution is stable, the PLC issues a command to slowly open the first valve (pneumatic butterfly valve) connecting the bottom of the two chambers. Due to pressure balance or slight pressure difference, the pre-deoxygenated, high-temperature blanching solution flows into the material through the connecting pipe until the vegetables in the material basket are completely submerged.

[0064] Dynamic oxygen concentration control: During the entire blanching process, the PLC continuously reads the data from the oxygen concentration sensor, and the system presets a safe oxygen concentration threshold (such as 0.5%).

[0065] Feedback control: If the detected oxygen concentration is >0.5%, the PLC will immediately interrupt the normal timing sequence and trigger a "remedial subroutine". This subroutine will quickly close the first valve and then, depending on the situation, either start a short vacuum-nitrogen filling cycle (calling part of the logic in step two) or directly inject nitrogen until the oxygen concentration returns to below the threshold. This process is fully automated and forms a real-time feedback control closed loop.

[0066] Timing and End: Provided the oxygen concentration meets the standard, the PLC starts timing according to the set scalding time (e.g., 90 seconds). When the time is up, the heating unit is turned off and preparations are made for the next cooling step.

[0067] S4, rapid cooling without oxygen;

[0068] Drainage and Transfer Preparation: After the scalding and bleaching is completed, the PLC first opens the first valve and the drain valve of the scalding and bleaching liquid chamber to drain the scalding and bleaching liquid back to the treatment tank or discharge it. At the same time, the closed cooling tank of the cooling unit has been filled with nitrogen through its inert gas covering pipe, and the internal cooling medium (such as ice water mixture, maintained at 0-4℃ by the refrigeration unit) is ready.

[0069] Anaerobic transfer: Under the protection of a slightly positive pressure inert gas atmosphere inside the system, the operator or automatic actuator opens the sealed door on the side of the material chamber and pushes the entire material basket carrying the blanched high-temperature vegetables quickly and horizontally into the liquid surface of the closed cooling tank through the transfer track. The whole process is completed within a few seconds, and the risk of material exposure is extremely low.

[0070] Rapid cooling and endpoint determination: Vegetables undergo intense heat exchange in the cooling medium, which can be monitored by inserting a temperature probe (such as a Fluke thermometer) into the center of a representative vegetable. The PLC or operator monitors the temperature until the temperature at the center of the vegetable drops below a safe threshold (such as 15°C). After cooling is complete, the material basket can be removed under inert gas protection for subsequent processing.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Content not described in detail in this specification is prior art known to those skilled in the art.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A vegetable blanching system based on vacuum deoxidization and nitrogen filling, comprising a double-chamber blanching tank, a vacuum deoxidization unit, an inert gas protection unit, a cooling unit, and an intelligent control system, characterized in that: The double-chamber blanching tank is provided with a sealing partition plate, and is divided into a material chamber and a blanching liquid chamber by the sealing partition plate. The material chamber is provided with a closable feeding port and a pullable material basket. The blanching liquid chamber is provided with a liquid inlet and a liquid outlet. The bottom of the material chamber and the bottom of the blanching liquid chamber are connected by one or more connecting pipelines. Each connecting pipeline is provided with a controllable first valve. The heating unit is arranged in the blanching liquid chamber to heat and control the temperature of the blanching liquid. The vacuum deoxidization unit comprises a vacuum pump group, and a first vacuum pipeline and a second vacuum pipeline connected with the vacuum pump group, the material chamber and the blanching liquid chamber. The first vacuum pipeline and the second vacuum pipeline are respectively provided with a second valve and a third valve. The inert gas protection unit comprises an inert gas source, and a first gas pipeline and a second gas pipeline connected with the inert gas source, the material chamber and the blanching liquid chamber. The first gas pipeline and the second gas pipeline are respectively provided with a fourth valve and a fifth valve. The cooling unit is connected with the material chamber, and receives and quickly cools the blanched vegetables transferred from the material chamber. The intelligent control system comprises a PLC controller, a sensor group and a man-machine interface. The sensor group comprises a pressure sensor, a temperature sensor and an oxygen concentration sensor. The intelligent control system is signal connected with the vacuum pump group, the first to fifth valves, the heating unit and the cooling unit.

2. The vacuum deoxidized nitrogen-flushed vegetable blanching system according to claim 1, wherein The vacuum deoxidization unit comprises a vacuum pump and a three-way valve. The three-way valve is switched to connect the material chamber and the blanching liquid chamber respectively or simultaneously.

3. The vacuum deoxidized nitrogen-flushed vegetable blanching system according to claim 1, wherein The oxygen concentration sensor is arranged at the top of the material chamber. The intelligent control system receives the feedback signal of the oxygen concentration sensor during the blanching process. When the oxygen concentration exceeds the set threshold, the supplementary vacuum pumping or inert gas filling operation is triggered. The intelligent control system is programmed to automatically control the second valve, the third valve, the fourth valve and the fifth valve according to the preset time sequence, so as to perform at least one cycle operation including "vacuum pumping to target absolute pressure and pressure maintaining for first time length-inert gas filling to target pressure and pressure maintaining for second time length" on the material chamber and the blanching liquid chamber.

4. The vacuum deoxidized nitrogen charged vegetable blanching system according to claim 1, wherein The cooling unit comprises a closed cooling tank. The closed cooling tank is filled with a cooling medium. The closed cooling tank is provided with an inert gas covering pipe and a material basket transfer track, so as to realize the oxygen-free connection and transfer with the material chamber.

5. The vacuum deoxidized nitrogen charged vegetable blanching system according to claim 1, wherein The heating unit in the blanching liquid chamber is one of a coil type electric heater, an external jacket type steam heater and an electromagnetic induction heater. A perforated partition plate is arranged above the heating unit in the blanching liquid chamber.

6. The method of using a vacuum deoxidized nitrogen-flushed vegetable blanching system according to any one of claims 1-5, wherein, The method comprises the following steps: S1. Filling and sealing: vegetables are placed in a material basket in a closed material chamber, and blanching liquid is injected into a closed blanching liquid chamber connected with the bottom of the material chamber through a pipeline provided with a valve; S2. Vacuum pulse deoxidization: independent vacuum pulse deoxidization operations are performed on the material chamber and the blanching liquid chamber. The vacuum pulse deoxidization operation comprises at least one cycle. The cycle is: first, vacuum pumping to a first absolute pressure of 5-20 kPa and maintaining for a first time length of 1-5 minutes, and then filling inert gas into the chamber to normal pressure or slightly positive pressure and maintaining for a second time length of 0.5-2 minutes. S3. Oxygen-free blanching: maintaining inert gas environment in the material chamber after deoxidization; meanwhile, heating the blanching liquid in the blanching liquid chamber to a set temperature of 90-100℃; then, opening the communication valve between the material chamber and the blanching liquid chamber to make the blanching liquid enter and immerse the vegetables in the material chamber, and blanching is carried out under the protection of inert gas; S4. Rapid cooling: after blanching, the material basket is rapidly transferred to a cooling unit under the protection of inert gas for rapid cooling.

7. The method of using a vacuum deoxidized nitrogen-flushed vegetable blanching system according to claim 6, wherein, In step S2, the number of cycles of the vacuum pulsation deoxidization operation is 2-4, and after the last cycle, inert gas is filled into the chamber to a pressure of 10-30 kPa higher than atmospheric pressure, forming a micro-positive pressure protection.

8. The method of using a vacuum deoxidized nitrogen-flushed vegetable blanching system of claim 6, wherein, In step S2, the absolute pressure of vacuumizing the material chamber and the blanching liquid chamber is independently controlled in the range of 5-15 kPa, and the pressure maintaining time is independently controlled in the range of 2-4 minutes.

9. The method of using a vacuum deoxidized nitrogen-flushed vegetable blanching system of claim 6, wherein, During the whole blanching process in step S3, the oxygen concentration in the material chamber is monitored and maintained below 0.5%.

10. The method of using a vacuum deoxidized nitrogen-flushed vegetable blanching system of claim 6, wherein, In step S4, the cooling is carried out in a closed cooling tank filled with cooling medium and covered with inert gas until the center temperature of the vegetables is reduced to below 15℃.

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