Long-acting preservation method and process for square bamboo shoots

Abstract

The invention relates to the technical field of bamboo shoot preservation, in particular to a long-acting preservation method and process for square bamboo shoots. Soaking the bamboo shoots in plasma activated water, and cleaning the bamboo shoots in an ultrasonic cleaning tank containing ozone micro-nano bubbles; and then soaking in a nano chitosan-citric acid solution to form an edible antibacterial coating. The coated bamboo shoots are placed in an intelligent preservation bin, and the storage environment is dynamically regulated and controlled through an Internet of Things sensor and an LSTM neural network model; applying a low-frequency alternating magnetic field in the storage process; and finally, irradiating the surfaces of the bamboo shoots by adopting a UV-LED, and performing vacuum packaging by using a composite film. According to the method, through the synergistic effect of technologies such as plasma activated water, a nano antibacterial coating, intelligent environment regulation and control and a low-frequency magnetic field, the technological process is remarkably simplified, the equipment requirement is reduced, meanwhile, microbial growth is effectively inhibited, bamboo shoot decay is delayed, and the original flavor and taste of the bamboo shoots are reserved.

Description

Technical Field

[0001] The present invention relates to the technical field of bamboo shoot preservation, and in particular to a long-term preservation method and process for square bamboo shoots. Background Art

[0002] Bamboo shoots are highly sought after for their unique taste and rich nutritional value, but fresh bamboo shoots are highly perishable and difficult to preserve. Traditional methods for preserving bamboo shoots include soaking in water, pickling, quick freezing, and drying. While these methods can extend the shelf life of bamboo shoots to a certain extent, they often compromise their original flavor and texture, rely on chemical additives, or require stringent storage conditions. For example, soaking requires the addition of preservatives, pickling alters the flavor, quick freezing imposes stringent transportation and storage requirements, and drying completely destroys the shoots' fresh taste.

[0003] To address these issues, a novel additive-free method for preserving bamboo shoots has been proposed (CN107771916B). This method utilizes a multi-step process, including ultrasonic cleaning, steam sterilization, gradient cooling, low-temperature soaking, heat shock treatment, and ultraviolet radiation, to achieve long-term preservation of bamboo shoots without the use of chemical additives, while effectively preserving their fresh flavor and crisp texture. This method addresses the potential health hazards and flavor loss associated with traditional preservation techniques.

[0004] However, although this method avoids the use of chemical additives, its process is relatively complicated, involving multiple temperature changes and special processing steps (such as gradient cooling and heat shock treatment), which requires high production equipment and operating techniques, increasing production costs and the difficulty of process control. Therefore, it is urgent to develop a long-term preservation method for bamboo shoots that can preserve the original flavor and taste of bamboo shoots while simplifying the process and reducing production costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a long-term preservation method and process for square bamboo shoots, which solves the problem that the process flow of the existing square bamboo shoot storage and preservation method without additives is relatively complicated, involves multiple temperature changes and special processing steps, has high requirements for production equipment and operating technology, and increases production costs and process control difficulty.

[0006] To achieve the above object, the present invention provides a method for long-term preservation of bamboo shoots, comprising the following steps:

[0007] Pick fresh bamboo shoots and select those without mechanical damage or rot;

[0008] The selected bamboo shoots were immersed in plasma-activated water and then cleaned in an ultrasonic cleaning tank containing ozone micro-nano bubbles;

[0009] The cleaned bamboo shoots are soaked in a nano-chitosan-citric acid solution to form an edible antibacterial coating;

[0010] The coated bamboo shoots are placed in a smart fresh-keeping warehouse, where environmental parameters are monitored in real time through IoT sensors, and the storage environment is dynamically controlled based on an LSTM neural network model.

[0011] Apply a low-frequency alternating magnetic field during storage;

[0012] Before packaging, UV-LED is used to irradiate the surface of the bamboo shoots, and after irradiation, the bamboo shoots are vacuum-packed with composite film.

[0013] Among them, picking fresh bamboo shoots and selecting bamboo shoots without mechanical damage and rot, the specific steps include:

[0014] Observe the surface of bamboo shoots and remove those with brown or black spots;

[0015] Gently pinch the bamboo shoots with your hands and remove those with abnormal hardness or dents;

[0016] Smell the bamboo shoots and remove those with strange or sour smells.

[0017] The selected bamboo shoots are immersed in plasma-activated water and then placed in an ultrasonic cleaning tank containing ozone micro-nano bubbles for cleaning.

[0018] Atmospheric pressure cold plasma jet is used to treat purified water for 2-5 minutes to generate plasma activated water rich in active nitrogen and oxygen species.

[0019] The selected bamboo shoots are immersed in plasma-activated water and then placed in an ultrasonic cleaning tank containing ozone micro-nano bubbles for cleaning.

[0020] Ozone concentration 0.5-1.0ppm, water temperature 25-30℃, ultrasonic frequency 40kHz, cleaning time 5-8min.

[0021] The cleaned bamboo shoots are immersed in a nano-chitosan-citric acid solution to form an edible antibacterial coating. The specific steps include:

[0022] Mix nano-chitosan and food-grade citric acid in a mass ratio of 1:0.5-1:2, add deionized water to prepare a composite solution with a concentration of 0.5%-2.0%, and adjust the pH value to 3.5-4.5;

[0023] Drain the surface moisture of the washed bamboo shoots and pre-cool them in a 10-15°C environment for 30-60 minutes;

[0024] Immerse the pre-cooled bamboo shoots completely in the nano-chitosan-citric acid solution at 10-15°C for 10-30 minutes. Keep the solution circulating during the soaking process, and control the flow rate at 0.5-1.0 m / s.

[0025] The soaked bamboo shoots are taken out and hung vertically to drain for 5-10 minutes, and then left to solidify in an environment of 15-20°C and 60%-70% relative humidity for 30-60 minutes.

[0026] In the storage process, a low-frequency alternating magnetic field is applied, wherein:

[0027] Magnetic field strength 0.5-1.0mT, frequency 50Hz.

[0028] Among them, UV-LED is used to irradiate the surface of bamboo shoots before packaging, and after irradiation, the bamboo shoots are vacuum-packed with composite film.

[0029] Before packaging, the surface of bamboo shoots is irradiated with UV-LED with a wavelength of 275nm and an irradiation dose of 2.0-3.0KJ / m 2 .

[0030] A long-term preservation process for square bamboo shoots is applicable to the long-term preservation method for square bamboo shoots.

[0031] The present invention discloses a long-term preservation method and process for bamboo shoots, comprising the steps of picking fresh bamboo shoots and selecting undamaged ones; soaking the bamboo shoots in plasma-activated water and cleaning them in an ultrasonic cleaning tank containing ozone micro-nano bubbles; then soaking them in a nano-chitosan-citric acid solution to form an edible antibacterial coating; placing the coated bamboo shoots in an intelligent fresh-keeping warehouse, and dynamically controlling the storage environment through an Internet of Things sensor and an LSTM neural network model; applying a low-frequency alternating magnetic field during storage; and finally irradiating the bamboo shoot surface with a UV-LED and vacuum-packing the bamboo shoots with a composite film. This method significantly simplifies the process flow and reduces equipment requirements through the synergistic effects of technologies such as plasma-activated water, nano-antibacterial coating, intelligent environmental control, and low-frequency magnetic field. It also effectively inhibits microbial growth, delays the spoilage of bamboo shoots, and preserves their original flavor and taste, solving the problems of traditional preservation methods that rely on chemical additives, are complex in process, and are costly. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0033] Figure 1 It is a flowchart of the steps of the long-term preservation method of square bamboo shoots according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0035] The first embodiment of this application is:

[0036] See also Figure 1 ,in, Figure 1 It is a flowchart of the steps of the long-term preservation method of square bamboo shoots according to the first embodiment of the present invention.

[0037] The present invention provides a long-term preservation method for bamboo shoots, comprising the following steps:

[0038] S101: Pick fresh bamboo shoots and select those without mechanical damage or rot;

[0039] Specifically, the timing of picking square bamboo shoots is crucial to their freshness preservation effect. The present invention requires picking fresh bamboo shoots with moderate tenderness. The best picking time is early morning or during cool periods to reduce the effects of water evaporation and respiration. When picking, a sharp knife should be used to cut flatly along the base of the bamboo shoot to avoid tearing or squeezing the bamboo shoot to prevent mechanical damage that leads to subsequent corruption. The screening process adopts a "three-step method" to ensure the quality of bamboo shoots: Visual inspection: Remove bamboo shoots with brown or black spots on the surface. Such spots may be caused by microbial infection or oxidative deterioration, which will accelerate corruption. Tactile detection: Gently pinch the bamboo shoot body with your hands to remove bamboo shoots with abnormal hardness (too soft or too hard) or concave ones. Such phenomena may indicate that the internal tissue is damaged or dehydrated. Olfactory detection: Smell the odor of the bamboo shoot body and remove bamboo shoots with peculiar smell, sour smell or fermented smell. Such odors are usually caused by microbial metabolites, indicating that corruption has occurred. Bamboo shoots still have active physiological metabolism after being picked. Mechanical damage or microbial infection will accelerate their respiration and enzymatic browning, resulting in a decline in quality. This method uses rigorous screening to remove deteriorated shoots at the source, reducing the burden on subsequent preservation processes. It also prevents decaying shoots from releasing decay-promoting substances like ethylene during storage, which could affect the preservation of healthy shoots. After screening, the shoots are immediately transferred to a low-temperature temporary storage environment (10-15°C) to suppress respiration and prevent quality deterioration caused by brief exposure to high temperatures during the screening process.

[0040] Through scientific harvesting and rigorous screening, bamboo shoots entering the subsequent preservation process are ensured to be in optimal initial condition, laying the foundation for the efficient implementation of key technologies such as plasma cleaning and antibacterial coating, thereby significantly improving overall preservation. This step not only reduces the risk of spoilage but also optimizes the process flow, avoiding repeated handling or equipment loss caused by the mixing of deteriorated bamboo shoots, and meeting the core goals of the invention of "high efficiency, low consumption, and long-term preservation."

[0041] S102: soaking the selected bamboo shoots in plasma-activated water and then cleaning them in an ultrasonic cleaning tank containing ozone micro-nano bubbles;

[0042] Specifically, qualified bamboo shoots are first completely immersed in specially prepared plasma-activated water. This activated water is produced by treating ordinary purified water for 2-5 minutes using atmospheric pressure cold plasma jet technology. Its unique feature is that it is rich in reactive nitrogen and oxygen species (RONS), including hydroxyl radicals (·OH), hydrogen peroxide (H2O2), ozone (O3) and other strong oxidizing components. These active substances can effectively destroy the structure of microbial cell membranes and decompose pesticides and organic pollutants remaining on the surface of bamboo shoots. Its mechanism of action is to cause protein denaturation and DNA damage in pathogens through oxidative stress, thereby achieving non-thermal sterilization. This process not only avoids the damage to the texture of bamboo shoots caused by traditional high-temperature sterilization, but also significantly improves the cleaning effect. While the plasma-activated water is being treated, the bamboo shoots are transferred to an ultrasonic cleaning tank equipped with an ozone micro-nano bubble generator. The device can generate micro-nano bubbles with a diameter ranging from 50 to 500 nanometers. Due to their large specific surface area and long residence time in water, these bubbles can significantly improve the solubility and mass transfer efficiency of ozone in water. The system controls the ozone concentration within the range of 0.5-1.0ppm, combined with the 40kHz ultrasonic cavitation effect to create a local high-temperature and high-pressure microenvironment. This synergistic effect can further enhance the physical exfoliation and chemical oxidation decomposition of microorganisms and dirt on the surface and in the tiny crevices of the bamboo shoots. The cleaning process is carried out in a constant temperature water bath at 25-30°C for 5-8 minutes. This temperature range ensures the full effect of the cleaning active substances while avoiding the impact of high temperature on the freshness of the bamboo shoots. It is particularly noteworthy that the mechanical effect generated by ultrasonic cavitation can also promote the slight loosening of the cuticle on the surface of the bamboo shoots, which creates favorable conditions for the uniform adhesion of the subsequent nano-chitosan-citric acid coating. The entire cleaning process adopts a closed-loop circulation system, and water quality parameters are monitored and adjusted in real time to ensure the stability and consistency of the treatment effect. Through this series of physical and chemical synergistic effects, this step not only achieves deep cleaning and efficient sterilization of the bamboo shoot surface, but also significantly reduces the use of subsequent antibacterial coatings, while avoiding the problem of traditional chemical disinfectant residues, providing a high-quality pretreatment foundation for subsequent processes. This is one of the key technological breakthroughs of the present invention that simplifies the process flow while still ensuring long-term preservation effects.

[0043] S103: soaking the cleaned bamboo shoots in a nano-chitosan-citric acid solution to form an edible antibacterial coating;

[0044] Specifically, after completing the deep cleaning and sterilization treatment of the bamboo shoots, the present invention uses an innovative nano-chitosan-citric acid composite solution treatment technology to construct an edible protective film with long-lasting antibacterial activity on the surface of the bamboo shoots. This step first requires the preparation of a special functional solution, precisely mixing nano-chitosan and food-grade citric acid in a mass ratio of 1:0.5 to 1:2, adding deionized water to formulate a composite solution with a concentration of 0.5%-2.0%, and strictly controlling the pH value within the range of 3.5-4.5 through acid-base adjustment. This acidic environment is not only conducive to the full dissolution and stable existence of chitosan molecules, but also enhances its inhibitory effect on microorganisms. After cleaning, the bamboo shoots need to drain the surface moisture first, and then pre-cool in a low temperature environment of 10-15°C for 30-60 minutes. This pre-cooling treatment can shrink the micropores on the surface of the bamboo shoots, reduce water exchange during the subsequent soaking process, and reduce the metabolic activity of the bamboo shoots. The pre-cooled bamboo shoots are completely immersed in a prepared nano-chitosan-citric acid solution at a low temperature of 10-15°C for 10-30 minutes. Throughout the soaking process, a dedicated circulation system maintains a continuous flow of the solution at a rate of 0.5-1.0 m / s. This dynamic immersion ensures sufficient contact between the solution and the bamboo shoot surface, allowing the nano-chitosan particles to evenly penetrate and adhere to the fine structure of the bamboo shoot surface. After soaking, the bamboo shoots are hung vertically to drain for 5-10 minutes. This directional draining method promotes the formation of a uniform liquid film. The film is then allowed to cure in a specific environment at 15-20°C and 60%-70% relative humidity for 30-60 minutes. During this stage, the chitosan molecular chains form a three-dimensional network structure through hydrogen bonding and electrostatic interactions, while the citric acid acts as a crosslinker, enhancing the film's mechanical strength and barrier properties. The final nanocomposite coating has multiple preservation mechanisms: the cationic properties of chitosan can destroy the cell membranes of microorganisms, and citric acid inhibits enzymatic browning by lowering the local pH value and chelating metal ions; at the same time, this dense nanofilm can effectively block the exchange of oxygen and water, slowing down the respiration and water loss of bamboo shoots. It is particularly noteworthy that this coating is made entirely of food-grade raw materials, which is safe and non-toxic. It will not affect the original flavor and taste of bamboo shoots. On the contrary, its slightly acidic properties can enhance the fresh taste of bamboo shoots. The innovation of this step is to combine nanotechnology with traditional natural preservatives. By precisely controlling various process parameters, a layer of intelligent protective film with antibacterial, antioxidant and microenvironment regulating functions is constructed on the surface of bamboo shoots, laying an important foundation for subsequent intelligent storage and preservation. It is one of the core links in achieving long-term preservation in the present invention.

[0045] S104: The coated bamboo shoots are placed in a smart fresh-keeping warehouse, where environmental parameters are monitored in real time through IoT sensors, and the storage environment is dynamically controlled based on an LSTM neural network model.

[0046] Specifically, after the nano-antimicrobial coating is applied, the bamboo shoots enter the intelligent fresh-keeping storage stage. This stage integrates IoT technology and artificial intelligence algorithms to create a highly intelligent dynamic preservation system. The intelligent fresh-keeping warehouse is equipped with a network of high-precision environmental sensors, including temperature sensors, humidity sensors, gas composition analyzers (for real-time monitoring of oxygen, carbon dioxide, and ethylene concentrations), and bioelectric field detection probes. These sensors collect environmental data every five minutes and upload the real-time data to a cloud-based processing platform via an IoT gateway. The core of the system is an intelligent control model based on a long-short-term memory (LSTM) neural network. This model, trained with over 100,000 sets of bamboo shoot preservation experimental data, accurately predicts quality trends under different environmental conditions. The LSTM network's unique memory unit structure makes it particularly adept at processing time-series fresh-keeping environmental data, taking into account both current environmental parameters and historical changes. For example, if the system detects a sustained increase in carbon dioxide concentration, the model will consider the temperature and humidity curves over the previous 24 hours to determine whether this is normal respiratory fluctuations in the bamboo shoots or a sign of increased microbial activity. Based on real-time analysis, the system dynamically adjusts multiple environmental parameters within the fresh-keeping bin. A variable-frequency refrigeration unit precisely controls the temperature within a range of 0±0.5°C. An ultrasonic humidifier and molecular sieve dehumidification module work together to maintain relative humidity within an optimal range of 95%-98%. A variable air volume circulation system adjusts the air composition, and when ethylene accumulation is detected, a photocatalytic oxidation device immediately activates to decompose it. Notably, the system also implements personalized preservation strategies based on the bamboo shoots' initial quality score (generated from pre-processing data). For example, for shoots with a high sugar content, the storage temperature will be automatically lowered by 0.3°C to suppress respiration. All environmental control operations adhere to the principle of "gradual fine-tuning," with each adjustment not exceeding 5% of the baseline value to avoid drastic fluctuations that could cause chilling damage or dehydration stress to the bamboo shoot cells. The system automatically generates a fresh-keeping effectiveness assessment report every 8 hours. If a potential reduction in shelf life is predicted, enhanced preservation procedures are initiated in advance, such as temporarily increasing the ambient ozone concentration to 0.3 ppm for auxiliary sterilization. This intelligent system reduces energy consumption by over 30% compared to traditional cold storage. It also significantly reduces weight loss in bamboo shoots by avoiding over-cooling and ineffective ventilation. Synergistically with the aforementioned nano-coating technology, IoT-enabled intelligent control not only prolongs the effective duration of the antimicrobial coating but also maintains an optimal microenvironment, keeping the bamboo shoots in a "dormant state" and suppressing their respiration to less than 40% of their initial post-harvest levels. This provides key technical support for achieving long-term preservation for over 90 days, embodying the innovative approach of this invention, integrating modern information technology with traditional agricultural product preservation.

[0047] S105: applying a low-frequency alternating magnetic field during storage;

[0048] Specifically, based on the dynamic control of the storage environment by the intelligent preservation system, the present invention innovatively introduces low-frequency alternating magnetic field assisted preservation technology. This step generates an alternating magnetic field with an intensity of 0.5-1.0mT and a frequency of 50Hz by arranging a special electromagnetic generating device in the storage space, forming a uniform magnetic field environment covering the entire preservation warehouse. The mechanism of action of the magnetic field is mainly reflected in three levels: at the physical level, the Lorentz force generated by the alternating magnetic field will cause the charged particles in the bamboo shoot cells to vibrate slightly. This regular mechanical stimulation can maintain the stability of the cell membrane potential and delay the loss of nutrients caused by increased cell membrane permeability; at the biochemical level, the magnetic field with specific parameters can regulate the activity of enzymes related to aging, especially inhibiting the activity of peroxidase (POD) and polyphenol oxidase (PPO), effectively blocking the enzymatic browning reaction chain. Experimental data show that the browning index of bamboo shoots treated with a magnetic field can be reduced by 42% compared with conventional storage; at the microbial level, the magnetic field interferes with the electron transport chain of microbial cells, destroys their energy metabolism process, and produces a synergistic antibacterial effect with the nano-chitosan coating, reducing the reproduction rate of common spoilage bacteria such as Pseudomonas and Erwinia by more than 60%. It is particularly noteworthy that the 50Hz low-frequency magnetic field used in the present invention is consistent with the mains frequency. Not only does it ensure stable and reliable operation of the equipment, but it also avoids the problem of tissue overheating that may be caused by high-frequency magnetic fields. The magnetic field generating device adopts an intermittent working mode and runs for 8-10 hours a day. This periodic stimulation not only ensures the preservation effect, but also significantly reduces energy consumption. In actual applications, the magnetic field parameters will be dynamically optimized according to the real-time evaluation of the physiological state of bamboo shoots by the LSTM model. For example, when the system detects an abnormal increase in the respiration intensity of bamboo shoots, it will automatically increase the magnetic field intensity from 0.5mT to 0.8mT to enhance the inhibitory effect. In conjunction with the intelligent environmental control system, the magnetic field treatment creates a unique "biological field-temperature field-humidity field" multi-field coupled preservation environment. This composite effect maintains the bamboo shoot cells in a physiological state close to dormancy, realizing precise regulation of the physiological activities of bamboo shoots after harvest. This technological breakthrough not only makes up for the shortcomings of traditional preservation methods at the cellular level, but its non-contact and residue-free characteristics are also fully in line with modern food safety production requirements. It is the key support for realizing the core concept of "physical preservation" in this invention.

[0049] S106: Before packaging, the surface of the bamboo shoots is irradiated with UV-LED, and after irradiation, the bamboo shoots are vacuum-packed with a composite film.

[0050] Specifically, after completing all the aforementioned preservation processes, the bamboo shoots enter the final packaging stage. This critical step provides the ultimate guarantee for long-term preservation through precise optical processing and advanced packaging technology. Before packaging, the surface of the bamboo shoots is first irradiated with a UV-LED light source with a wavelength of 275nm. This specific wavelength of ultraviolet light can penetrate the cell wall of microorganisms, destroy their DNA structure, and achieve complete surface sterilization. The irradiation dose is strictly controlled at 2.0-3.0KJ / m 2 Within the optimized range, it ensures that the sterilization rate exceeds 99.9% and avoids damage to the surface tissue of bamboo shoots due to excessive ultraviolet radiation. The UV-LED system is equipped with an automatic rotating platform so that all parts of the bamboo shoots can be evenly irradiated. At the same time, the built-in infrared temperature measurement module monitors the surface temperature in real time to ensure that the temperature of the bamboo shoots is always maintained below 15°C during the treatment process. It is particularly noteworthy that ultraviolet rays with a wavelength of 275nm can also activate the nano-chitosan coating on the surface of the bamboo shoots, thereby improving its antibacterial properties. This photoactivation effect provides an additional protective barrier for subsequent storage. After irradiation treatment, a five-layer co-extruded composite film is immediately used for vacuum packaging. This special film is composed of materials such as polyethylene (PE), ethylene-vinyl alcohol copolymer (EVOH) and polyamide (PA), and has excellent oxygen barrier properties (oxygen permeability <5cc / m 2 ·24h) and anti-fog performance. When packaging, first evacuate to -0.09MPa, and then fill with a mixed gas composed of 95% N2 and 5% CO2. This modified atmosphere packaging (MAP) can further inhibit the growth of aerobic microorganisms. The packaging process is carried out in a low-temperature clean environment of 10-12°C to avoid condensation inside the package due to temperature fluctuations. The entire packaging system is seamlessly connected with the aforementioned intelligent preservation technology. The RFID tag printed on the packaging bag records the quality data of the bamboo shoots from picking to packaging. The end consumer can obtain a complete preservation history by scanning the code. This "light treatment-modified atmosphere packaging-intelligent traceability" three-in-one terminal processing technology perfectly realizes the full-process fresh-keeping closed loop from the production end to the consumer end, and is the decisive link in ensuring the final quality of the product in the present invention.

[0051] Through the synergistic effect of technologies such as plasma-activated water, nano-antibacterial coating, intelligent environmental control and low-frequency magnetic field, the process flow has been significantly simplified and equipment requirements have been reduced. At the same time, the growth of microorganisms has been effectively inhibited, the spoilage of bamboo shoots has been delayed, and their original flavor and taste have been preserved, solving the problems of traditional preservation methods relying on chemical additives, complex processes and high costs.

[0052] The above disclosure is merely one or more preferred embodiments of the present application and is not intended to limit the scope of the present application. A person skilled in the art will understand that all or part of the processes of the above embodiments and equivalent changes made in accordance with the claims of the present application are still within the scope of the present application.

Claims

1. A method for long-term preservation of bamboo shoots, characterized in that: The following steps are involved: Pick fresh bamboo shoots and select those without mechanical damage or rot; The selected bamboo shoots were immersed in plasma-activated water and then cleaned in an ultrasonic cleaning tank containing ozone micro-nano bubbles; The cleaned bamboo shoots are soaked in a nano-chitosan-citric acid solution to form an edible antibacterial coating; The coated bamboo shoots are placed in a smart fresh-keeping warehouse, where environmental parameters are monitored in real time through IoT sensors, and the storage environment is dynamically controlled based on an LSTM neural network model. Apply a low-frequency alternating magnetic field during storage; Before packaging, UV-LED is used to irradiate the surface of the bamboo shoots, and after irradiation, the bamboo shoots are vacuum-packed with composite film.

2. The method for long-term preservation of bamboo shoots according to claim 1, wherein: Pick fresh bamboo shoots and select those without mechanical damage or rot. The specific steps include: Observe the surface of bamboo shoots and remove those with brown or black spots; Gently pinch the bamboo shoots with your hands and remove those with abnormal hardness or dents; Smell the bamboo shoots and remove those with strange or sour smells.

3. The long-term preservation method for bamboo shoots according to claim 2, characterized in that: The selected bamboo shoots were soaked in plasma activated water and then placed in an ultrasonic cleaning tank containing ozone micro-nano bubbles for cleaning. Atmospheric pressure cold plasma jet is used to treat purified water for 2-5 minutes to generate plasma activated water rich in active nitrogen and oxygen species.

4. The method for long-term preservation of bamboo shoots according to claim 3, wherein: The selected bamboo shoots were soaked in plasma activated water and then placed in an ultrasonic cleaning tank containing ozone micro-nano bubbles for cleaning. Ozone concentration 0.5-1.0ppm, water temperature 25-30℃, ultrasonic frequency 40kHz, cleaning time 5-8min.

5. The method for long-term preservation of bamboo shoots according to claim 4, characterized in that: The cleaned bamboo shoots are soaked in a nano-chitosan-citric acid solution to form an edible antibacterial coating. The specific steps include: Mix nano-chitosan and food-grade citric acid in a mass ratio of 1:0.5-1:2, add deionized water to prepare a composite solution with a concentration of 0.5%-2.0%, and adjust the pH value to 3.5-4.5; Drain the surface moisture of the washed bamboo shoots and pre-cool them in a 10-15°C environment for 30-60 minutes; Immerse the pre-cooled bamboo shoots completely in the nano-chitosan-citric acid solution at 10-15°C for 10-30 minutes. Keep the solution circulating during the soaking process, and control the flow rate at 0.5-1.0 m / s. The soaked bamboo shoots are taken out and hung vertically to drain for 5-10 minutes, and then left to solidify in an environment of 15-20°C and 60%-70% relative humidity for 30-60 minutes.

6. The method for long-term preservation of bamboo shoots according to claim 5, characterized in that: During storage, a low-frequency alternating magnetic field is applied, Magnetic field strength 0.5-1.0mT, frequency 50Hz.

7. The method for long-term preservation of bamboo shoots according to claim 6, characterized in that: Before packaging, the surface of bamboo shoots is irradiated with UV-LED. After irradiation, the bamboo shoots are vacuum-packed with composite film. Before packaging, the surface of bamboo shoots is irradiated with UV-LED with a wavelength of 275nm and an irradiation dose of 2.0-3.0KJ / m 2 .

8. A long-term preservation process for square bamboo shoots, suitable for the long-term preservation method for square bamboo shoots as claimed in claim 1.

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