Areca nut preservation method based on composite treatment

Abstract

The invention relates to the technical field of food preservation, in particular to a betel nut preservation method based on composite treatment.The betel nut preservation method comprises the steps that raw materials are sorted and then washed with 2 ppm ozone water, the raw materials are soaked in a color protection solution containing ascorbic acid, citric acid, phytic acid and EDTA, a chitosan-tea polyphenol-nano zinc oxide-silver composite solution is subjected to electrostatic spraying for film coating, vacuum precooling is conducted to 8 DEG C, and the betel nut is obtained. And after modified atmosphere packaging, carrying out pulsed electric field and ultrasonic cooperative treatment and 2.5 kGy gamma irradiation, and finally, intelligently storing at a constant temperature of 4 DEG C. Through cooperation of multiple technologies, the problems of microorganism exceeding, water loss and component volatilization are solved, the refreshing time reaches 4 months, the total number of bacterial colonies within 120 days is smaller than or equal to 1.5 * 10 < 3 > CFU / g, the retention rate of arecoline is larger than or equal to 92%, the weight loss rate is smaller than or equal to 4.8%, the cost is low, and large-scale production is easy.

Description

Technical Field

[0001] The invention relates to the technical field of food preservation, in particular to a betel nut preservation method based on composite processing. Background Art

[0002] When it comes to betel nut preservation, current mainstream preservation technologies have significant limitations. Most existing technologies rely on a single refrigeration method, storing betel nuts at 4-6°C. This approach fails to effectively address the core issues inherent in betel nut preservation. Firstly, due to the lack of enzyme inhibition and the inability to prevent microbial growth, betel nuts quickly develop browning and spoilage. Secondly, during refrigeration, betel nuts lose a significant amount of moisture, severely impacting their taste. Furthermore, active ingredients like arecoline are also lost through volatilization, significantly reducing their quality and value.

[0003] While some similar technologies have proposed the concept of modified atmosphere packaging (MAP), they suffer from significant shortcomings in practical application. These technologies fail to integrate irradiation treatment with chemical preservation techniques, and MAP alone cannot completely address the problem of mold growth. Due to the lack of synergistic effects from these multiple technologies, MAP's effectiveness in inhibiting microbial growth is limited, making it difficult to maintain the freshness of betel nut for an extended period, and failing to meet the market's higher demands for shelf life and quality.

[0004] Given the numerous challenges existing betel nut preservation technologies face in terms of shelf life, moisture retention, retention of active ingredients, and microbial inhibition, there is an urgent need to develop a multi-technology synergistic preservation solution. This solution must effectively address the issue of excessive microorganisms and achieve bidirectional regulation of moisture and gas to slow the metabolic process of betel nut, thereby significantly extending its shelf life and improving its quality. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the deficiencies in the prior art, the present invention provides a betel nut preservation method based on composite treatment.

[0007] (2) Technical solution

[0008] A betel nut preservation method based on composite treatment comprises the following steps:

[0009] S1. Raw materials are sorted by an industrial visual sorter. Fruits free of pests and diseases are cleaned in an ultrasonic cleaning tank using ozone water. Ozone generation is monitored in real time by an ozone concentration sensor.

[0010] S2. Immerse in a color-protecting solution containing ascorbic acid, citric acid, phytic acid, and EDTA. Adjust the pH to 3.5 ± 0.1 with citric acid. Stir in a 25°C water bath to allow EDTA to chelate the metal ions.

[0011] S3. Electrostatic spraying of chitosan-tea polyphenols-nano zinc oxide-silver composite solution, wherein the chitosan concentration is 2%, dissolved in 2% acetic acid solution, the tea polyphenol concentration is 0.1%, 50nm zinc oxide 0.05%, 10nm silver particles 0.01%, the solution is ultrasonically dispersed and sprayed by an electrostatic spray device to form a film layer, which is then cured by 365nm ultraviolet light and ozone;

[0012] S4. Precool the sample to 8 ± 1°C in a vacuum cooler. During the precooling process, introduce nitrogen containing ethanol and maintain the humidity at 90% ± 5%.

[0013] S5. The modified atmosphere packaging utilizes a three-layer co-extruded PE / PVA-nano-TiO2 film, produced via a twin-screw extruder, with a 0.3% nano-TiO2 content. It also incorporates pH-responsive CO2 sustained-release microspheres, comprised of 80-mesh calcium carbonate and citric acid encapsulated in a calcium alginate gel. These release CO2 upon exposure to acid at a rate of 0.5±0.1 mg / g·h. The humidity-regulating layer is a montmorillonite-chitosan composite layer, forming a mesoporous structure with pore sizes of 5-10 nm. The packaging gas composition is 85% N2, 10% CO2, and 5% O2.

[0014] S6. First, the betel nuts were treated with a pulsed electric field-ultrasonic wave synergistic treatment device and ultrasound for 10 minutes, using a 0.1% sodium chloride + 0.05% chitosan solution; then, they were irradiated with 2.5 kGy gamma radiation using a cobalt-60 radiation source. The betel nut stacking density was ≤15 kg / m 3 , placed in a rotary irradiation rack, and packaged and sealed within 30 minutes after irradiation;

[0015] S7. Store in an intelligent constant-temperature storage system at an ambient humidity of 70% ± 5%. Real-time monitoring of weight loss using an infrared sensor and linkage control using a weighing sensor are used. An oxygen sensor monitors the O2 concentration within the package, and automatically replenishes with a 9:1 N2:O2 mixture when O2 is < 3%. Arecoline content is monitored every 30 days using a near-infrared spectrometer.

[0016] Preferably, when preparing the color protection solution, EDTA needs to be pre-dissolved in 50±2°C deionized water, and then ascorbic acid, citric acid, and phytic acid are added in sequence, stirred at 20-25°C for 15 minutes until completely dissolved, and the solution is filtered through a 0.45μm filter membrane before use.

[0017] Preferably, when preparing the composite coating liquid, the silver nanoparticles are prepared by mixing 0.01 mol / L silver nitrate solution and 0.03 mol / L sodium citrate solution in a volume ratio of 1:2, stirring in a 70°C water bath for 30 minutes, cooling to room temperature and ultrasonically blending with chitosan solution for 45 minutes, adjusting the solution pH to 5.0-5.5 with acetic acid, and standing for degassing for 10 minutes.

[0018] Preferably, the pH-responsive CO2 sustained-release microspheres are prepared by a double emulsion method, with Span-80 as an emulsifier, an emulsification speed of 2000 rpm, a calcium chloride solution temperature of 25°C during cross-linking, a moisture content of ≤8% after drying of the microspheres, and a cumulative CO2 release of ≥90% in a pH 3.5 buffer solution within 24 hours.

[0019] Preferably, when pulse electric field and ultrasound are used in synergistic treatment, 10 g of chitosan is added to every 100 L of the treatment liquid, the temperature is maintained at 15-20° C. by a circulating cooling system, the ultrasonic probe is inserted into the treatment liquid to a depth of 5 cm, ultrasound continues to work during the pulse electric field treatment, and the liquid flow rate is 0.5 m / s.

[0020] Preferably, the montmorillonite-chitosan humidity control layer is prepared by a tape casting method, wherein montmorillonite and chitosan solution are blended to a tape casting thickness of 50 μm, cross-linked in a 0.5% calcium chloride solution for 2 hours, and dried to form a mesoporous structure with a crystallinity of 30%-40%, and a moisture absorption rate of ≥0.5 g / (m 2 ·h), desorption rate ≥0.3g / (m 2 ·h).

[0021] Preferably, betel nut needs to be pre-packaged before gamma irradiation treatment, the irradiation dose is calibrated by a Farmer-type ionization chamber, the angular velocity error of the rotating frame is ≤±0.1rpm, and the ambient temperature during irradiation is ≤25°C and the humidity is ≤60%.

[0022] Preferably, the ultraviolet light transmittance of the three-layer co-extruded film is ≤3%, the oxygen barrier property is improved by 40% compared with the pure PE / PVA film, the tensile strength of the film is ≥30MPa, the elongation at break is ≥200%, the heat sealing temperature is 140-160°C, and the heat sealing strength is ≥15N / 15mm.

[0023] Preferably, the intelligent monitoring system during storage uses a PLC controller with a data acquisition frequency of 1 time per hour. When the total bacterial count is greater than 1.5×10 3 When the CFU / g or arecoline retention rate is less than 92%, an automatic alarm is given. The weight loss rate is calculated using the dynamic weighing method, and the water activity is maintained at 0.62±0.03 using an Aw meter.

[0024] Preferably, the total bacterial count of the processed betel nut is ≤1.5×10 3CFU / g, pulp firmness retention rate ≥88%, weight loss rate ≤4.8%, the shelf life is extended by more than 5 times compared with the traditional refrigeration method, and the arecoline loss rate ≤8%, and the sensory score ≥85 points.

[0025] (3) Beneficial technical effects

[0026] Compared with the existing technology, the beneficial effects of the present invention are:

[0027] 1. By adopting a composite antibacterial system, the problem of excessive microorganisms is effectively solved, protecting betel nut from microbial invasion during storage and ensuring food safety.

[0028] 2. Utilizing a two-way moisture-gas control technology, the metabolic process of betel nut is slowed, reducing water loss and maintaining its excellent taste for a longer period. The application of low-temperature co-processing significantly extends the shelf life of betel nut, resolving the short shelf life problem associated with traditional preservation methods.

[0029] 3. This preservation method also effectively preserves the active ingredients in betel nut, reducing the loss of active ingredients such as arecoline, allowing the betel nut to maintain its high medicinal and edible value after storage. Furthermore, the entire preservation process is environmentally friendly and safe, causing no pollution to the betel nut and reducing preservation costs. This provides strong support for the large-scale storage and transportation of betel nut, with positive economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a betel nut preservation method based on composite treatment proposed by the present invention;

[0031] Figure 2 120-day arecoline retention rate and pulp firmness retention rate broken line comparison chart of the embodiment and the comparative example;

[0032] Figure 3 1 is a fitting curve of the change of arecoline retention rate with storage period in Example 1, Example 2 and the comparative example;

[0033] Figure 4 3 is a fitting curve of the change in weight loss rate and storage time of Example 1, Example 3 and the comparative example. DETAILED DESCRIPTION

[0034] according to Figures 1 to 4 , the specific implementation of the present invention is as follows:

[0035] Example 1: Betel nut preservation method based on composite treatment

[0036] 1. Raw material sorting and ozone water cleaning

[0037] An industrial visual sorting machine with a resolution of 2048×1536 pixels and a sorting speed of 50 pieces / minute was used to screen betel nut fruits with a diameter of 2.5-3.5 cm and free of pests and diseases. The fruits were placed in an ultrasonic cleaning tank with a power of 300W and a frequency of 40kHz and cleaned at 20-25℃ for 5 minutes using 2ppm ozone water and real-time monitoring by an ozone concentration sensor.

[0038] 2. Soaking in color protection liquid

[0039] Dissolve 5g ascorbic acid (purity ≥99%), 3g analytical grade citric acid, 1g phytic acid 50% aqueous solution, and 0.5g EDTA disodium salt in 1L deionized water. Adjust the pH to 3.5±0.1 with citric acid. Stir at 300rpm for 10 minutes in a 25°C constant temperature water bath with a temperature control accuracy of ±0.5°C. The solution transmittance should be ≥90%. EDTA will react with the metal ions to form a chelate reaction.

[0040] 3. Preparation of composite coating liquid and electrostatic spraying

[0041] 20g chitosan with a deacetylation degree of ≥95% was dissolved in 1L 2% acetic acid solution and stirred in a water bath at 60℃ for 30 minutes until completely dissolved. 1g tea polyphenols with a purity of ≥98%, 0.5g 50nm zinc oxide, and 0.1g 10nm silver particles were prepared by stirring in a water bath at 70℃ for 30 minutes with 0.01mol / L silver nitrate and 0.03mol / L sodium citrate in a volume ratio of 1:2. The mixture was dispersed by 40kHz ultrasonic power of 400W for 45 minutes. The electrostatic spray device was used with a voltage of 20kV and a nozzle distance of 15cm to form a 50±5μm film layer. The film was then irradiated with a 365nm ultraviolet lamp with a power density of 5mW / cm 2 Co-curing with 1ppm ozone in a humidity environment of 40%-50% for 1 minute.

[0042] 4. Vacuum pre-cooling and modified atmosphere packaging

[0043] In a pre-cooler with a vacuum degree of 8-10kPa, nitrogen containing 0.5% ethanol at a relative humidity of 90% ± 5% is introduced for 30 minutes to a temperature of 8 ± 1°C, with the temperature difference between the center and the surface of the fruit ≤ 2°C. The product is packaged using a three-layer co-extruded PE / PVA-nano-TiO2 film with a 50μm PE layer and a 20μm PVA layer, with 0.3% nano-TiO2 dispersed in the PE layer, and an oxygen permeability of 3.2 ± 0.2cm 3 / m 2 ·24h, moisture permeability ≤5g / m 2·24h; built-in pH-responsive CO2 sustained-release microspheres with a molar ratio of calcium carbonate and citric acid of 1:1, coated with calcium alginate, with a particle size of 50-100μm, 5g is added for every 100g of betel nut, and the CO2 release rate in the presence of acid is 0.5±0.1mg / g·h; the mass ratio of montmorillonite-chitosan humidity control layer is 1:2, and 0.5% calcium chloride is cross-linked for 2 hours to form a 5-10nm mesoporous structure, which can regulate RH65%-75%; it is filled with N285%, CO210%, and O25% with a distribution accuracy of ±0.5%.

[0044] 5. Pulsed Electric Field-Ultrasound Co-treatment and γ-Irradiation

[0045] The betel nuts were treated in a 0.1% sodium chloride + 0.05% chitosan solution at 15-20°C for 10 minutes at a pulsed electric field of 20 kV / cm with a pulse width of 100 μs, a frequency of 500 Hz, and a 20 kHz ultrasonic power of 300 W. The electrodes were spaced 2 cm apart and the betel nut was immersed to a depth of 3 cm. The betel nuts were irradiated with 2.5 kGy of gamma radiation using a cobalt-60 source at a dose rate of 0.5 kGy / h. The betel nuts were stacked at a density of 15 kg / m 3 The irradiation source is placed on a rotating irradiation rack with a rotation speed of 5 rpm and is 50 cm away from the material. The dose uniformity deviation is ≤±3%. The material should be sealed and packaged within 30 minutes after irradiation.

[0046] 6. Intelligent constant temperature storage

[0047] Stored in an intelligent storage system at 4℃±0.5℃ and RH70%±5%, the temperature fluctuates by ±1℃ every 12 hours. The weight loss rate is monitored by an infrared sensor with an accuracy of ±0.1%. When the O2 concentration is less than 3%, the N2:O2=9:1 mixed gas is automatically replenished with a gas pressure of 0.1MPa. The arecoline content is monitored every 30 days using a near-infrared spectrometer.

[0048] Example 2: Preservation method with optimized EDTA content of color-protecting liquid

[0049] 1. Raw material sorting and ozone water cleaning

[0050] An industrial visual sorting machine with a resolution of 2048×1536 pixels and a sorting speed of 50 pieces / minute was used to screen betel nut fruits with a diameter of 2.5-3.5 cm and free of pests and diseases. The fruits were placed in an ultrasonic cleaning tank with a power of 300W and a frequency of 40kHz and cleaned at 20-25℃ for 5 minutes using 2ppm ozone water and real-time monitoring by an ozone concentration sensor.

[0051] 2. Soaking in color protection liquid

[0052] Dissolve 5 g ascorbic acid (≥99% purity), 3 g analytical grade citric acid, 1 g phytic acid 50% aqueous solution, and 0.8 g EDTA disodium salt in 1 L deionized water. Adjust the pH to 3.6±0.1 with citric acid. Stir at 300 rpm for 10 minutes in a 25°C constant temperature water bath with a temperature control accuracy of ±0.5°C. The solution has a light transmittance of 88%.

[0053] 3. Preparation of composite coating liquid and electrostatic spraying

[0054] 20g chitosan with a deacetylation degree of ≥95% was dissolved in 1L 2% acetic acid solution and stirred in a water bath at 60℃ for 30 minutes until completely dissolved. 1g tea polyphenols with a purity of ≥98%, 0.5g 50nm zinc oxide, and 0.1g 10nm silver particles were prepared by stirring in a water bath at 70℃ for 30 minutes with 0.01mol / L silver nitrate and 0.03mol / L sodium citrate in a volume ratio of 1:2. The mixture was dispersed by 40kHz ultrasonic power of 400W for 45 minutes. The electrostatic spray device was used with a voltage of 20kV and a nozzle distance of 15cm to form a 50±5μm film layer. The film was then irradiated with a 365nm ultraviolet lamp with a power density of 5mW / cm 2 Co-curing with 1ppm ozone in a humidity environment of 40%-50% for 1 minute.

[0055] 4. Vacuum pre-cooling and modified atmosphere packaging

[0056] In a pre-cooler with a vacuum degree of 8-10kPa, nitrogen containing 0.5% ethanol at a relative humidity of 90% ± 5% is introduced for 30 minutes to a temperature of 8 ± 1°C, with the temperature difference between the center and the surface of the fruit ≤ 2°C. The product is packaged using a three-layer co-extruded PE / PVA-nano-TiO2 film with a 50μm PE layer and a 20μm PVA layer, with 0.3% nano-TiO2 dispersed in the PE layer, and an oxygen permeability of 3.2 ± 0.2cm 3 / m 2 ·24h, moisture permeability ≤5g / m 2 ·24h; built-in pH-responsive CO2 sustained-release microspheres with a molar ratio of calcium carbonate and citric acid of 1:1, coated with calcium alginate, with a particle size of 50-100μm, 5g is added for every 100g of betel nut, and the CO2 release rate in the presence of acid is 0.5±0.1mg / g·h; the mass ratio of montmorillonite-chitosan humidity control layer is 1:2, and 0.5% calcium chloride is cross-linked for 2 hours to form a 5-10nm mesoporous structure, which can regulate RH65%-75%; it is filled with N285%, CO210%, and O25% with a distribution accuracy of ±0.5%.

[0057] 5. Pulsed Electric Field-Ultrasound Co-treatment and γ-Irradiation

[0058] The betel nuts were treated in a 0.1% sodium chloride + 0.05% chitosan solution at 15-20°C for 10 minutes at a pulsed electric field of 20 kV / cm with a pulse width of 100 μs, a frequency of 500 Hz, and a 20 kHz ultrasonic power of 300 W. The electrodes were spaced 2 cm apart and the betel nut was immersed to a depth of 3 cm. The betel nuts were irradiated with 2.5 kGy of gamma radiation using a cobalt-60 source at a dose rate of 0.5 kGy / h. The betel nuts were stacked at a density of 15 kg / m 3 The irradiation source is placed on a rotating irradiation rack with a rotation speed of 5 rpm and is 50 cm away from the material. The dose uniformity deviation is ≤±3%. The material should be sealed and packaged within 30 minutes after irradiation.

[0059] 6. Intelligent constant temperature storage

[0060] Stored in an intelligent storage system at 4℃±0.5℃ and RH70%±5%, the temperature fluctuates by ±1℃ every 12 hours. The weight loss rate is monitored by an infrared sensor with an accuracy of ±0.1%. When the O2 concentration is less than 3%, the N2:O2=9:1 mixed gas is automatically replenished with a gas pressure of 0.1MPa. The arecoline content is monitored every 30 days using a near-infrared spectrometer.

[0061] Example 3: Pulsed electric field-ultrasound synergistic parameter optimization preservation method

[0062] 1. Raw material sorting and ozone water cleaning

[0063] An industrial visual sorting machine with a resolution of 2048×1536 pixels and a sorting speed of 50 pieces / minute was used to screen betel nut fruits with a diameter of 2.5-3.5 cm and free of pests and diseases. The fruits were placed in an ultrasonic cleaning tank with a power of 300W and a frequency of 40kHz and cleaned at 20-25℃ for 5 minutes using 2ppm ozone water and real-time monitoring by an ozone concentration sensor.

[0064] 2. Soaking in color protection liquid

[0065] Dissolve 5 g ascorbic acid (≥99% purity), 3 g analytical grade citric acid, 1 g phytic acid 50% aqueous solution, and 0.5 g EDTA disodium salt in 1 L deionized water. Adjust the pH to 3.5±0.1 with citric acid. Stir at 300 rpm for 10 minutes in a 25°C constant temperature water bath with a temperature control accuracy of ±0.5°C. The solution should have a transmittance of ≥90%.

[0066] 3. Preparation of composite coating liquid and electrostatic spraying

[0067] 20g chitosan with a deacetylation degree of ≥95% was dissolved in 1L 2% acetic acid solution and stirred in a water bath at 60℃ for 30 minutes until completely dissolved. 1g tea polyphenols with a purity of ≥98%, 0.5g 50nm zinc oxide, and 0.1g 10nm silver particles were prepared by stirring in a water bath at 70℃ for 30 minutes with 0.01mol / L silver nitrate and 0.03mol / L sodium citrate in a volume ratio of 1:2. The mixture was dispersed by 40kHz ultrasonic power of 400W for 45 minutes. The electrostatic spray device was used with a voltage of 20kV and a nozzle distance of 15cm to form a 50±5μm film layer. The film was then irradiated with a 365nm ultraviolet lamp with a power density of 5mW / cm 2 Co-curing with 1ppm ozone in a humidity environment of 40%-50% for 1 minute.

[0068] 4. Vacuum pre-cooling and modified atmosphere packaging

[0069] In a pre-cooler with a vacuum degree of 8-10kPa, nitrogen containing 0.5% ethanol at a relative humidity of 90% ± 5% is introduced for 30 minutes to a temperature of 8 ± 1°C, with the temperature difference between the center and the surface of the fruit ≤ 2°C. The product is packaged using a three-layer co-extruded PE / PVA-nano-TiO2 film with a 50μm PE layer and a 20μm PVA layer, with 0.3% nano-TiO2 dispersed in the PE layer, and an oxygen permeability of 3.2 ± 0.2cm 3 / m 2 ·24h, moisture permeability ≤5g / m 2 ·24h; built-in pH-responsive CO2 sustained-release microspheres with a molar ratio of calcium carbonate and citric acid of 1:1, coated with calcium alginate, with a particle size of 50-100μm, 5g is added for every 100g of betel nut, and the CO2 release rate in the presence of acid is 0.5±0.1mg / g·h; the mass ratio of montmorillonite-chitosan humidity control layer is 1:2, and 0.5% calcium chloride is cross-linked for 2 hours to form a 5-10nm mesoporous structure, which can regulate RH65%-75%; it is filled with N285%, CO210%, and O25% with a distribution accuracy of ±0.5%.

[0070] 5. Pulsed Electric Field-Ultrasound Co-treatment and γ-Irradiation

[0071] The betel nuts were treated in a 0.1% sodium chloride + 0.1% chitosan solution at 15-20°C for 10 minutes at a pulsed electric field of 20 kV / cm with a pulse width of 100 μs, a frequency of 800 Hz, and a 20 kHz ultrasonic power of 400 W. The electrodes were spaced 2 cm apart and the betel nut was immersed to a depth of 3 cm. The betel nuts were irradiated with 2.5 kGy of gamma radiation using a cobalt-60 source at a dose rate of 0.5 kGy / h. The betel nuts were stacked at a density of 15 kg / m 3 The irradiation source is placed on a rotating irradiation rack with a rotation speed of 5 rpm and is 50 cm away from the material. The dose uniformity deviation is ≤±3%. The material should be sealed and packaged within 30 minutes after irradiation.

[0072] 6. Intelligent constant temperature storage

[0073] Stored in an intelligent storage system at 4°C ± 0.5°C and RH 70% ± 5%, the temperature fluctuates by ±1°C every 12 hours. The weight loss rate is monitored by an infrared sensor with an accuracy of ±0.1%. When the O2 concentration is less than 3%, a 9:1 N2:O2 mixture is automatically replenished at a pressure of 0.1 MPa. Arecoline content is monitored every 30 days using a near-infrared spectrometer. Comparative Example: Traditional single refrigeration preservation method

[0074] 1. Raw material sorting and cleaning

[0075] An industrial visual sorting machine with a resolution of 2048×1536 pixels and a sorting speed of 50 pieces / minute was used to screen betel nut fruits with a diameter of 2.5-3.5 cm and no pests and diseases. The fruits were placed in an ultrasonic cleaning tank with a power of 300 W and a frequency of 40 kHz and cleaned with clean water at 20-25°C for 5 minutes.

[0076] 2. Storage conditions

[0077] The cleaned betel nuts were directly placed in a cold storage at 4-6℃ and RH70% for 120 days without color protection, coating, modified atmosphere packaging, irradiation or intelligent monitoring.

[0078] The total bacterial count and arecoline retention rate of the embodiment and the comparative example are compared in the following table:

[0079] Table 1

[0080] Group Example 1 Example 2 Example 3 Comparative Example Total colony count after 120 days (CFU / g) <![CDATA[≤1.5×10 3 ]]> <![CDATA[1.3×10 3 ]]> <![CDATA[1.1×10 3 ]]> Unpredictable (corruption) Arecoline retention rate (%) 92.3 92.8 93.4 58.3

[0081] The total number of colonies in Examples 1-3 after 120 days was ≤1.5×10 3 The results show that the colony count of the control sample was 26.7% and the retention rate of arecoline was 1.2%. The results show that the colony count of the control sample was 26.7% and the retention rate was 1.2% higher than that of the control sample due to corruption. This demonstrates the significant effect of the multi-technique synergistic treatment on inhibiting microbial growth and maintaining the active ingredients.

[0082] The comparison of weight loss rate and pulp firmness retention rate is shown in the following table:

[0083] Table 2

[0084]

[0085]

[0086] Examples 1-3 achieved weight loss rates of ≤4.3% and firmness retention rates of ≥88.2%, while the control sample experienced a weight loss of 16.8% and retained only 28% of its firmness. By optimizing the humidity control layer, Example 3 achieved a 4.8% reduction in weight loss compared to Example 1, while improving firmness retention by 0.3%. This demonstrates the synergistic effect of the montmorillonite-chitosan composite layer in inhibiting water loss and maintaining pulp structure, significantly extending shelf life compared to traditional refrigeration methods.

[0087] The changes of microbial inactivation rate with treatment time are shown in the following table:

[0088] Table 3

[0089] Processing time (minutes) Example 1 Inactivation rate (%) Example 3 Inactivation rate (%) Comparative ratio inactivation rate (%) 0 0 0 0 5 92.5 95.3 12.7 10 99.9 99.99 25.4

[0090] The inactivation rates of Examples 1-3 increased rapidly with treatment time, reaching 99.9% and 99.99% at 10 minutes, respectively, compared to only 25.4% for the comparative example. In Example 3, the inactivation rate increased by 2.8% over Example 1 at 5 minutes due to an increase in the pulse frequency to 800 Hz, and near-complete inactivation was achieved at 10 minutes. This demonstrates that optimizing the synergistic treatment parameters can significantly shorten the inactivation time and improve the sterilization efficiency, providing a parameter basis for industrial continuous production.

[0091] The changes in arecoline retention rate during storage are shown in the following table:

[0092] Table 4

[0093] Storage time (days) Example 1 (%) Example 2 (%) Comparative ratio (%) 0 100 100 100 30 95.6 96.2 78.3 60 93.4 94.1 65.7 120 92.3 92.8 58.3

[0094] The retention rate of Examples 1-2 remained above 92% over 120 days, while that of the control dropped to 58.3%. Due to the increased EDTA content, the retention rate of Example 2 increased by 0.7% over Example 1 at 60 days and by 0.5% over 120 days. This demonstrates that EDTA chelation of metal ions effectively inhibits oxidative degradation. Combined with the barrier effect of the composite coating, it significantly slows the loss of active ingredients, demonstrating the importance of optimizing color-protecting solutions for maintaining pharmacological components. The relationship between weight loss rate and storage time is shown in the following table:

[0095] Table 5

[0096] Storage time (days) Example 1 (%) Example 3 (%) Comparative ratio (%) 0 0 0 0 30 1.8 1.5 5.7 60 2.9 2.6 10.3 120 4.2 4.0 16.8

[0097] The weight loss rates of Examples 1-3 increased linearly over time, reaching 4.2% and 4.0% after 120 days, respectively, compared to 16.8% for the comparative example. Due to the optimized mesoporous structure of the humidity-regulating layer, the weight loss slope of Example 3 (0.033% / day) was 5.7% lower than that of Example 1 (0.035% / day). This demonstrates that the moisture absorption-desorption equilibrium mechanism of the montmorillonite-chitosan composite layer effectively inhibits moisture migration. Combined with the microenvironmental control of modified atmosphere packaging, this allows for long-term, low-weight-loss preservation, addressing the issue of weight loss exceeding 15% in traditional refrigerated storage.

[0098] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A betel nut preservation method based on composite treatment, characterized in that: The following steps are involved: S1. Raw materials are sorted by an industrial visual sorter. Fruits free of pests and diseases are cleaned in an ultrasonic cleaning tank using ozone water. Ozone generation is monitored in real time by an ozone concentration sensor. S2. Immerse in a color-protecting solution containing ascorbic acid, citric acid, phytic acid, and EDTA. Adjust the pH to 3.5 ± 0.1 with citric acid. Stir in a 25°C water bath to allow EDTA to chelate the metal ions. S3. Electrostatic spraying of chitosan-tea polyphenols-nano zinc oxide-silver composite solution, wherein the chitosan concentration is 2%, dissolved in 2% acetic acid solution, the tea polyphenol concentration is 0.1%, 50nm zinc oxide 0.05%, 10nm silver particles 0.01%, the solution is ultrasonically dispersed and sprayed by an electrostatic spray device to form a film layer, which is then cured by 365nm ultraviolet light and ozone; S4. Precool the sample to 8 ± 1°C in a vacuum cooler. During the precooling process, introduce nitrogen containing ethanol and maintain the humidity at 90% ± 5%. S5. The modified atmosphere packaging utilizes a three-layer co-extruded PE / PVA-nano-TiO2 film, produced via a twin-screw extruder, with a 0.3% nano-TiO2 content. It also incorporates pH-responsive CO2 sustained-release microspheres, comprised of 80-mesh calcium carbonate and citric acid encapsulated in a calcium alginate gel. These release CO2 upon exposure to acid at a rate of 0.5±0.1 mg / g·h. The humidity-regulating layer is a montmorillonite-chitosan composite layer, forming a mesoporous structure with pore sizes of 5-10 nm. The packaging gas composition is 85% N2, 10% CO2, and 5% O2. S6. First, the betel nuts were treated with a pulsed electric field-ultrasonic wave synergistic treatment device and ultrasound for 10 minutes, using a 0.1% sodium chloride + 0.05% chitosan solution; then, they were irradiated with 2.5 kGy gamma radiation using a cobalt-60 radiation source. The betel nut stacking density was ≤15 kg / m 3 , placed in a rotary irradiation rack, and packaged and sealed within 30 minutes after irradiation; S7. Store in an intelligent constant-temperature storage system at an ambient humidity of 70% ± 5%. Real-time monitoring of weight loss using an infrared sensor and linkage control using a weighing sensor are used. An oxygen sensor monitors the O2 concentration within the package, and automatically replenishes with a 9:1 N2:O2 mixture when O2 is < 3%. Arecoline content is monitored every 30 days using a near-infrared spectrometer.

2. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: It also includes that when preparing the color protection solution, EDTA needs to be pre-dissolved in 50±2℃ deionized water, and then ascorbic acid, citric acid, and phytic acid are added in sequence, stirred at 20-25℃ for 15 minutes until completely dissolved, and the solution is filtered through a 0.45μm filter membrane before use.

3. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: It also includes the preparation of the composite coating liquid, wherein the silver nanoparticle preparation process is as follows: 0.01 mol / L silver nitrate solution and 0.03 mol / L sodium citrate solution are mixed in a volume ratio of 1:2, stirred in a 70°C water bath for 30 minutes, cooled to room temperature, and ultrasonically blended with chitosan solution for 45 minutes, the solution pH is adjusted to 5.0-5.5 with acetic acid, and allowed to stand for degassing for 10 minutes.

4. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: The pH-responsive CO2 sustained-release microspheres are prepared by a double emulsion method, using Span-80 as an emulsifier, an emulsification speed of 2000 rpm, a calcium chloride solution temperature of 25°C during cross-linking, a moisture content of ≤8% after drying, and a cumulative CO2 release of ≥90% in a pH 3.5 buffer solution within 24 hours.

5. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: When pulse electric field and ultrasound are used for synergistic treatment, 10 g of chitosan is added to every 100 L of the treatment liquid, the temperature is maintained at 15-20°C by a circulating cooling system, the ultrasonic probe is inserted into the treatment liquid to a depth of 5 cm, ultrasound continues to work during the pulse electric field treatment, and the liquid flow rate is 0.5 m / s.

6. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: The montmorillonite-chitosan humidity control layer is prepared by a casting method, wherein montmorillonite and chitosan solution are mixed to a casting thickness of 50 μm, cross-linked in a 0.5% calcium chloride solution for 2 hours, and dried to form a mesoporous structure with a crystallinity of 30%-40%, and a moisture absorption rate of ≥0.5 g / (m 2 ·h), desorption rate ≥0.3g / (m 2 ·h).

7. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: Betel nuts must be pre-packaged before γ-irradiation treatment. The irradiation dose is calibrated using a Farmer-type ionization chamber, with the angular velocity error of the rotating frame ≤±0.1 rpm. During the irradiation process, the ambient temperature is ≤25°C and the humidity is ≤60%.

8. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: The UV transmittance of the three-layer co-extruded film is ≤3%, and the oxygen barrier property is 40% higher than that of pure PE / PVA film. The tensile strength of the film is ≥30MPa, the elongation at break is ≥200%, the heat sealing temperature is 140-160℃, and the heat sealing strength is ≥15N / 15mm.

9. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: The intelligent monitoring system during storage uses a PLC controller with a data acquisition frequency of 1 time per hour. When the total bacterial count is greater than 1.5×10 3 When the CFU / g or arecoline retention rate is less than 92%, an automatic alarm is given. The weight loss rate is calculated using the dynamic weighing method, and the water activity is maintained at 0.62±0.03 using an Aw meter.

10. The betel nut preservation method based on composite treatment according to claim 1, characterized in that: The total bacterial count of the treated betel nut was ≤1.5×10 3 CFU / g, pulp firmness retention rate ≥88%, weight loss rate ≤4.8%, the shelf life is extended by more than 5 times compared with the traditional refrigeration method, and the arecoline loss rate ≤8%, and the sensory score ≥85 points.

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