NFC (Near Field Communication) fruit juice preparation method based on multi-stage vortex squeezing and on-line deoxidation filling system

Abstract

The invention discloses an NFC fruit juice preparation method based on a multi-stage vortex squeezing and online deoxidation filling system. The NFC fruit juice preparation method comprises the following steps of raw material pretreatment, liquid nitrogen vortex wall breaking, three-stage gradient squeezing, passivation treatment, biphase-anti-brown flavor stabilization, HPP-UV combined sterilization, online deoxidation treatment and sterile nitrogen filling filling. According to the NFC fruit juice preparation method based on the multi-stage vortex squeezing and on-line deoxidation filling system, the juice yield of produced NFC fruit juice is larger than or equal to 90% (common fruits and vegetables), the soft fruits are larger than or equal to 85%, the phenolic substance loss rate is smaller than 8%, the vitamin C retention rate is larger than or equal to 98%, the browning index (A420) during the 90-day storage period is smaller than or equal to 0.06, and the residual oxygen content is smaller than or equal to 0.15 ppm.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food technology, in particular to a NFC juice preparation method based on multi-stage vortex squeezing and online deoxygenation filling system. BACKGROUND

[0002] NFC (non-concentrated reduction) juice has a growing market demand due to its retention of natural flavor and nutrient components of fruits and vegetables, but the existing preparation technology has many bottlenecks: traditional squeezing equipment mostly uses single pressure extrusion, the cell wall breaking rate is only 75-80%, the juice yield is generally less than 72%, and high-temperature squeezing leads to a loss of 25-30% of heat-sensitive nutrients such as phenols and vitamins; juice browning and flavor attenuation are prominent, the existing stabilizer system cannot balance the oil phase and water phase stability, the Zeta potential control precision is insufficient, and the browning index (A420) during normal temperature storage period is as high as more than 0.38; the sterilization process has limitations, single HPP (ultra-high pressure) or UV treatment cannot balance sterilization efficiency and nutrient retention, and the residual oxygen content of traditional deoxygenation filling system is mostly 0.8-1.2ppm, resulting in a loss rate of 8-12% of vitamin C; at the same time, the existing equipment has problems such as high energy consumption, low processing capacity, and complex structure, which cannot meet the production demand of large-scale and high-quality NFC juice.

[0003] To solve the above technical problems, the present application provides an integrated technical solution integrating multi-stage vortex squeezing, two-phase anti-browning stabilization, HPP-UV collaborative sterilization and online precise deoxygenation filling, which realizes the simultaneous improvement of juice yield, nutrient retention rate and flavor stability through mechanical structure innovation and process parameter coupling, and fills the gap of existing technology in low-temperature and high-efficiency squeezing, collaborative sterilization and ppb-level residual oxygen control. SUMMARY

[0004] The purpose of the present application is to provide a NFC juice preparation method based on multi-stage vortex squeezing and online deoxygenation filling system, which has high juice yield, good nutrient retention, strong flavor stability, reliable sterilization effect and low energy consumption.

[0005] To solve the above technical problems, the present application provides the following technical solution: The present application provides a NFC juice preparation method based on multi-stage vortex squeezing and online deoxygenation filling system, comprising the following steps: S1. Raw material pretreatment: after washing and sorting fresh fruits and vegetables, freeze at-40℃~-30℃ for 60min~120min; S2. Liquid nitrogen vortex wall breaking: after quick freezing, the raw material is sent into a multi-stage vortex press, a plurality of atomizing nozzles distributed in a ring are started, 3L / min~8L / min flow rate is sprayed-196℃ liquid nitrogen, at the same time, the vortex cutter is activated, the rotating speed is adjusted to 1800rpm~2200rpm, the contact time between the raw material and the liquid nitrogen is ≤0.5s, and the cell pre-wall breaking is realized; S3. Three-stage gradient pressing: through the three-stage variable pitch screw of the multi-stage vortex press, the raw material is subjected to gradient increasing pressure; the screen temperature is maintained at 2℃~6℃ during the pressing process, the screen is prevented from being blocked by the ultrasonic self-cleaning device, and the pressed juice is collected; S4. Enzyme passivation treatment: the pressed juice is treated at 80℃~90℃ for 10s~20s to passivate the endogenous enzyme activity; S5. Biphasic-anti-brown flavor stability: a composite stabilizer system is added to the enzyme passivated juice, the composite stabilizer system includes an oil phase stabilizer, a water phase stabilizer and an anti-browning agent; wherein the oil phase stabilizer is: 0.4%~0.8% citrus fiber, 0.08%~0.12% lecithin; the water phase stabilizer is: 0.03%~0.07% gellan gum, 0.10%~0.14% pectin calcium; the anti-browning agent is 0.001%~0.003% L-cysteine, 0.0008%~0.0012% glutathione; the Zeta potential of the juice is adjusted to-35mV~-30mV; S6. HPP-UV combined sterilization: the stabilized juice is sent into an HPP-UV combined device, first treated at 500MPa~600MPa pressure for 3min~5min, at the same time, a UV-LED array is started, and a dose of ultraviolet radiation of 20mJ / cm²~30mJ / cm² is applied, and the working temperature of the device is controlled at 5℃~10℃; S7. Online deoxygenation treatment: the sterilized juice is introduced into an online deoxygenation filling system, first subjected to primary deoxygenation in a vacuum degassing chamber, and then subjected to secondary deoxygenation in a membrane deoxygenation module; S8. Aseptic nitrogen filling: when the dissolved oxygen concentration in the juice is ≤0.15ppm, the aseptic filling valve is started for aseptic filling, and the filling temperature is controlled at 3℃~8℃.

[0006] In step S2 of the present application, the use of liquid nitrogen instantaneous freezing forms ice crystals inside and outside the cells, and the mechanical shearing force of the vortex cutter realizes the pre-wall breaking of the cells and destroys the cell structure integrity.

[0007] Further, in step S2, the number of atomizing nozzles is 12~20, preferably 16. The atomizing particle size of the nozzle is preferably ≤80μm, which ensures uniform contact between the liquid nitrogen and the raw material. The contact time between the raw material and the liquid nitrogen is ≤0.5s, which prevents tissue freezing.

[0008] Furthermore, in step S2, the vortex cutter head is a titanium alloy vortex cutter head with a diameter of 350mm~400mm (preferably 380mm), and the surface is coated with DLC coating (friction coefficient <0.12) to reduce material adhesion and wear; it has 60 to 80 sets of curved cutting teeth, with a cutting angle of 14°±2°, a radius of curvature R2mm~3mm, a cutter head thickness of 70mm~90mm, and a rotation speed of 1800rpm~2200rpm, providing strong shearing force.

[0009] Further, in step S3, the pitch of the three-stage variable pitch screw is successively 120mm→80mm→50mm, and the gradient increasing pressure applied to the raw material is successively 0.5MPa→1.2MPa→2.0MPa. The screw gap is adjustable from 0.08mm to 2.2mm, and can be adjusted according to the characteristics of the raw material. A cooling jacket is provided to maintain a low-temperature environment during the pressing process.

[0010] Furthermore, in step S3, the ultrasonic self-cleaning device has an ultrasonic power of 400W~600W and a frequency of 35kHz~45kHz, pulses once every 8min~12min to prevent the screen from clogging.

[0011] Furthermore, in step S3, the screen material is 304 or 316L stainless steel, with a aperture of 0.4mm to 0.6mm, and is connected to a cooling liquid circulation system. The cooling liquid is a food-grade propylene glycol solution or ethylene glycol solution, which keeps the screen temperature at 2℃ to 6℃.

[0012] In step S4 of this invention, the activity of endogenous enzymes such as polyphenol oxidase and peroxidase that cause deterioration of juice quality (such as browning and precipitation) is rapidly passivated by heating passivation treatment, thereby inhibiting subsequent browning reactions and degradation of nutrients.

[0013] In step S5 of this invention, the citrus fiber and lecithin in the oil phase stabilizer form a composite encapsulation system, encapsulating fat-soluble flavor substances and reducing volatilization and oxidation. The gellan gum and calcium pectin in the aqueous phase stabilizer form a three-dimensional network structure through ionic cross-linking, regulating the zeta potential to -35mV to -30mV to maintain the stability of the aqueous phase system. The L-cysteine ​​and glutathione composite anti-browning agent works synergistically, effectively inhibiting browning reactions through mechanisms such as inhibiting polyphenol oxidase activity and scavenging free radicals. Further, the oil phase and aqueous phase are dissolved separately in 80°C hot pure water, and the anti-browning agent is dissolved in room temperature pure water.

[0014] Furthermore, step S5 also includes high-pressure micro-jet homogenization treatment, with a homogenization pressure of 160MPa~200MPa, so that the oil phase dispersion particle size D50=0.2μm~0.4μm; at the same time, the Ca²⁺ ion concentration in the aqueous phase system is controlled to be 50ppm~80ppm, further improving the stability of the system.

[0015] In step S6 of this invention, the stabilized fruit juice is fed into an HPP-UV combined equipment and first treated with a pressure of 500MPa~600MPa for 3min~5min to destroy the microbial cell membrane structure using high pressure; then, ultraviolet irradiation at a dose of 20mJ / cm²~30mJ / cm² is applied to destroy the microbial nucleic acid structure. High pressure makes it easier for ultraviolet light to penetrate microbial cells and destroy the nucleic acid structure, thereby improving the effect of ultraviolet sterilization.

[0016] Furthermore, in step S6, the operating temperature of the equipment is controlled at 5℃~10℃ to avoid the impact of high temperature on the quality of the juice. In some embodiments of the present invention, the HPP-UV combined equipment is equipped with a cooling jacket, through which a food-grade ethylene glycol solution at -15℃~-5℃ is circulated to control the batch temperature difference ΔT < 3℃ and maintain the stable operating temperature of the equipment.

[0017] Furthermore, in step S6, in the HPP-UV combined equipment, UV is activated when the pressure is ≥300MPa, and the UV intensity increases linearly by 12%~18% for every 80MPa~120MPa increase in pressure. Through pressure-light intensity coupling control, the sterilization effect is maximized, reducing energy consumption and heat damage while ensuring sterilization efficiency.

[0018] Furthermore, in step S6, the UV-LED array adopts a dual-band design of 254nm and 365nm, with an adjustable power density of 25mW / cm² to 35mW / cm². The 365nm band is designed to synergize with the direct sterilization effect of the 254nm band through photocatalytic reaction, jointly enhancing the killing efficiency against microorganisms. Preferably, the UV-LED array is uniformly distributed on the sidewalls of the HPP-UV combined device cavity to ensure uniform irradiation.

[0019] In step S7 of this invention, vacuum degassing removes free oxygen, and the membrane deoxygenation module deeply removes dissolved oxygen; a laser oxygen sensor monitors the oxygen concentration in real time, and the nitrogen flow rate is adjusted using a quadratic function model. Furthermore, in step S7, a two-stage Roots pump is installed in the vacuum degassing chamber, with a pumping speed of 350 m³ / h to 450 m³ / h, controlling the pressure inside the vacuum degassing chamber to be -0.1 MPa to -0.09 MPa, and the residual oxygen concentration ≤1500 ppm. In a preferred embodiment, a baffle plate is also provided inside the degassing chamber to optimize fluid distribution and improve degassing efficiency.

[0020] Further, in step S7, the membrane deoxygenation module uses a PTFE / PDMS composite hollow fiber membrane, which is based on a polytetrafluoroethylene (PTFE) hollow fiber membrane with a polydimethylsiloxane (PDMS) selective layer laminated on its surface. The PDMS layer has extremely high oxygen and nitrogen selectivity, which, combined with the mechanical strength of the PTFE substrate, can further improve the oxygen separation efficiency and permeation rate. Further, the PTFE / PDMS composite hollow fiber membrane has a surface area of ​​12m²~18m², an oxygen permeability coefficient of 450 Barrer~550 Barrer (25℃), an inner diameter of 0.6mm~1.0mm, and an outer diameter of 1.0mm~1.4mm.

[0021] Furthermore, in step S7, the online deoxygenation filling system also includes a nitrogen compensation zone, a cyclone mixer, a laser oxygen sensor, and a PLC control system. The nitrogen compensation zone performs nitrogen compensation to create an inert environment, and the laser oxygen sensor monitors the oxygen concentration in real time. Based on feedback from the laser oxygen sensor, the PLC control system controls the nitrogen valve in the nitrogen compensation zone according to formula Q. N2 =0.12×[O2]²+0.5 Adjusting the nitrogen flow rate allows for precise control of residual oxygen levels, delaying the oxidation and spoilage of the fruit juice. Where Q N2 [O2] represents the nitrogen flow rate in L / min; [O2] represents the real-time concentration of dissolved oxygen in the juice (ppm), used for intelligent adjustment of nitrogen flow rate based on a quadratic function model in the online deoxygenation system to achieve precise control of residual oxygen at the ppb level.

[0022] Preferably, the laser oxygen sensor has a detection limit of ≤0.02ppm and a response time of <0.8s, enabling real-time monitoring of dissolved oxygen concentration in the juice; it forms a closed-loop control with the nitrogen valve, automatically refluxing when the oxygen concentration exceeds the limit, ensuring product quality.

[0023] Furthermore, in step S7, a buffer tank is provided between the membrane deoxygenation module and the cyclone mixer of the online deoxygenation filling system. The buffer tank has a volume of 40L~60L and an internal pressure maintained at 0.08MPa~0.12Mpa to prevent fluctuations in the juice flow rate from affecting the deoxygenation effect.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: A dual breakthrough in juice yield and nutrient retention: Through the synergistic cell wall breaking design of liquid nitrogen instantaneous spraying and titanium alloy vortex cutter disc, combined with three-stage gradient pressing technology, the cell wall breaking rate is increased to over 95%, the juice yield of ordinary fruits and vegetables reaches over 90%, and the juice yield of soft fruits reaches over 85%, which is 45%-50% higher than traditional technology; the whole process is controlled at low temperature and combined with a biphasic anti-browning stabilization system, the loss rate of phenolic substances is <8%, the vitamin C retention rate is ≥98%, and the vitamin C retention rate is still over 92% after 90 days of storage, solving the pain point of serious nutrient loss in traditional pressing.

[0025] Significantly enhanced flavor stability: An innovative oil-water phase stabilization system is adopted, which encapsulates fat-soluble flavor substances through citrus fiber and lecithin, precisely regulates the zeta potential with gellan gum and pectin calcium, and combines L-cysteine ​​and glutathione as a compound anti-browning agent, so that the browning index (A420) of the juice during 90-day storage is ≤0.06, which is more than 80% lower than that of traditional technology, effectively maintaining the natural color and flavor of NFC juice.

[0026] Sterilization efficiency and safety are improved simultaneously: The HPP-UV combined equipment achieves high-pressure and ultraviolet synergistic sterilization, with an E. coli sterilization efficiency of over 6.0 log, which is more than 50% higher than that of traditional single HPP equipment; the active temperature control design keeps the processing temperature stable at 5℃~10℃, reducing heat damage by more than 90%, avoiding the destruction of juice quality by high-temperature sterilization, while the dual redundancy safety protection mechanism improves the safety of the production process.

[0027] Residual oxygen control reaches ppb-level precision: The online deoxygenation filling system adopts a closed-loop control of vacuum degassing + membrane deoxygenation + nitrogen compensation, combined with real-time feedback from a laser oxygen sensor, which reduces the residual oxygen content of the juice to below 0.15ppm, a reduction of more than 80% compared to traditional systems; the vitamin C loss rate is only ≤1%, a reduction of more than 90% compared to traditional technologies, significantly extending the product's shelf life.

[0028] The equipment boasts outstanding energy efficiency and production capacity advantages: the multi-stage vortex press consumes ≤12kWh per ton of raw material, which is more than 40% lower than traditional equipment; the HPP-UV combined equipment reduces energy consumption by more than 30% and reduces the floor space by more than 30%; the online deoxygenation filling system has a processing speed of more than 2500L / h, which is more than 150% higher than traditional systems, and reduces nitrogen consumption by more than 70%, achieving a balance between large-scale production and energy conservation. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1: Preparation of NFC Blood Orange Juice

[0030] This embodiment provides a method for preparing NFC blood orange juice, including the following steps: S1. Raw material pretreatment: Select fresh blood oranges, wash and sort them to remove rotten pulp and impurities, and quick-freeze them at -35℃ for 90 minutes.

[0031] S2. Liquid nitrogen vortex cell disruption: Quick-frozen blood oranges are fed into a multi-stage vortex press. Sixteen atomizing nozzles are activated to spray -196℃ liquid nitrogen at a flow rate of 5L / min, activating the 380mm diameter titanium alloy vortex cutter disc (rotation speed 2000rpm). The contact time between the raw material and liquid nitrogen is 0.3s.

[0032] S3. Three-stage gradient pressing: The pitch of the three-stage screw is 120mm→80mm→50mm respectively, the pressure is applied 0.5MPa→1.2MPa→2.0MPa, the screen temperature is maintained at 4℃, the ultrasonic self-cleaning parameter is 40kHz, and the pulse is once every 10min. The pressed juice is collected.

[0033] S4. Enzyme inactivation treatment: Treat the pressed juice at 85°C for 15 seconds.

[0034] S5. Biphasic-anti-browning flavor stabilization: Add 0.6% citrus fiber + 0.1% lecithin (oil phase stabilizer), 0.05% gellan gum + 0.12% calcium pectin (aqueous phase stabilizer), 0.002% L-cysteine ​​+ 0.001% glutathione (anti-browning agent), and adjust the Zeta potential to -32mV; then perform high-pressure microfluidic homogenization at 180MPa pressure to control the Ca²⁺ ion concentration to 60ppm.

[0035] S6. HPP-UV Combined Sterilization: The sample is fed into the HPP-UV combined equipment and treated at 550MPa pressure for 4 minutes. At the same time, the dual-band UV-LED array (254nm+365nm) is activated to apply 25mJ / cm² UV irradiation. The equipment operating temperature is controlled at 8℃.

[0036] S7. Online deoxygenation treatment: The online deoxygenation filling system is introduced, the vacuum degassing chamber pressure is -0.095MPa, the membrane deoxygenation module adopts PTFE / PDMS composite hollow fiber membrane, and the nitrogen coverage flow rate is 10L / min.

[0037] S8. Aseptic nitrogen filling: When the dissolved oxygen concentration is ≤0.15ppm, aseptic filling is carried out at 5℃ to obtain NFC blood orange juice. Example 2: Preparation of NFC Strawberry Juice

[0038] This embodiment provides a method for preparing NFC strawberry juice, including the following steps: S1. Raw material pretreatment: Select fresh strawberries, wash and remove the stems, and then quick-freeze at -38℃ for 80 minutes.

[0039] S2. Liquid nitrogen vortex cell disruption: Quick-frozen strawberries are fed into a multi-stage vortex press, and 16 atomizing nozzles are activated to spray -196℃ liquid nitrogen at a flow rate of 4L / min, activating the 380mm diameter titanium alloy vortex cutter disc (rotation speed 1900rpm). The contact time between the raw material and liquid nitrogen is 0.4s.

[0040] S3. Three-stage gradient pressing: The pitch of the three-stage spiral is 120mm→80mm→50mm respectively, the applied pressure is 0.5MPa→1.2MPa→2.0MPa, the screen temperature is maintained at 3℃, and the ultrasonic self-cleaning parameter is 38kHz, pulse once every 9min.

[0041] S4. Enzyme inactivation treatment: The pressed juice was treated at 82°C for 18 seconds.

[0042] S5. Biphasic-anti-browning flavor stabilizer: Added 0.5% citrus fiber + 0.09% lecithin, 0.04% gellan gum + 0.11% calcium pectin, 0.0015% L-cysteine ​​+ 0.0009% glutathione, adjusting the zeta potential to -33mV; 170MPa high-pressure microfluidic homogenization, Ca²⁺ ion concentration 50ppm.

[0043] S6. HPP-UV Combined Sterilization: The sample is fed into the HPP-UV combined equipment and treated at 520MPa pressure for 4.5 minutes. At the same time, the dual-band UV-LED array (254nm+365nm) is activated to apply 23mJ / cm² UV irradiation. The equipment operating temperature is controlled at 6℃.

[0044] S7. Online deoxygenation treatment: The online deoxygenation filling system is introduced, the vacuum degassing chamber pressure is -0.092MPa, the membrane deoxygenation module adopts PTFE / PDMS composite hollow fiber membrane, and the nitrogen coverage flow rate is 12L / min.

[0045] S8. Aseptic nitrogen filling: When the dissolved oxygen concentration is ≤0.15ppm, aseptic filling is carried out at 4℃ to obtain NFC strawberry juice. Example 3: Preparation of NFC Apple Juice

[0046] This embodiment provides a method for preparing NFC apple juice, including the following steps: S1. Raw material pretreatment: Fresh apples are washed, peeled and cored, and then quick-frozen at -32℃ for 100 minutes.

[0047] S2. Liquid nitrogen vortex cell disruption: Quick-frozen apples are fed into a multi-stage vortex press, and 16 atomizing nozzles are activated to spray -196℃ liquid nitrogen at a flow rate of 6L / min, activating the 380mm diameter titanium alloy vortex cutter disc (speed 2100rpm). The contact time between the raw material and liquid nitrogen is 0.5s.

[0048] S3. Three-stage gradient pressing: The pitch of the three-stage spiral is 120mm→80mm→50mm respectively, the applied pressure is 0.5MPa→1.2MPa→2.0MPa, the screen temperature is 5℃, and the ultrasonic self-cleaning is 42kHz, pulsed once every 11min.

[0049] S4. Enzyme inactivation treatment: Treat the pressed juice at 88℃ for 12s.

[0050] S5. Biphasic-anti-browning flavor stabilizer: Added 0.7% citrus fiber + 0.11% lecithin, 0.06% gellan gum + 0.13% calcium pectin, 0.0025% L-cysteine ​​+ 0.0011% glutathione, adjusting the zeta potential to -34mV; 190MPa high-pressure microfluidic homogenization, Ca²⁺ ion concentration 80ppm.

[0051] S6. HPP-UV Combined Sterilization: The sample is fed into the HPP-UV combined equipment and treated at 580MPa pressure for 3.5 minutes. At the same time, the dual-band UV-LED array (254nm+365nm) is activated to apply 28mJ / cm² UV irradiation. The equipment operating temperature is controlled at 10℃.

[0052] S7. Online deoxygenation treatment: The online deoxygenation filling system is introduced, the vacuum degassing chamber pressure is -0.098MPa, the membrane deoxygenation module adopts PTFE / PDMS composite hollow fiber membrane, and the nitrogen coverage flow rate is 8L / min.

[0053] S8. Aseptic nitrogen filling: When the dissolved oxygen concentration is ≤0.15ppm, aseptic filling is carried out at 6℃ to obtain NFC apple juice. Comparative Example 1

[0054] The preparation steps of Comparative Example 1 are the same as those of Example 1, except that in step S2, liquid nitrogen spraying and vortex cutter disc are cancelled, and traditional single-stage screw pressing is used with a pressure of 1.2 MPa and a screw pitch of 100 mm. Comparative Example 2

[0055] The preparation steps of Comparative Example 2 are the same as those of Example 1, except that in step S5, the biphasic stabilizer is removed and only 0.003% L-cysteine ​​is added as a single anti-browning agent. Comparative Example 3

[0056] The preparation steps of Comparative Example 3 were the same as those of Example 1, except that in step S6, UV irradiation was cancelled and only HPP sterilization (550MPa / 4min) was used. Comparative Example 4

[0057] The preparation steps of Comparative Example 4 are the same as those of Example 1, except that in step S7, the membrane deoxygenation module is removed and only vacuum degassing + nitrogen purging (traditional deoxygenation method) is used.

[0058] The test results of the NFC juices prepared in Examples 1-3 and Comparative Examples 1-4 are shown in Table 1.

[0059] Table 1

[0060] As shown in Table 1, Comparative Example 1, lacking the synergistic cell wall disruption effect of liquid nitrogen instantaneous freezing and vortex cutter disc, and without a gradient pressure increase design, had a juice yield that decreased by 24.3% and a cell wall disruption rate that decreased by 22.5% compared to Example 1. At the same time, the increased temperature during the traditional pressing process led to a significant increase in the loss rate of phenolic substances and vitamin C, with a vitamin C retention rate of only 58.7% after 90 days of storage. This fully verifies the core advantages of the pressing technology of this invention in improving juice yield and reducing nutrient loss.

[0061] Comparative Example 2, which uses only a single anti-browning agent, cannot simultaneously ensure the stability of the oil-water phase. After 90 days of storage, the browning index reached 0.21, which is 425% higher than that of Example 1. The stratification rate increased to 8.5%, and the VC retention rate decreased by 24.9%. This demonstrates that the synergistic effect of the biphase stabilizer and the compound anti-browning agent can effectively inhibit browning and stratification, and maintain the flavor and stability of the juice.

[0062] Comparative Example 3 showed that the sterilization efficiency of E. coli using single HPP sterilization was only 4.6 log, a decrease of 32.4% compared to Example 1. Furthermore, due to the lack of UV synergistic effect, higher energy consumption was required to maintain the sterilization effect, with the energy consumption per ton of juice increasing to 85.3 kWh, an increase of 64.7% compared to Example 1. This demonstrates the significant advantages of the synergistic sterilization process of the present invention in improving sterilization efficiency and reducing energy consumption.

[0063] Comparative Example 4, using a traditional deoxygenation method, had a residual oxygen content of 0.95 ppm, which was 691.7% higher than that of Example 1. This led to increased VC oxidation loss, with the VC retention rate at only 70.5% during a 90-day storage period and the phenolic substance loss rate rising to 10.3%. This verifies that the vacuum degassing + membrane deoxygenation + nitrogen compensation closed-loop control of the present invention can achieve precise control of residual oxygen at the ppb level and significantly reduce oxidation loss.

[0064] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing NFC juice based on a multi-stage vortex pressing and online deoxygenation filling system, characterized in that, Includes the following steps: S1. Raw material pretreatment: After washing and sorting fresh fruits and vegetables, quick-freeze them at -40℃ to -30℃ for 60min to 120min; S2. Liquid nitrogen vortex cell disruption: The quick-frozen raw material is fed into a multi-stage vortex press. Multiple atomizing nozzles distributed in a ring are activated to spray -196℃ liquid nitrogen at a flow rate of 3L / min~8L / min. At the same time, the vortex cutter disc is activated and the rotation speed is adjusted to 1800rpm~2200rpm. The contact time between the raw material and the liquid nitrogen is ≤0.5s to achieve pre-cell disruption. S3. Three-stage gradient pressing: The three-stage variable pitch screw of the multi-stage vortex press applies progressively increasing pressure to the raw material; the screen temperature is maintained at 2℃~6℃ during the pressing process, the ultrasonic self-cleaning device is activated to prevent screen clogging, and the pressed juice is collected. S4. Enzyme inactivation treatment: The collected pressed juice is treated at 80℃~90℃ for 10s~20s to inactivate the endogenous enzyme activity; S5. Biphasic-anti-browning flavor stabilization: A complex stabilizer system is added to the enzyme-inactivated juice, the complex stabilizer system comprising an oil phase stabilizer, an aqueous phase stabilizer, and an anti-browning agent; wherein the oil phase stabilizer is: 0.4%~0.8% citrus fiber, 0.08%~0.12% lecithin; the aqueous phase stabilizer is: 0.03%~0.07% gellan gum, 0.10%~0.14% calcium pectin; the anti-browning agent is: 0.001%~0.003% L-cysteine, 0.0008%~0.0012% glutathione; the zeta potential of the juice is adjusted to -35mV~-30mV; S6. HPP-UV combined sterilization: The stabilized juice is sent into the HPP-UV combined equipment and treated with a pressure of 500MPa~600MPa for 3min~5min. At the same time, the UV-LED array is started to apply ultraviolet irradiation with a dose of 20 mJ / cm²~30mJ / cm². The operating temperature of the equipment is controlled at 5℃~10℃. S7. Online deoxygenation treatment: The sterilized juice is fed into the online deoxygenation filling system, where it first undergoes primary deoxygenation in the vacuum degassing chamber, and then undergoes secondary deoxygenation through the membrane deoxygenation module; S8. Aseptic nitrogen filling: When the dissolved oxygen concentration in the juice is ≤0.15ppm, start the filling valve for aseptic filling, and control the filling temperature at 3℃~8℃.

2. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S2, the number of atomizing nozzles is 12 to 20, and the atomizing particle size of the nozzles is ≤80μm; The scroll cutter head is a titanium alloy scroll cutter head with a diameter of 350mm~400mm and its surface has a DLC coating.

3. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S3, the pitch of the three-stage variable pitch screw is 120mm→80mm→50mm, and the gradient increasing pressure applied to the raw material is 0.5MPa→1.2MPa→2.0MPa.

4. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S3, the ultrasonic self-cleaning device has an ultrasonic power of 400W~600W, a frequency of 35kHz~45kHz, and pulses every 8min~12min.

5. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S5, after adding the compound stabilizer system to the enzyme-inactivated juice, high-pressure microfluidic homogenization is performed at a pressure of 160MPa~200MPa to make the oil phase dispersed particle size D50=0.2μm~0.4μm; at the same time, the Ca²⁺ ion concentration in the aqueous phase system is controlled to be 50ppm~80ppm.

6. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S6, in the HPP-UV combined equipment, UV is activated when the pressure is ≥300MPa, and the UV intensity increases linearly by 12% to 18% for every 80MPa~120MPa increase in pressure.

7. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S6, the UV-LED array adopts a dual-band design of 254nm and 365nm, and the power density is adjustable from 25mW / cm² to 35mW / cm².

8. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S7, the membrane deoxygenation module uses a PTFE / PDMS composite hollow fiber membrane with a surface area of ​​12m²~18m², an oxygen permeability coefficient of 450Barrer~550Barrer, an inner diameter of 0.6mm~1.0mm, and an outer diameter of 1.0mm~1.4mm.

9. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S7, the online deoxygenation filling system further includes a nitrogen compensation zone, a cyclone mixer, a laser oxygen sensor, and a PLC control system; based on feedback from the laser oxygen sensor, the PLC control system controls the nitrogen valve in the nitrogen compensation zone according to formula Q. N2 =0.12×[O2]²+0.5 to adjust the flow rate of nitrogen.

10. The NFC juice preparation method based on a multi-stage vortex pressing and online deoxygenation filling system according to claim 1, characterized in that, In step S7, a buffer tank is provided between the membrane deoxygenation module and the cyclone mixer of the online deoxygenation filling system. The buffer tank has a volume of 40L to 60L and an internal pressure maintained at 0.08MPa to 0.12MPa.

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