A NFC fresh orange juice preservation processing method

Abstract

This invention discloses an NFC (Not From Concentrate) fresh-squeezed orange juice preservation and processing method, which adopts a process integrating raw material selection and pretreatment, nitrogen atmosphere anaerobic cold pressing, low-temperature compound enzyme inactivation, multi-stage fine filtration, ultrasonic-assisted low-temperature sterilization, natural component compound antioxidant color protection, vacuum degassing and homogenization, aseptic cold filling, and gradient temperature-controlled cooling. The entire process adopts low-temperature, low-oxygen, and closed operation, without the addition of chemical preservatives, and synergistically achieves multiple effects of enzyme inactivation, antibacterial, antioxidant, and color protection. This invention can significantly retain heat-sensitive nutrients such as vitamin C and total phenols in orange juice, effectively inhibit enzymatic browning and oxidative deterioration, and the prepared NFC fresh-squeezed orange juice has a taste close to that of freshly squeezed juice. The shelf life can reach 6 months when refrigerated at 0-4℃ and 3 months when stored at room temperature away from light. The process is suitable for industrial mass production and has high application and promotion value.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product deep processing technology, specifically relating to an NFC fresh-squeezed orange juice preservation processing method. Background Technology

[0002] NFC (Not From Concentrate) freshly squeezed orange juice is 100% pure juice made by directly washing, pressing, sterilizing, and bottling fresh oranges. It undergoes no concentration, reconstitution, or the addition of any preservatives, colorings, or flavorings, thus preserving the orange's natural nutrients, flavor, and color to the greatest extent possible. In recent years, with the increasing demand from consumers for healthy and natural foods, NFC orange juice has become a mainstream product in the high-end juice market due to its fresh and mellow taste and rich nutritional value.

[0003] However, existing NFC orange juice processing technology has a core technical problem: it cannot simultaneously preserve freshness, nutrition, and flavor, resulting in a short shelf life and poor quality stability. Specifically:

[0004] Traditional heat sterilization (pasteurization / high-temperature instantaneous sterilization): While it can kill microorganisms and extend shelf life, the high temperature (72-95℃, 15-30s) causes a significant degradation of heat-sensitive nutrients (vitamin C, total phenols, flavonoids) in orange juice, leading to the volatilization of flavor compounds, the development of a "cooked" taste, browning, and ruining the freshly squeezed flavor. For example, after conventional pasteurization, the vitamin C loss rate can reach 30%-50%, and the browning index increases by more than 15%.

[0005] Cold sterilization technology (such as HPP ultra-high pressure): can better preserve nutrients and flavor, but the equipment cost is high, the processing efficiency is low, and it cannot completely inactivate endogenous enzymes (polyphenol oxidase, peroxidase) in orange juice. During storage, enzymatic browning and flavor deterioration are likely to occur, the shelf life is only 20-40 days, and it must be transported and stored in a cold chain at 0-4℃ throughout the process, resulting in extremely high logistics costs.

[0006] Existing processes lack targeted color protection and antioxidant synergistic mechanisms: Orange juice is rich in easily oxidized components such as polyphenols and vitamin C. After juicing, it quickly undergoes non-enzymatic browning and oxidation reactions upon contact with oxygen, resulting in darkening of color, rancidity of flavor, and loss of nutrients. Even with low-temperature refrigeration, the quality will significantly decline within 7-10 days.

[0007] Inadequate aseptic control: Secondary contamination can easily occur during juicing, filtration, sterilization, and bottling. Microbial residues and reproduction accelerate the spoilage of orange juice, further shortening its shelf life.

[0008] Currently, NFC orange juice on the market either sacrifices nutrition and flavor for a longer shelf life, or retains freshness but has a very short shelf life and high costs. It cannot simultaneously achieve the comprehensive preservation goals of "high nutrient retention, strong flavor stability, long shelf life, and low reliance on cold chain", which seriously restricts the large-scale and market-oriented development of the NFC orange juice industry. Summary of the Invention

[0009] This invention addresses the core technical problems of NFC orange juice, which suffer from the inability to simultaneously preserve freshness, nutrition, and flavor, as well as short shelf life and poor quality stability. It provides an integrated technology solution for preserving NFC fresh-squeezed orange juice. This solution utilizes a combination of low-temperature enzyme inactivation coupled with ultrasound-assisted sterilization, multi-stage antioxidant color protection, fully anaerobic and aseptic processing, and precise temperature control for preservation. Without adding any preservatives, it maximizes the preservation of the orange juice's nutrition and flavor, while extending the shelf life to 6 months (refrigerated at 0-4℃) or 3 months (at room temperature and away from light), significantly improving quality stability and market applicability.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A method for preserving NFC fresh-squeezed orange juice includes the following steps: Step 1, Raw material selection and pretreatment: Select fresh oranges that are 80-90% ripe, free from rot, and have qualified pesticide residues. After three-stage washing, drain the water. Step 2, Anaerobic cold pressing: Under nitrogen protection, temperature 10-15℃, speed 30-40rpm, and pressure 0.3-0.5MPa, cold press the juice and separate the pulp to obtain crude orange juice; Step 3, Low-temperature synergistic enzyme inactivation: Crude orange juice is heated at 15-20℃ under nitrogen protection, and 0.08%-0.12% (w / w) of a compound enzyme inactivation agent is added, and the mixture is kept warm for 10-15 minutes. Step 4, multi-stage fine filtration: The orange juice is filtered sequentially through a 50-mesh coarse filter, a 200-mesh fine filter, and a 5μm microporous membrane to obtain clear orange juice; Step 5, Ultrasonic-assisted low-temperature sterilization: Clarified orange juice is treated with ultrasound at a frequency of 20-25kHz and a power density of 300-400W / L for 8-12 minutes at 40-45℃, under nitrogen protection and a flow rate of 1.5-2.0m / s. Step 6, Compound Antioxidant Color Protection: After sterilization, add 0.05%-0.08% by mass of natural compound antioxidant to the orange juice under anaerobic conditions, and stir for 5-8 minutes; Step 7, vacuum degassing and homogenization: degas at a vacuum of -0.08 to -0.09 MPa for 3-5 minutes, and homogenize at 20-25℃ and 20-25 MPa 2-3 times; Step 8, Aseptic Cold Filling: In a Class 100 cleanroom and oxygen-free environment, fill the composite sterilized packaging container and vacuum seal it; Step 9, gradient temperature control preservation: After bottling, the orange juice is cooled at a gradient of 25℃→15℃→4℃ for 15-20 minutes, and then refrigerated at 0-4℃.

[0011] In a preferred embodiment of the present invention, in step 3, the compound enzyme-inactivating agent is composed of ascorbic acid, citric acid, and sodium phytate in a mass ratio of 3:2:1.

[0012] In a preferred embodiment of the present invention, in step 6, the natural compound antioxidant is composed of vitamin E, rosemary extract, and tea polyphenols in a mass ratio of 2:3:1.

[0013] In a preferred embodiment of the present invention, in steps 2, 3, 5, and 6, nitrogen protection is maintained throughout the process, and the oxygen concentration is controlled at ≤0.5%.

[0014] In a preferred embodiment of the present invention, in step 4, the microporous membrane filtration uses a polyvinylidene fluoride membrane, with a filtration temperature of 15-20℃ and a pressure of 0.2-0.3MPa.

[0015] In a preferred embodiment of the present invention, in step 8, the sterilization conditions for the packaging container are: ultraviolet irradiation for 15-20 seconds, spraying with 3% hydrogen peroxide, followed by hot air drying at 60-65°C for 10-15 seconds.

[0016] In a preferred embodiment of the present invention, in step 1, the orange sugar content is ≥11°Brix and the titratable acidity is 0.8%-1.2%.

[0017] In a preferred embodiment of the present invention, in step 9, the residence time of each section of the gradient cooling is equal, which is 5-7 minutes.

[0018] In a preferred embodiment of the present invention, in step 5, the microbial kill rate of orange juice during ultrasonic treatment is ≥99.99%.

[0019] An NFC fresh-squeezed orange juice is prepared by the above-mentioned preservation and processing method. The orange juice has a vitamin C retention rate of ≥92%, a shelf life of 6 months when refrigerated at 0-4℃, and a shelf life of 3 months when stored at room temperature away from light.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. Precisely solve core technical problems: Addressing the issue of "the inability to simultaneously preserve freshness, nutrition, and flavor, resulting in a short shelf life," we achieve synergistic optimization of preservation effect, nutrient retention, and flavor stability. Based on "low-temperature anaerobic full-process control," and with "enzyme inactivation, sterilization, and antioxidant color protection" as core methods, we ensure that preservation, nutrition, and flavor support and promote each other rather than restrict each other. By precisely controlling the preservation process parameters, we completely break through the bottleneck of existing technologies where "preserving freshness results in the loss of nutrition and flavor, while preserving nutrition and flavor results in a short shelf life."

[0021] 2. Maximum preservation of nutrition and flavor: The entire process is processed at low temperature (≤45℃) to avoid heat damage. Combined with an anaerobic environment and natural antioxidants, the retention rate of vitamin C, total phenols and flavonoids is ≥90%, and the flavor substances are completely preserved, with a taste close to freshly squeezed orange juice.

[0022] 3. Significantly extended shelf life: Low-temperature inactivation completely inhibits endogenous enzyme activity, ultrasonic low-temperature sterilization effectively kills microorganisms, and anaerobic and sterile control blocks oxidation and contamination. The shelf life is up to 6 months when refrigerated at 0-4℃ and 3 months when kept at room temperature away from light, which is far superior to existing NFC orange juice (20-40 days).

[0023] 4. Controllable cost and strong applicability: No need for expensive equipment such as ultra-high pressure, the process is compatible with existing juice production lines, reducing production costs; at the same time, it reduces reliance on cold chain and expands market circulation.

[0024] 5. Green, natural, safe and healthy: No chemical preservatives, pigments or flavorings are added throughout the entire process, meeting green food standards and ensuring high safety. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates an NFC fresh-squeezed orange juice preservation processing method provided in this embodiment of the invention.

[0027] Figure 2 This invention provides a flowchart of a gradient temperature control preservation step.

[0028] Figure 3 This is a comparison chart showing the quality of NFC freshly squeezed orange juice prepared according to the present invention with that of ordinary NFC orange juice during storage. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] like Figure 1 As shown, the present invention provides an NFC fresh-squeezed orange juice preservation processing method, comprising the following steps: Step 1, Raw material selection and pretreatment: Select fresh oranges that are 80-90% ripe, free from rot, and have qualified pesticide residues. After three-stage washing, drain the water. The three-stage washing includes bubbling washing, brush washing, and water spraying to remove the fruit stem, navel, and impurities.

[0031] Step 2, Anaerobic Cold Press Juicing: Juicing is performed under nitrogen protection, at a temperature of 10-15℃, a rotation speed of 30-40 rpm, and a pressure of 0.3-0.5 MPa. The pulp is then separated to obtain crude orange juice. Specifically, Step 2 includes: feeding the washed oranges into an anaerobic screw juicer; cold pressing is performed under a nitrogen-protected atmosphere (oxygen concentration ≤0.5%), a rotation speed of 30-40 rpm, and a pressure of 0.3-0.5 MPa; the juicing temperature is controlled at 10-15℃; and the peel and pulp are separated to obtain crude orange juice.

[0032] Step 3, Low-Temperature Synergistic Enzyme Inactivation: Under nitrogen protection, 0.08%-0.12% (w / w) of a compound enzyme inactivation agent is added to the crude orange juice at 15-20℃, and the mixture is kept at this temperature for 10-15 minutes. Specifically, Step 3 involves quickly transferring the crude orange juice into a low-temperature enzyme inactivation tank, adding the compound enzyme inactivation agent at 15-20℃ under nitrogen protection, stirring thoroughly, and then keeping the mixture at this temperature for 10-15 minutes. This process inactivates over 95% of the polyphenol oxidase, peroxidase, and pectinase in the orange juice.

[0033] Step 4, multi-stage fine filtration: The orange juice after enzyme inactivation is filtered sequentially through a 50-mesh coarse filter, a 200-mesh fine filter, and a 5μm microporous membrane filter to remove pulp residue and suspended matter, resulting in clear orange juice.

[0034] Step 5, Ultrasonic-Assisted Low-Temperature Sterilization: Clarified orange juice is treated with ultrasound at 40-45℃, under nitrogen protection, and a flow rate of 1.5-2.0 m / s for 8-12 minutes at a frequency of 20-25 kHz and a power density of 300-400 W / L. Specifically, Step 5 involves placing the clarified orange juice into an ultrasonic sterilization device and treating it at 40-45℃ under nitrogen protection using ultrasound at a frequency of 20-25 kHz and a power density of 300-400 W / L for 8-12 minutes, achieving a microbial kill rate ≥99.99%.

[0035] Step 6, Compound Antioxidant Color Protection: After sterilization, add 0.05%-0.08% (w / w) of a natural compound antioxidant to the orange juice under anaerobic conditions, and stir for 5-8 minutes to fully inhibit the oxidation reaction. Specifically, Step 6 includes: sending the clarified orange juice into an ultrasonic sterilization device, and treating it at 40-45℃ under nitrogen protection using ultrasound at a frequency of 20-25kHz and a power density of 300-400W / L for 8-12 minutes to achieve a microbial kill rate ≥99.99%.

[0036] Step 7, Vacuum degassing and homogenization: Degas at a vacuum of -0.08 to -0.09 MPa for 3-5 minutes, and homogenize at 20-25℃ and 20-25 MPa 2-3 times; Step 7 specifically includes: after color protection, the orange juice is degassed at a vacuum of -0.08 to -0.09 MPa for 3-5 minutes to remove dissolved oxygen and air bubbles, and then homogenized at 20-25℃ and 20-25 MPa for 2-3 minutes to improve the stability and taste of the orange juice.

[0037] Step 8, Aseptic Cold Filling: In a Class 100 clean, anaerobic environment, the orange juice is filled into composite sterilized packaging containers and vacuum-sealed. Specifically, Step 8 includes: filling the homogenized orange juice into packaging containers sterilized by a UV + hydrogen peroxide composite process using an aseptic filling machine in a Class 100 clean, anaerobic environment, and then vacuum-sealing the containers.

[0038] Step 9, Gradient Temperature Control Preservation: After bottling, the orange juice undergoes gradient cooling at 25℃→15℃→4℃ for 15-20 minutes, and is then refrigerated at 0-4℃. Specifically, Step 9 involves rapidly subjecting the bottling orange juice to gradient cooling, sequentially passing through cooling sections of 25℃→15℃→4℃, with a total cooling time of 15-20 minutes, before finally transferring it to a 0-4℃ cold storage.

[0039] In step 1, the oranges have a sugar content ≥11°Brix and a titratable acidity of 0.8%-1.2% to ensure the taste and flavor of the orange juice.

[0040] In step 3, the compound enzyme-inactivating agent is composed of ascorbic acid, citric acid, and sodium phytate in a mass ratio of 3:2:1, and the amount added is 0.08%-0.12% of the orange juice mass.

[0041] In step 5, the microbial kill rate of orange juice during ultrasonic treatment is ≥99.99%. During the ultrasonic-assisted low-temperature sterilization process, the flow rate of orange juice is controlled at 1.5-2.0 m / s to ensure uniform sterilization.

[0042] In step 6, the natural compound antioxidant is composed of vitamin E, rosemary extract and tea polyphenols in a mass ratio of 2:3:1, and the amount added is 0.05%-0.08% of the orange juice mass.

[0043] In steps 2, 3, 5, and 6, nitrogen protection is maintained throughout the process, and the oxygen concentration is controlled at ≤0.5%. That is, the anaerobic screw juicer, low-temperature enzyme inactivation tank, ultrasonic sterilization device, color protection tank, and deaeration homogenization equipment are all equipped with a nitrogen circulation system, and the oxygen concentration is controlled at ≤0.5% throughout the process.

[0044] In step 4, the microporous membrane filtration uses a polyvinylidene fluoride membrane, with a filtration temperature of 15-20℃ and a pressure of 0.2-0.3MPa.

[0045] In step 8, the sterilization conditions for the packaging containers are: UV irradiation for 15-20 seconds, followed by spraying with 3% hydrogen peroxide and hot air drying at 60-65℃ for 10-15 seconds. The packaging containers are aseptic Tetra Pak cartons or PET bottles, and the sterilization conditions are: UV irradiation for 15-20 seconds, followed by spraying with 3% hydrogen peroxide and hot air drying (60-65℃, 10-15 seconds).

[0046] In step 9, the residence time in each section of the gradient cooling is equal, ranging from 5 to 7 minutes. For example... Figure 2 As shown, step 9 specifically includes the following: Step 91, Finished Product Conveying and Sealing: After aseptic cold filling and vacuum sealing, the fully sealed NFC fresh-squeezed orange juice packaging must be free from leakage, incomplete sealing, bottle deformation, or bulging of the Tetra Pak. It is smoothly and evenly conveyed by a Class 100 clean aseptic conveyor chain to the sealed feed port of the gradient temperature-controlled preservation and cooling system. The entire conveying process is kept clean, with no direct wind, no external dust, and no temperature difference airflow interference. The conveying speed is precisely matched with the operating rhythm of the cooling system to ensure that the finished orange juice enters the warehouse continuously and orderly without accumulation, stagnation, or premature or delayed conveying. The interval from the completion of filling and sealing to entering the cooling section is strictly controlled within 2 minutes to prevent the juice from being left at room temperature for a long time, which may cause slight oxidation on the surface and initial temperature fluctuations.

[0047] Step 92, Precise Cooling Process in the First-Stage Constant Temperature Pre-cooling Zone: The delivered NFC orange juice is automatically sent to the first cooling zone. This zone has a preset constant ambient temperature of 25℃, and the humidity inside the cooling chamber is maintained at 55%±5% to prevent condensation on the outer wall of the packaging and avoid water droplets seeping into subsequent storage or breeding microorganisms on the outer wall. The finished product is kept at a constant temperature in this first-stage cooling zone for 6 minutes. The cooling system adopts an internal circulation silent air-cooling mode, with the wind speed controlled at a low level for gentle airflow. Strong winds are strictly prohibited from blowing directly onto the orange juice packaging body. The temperature inside and outside of the juice is simultaneously and slowly reduced through uniform heat exchange in the chamber environment. This allows the overall temperature of the orange juice, which was initially at room temperature after filling, to steadily drop back to 24℃±0.5℃, completing the initial pre-temperature buffer and avoiding the problem of drastic fluctuations in flavor molecules inside the juice, resulting in taste stratification and slight quality deterioration caused by sudden temperature changes.

[0048] Step 93, Secondary Medium-Temperature Transition Constant Temperature and Pressure Cooling Treatment: After the primary pre-cooling, the finished orange juice is automatically and smoothly transferred to the second cooling section via the conveyor chain. This section has a preset constant ambient temperature of 15℃, and the humidity of the storage chamber is kept consistent with that of the primary cooling section to maintain a stable and consistent heat exchange environment. The finished orange juice is also kept at a constant temperature for 6 minutes in this secondary cooling section, continuing the gentle internal circulation air-cooling heat exchange mode without changing the air supply method or heat exchange intensity. This achieves a steady decrease in the orange juice temperature gradient without any abrupt drop in temperature, continuously deactivating the activity of residual trace active enzyme molecules inside the juice, while stabilizing the homogeneity of the juice and avoiding the formation of trace sedimentation and stratification of the pulp caused by rapid cooling. After the treatment, the overall temperature of the orange juice is accurately reduced to 14℃±0.5℃, completing the medium-temperature transition buffer connection and laying a solid quality foundation for the final low-temperature refrigeration and shaping.

[0049] Step 94, Three-stage low-temperature shaping and constant-temperature preservation cooling treatment: The orange juice finished product that has completed the second-stage transition cooling continues to be transferred to the third cooling section by the conveyor chain. This section is preset to a constant low-temperature environment temperature of 4℃, which is strictly adapted to the base temperature of subsequent long-term cold storage. The constant temperature and humidity system of the warehouse continues to operate stably, eliminating temperature fluctuations. The orange juice finished product is kept at a constant temperature in this third-stage cooling section for 6 minutes, and a gentle, windless direct airflow environmental heat exchange is continuously used to make the core temperature and surface temperature of the juice completely uniform. This completely locks in the internal nutrients, natural flavor substances and color of the juice, and completely inhibits enzymatic browning, oxidation reactions and potential microbial reproduction. After the treatment, the overall core temperature of the orange juice is stably reduced to the standard cold storage temperature range of 0-4℃.

[0050] Step 95, Cooling, Discharge, Quality Inspection, and Constant Temperature Storage: After the NFC fresh-squeezed orange juice has undergone a three-stage gradient temperature control cooling process, samples are immediately taken from the third cooling section to test the core temperature, packaging seal, and appearance. Products with substandard temperatures, damaged packaging, or abnormal appearance are rejected. Qualified products are immediately transferred to a dedicated 0-4℃ constant temperature cold storage warehouse via a sealed, insulated conveyor channel. After entering the warehouse, the products are neatly stacked in designated areas. The warehouse maintains real-time temperature control, regular ventilation and dehumidification, and a sterile environment throughout the process. Secondary reheating at room temperature and repeated temperature fluctuations are strictly prohibited to ensure the quality stability, nutrient retention, and shelf life of the NFC fresh-squeezed orange juice during long-term storage.

[0051] This invention also provides an NFC fresh-squeezed orange juice, prepared by the above-mentioned preservation and processing method. The orange juice has a vitamin C retention rate of ≥92%, a shelf life of 6 months when refrigerated at 0-4℃, and a shelf life of 3 months when stored at room temperature away from light.

[0052] Example 1 A method for preserving NFC fresh-squeezed orange juice, comprising the following steps: Raw material selection and pretreatment: Select fresh navel oranges with a maturity of 85%, sugar content of 12.3°Brix, titratable acidity of 0.95%, and no rot. They are then subjected to a three-stage cleaning process: 5 minutes of bubbling wash, 3 minutes of brush wash, and 2 minutes of water spray to remove fruit stems and impurities, and drained. Anaerobic cold pressing juice: The juice is fed into an anaerobic screw juicer under nitrogen protection (oxygen concentration 0.4%), speed 35 rpm, pressure 0.4 MPa, and temperature 12℃. The pulp is separated to obtain crude orange juice. Low-temperature synergistic enzyme inactivation: Transfer to a low-temperature enzyme inactivation vessel, add 0.1% of a compound enzyme inactivation agent (ascorbic acid: citric acid: sodium phytate = 3:2:1) at 18°C ​​under nitrogen protection, and incubate for 12 minutes. The enzyme inactivation rate is 98%. Multi-stage fine filtration: The juice is filtered sequentially through a 50-mesh coarse filter, a 200-mesh fine filter, and a 5μm PVDF microporous membrane (18℃, 0.25MPa pressure) to obtain clear orange juice; Ultrasonic-assisted low-temperature sterilization: The sample is placed in an ultrasonic sterilization device and treated with ultrasound at 42°C, nitrogen protection, flow rate of 1.8 m / s, frequency of 22 kHz, and power density of 350 W / L for 10 minutes, achieving a microbial kill rate of 99.995%. Compound antioxidant color protection: Transfer to a color protection container, add 0.06% natural compound antioxidant (vitamin E: rosemary extract: tea polyphenols = 2:3:1) under anaerobic conditions, and stir for 6 minutes; Vacuum degassing and homogenization: degassing at a vacuum of -0.085 MPa for 4 min, followed by homogenization twice at 22℃ and 22 MPa; Aseptic cold filling: In a Class 100 clean and oxygen-free environment, aseptic Tetra Pak cartons sterilized by ultraviolet light (18s) + 3% hydrogen peroxide (12s) are filled and vacuum sealed. Gradient temperature control preservation: sequentially cooled at 25℃ (6min) → 15℃ (6min) → 4℃ (6min) for a total of 18min, then transferred to 0-4℃ refrigeration.

[0053] Comparative Example 1 (Traditional Pasteurized NFC Orange Juice): The raw materials were the same as in Example 1. After washing, the juice was extracted using conventional methods (aerobic), coarsely filtered, and then pasteurized (75°C, 15s). The juice was then hot-filled and refrigerated at 0-4°C.

[0054] Comparative Example 2 (HPP Ultra-High Pressure NFC Orange Juice): The raw materials were the same as in Example 1. After anaerobic juicing and filtration, the juice was treated with HPP ultra-high pressure (500MPa, 5min, 25℃), aseptically filled, and refrigerated at 0-4℃.

[0055] Quality test results: Table 1 compares the quality indicators of orange juice from the example and the comparative example.

[0056] Table 1

[0057] As shown in Table 1, the orange juice prepared by the method of the present invention is significantly superior to traditional pasteurization and HPP ultra-high pressure processes in terms of nutrient retention, color, flavor and shelf life, effectively solving the technical problem of not being able to balance preservation with nutrition and flavor.

[0058] Figure 3 The line graph comparing the quality of NFC fresh-squeezed orange juice prepared for this invention with that of ordinary NFC orange juice during storage is a chart used to visually illustrate the changes in the quality retention rate of the two orange juices under different storage times. The horizontal axis represents storage time in months, with scales including 1 month, 2 months, 3 months, 5 months, and 6 months, covering the 6-month refrigerated shelf life of the orange juice of this invention. The vertical axis represents quality retention rate in percentage, with a scale range of 0-100%. The higher the value, the better the overall quality retention of the orange juice, including nutrition, flavor, and color.

[0059] The NFC orange juice curve of this invention shows a generally flat and slow downward trend. The quality retention rate is close to 100% after 1 month of storage. It drops slightly in February and March, but still remains above 90%. It drops slightly in May, but still remains above 5%. At the end of the 6-month storage period, the quality retention rate is still above 80%, and the quality degradation is minimal throughout the entire process.

[0060] The NFC orange juice curve for ordinary processing shows a rapid and steep downward trend. After one month of storage, the quality retention rate has dropped to about 84%. It continues to decline sharply in February and March, falling below 60% in March. It continues to decrease in May and June, with the quality retention rate at only about 40% after six months, indicating extremely rapid quality deterioration.

[0061] The NFC fresh-squeezed orange juice prepared by the process of this invention has a much higher overall quality retention rate than NFC orange juice prepared by ordinary process during a storage period of 6 months at 0-4℃. It has stronger storage stability and can effectively inhibit the loss of nutrients, deterioration of flavor and browning of color in orange juice during storage, thus verifying the superiority of the preservation and processing method of this invention.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preserving and processing NFC fresh-squeezed orange juice, characterized in that, Includes the following steps: Step 1, Raw material selection and pretreatment: Select fresh oranges that are 80-90% ripe, free from rot, and have qualified pesticide residues. After three-stage washing, drain the water. Step 2, Anaerobic cold pressing: Under nitrogen protection, temperature 10-15℃, speed 30-40rpm, and pressure 0.3-0.5MPa, cold press the juice and separate the pulp to obtain crude orange juice; Step 3, Low-temperature synergistic enzyme inactivation: Crude orange juice is heated at 15-20℃ under nitrogen protection, and 0.08%-0.12% (w / w) of a compound enzyme inactivation agent is added, and the mixture is kept warm for 10-15 minutes. Step 4, multi-stage fine filtration: The orange juice is filtered sequentially through a 50-mesh coarse filter, a 200-mesh fine filter, and a 5μm microporous membrane to obtain clear orange juice; Step 5, Ultrasonic-assisted low-temperature sterilization: Clarified orange juice is treated with ultrasound at a frequency of 20-25kHz and a power density of 300-400W / L for 8-12 minutes at 40-45℃, under nitrogen protection and a flow rate of 1.5-2.0m / s. Step 6, Compound Antioxidant Color Protection: After sterilization, add 0.05%-0.08% by mass of natural compound antioxidant to the orange juice under anaerobic conditions, and stir for 5-8 minutes; Step 7, vacuum degassing and homogenization: degas at a vacuum of -0.08 to -0.09 MPa for 3-5 minutes, and homogenize at 20-25℃ and 20-25 MPa 2-3 times; Step 8, Aseptic Cold Filling: In a Class 100 cleanroom and oxygen-free environment, fill the composite sterilized packaging container and vacuum seal it; Step 9, gradient temperature control preservation: After bottling, the orange juice is cooled at a gradient of 25℃→15℃→4℃ for 15-20 minutes, and then refrigerated at 0-4℃.

2. The preservation processing method according to claim 1, characterized in that, In step 3, the compound enzyme-inactivating agent is composed of ascorbic acid, citric acid, and sodium phytate in a mass ratio of 3:2:

1.

3. The preservation processing method according to claim 1, characterized in that, In step 6, the natural complex antioxidant is composed of vitamin E, rosemary extract, and tea polyphenols in a mass ratio of 2:3:

1.

4. The preservation processing method according to claim 1, characterized in that, In steps 2, 3, 5, and 6, nitrogen protection is maintained throughout the process, and the oxygen concentration is controlled at ≤0.5%.

5. The preservation processing method according to claim 1, characterized in that, In step 4, the microporous membrane filtration uses a polyvinylidene fluoride membrane, with a filtration temperature of 15-20℃ and a pressure of 0.2-0.3MPa.

6. The preservation processing method according to claim 1, characterized in that, In step 8, the sterilization conditions for the packaging containers are: ultraviolet irradiation for 15-20 seconds, spraying with 3% hydrogen peroxide, followed by hot air drying at 60-65℃ for 10-15 seconds.

7. The preservation processing method according to claim 1, characterized in that, In step 1, the oranges have a sugar content ≥11°Brix and a titratable acidity of 0.8%-1.2%.

8. The preservation processing method according to claim 1, characterized in that, In step 9, the residence time in each section of the gradient cooling is equal, ranging from 5 to 7 minutes.

9. The preservation processing method according to claim 1, characterized in that, In step 5, the microbial kill rate of orange juice during ultrasonic treatment is ≥99.99%.

10. An NFC fresh-squeezed orange juice, characterized in that, Prepared by any one of the preservation processing methods described in claims 1-9, the orange juice has a vitamin C retention rate of ≥92%, a shelf life of 6 months when refrigerated at 0-4℃, and a shelf life of 3 months when stored at room temperature away from light.

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