Highly antioxidative linseed oil and method for preparing the same

Abstract

This invention relates to the field of edible vegetable oils and oil processing. It provides a high-antioxidant flaxseed oil and its preparation method. The final product consists of a flaxseed oil matrix and a nano-assembly concentrate. The nano-assembly concentrate uses the flaxseed oil matrix as the continuous oil phase, and is formed by nano-aggregate dispersion system of flaxseed oil phospholipid-rich phase and flaxseed oil unsaponifiable concentrate in a mass ratio of 3:1-8:1. The nano-assembly concentrate has a particle size D50 of 20-80 nm, a polydispersity index of 0.05-0.30, a total phosphorus content of 20-120 mg / kg, an α-linolenic acid mass fraction of 45.0-70.0 wt%, and an oxidation stability time of 4.0-8.0 h measured at 110℃ according to ISO 6886:2016. This method balances α-linolenic acid content and oxidation stability, and meets the requirements for low moisture, low residue, and filterable filling. It is suitable for the preparation and application of high-antioxidant flaxseed oil in light-proof containers.

Description

Technical Field

[0001] This invention relates to the field of edible vegetable oils and oils processing, specifically to a flaxseed oil with high antioxidant properties and its preparation method. Background Technology

[0002] Flaxseed oil possesses significant nutritional value due to its high content of alpha-linolenic acid (ALA). However, ALA makes the oil phase more susceptible to oxidation during storage, transportation, and use, leading to changes in acid value and peroxide value, and affecting food safety. Therefore, higher requirements are placed on the antioxidant properties of flaxseed oil in the edible vegetable oil and oil processing industry. To achieve stable product quality, it is necessary to control the introduction of oxygen and light in raw material pretreatment, pressing, clarification, filtration, and bottling processes to reduce the content of insoluble impurities in the flaxseed oil matrix. While ensuring the mass fraction of ALA, it is also crucial to rationally utilize the active substances such as tocopherols and sterols carried by phospholipids and unsaponifiable concentrates to construct a long-term stable dispersion system in the continuous oil phase. This improves oxidative stability without significantly increasing processing burden, facilitating subsequent bottling in light-proof containers and quality monitoring. Simultaneously, process control of the product is required, taking into account indicators such as acid value, peroxide value, total phosphorus content, and oxidation stabilization time, while ensuring that the residual moisture and total ethanol and ethyl acetate levels are within safe limits to support the repeatability of large-scale production.

[0003] Currently, common approaches to improving the antioxidant properties of flaxseed oil include degumming, clarification, and refining after pressing, or delaying oxidation by introducing unsaponifiable concentrates such as tocopherols and sterols. However, different measures still face constraints in controlling the content of insoluble impurities, maintaining α-linolenic acid, and achieving a filterable bottling processing window. For example, Chinese patent CN106350209A discloses a nanoemulsion system and preparation method based on perilla oil or flaxseed oil, employing ultrasonic treatment and adding components in the post-processing stage. However, this approach involves multiple steps and is sensitive to process fluctuations. Similarly, Chinese patent CN102978009B discloses a flaxseed oil preparation method that focuses on microwave heating of oilseeds and the oil extraction process. However, it lacks a systematic design for the synergistic nanoassembly of phospholipid enrichment and unsaponifiable concentrates, the construction of nano-aggregate dispersion systems, and the synergistic constraints on moisture and residue levels, thus making it difficult to simultaneously meet the requirements of narrow distribution stability and food safety boundaries. Summary of the Invention

[0004] The purpose of this invention is to provide a flaxseed oil with high antioxidant properties and its preparation method, which solves the pain points of the current flaxseed oil system, such as the difficulty in balancing the retention and oxidative stability time of α-linolenic acid, the difficulty in stabilizing the nano-assembly of phospholipid enrichment and unsaponifiable enrichment in the continuous oil phase, and the difficulty in unifying filterable filling under the boundary constraints of low moisture and low residue.

[0005] This invention is based on the non-covalent intermolecular interaction between the phospholipid-rich phase of flaxseed oil and the unsaponifiable concentrate of flaxseed oil. A nano-aggregate dispersion system is formed by nano-assembly in the continuous oil phase of flaxseed oil matrix. In conjunction with nitrogen protection, degassing filtration and light-proof container filling, α-linolenic acid can achieve a longer oxidative stability time under low moisture and low residue conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A flaxseed oil with high antioxidant properties, comprising, by mass percentage of the final product formulation components:

[0008] The flaxseed oil matrix comprises 98.0-99.7 wt% flaxseed oil, wherein the content of insoluble impurities in the flaxseed oil matrix is ​​≤0.20 wt%.

[0009] 0.3-2.0wt% nano-assembly concentrate;

[0010] The sum of the mass percentages of each formulation component is 100wt%. The nano-assembly concentrate is formed by flaxseed oil phospholipid enriched phase, flaxseed oil unsaponifiable concentrate and flaxseed oil matrix. The mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiable concentrate in the nano-assembly concentrate is 3:1-8:1. The flaxseed oil matrix is ​​a continuous oil phase.

[0011] The particle size D50 of the nano-assembly concentrate is 20-80 nm, and the polydispersity index is 0.05-0.30.

[0012] Based on phosphorus (P), the total phosphorus content in high antioxidant flaxseed oil is 20-120 mg / kg, the α-linolenic acid mass fraction is 45.0-70.0 wt%, and the oxidative stability time measured at 110℃ according to ISO 6886:2016 is 4.0-8.0 h.

[0013] Furthermore, the flaxseed oil matrix is ​​prepared through the following steps:

[0014] A01. Raw material preparation: 100 parts by weight of flaxseed; nitrogen is used as a protective gas;

[0015] A02. Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 4.0-8.0 wt%.

[0016] A03. Pressing: Press at 35-55℃ under nitrogen protection for 10-40 minutes;

[0017] A04. Clarification: Centrifuge the obtained pressed oil at 25-45℃ for 10-30 minutes. If the content of insoluble impurities in the oil phase obtained after centrifugation is still higher than 0.20wt%, then filter it to obtain flaxseed oil matrix with insoluble impurity content ≤0.20wt%.

[0018] Furthermore, the phospholipid-enriched phase of flaxseed oil was prepared through the following steps:

[0019] B01. Raw material preparation: 100 parts by weight of any one of flaxseed oil base and flaxseed oil; 0.02-0.20 parts by weight of citric acid; 1-5 parts by weight of deionized water; and 2-6 parts by weight of ethanol in total.

[0020] B02. Degumming: Stir for 10-30 minutes at 45-60℃ under nitrogen protection;

[0021] B03. Separation: Centrifuge for 10-30 minutes at a relative centrifugal force of 3000-6000g to separate the colloidal phase;

[0022] B04. Washing and post-treatment: Wash the colloidal phase 1-3 times with the ethanol, each time at 30-45°C for 10-20 min, and then dry at 35-45°C and vacuum degree of -0.080 to -0.095 MPa for 1-4 h;

[0023] B05. Quality control: Obtain flaxseed oil phospholipid-rich phase with a total phosphorus content of 0.20-2.00wt% and a moisture content of 0.50-5.00wt%.

[0024] Furthermore, the unsaponifiable concentrate of flaxseed oil was prepared through the following steps:

[0025] C01. Raw material preparation: 100 parts by weight of any one of flaxseed oil base and flaxseed oil; 60-140 parts by weight of ethanol; 5-15 parts by weight of potassium hydroxide; 20-100 parts by weight of deionized water; and 60-150 parts by weight of ethyl acetate.

[0026] CO2. Saponification: The ethanol and potassium hydroxide are mixed and then added to the oil phase, and the mixture is reacted at 50-65°C under nitrogen protection for 0.5-2.0 h.

[0027] CO3. Extraction: After cooling to 20-40℃, add the total amount of deionized water and ethyl acetate in 2-4 portions for liquid-liquid extraction, with each contact lasting 10-30 minutes;

[0028] C04. Washing and concentration: Collect the organic phase and wash it with deionized water until the pH of the washing solution is 6.0-8.0. Then concentrate it for 1-3 hours at 30-45℃ and vacuum degree of -0.080 to -0.095MPa.

[0029] C05. Quality control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 20.0-80.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

[0030] Furthermore, the nano-assembly concentrate is prepared through the following steps:

[0031] D01. Raw material preparation: Based on the total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate are prepared at a mass ratio of 3:1-8:1, and 50-300 parts by mass of flaxseed oil matrix are added as continuous oil phase.

[0032] D02. Pre-dispersion: High-shear dispersion at 3000-8000 rpm for 10-30 min under nitrogen protection at 35-45℃;

[0033] D03. Nanoassembly: Using a probe-type ultrasonic instrument, ultrasonic treatment is carried out in continuous or pulse mode for 5-15 minutes at 20-40kHz and 100-500W. Cooling is used during the ultrasonic process to control the system temperature to not exceed 45℃.

[0034] D04. Degassing and filtration: Degas for 5-20 minutes at 25-40℃ and a vacuum of -0.06 to -0.095 MPa, then filter through a 0.22-0.45 μm filter;

[0035] D05. Quality control: Obtain a nano-assembly concentrate with a particle size D50 of 20-80 nm, a polydispersity index of 0.05-0.30, a total phosphorus content of 0.10-1.19 wt% (based on P), and a moisture content of 0.09-2.96 wt%.

[0036] Furthermore, the amount of nano-assembly concentrate added is 0.5-1.5 wt% based on the total mass of the final product formulation, and the mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiable concentrate is 4:1-6:1.

[0037] Furthermore, the particle size D50 of the nano-assembly concentrate is 25-60 nm, the polydispersity index is 0.10-0.25, and the total phosphorus content of the high antioxidant flaxseed oil is 30-100 mg / kg (calculated as P).

[0038] Furthermore, the high antioxidant flaxseed oil is packaged in a light-proof container, and the oxygen content in the top space of the package, measured immediately after sealing at 25°C, is 0.1-1.0 vol.

[0039] Furthermore, the flaxseed oil with high antioxidant properties has an acid value of 0.2-2.0 mgKOH / g and a peroxide value of 0.5-5.0 meq / kg.

[0040] As a concept of this invention, the compound design of flaxseed oil matrix and nano-assembled concentrate is mainly used to enhance the oxidative stability of flaxseed oil with high antioxidant properties and retain α-linolenic acid. By nano-assembling the phospholipid-rich phase and the unsaponifiable concentrate of flaxseed oil in the continuous oil phase of flaxseed oil matrix, a nano-aggregate dispersion system with controllable particle size D50 and polydispersity index is formed, so that tocopherol and sterol components are stably dispersed in the oil phase, thereby slowing down the oxidation process. At the same time, by controlling the content of insoluble impurities in flaxseed oil matrix and limiting the range of total phosphorus content, the consistency of the final product is maintained under filtration and filling conditions. Finally, the antioxidant level is characterized by the oxidation stability time measured at 110°C according to ISO 6886:2016.

[0041] This invention also discloses a method for preparing flaxseed oil with high antioxidant properties, comprising the following steps:

[0042] S1. Provides flaxseed oil as a base;

[0043] S2. Provides nano-assembly concentrate;

[0044] S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed according to the final product formulation component mass percentages of 98.0-99.7wt% and 0.3-2.0wt%, respectively, so that the sum of the two mass percentages is 100wt%. The mixture is mechanically stirred at 50-300rpm for 10-30min under nitrogen protection at 25-35℃. After filtration through a filter material with a pore size of 0.45-5μm, the mixture is filled with nitrogen to obtain flaxseed oil with high antioxidant properties.

[0045] Furthermore, the flaxseed moisture adjustment in step A02 is achieved by adding water for humidification or by drying, with the measured moisture content reaching 4.0-8.0 wt% as the adjustment endpoint.

[0046] Furthermore, in step A03, the pressing is performed using a cold screw press or a hydraulic cold press, and the oil temperature at the pressing outlet is maintained at 35-55℃.

[0047] Furthermore, in step A04, the centrifugation operation has a relative centrifugal force of 1000-5000g and a centrifugation temperature of 25-45℃; when using filtration, the filter media has a pore size of 1-20μm.

[0048] Furthermore, in steps B01 and C01, when the raw material used is flaxseed oil, the content of insoluble impurities in the flaxseed oil does not exceed 0.20 wt%.

[0049] Furthermore, before degumming in step B02, citric acid is dissolved in deionized water to prepare an aqueous citric acid phase, and then the aqueous citric acid phase is added to the oil phase for degumming and stirring.

[0050] Furthermore, the degumming stirring in step B02 is carried out using a mechanical paddle mixer with a stirring speed of 100-400 rpm.

[0051] Furthermore, the centrifugation temperature in step B03 is 20-40℃.

[0052] Furthermore, in the ethanol washing step B04, after each contact between ethanol and the colloidal phase for 10-20 minutes, the ethanol washing solution is removed by centrifugation at a relative centrifugal force of 1000-3000g for 5-15 minutes before the next washing is performed.

[0053] Furthermore, the quality control indicators for step B05 include ≤0.05wt% residual ethanol in the phospholipid-rich phase of flaxseed oil.

[0054] Furthermore, in step CO2, potassium hydroxide is added to ethanol and fully dissolved to form an alcoholic saponification solution, which is then added to the oil phase to carry out the saponification reaction.

[0055] Further, in the liquid-liquid extraction of step C03, the total amount of ethyl acetate is added in 2-4 batches. After each addition, the mixture is thoroughly mixed and contacted for 10-30 minutes. Phase separation is achieved by standing for at least 15 minutes or by centrifugation at a relative centrifugal force of 500-2000g for 5-15 minutes. The upper organic phase is collected, and the operation is repeated until the total amount of ethyl acetate is exhausted.

[0056] Furthermore, in step S3, based on the measured total phosphorus content (in terms of P) of the nano-assembly concentrate provided in step S2, the actual amount of nano-assembly concentrate added is adjusted within the range of 0.3-2.0 wt% so that the total phosphorus content (in terms of P) of the final product is within the range of 20-120 mg / kg.

[0057] Furthermore, the particle size D50 and polydispersity index of the nano-dispersants in the nano-assembly concentrate were determined by dynamic light scattering method. The particle size D50 is the median particle size of the intensity-weighted distribution. During the determination, the sample was diluted with n-hexane as the test medium, the measurement temperature was 25±0.5℃, and the number of parallel measurements was not less than 3. The average value of each measurement result was taken as the final detection value.

[0058] Furthermore, the sample obtained after solvent extraction and separation of the free oil phase from the nano-assembly concentrate and the phospholipid-rich phase of flaxseed oil were subjected to Fourier transform infrared spectroscopy. In the comparative spectra of the two, the characteristic peak of the P=O stretching vibration of phosphate esters was located at 1220-1260 cm⁻¹. - ¹ The characteristic peaks of the nano-assembled concentrate sample show a peak position shift compared to the corresponding peaks in the flaxseed oil phospholipid enriched phase; the peak position shift can serve as one of the auxiliary characterization evidences of non-covalent intermolecular interactions between the polar head groups of phospholipids in the flaxseed oil phospholipid enriched phase and the tocopherol and sterol unsaponifiable components in the unsaponifiable flaxseed oil enrichment.

[0059] Furthermore, the nano-assembly concentrate is a nano-aggregate dispersion system with flaxseed oil as the continuous phase, formed by non-covalent intermolecular interactions between phospholipids in the flaxseed oil phospholipid enrichment phase and tocopherols and sterols in the unsaponifiable concentrate of flaxseed oil.

[0060] Furthermore, the total content of flaxseed oil matrix in the final product consists of two parts: the flaxseed oil matrix directly added in step S3 and the flaxseed oil matrix contained in the nano-assembly concentrate. Both exist in the final product in the form of flaxseed oil matrix with an insoluble impurity content of ≤0.20wt%.

[0061] As another aspect of this invention, the present invention employs a nano-assembly concentrate preparation and compounding process using flaxseed oil as the continuous oil phase. This process is primarily used to obtain a nano-aggregate dispersion system with stable particle size D50 and polydispersity index under filterable filling conditions. The process involves pressing, degumming, saponification, extraction, and vacuum concentration under nitrogen protection, followed by nano-assembly under high-shear dispersion and probe-type ultrasonic conditions. Degassing and filtration are then performed to control the residual moisture, ethanol, and ethyl acetate, ensuring that the final product's total phosphorus content, α-linolenic acid mass fraction, and oxidative stabilization time are within the limits specified in the technical solution. This improves the reproducibility of the preparation method and the consistency of the product.

[0062] The phospholipid-rich phase of flaxseed oil contains polar phospholipid head groups, which can participate in nanoassembly and provide structural constraints in the continuous oil phase of the flaxseed oil matrix. The unsaponifiable concentrate of flaxseed oil is rich in tocopherols and sterols, which can provide antioxidant activity and participate in non-covalent intermolecular interactions. The synergistic effect of the two forms a nano-aggregate dispersion system, making the active components more uniform and stable in the oil phase, thereby reducing the reaction opportunity of α-linolenic acid during oxidation, prolonging the oxidation stability time measured according to ISO 6886:2016, and helping to inhibit the rise of acid value and peroxide value. At the same time, the total phosphorus content can reflect the degree of assembly of phospholipid-related components, and the peak position shift of the characteristic peak of the P=O stretching vibration of phosphate esters in Fourier transform infrared spectroscopy can serve as auxiliary characterization evidence of the existence of non-covalent intermolecular interactions, supporting long-term stability.

[0063] Beneficial technical effects

[0064] 1. A nano-aggregate dispersion system is formed by nano-assembling linseed oil phospholipid enriched phase and linseed oil unsaponifiables. While maintaining the α-linolenic acid mass fraction of 45.0-70.0wt%, the oxidative stability time measured at 110℃ according to ISO6886:2016 reaches 4.0-8.0h, which is convenient for evaluation and release according to standardized indicators.

[0065] 2. The flaxseed oil matrix contains ≤0.20wt% insoluble impurities, and the nano-assembly concentrate has a particle size D50 of 20-80nm and a polydispersity index of 0.05-0.30. This ensures that the final product maintains a stable dispersion system after filtration through 0.45-5μm filters. It can also be filled in nitrogen-filled containers under nitrogen protection and in light-proof containers, reducing the risk of oxygen introduction.

[0066] 3. By vacuum drying and vacuum concentration combined with degassing and filtration, the water content of the nano-assembly concentrate is 0.09-2.96wt%, the residual alkali of the flaxseed oil unsaponifiable concentrate is ≤0.05wt%, and the total residual ethanol and ethyl acetate is ≤0.50wt%, which ensures that the total residual ethanol and ethyl acetate in the final product meets the limit requirements of GB2716-2018, which is conducive to compliant production.

[0067] 4. The total phosphorus content, calculated as P, is limited to 20-120 mg / kg. It also provides auxiliary evidence for determining particle size D50 and polydispersity index by dynamic light scattering method and monitoring the peak position shift of characteristic peak of P=O stretching vibration of phosphate ester by Fourier transform infrared spectroscopy. It can be used for batch consistency assessment and process deviation traceability. Attached Figure Description

[0068] Figure 1 The diagram shows the differential and cumulative distribution of particle size intensity of the concentrated solution of nano-assembly in Example 1, Comparative Example 5, and Comparative Example 7.

[0069] Figure 2 This is a graph showing the evolution of the particle size difference distribution of the nano-assembly concentrate in Example 1 over storage time.

[0070] Figure 3 The stability curves of the D50 particle size of the nano-assembly concentrate of Example 1, Comparative Example 5 and Comparative Example 7 as a function of storage time are shown.

[0071] Figure 4 The test samples, after solvent extraction to remove the free oil phase from the phospholipid-rich phase of flaxseed oil and the nano-assembly concentrates of Examples 1, 3, and 4, were measured at 1150–1310 cm⁻¹. - ¹ Normalized infrared spectrum overlay of phosphate ester P=O stretching vibration.

[0072] Figure 5Scatter plot of independent repeated determinations of oxidative stability time of high antioxidant flaxseed oil in Example 1, Comparative Example 1, and Comparative Example 8, and the mean plus or minus the standard deviation.

[0073] Figure 6 The results of high performance liquid chromatography determination of the content of tocopherol homologues in the base flaxseed oil, comparative example 1, and example 1 are shown in the figure.

[0074] Figure 7 This is a transmission electron microscope image of the nano-assembly concentrate from Example 1.

[0075] Figure 8 This is a scanning electron microscope image of the nano-assembly concentrate from Example 1.

[0076] Figure 9 This is a macroscopic optical photograph of the high antioxidant flaxseed oil from Example 1. Detailed Implementation

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0078] Example 1

[0079] The high-antioxidant flaxseed oil of this embodiment, based on the final product formulation composition by mass percentage, comprises 99.0 wt% flaxseed oil matrix and 1.0 wt% nano-assembled concentrate, with the sum of the mass percentages of all components being 100 wt%. The insoluble impurity content of the flaxseed oil matrix in this embodiment is ≤0.20 wt%. The nano-assembled concentrate of this embodiment is formed from a flaxseed oil phospholipid-enriched phase, a flaxseed oil unsaponifiable concentrate, and the flaxseed oil matrix, wherein the mass ratio of the flaxseed oil phospholipid-enriched phase to the flaxseed oil unsaponifiable concentrate is 5:1, and the flaxseed oil matrix is ​​a continuous oil phase. The particle size D50 of the nano-assembled concentrate of this embodiment is 50 nm, and the polydispersity index is 0.18. Based on phosphorus (P), the high-antioxidant flaxseed oil of this embodiment contains 70 mg / kg of total phosphorus, 57.0 wt% α-linolenic acid, and has an oxidative stability time of 6.0 h measured at 110°C according to ISO 6886:2016. The high antioxidant flaxseed oil in this embodiment was packaged in a light-proof container. The oxygen content in the top space of the package was 0.5 vol% immediately after sealing, the acid value was 1.1 mg KOH / g, and the peroxide value was 2.8 meq / kg.

[0080] The flaxseed oil matrix in this embodiment is prepared through the following steps:

[0081] Step A01, Raw material preparation: Take 100 parts by weight of flaxseed, using nitrogen as a protective gas.

[0082] Step A02, Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 6.0 wt% by adding water. The actual moisture content of 6.0 wt% is taken as the adjustment endpoint.

[0083] Step A03, pressing: Use a cold screw press and press for 25 minutes at 45℃ under nitrogen protection, maintaining the oil temperature at the pressing outlet at 45℃.

[0084] Step A04, Clarification: The pressed oil obtained in Step A03 is centrifuged at 35°C with a relative centrifugal force of 3000g for 20 minutes. After centrifugation, the content of insoluble impurities in the oil phase is ≤0.20wt%, thus obtaining the flaxseed oil matrix of this embodiment. The total content of flaxseed oil matrix in the final product of this embodiment consists of two parts: the flaxseed oil matrix directly added in Step S3 and the flaxseed oil matrix contained in the nano-assembly concentrate. Both exist in the final product in the form of flaxseed oil matrix with an insoluble impurity content of ≤0.20wt%.

[0085] The flaxseed oil phospholipid-enriched phase of this embodiment is prepared through the following steps. The raw material used in step B01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0086] Step B01, Raw material preparation: 100 parts by weight of flaxseed oil base; 0.10 parts by weight of citric acid; 3 parts by weight of deionized water; 4 parts by weight of ethanol.

[0087] Step B02, Degumming: Before degumming, citric acid is dissolved in deionized water to prepare an aqueous phase of citric acid. Then, the aqueous phase of citric acid is added to the oil phase. The mixture is stirred mechanically with a paddle at 250 rpm for 20 minutes under nitrogen protection at 52°C.

[0088] Step B03, Separation: Centrifuge for 20 minutes at a centrifugation temperature of 30℃ and a relative centrifugal force of 4500g to separate the gel phase.

[0089] Step B04, washing and post-treatment: The colloidal phase of this embodiment is washed twice with ethanol of this embodiment. Each time, after contacting at 38°C for 15 min, the ethanol washing liquid is removed by centrifugation at a relative centrifugal force of 2000g for 10 min, and then the next washing is performed. After washing, it is dried at 40°C and a vacuum degree of -0.090MPa for 2.5 h.

[0090] Step B05, Quality Control: A flaxseed oil phospholipid-rich phase with a total phosphorus content of 1.68 wt%, a moisture content of 2.50 wt%, and an ethanol residue of ≤0.05 wt% was obtained.

[0091] The flaxseed oil unsaponifiable concentrate of this embodiment is obtained through the following steps. The raw material used in step C01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0092] Step C01, Raw material preparation: 100 parts by weight of flaxseed oil base; 100 parts by weight of ethanol; 10 parts by weight of potassium hydroxide; 60 parts by weight of deionized water; 105 parts by weight of ethyl acetate.

[0093] Step CO2, Saponification: Potassium hydroxide is added to ethanol and fully dissolved to form an alcoholic saponification solution. The alcoholic saponification solution is then added to the oil phase and reacted at 58°C under nitrogen protection for 1.25 h.

[0094] Step C03, Extraction: After cooling to 30°C, the total amount of deionized water and ethyl acetate in this embodiment is added in three portions for liquid-liquid extraction. After each addition, the mixture is thoroughly mixed and contacted for 20 minutes. Phase separation is achieved by standing for at least 15 minutes. The upper organic phase is collected. The operation is repeated until the total amount of ethyl acetate is exhausted.

[0095] Step C04, washing and concentration: collect the organic phase and wash it with deionized water until the pH of the washing solution is 7.0, then concentrate it for 2.0 h at 38 °C and a vacuum of -0.090 MPa.

[0096] Step C05, Quality Control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 50.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

[0097] The nano-assembly concentrate in this embodiment is prepared through the following steps:

[0098] Step D01, Raw material preparation: Based on a total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, 83.3 parts by mass of flaxseed oil phospholipid enriched phase and 16.7 parts by mass of flaxseed oil unsaponifiable concentrate were prepared at a mass ratio of 5:1, and 100 parts by mass of flaxseed oil matrix were added as a continuous oil phase, for a total system mass of 200 parts by mass.

[0099] Step D02, pre-dispersion: high-shear dispersion at 5500 rpm for 20 min under nitrogen protection at 40℃.

[0100] Step D03, Nanoassembly: Using a probe-type ultrasonic instrument, the system is continuously ultrasonicated for 10 minutes at 30 kHz and 300 W. During the ultrasonic process, the system temperature is controlled to not exceed 45 ℃ using a cooling method.

[0101] Step D04, degassing and filtration: Degas for 12 min at 32℃ and a vacuum of -0.080MPa, then filter through a 0.45μm filter.

[0102] Step D05, Quality Control: A nano-assembly concentrate with a particle size D50 of 50 nm, a polydispersity index of 0.18, a total phosphorus content (calculated as P) of 0.70 wt% (derived from the 1.68 wt% total phosphorus in the phospholipid-enriched phase in Step B05 and its proportion in the total formulation of 83.3 / 200), and a moisture content of 1.04 wt% (derived from the 2.50 wt% moisture in the phospholipid-enriched phase in Step B05 and its proportion of 83.3 / 200) was obtained. The particle size D50 and polydispersity index of the nano-dispersions in the nano-assembly concentrate were determined by dynamic light scattering method. The particle size D50 is the median particle size of the intensity-weighted distribution. During the determination, the sample was diluted with n-hexane as the test medium, the measurement temperature was 25 ± 0.5℃, and the number of parallel determinations was not less than 3. The average value of each determination result was used as the final detection value. The nano-assembly concentrate in this embodiment is a nano-aggregate dispersion system with flaxseed oil as the continuous phase, formed by non-covalent intermolecular interactions between phospholipids in the flaxseed oil phospholipid enriched phase and tocopherols and sterols in the unsaponifiable concentrate of flaxseed oil. The sample obtained after solvent extraction to separate the free oil phase from the nano-assembly concentrate and the flaxseed oil phospholipid enriched phase were subjected to Fourier transform infrared spectroscopy (FTIR) measurements. In the comparative spectra, the characteristic peak of the P=O stretching vibration of phosphate esters was located at 1220-1260 cm⁻¹. - The characteristic peaks of the nano-assembled concentrate sample showed a shift in position compared to the corresponding peaks in the phospholipid-rich phase of flaxseed oil. This shift can serve as one of the auxiliary characterization evidences for the non-covalent intermolecular interactions between the polar head groups of phospholipids and the tocopherol and sterol unsaponifiable components.

[0103] The high antioxidant flaxseed oil in this embodiment is prepared through the following steps:

[0104] S1. Prepare the flaxseed oil matrix according to the methods described in steps A01 to A04 above;

[0105] S2. Prepare the nano-assembly concentrate according to the methods described in steps D01 to D05 above;

[0106] S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed at mass percentages of 99.0 wt% and 1.0 wt% respectively, so that the sum of their mass percentages is 100 wt%. The amount of the 1.0 wt% nano-assembly concentrate added is determined based on the measured total phosphorus content (as P) of the nano-assembly concentrate provided in step S2, so that the total phosphorus content (as P) of the final product is within the range of 20-120 mg / kg. The mixture is mechanically stirred at 175 rpm for 20 min at 30°C under nitrogen protection, filtered through a filter material with a pore size of 2 μm, and then filled with nitrogen and packaged in light-proof containers to obtain the high antioxidant flaxseed oil of this embodiment. The total residual amount of ethyl acetate and ethanol in the final product is quantitatively verified by headspace gas chromatography to ensure that the low residual solvent meets the food safety boundary.

[0107] The process parameters in this embodiment are moderate, the operation window for each step is wide, and the reproducibility is strong. It is suitable as a benchmark formula for standardized large-scale production. The product is applicable to daily edible oils, bottled functional vegetable oils and other products. It can be used in application scenarios that do not involve high-temperature heating, such as cold dishes, dipping sauces, low-temperature seasoning and dietary preparation. It can also be used as a functional oil raw material for fortified foods.

[0108] Example 2

[0109] The high-antioxidant flaxseed oil of this embodiment, based on the final product formulation composition by mass percentage, comprises 98.8 wt% flaxseed oil matrix and 1.2 wt% nano-assembled concentrate, with the sum of the mass percentages of all components being 100 wt%. The insoluble impurity content of the flaxseed oil matrix in this embodiment is ≤0.20 wt%. The nano-assembled concentrate of this embodiment is formed from a flaxseed oil phospholipid-rich phase, a flaxseed oil unsaponifiable concentrate, and the flaxseed oil matrix, wherein the mass ratio of the flaxseed oil phospholipid-rich phase to the flaxseed oil unsaponifiable concentrate is 6:1, and the flaxseed oil matrix is ​​a continuous oil phase. The particle size D50 of the nano-assembled concentrate of this embodiment is 35 nm, and the polydispersity index is 0.12. Based on phosphorus (P), the high-antioxidant flaxseed oil of this embodiment contains 85 mg / kg of total phosphorus, has an α-linolenic acid mass fraction of 63.0 wt%, and has an oxidative stability time of 7.0 h measured at 110°C according to ISO 6886:2016. The high antioxidant flaxseed oil in this embodiment was packaged in a light-proof container. The oxygen content in the top space of the package was 0.3 vol% immediately after sealing, the acid value was 0.8 mg KOH / g, and the peroxide value was 1.5 meq / kg.

[0110] The flaxseed oil matrix in this embodiment is prepared through the following steps:

[0111] Step A01, Raw material preparation: Take 100 parts by weight of flaxseed, using nitrogen as a protective gas.

[0112] Step A02, Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 5.0 wt% by adding water. The actual moisture content of 5.0 wt% is taken as the adjustment endpoint.

[0113] Step A03, pressing: Use a cold screw press and press for 20 minutes at 40℃ under nitrogen protection, maintaining the oil temperature at the pressing outlet at 40℃.

[0114] Step A04, Clarification: The pressed oil obtained in Step A03 is centrifuged at 30°C with a relative centrifugal force of 3500g for 15 minutes. After centrifugation, the content of insoluble impurities in the oil phase is ≤0.20wt%, thus obtaining the flaxseed oil matrix of this embodiment. The total content of flaxseed oil matrix in the final product of this embodiment consists of two parts: the flaxseed oil matrix directly added in Step S3 and the flaxseed oil matrix contained in the nano-assembly concentrate. Both exist in the final product in the form of flaxseed oil matrix with an insoluble impurity content of ≤0.20wt%.

[0115] The flaxseed oil phospholipid-enriched phase of this embodiment is prepared through the following steps. The raw material used in step B01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0116] Step B01, Raw material preparation: 100 parts by weight of flaxseed oil base; 0.08 parts by weight of citric acid; 2.5 parts by weight of deionized water; 3.5 parts by weight of ethanol.

[0117] Step B02, Degumming: Before degumming, citric acid is dissolved in deionized water to prepare an aqueous phase of citric acid. Then, the aqueous phase of citric acid is added to the oil phase. The mixture is stirred mechanically with a paddle at 200 rpm for 15 minutes under nitrogen protection at 48°C.

[0118] Step B03, Separation: Centrifuge for 15 minutes at a centrifugation temperature of 25℃ and a relative centrifugal force of 5500g to separate the gel phase.

[0119] Step B04, washing and post-treatment: The colloidal phase of this embodiment is washed twice with ethanol of this embodiment. Each time, after contacting at 35°C for 12 min, the ethanol washing liquid is removed by centrifugation at 1500g for 8 min, and then the next washing is performed. After washing, it is dried at 38°C and vacuum degree of -0.085MPa for 2.0 h.

[0120] Step B05, Quality Control: Obtain a flaxseed oil phospholipid enriched phase with a total phosphorus content of 1.50 wt%, a moisture content of 2.00 wt%, and an ethanol residue of ≤0.05 wt%.

[0121] The flaxseed oil unsaponifiable concentrate of this embodiment is obtained through the following steps. The raw material used in step C01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0122] Step C01, Raw material preparation: 100 parts by weight of flaxseed oil base; 80 parts by weight of ethanol; 8 parts by weight of potassium hydroxide; 45 parts by weight of deionized water; 90 parts by weight of ethyl acetate.

[0123] Step CO2, Saponification: Potassium hydroxide is added to ethanol and fully dissolved to form an alcoholic saponification solution. The alcoholic saponification solution is then added to the oil phase and reacted at 55°C under nitrogen protection for 1.0 h.

[0124] Step C03, Extraction: After cooling to 25°C, the total amount of deionized water and ethyl acetate in this embodiment is added in three portions for liquid-liquid extraction. After each addition, the mixture is thoroughly mixed and contacted for 15 minutes. Phase separation is achieved by centrifugation at a relative centrifugal force of 1000g for 10 minutes. The upper organic phase is collected, and the operation is repeated until the total amount of ethyl acetate is exhausted.

[0125] Step C04, washing and concentration: collect the organic phase and wash it with deionized water until the pH of the washing solution is 7.0, then concentrate it for 1.5 h at 35 °C and a vacuum of -0.085 MPa.

[0126] Step C05, Quality Control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 40.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

[0127] The nano-assembly concentrate in this embodiment is prepared through the following steps:

[0128] Step D01, Raw material preparation: Based on a total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, 85.7 parts by mass of flaxseed oil phospholipid enriched phase and 14.3 parts by mass of flaxseed oil unsaponifiable concentrate were prepared at a mass ratio of 6:1, and 80 parts by mass of flaxseed oil matrix were added as a continuous oil phase, for a total system mass of 180 parts by mass.

[0129] Step D02, pre-dispersion: high-shear dispersion at 6500 rpm for 15 min under nitrogen protection at 38℃.

[0130] Step D03, Nanoassembly: Using a probe-type ultrasonic instrument, the system was continuously ultrasonicated for 8 minutes at 25 kHz and 250 W. During the ultrasonication process, the system temperature was controlled to not exceed 45 ℃ using a cooling method.

[0131] Step D04, degassing and filtration: Degas for 10 min at 30℃ and a vacuum of -0.075MPa, then filter through a 0.22μm filter.

[0132] Step D05, Quality Control: A nano-assembly concentrate with a particle size D50 of 35 nm, a polydispersity index of 0.12, a total phosphorus content (calculated as P) of 0.71 wt% (derived from the 1.50 wt% total phosphorus in the phospholipid-enriched phase in Step B05 and its proportion in the total formulation of 85.7 / 180), and a moisture content of 0.95 wt% (derived from the 2.00 wt% moisture in the phospholipid-enriched phase in Step B05 and its proportion of 85.7 / 180) was obtained. The particle size D50 and polydispersity index of the nano-dispersions in the nano-assembly concentrate were determined by dynamic light scattering method. The particle size D50 is the median particle size of the intensity-weighted distribution. During the determination, the sample was diluted with n-hexane as the test medium, the determination temperature was 25 ± 0.5℃, and the number of parallel determinations was not less than 3. The average value of each determination result was taken as the final detection value. The nano-assembly concentrate in this embodiment is a nano-aggregate dispersion system with flaxseed oil as the continuous phase, formed by non-covalent intermolecular interactions between phospholipids in the flaxseed oil phospholipid enriched phase and tocopherols and sterols in the unsaponifiable concentrate of flaxseed oil. The sample obtained after solvent extraction to separate the free oil phase from the nano-assembly concentrate and the flaxseed oil phospholipid enriched phase were subjected to Fourier transform infrared spectroscopy (FTIR) measurements. In the comparative spectra, the characteristic peak of the P=O stretching vibration of phosphate esters was located at 1220-1260 cm⁻¹. - The characteristic peaks of the nano-assembled concentrate sample showed a shift in position compared to the corresponding peaks in the phospholipid-rich phase of flaxseed oil. This shift can serve as one of the auxiliary characterization evidences for the non-covalent intermolecular interactions between the polar head groups of phospholipids and the tocopherol and sterol unsaponifiable components.

[0133] The high antioxidant flaxseed oil in this embodiment is prepared through the following steps:

[0134] S1. Prepare the flaxseed oil matrix according to the methods described in steps A01 to A04 above;

[0135] S2. Prepare the nano-assembly concentrate according to the methods described in steps D01 to D05 above;

[0136] S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed at mass percentages of 98.8 wt% and 1.2 wt% respectively, so that the sum of their mass percentages is 100 wt%. The amount of the 1.2 wt% nano-assembly concentrate added is determined based on the measured total phosphorus content (as P) of the nano-assembly concentrate provided in step S2, so that the total phosphorus content (as P) of the final product is within the range of 20-120 mg / kg. The mixture is mechanically stirred at 200 rpm for 15 min at 28°C under nitrogen protection, filtered through a filter material with a pore size of 1 μm, and then filled with nitrogen and packaged in light-proof containers to obtain the high antioxidant flaxseed oil of this embodiment. The total residual amount of ethyl acetate and ethanol in the final product is quantitatively verified by headspace gas chromatography to ensure that the low residual solvent meets the food safety boundary.

[0137] This embodiment is applicable to high-end functional edible flaxseed oil products that require high oil oxidation stability. It can be used in high-end cold dressing oils, functional oils for nutrition bars and nutritional meals, oils for baby food additives, and oils for sports nutrition foods. It is especially suitable for the industrial production of bottled high-end vegetable oils and functional food raw materials with long shelf life requirements.

[0138] Example 3

[0139] The high-antioxidant flaxseed oil of this embodiment, based on the final product formulation composition by mass percentage, comprises 99.3 wt% flaxseed oil matrix and 0.7 wt% nano-assembly concentrate, with the sum of the mass percentages of all components being 100 wt%. The insoluble impurity content of the flaxseed oil matrix in this embodiment is ≤0.20 wt%. The nano-assembly concentrate of this embodiment is formed from flaxseed oil phospholipid-rich phase, flaxseed oil unsaponifiable concentrate, and flaxseed oil matrix, wherein the mass ratio of the flaxseed oil phospholipid-rich phase to the flaxseed oil unsaponifiable concentrate is 4:1, and the flaxseed oil matrix is ​​a continuous oil phase. The particle size D50 of the nano-assembly concentrate of this embodiment is 65 nm, and the polydispersity index is 0.23. Based on phosphorus (P), the high-antioxidant flaxseed oil of this embodiment contains 36 mg / kg of total phosphorus, 51.0 wt% of α-linolenic acid, and has an oxidative stability time of 5.0 h measured at 110°C according to ISO 6886:2016. The high antioxidant flaxseed oil in this embodiment was packaged in a light-proof container. The oxygen content in the top space of the package was 0.7 vol% immediately after sealing, the acid value was 1.5 mg KOH / g, and the peroxide value was 3.8 meq / kg.

[0140] The flaxseed oil matrix in this embodiment is prepared through the following steps:

[0141] Step A01, Raw material preparation: Take 100 parts by weight of flaxseed, using nitrogen as a protective gas.

[0142] Step A02, Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 7.0 wt% by adding water. The actual moisture content of 7.0 wt% is taken as the adjustment endpoint.

[0143] Step A03, pressing: Use a cold screw press and press for 35 minutes at 50℃ under nitrogen protection, maintaining the oil temperature at the pressing outlet at 50℃.

[0144] Step A04, Clarification: The pressed oil obtained in Step A03 is centrifuged at 42°C with a relative centrifugal force of 4000g for 25 minutes. After centrifugation, the content of insoluble impurities in the oil phase is still higher than 0.20 wt%. The oil is then filtered through a filter medium with a pore size of 15 μm to obtain the flaxseed oil matrix of this embodiment with an insoluble impurity content ≤0.20 wt%. The total content of flaxseed oil matrix in the final product of this embodiment consists of two parts: the flaxseed oil matrix directly added in Step S3 and the flaxseed oil matrix contained in the nano-assembly concentrate. Both exist in the final product in the form of flaxseed oil matrix with an insoluble impurity content ≤0.20 wt%.

[0145] The flaxseed oil phospholipid-enriched phase of this embodiment is prepared through the following steps. The raw material used in step B01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0146] Step B01, Raw material preparation: 100 parts by weight of flaxseed oil base; 0.15 parts by weight of citric acid; 4.5 parts by weight of deionized water; 5.0 parts by weight of ethanol.

[0147] Step B02, Degumming: Before degumming, citric acid is dissolved in deionized water to prepare an aqueous phase of citric acid. Then, the aqueous phase of citric acid is added to the oil phase. The mixture is stirred mechanically at 350 rpm for 25 minutes under nitrogen protection at 57°C.

[0148] Step B03, separation: Centrifuge for 25 minutes at a centrifugation temperature of 35℃ and a relative centrifugal force of 3500g to separate the gel phase.

[0149] Step B04, washing and post-treatment: The colloidal phase of this embodiment is washed three times with ethanol of this embodiment. Each time, after contacting at 42°C for 18 min, the ethanol washing liquid is removed by centrifugation at a relative centrifugal force of 2500g for 12 min, and then the next washing is performed. After washing, it is dried at 43°C and a vacuum degree of -0.093MPa for 3.5 h.

[0150] Step B05, Quality Control: Obtain a flaxseed oil phospholipid enriched phase with a total phosphorus content of 1.40 wt%, a moisture content of 3.50 wt%, and an ethanol residue of ≤0.05 wt%.

[0151] The flaxseed oil unsaponifiable concentrate of this embodiment is obtained through the following steps. The raw material used in step C01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0152] Step C01, Raw material preparation: 100 parts by weight of flaxseed oil base; 120 parts by weight of ethanol; 12 parts by weight of potassium hydroxide; 80 parts by weight of deionized water; 130 parts by weight of ethyl acetate.

[0153] Step CO2, Saponification: Potassium hydroxide is added to ethanol and fully dissolved to form an alcoholic saponification solution. The alcoholic saponification solution is then added to the oil phase and reacted at 62°C under nitrogen protection for 1.75 h.

[0154] Step C03, Extraction: After cooling to 35°C, the total amount of deionized water and ethyl acetate in this embodiment is added in 4 portions for liquid-liquid extraction. After each addition, the mixture is thoroughly mixed and contacted for 25 minutes. Phase separation is achieved by centrifugation at a relative centrifugal force of 1500g for 12 minutes. The upper organic phase is collected. The operation is repeated until the total amount of ethyl acetate is exhausted.

[0155] Step C04, washing and concentration: Collect the organic phase and wash it with deionized water until the pH of the washing solution is 6.5, and then concentrate it for 2.5 h at 42 °C and a vacuum of -0.093 MPa.

[0156] Step C05, Quality Control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 65.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

[0157] The nano-assembly concentrate in this embodiment is prepared through the following steps:

[0158] Step D01, Raw material preparation: Based on a total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, 80.0 parts by mass of flaxseed oil phospholipid enriched phase and 20.0 parts by mass of flaxseed oil unsaponifiable concentrate are prepared at a mass ratio of 4:1, and 120 parts by mass of flaxseed oil matrix is ​​added as a continuous oil phase, for a total system mass of 220 parts by mass.

[0159] Step D02, pre-dispersion: high-shear dispersion at 4000 rpm for 25 min under nitrogen protection at 42℃.

[0160] Step D03, Nanoassembly: Using a probe-type ultrasonic instrument, ultrasonic treatment was performed in pulse mode at 35kHz and 150W for 13 minutes. During the ultrasonic process, cooling was used to control the system temperature to not exceed 45℃.

[0161] Step D04, degassing and filtration: Degas for 17 min at 38℃ and a vacuum of -0.088MPa, then filter through a 0.45μm filter.

[0162] Step D05, Quality Control: A nano-assembly concentrate with a particle size D50 of 65 nm, a polydispersity index of 0.23, a total phosphorus content (calculated as P) of 0.51 wt% (derived from the 1.40 wt% total phosphorus in the phospholipid-enriched phase in Step B05 and its proportion in the total formulation of 80.0 / 220), and a moisture content of 1.27 wt% (derived from the 3.50 wt% moisture in the phospholipid-enriched phase in Step B05 and its proportion of 80.0 / 220) was obtained. The particle size D50 and polydispersity index of the nano-dispersions in the nano-assembly concentrate were determined by dynamic light scattering method. The particle size D50 is the median particle size of the intensity-weighted distribution. During the determination, the sample was diluted with n-hexane as the test medium, the determination temperature was 25 ± 0.5℃, and the number of parallel determinations was not less than 3. The average value of each determination result was taken as the final detection value. The nano-assembly concentrate in this embodiment is a nano-aggregate dispersion system with flaxseed oil as the continuous phase, formed by non-covalent intermolecular interactions between phospholipids in the flaxseed oil phospholipid enriched phase and tocopherols and sterols in the unsaponifiable concentrate of flaxseed oil. The sample obtained after solvent extraction to separate the free oil phase from the nano-assembly concentrate and the flaxseed oil phospholipid enriched phase were subjected to Fourier transform infrared spectroscopy (FTIR) measurements. In the comparative spectra, the characteristic peak of the P=O stretching vibration of phosphate esters was located at 1220-1260 cm⁻¹. - The characteristic peaks of the nano-assembled concentrate sample showed a shift in position compared to the corresponding peaks in the phospholipid-rich phase of flaxseed oil. This shift can serve as one of the auxiliary characterization evidences for the non-covalent intermolecular interactions between the polar head groups of phospholipids and the tocopherol and sterol unsaponifiable components.

[0163] The high antioxidant flaxseed oil in this embodiment is prepared through the following steps:

[0164] S1. Prepare the flaxseed oil matrix according to the methods described in steps A01 to A04 above;

[0165] S2. Prepare the nano-assembly concentrate according to the methods described in steps D01 to D05 above;

[0166] S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed at mass percentages of 99.3 wt% and 0.7 wt% respectively, so that the sum of their mass percentages is 100 wt%. The amount of the 0.7 wt% nano-assembly concentrate added is determined based on the measured total phosphorus content (as P) of the nano-assembly concentrate provided in step S2, so that the total phosphorus content (as P) of the final product is within the range of 20-120 mg / kg. The mixture is mechanically stirred at 100 rpm for 25 min at 27°C under nitrogen protection, filtered through a filter material with a pore size of 3 μm, and then filled with nitrogen and packaged in light-proof containers to obtain the high antioxidant flaxseed oil of this embodiment. The total residual amounts of ethyl acetate and ethanol in the final product are quantitatively verified by headspace gas chromatography to ensure that the low residual solvents meet the food safety boundary.

[0167] The process conditions in this embodiment are mild and the equipment requirements are low. It is suitable for small and medium-sized production lines with relatively high raw material moisture content and a pursuit of a balance between oil yield and energy saving. The product can be applied to the general functional edible oil market, meeting the application scenarios that require certain antioxidant effects for daily edible flaxseed oil but have relatively moderate requirements for extreme protection. It is suitable for table oils for daily household seasoning and food preparation, as well as for vegetable oil raw materials in the food industry that require certain antioxidant protection.

[0168] Example 4

[0169] The high-antioxidant flaxseed oil of this embodiment, based on the final product formulation composition by mass percentage, comprises 98.15 wt% flaxseed oil matrix and 1.85 wt% nano-assembly concentrate, with the sum of the mass percentages of all components being 100 wt%. The insoluble impurity content of the flaxseed oil matrix in this embodiment is ≤0.20 wt%. The nano-assembly concentrate of this embodiment is formed from a flaxseed oil phospholipid-rich phase, a flaxseed oil unsaponifiable concentrate, and the flaxseed oil matrix, wherein the mass ratio of the flaxseed oil phospholipid-rich phase to the flaxseed oil unsaponifiable concentrate is 6:1, and the flaxseed oil matrix is ​​a continuous oil phase. The particle size D50 of the nano-assembly concentrate of this embodiment is 24 nm, and the polydispersity index is 0.27. Based on phosphorus (P), the high-antioxidant flaxseed oil of this embodiment contains 105 mg / kg of total phosphorus, 65.0 wt% α-linolenic acid, and has an oxidative stability time of 7.5 h measured at 110°C according to ISO 6886:2016. The high antioxidant flaxseed oil in this embodiment was packaged in a light-proof container. The oxygen content in the top space of the package was 0.2 vol% immediately after sealing, the acid value was 0.6 mg KOH / g, and the peroxide value was 1.2 meq / kg.

[0170] The flaxseed oil matrix in this embodiment is prepared through the following steps:

[0171] Step A01, Raw material preparation: Take 100 parts by weight of flaxseed, using nitrogen as a protective gas.

[0172] Step A02, Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 4.5wt% by adding water. The actual moisture content of 4.5wt% is taken as the adjustment endpoint.

[0173] Step A03, pressing: Use a hydraulic cold press and press for 15 minutes at 38°C under nitrogen protection, maintaining the oil temperature at the pressing outlet at 38°C.

[0174] Step A04, Clarification: The pressed oil obtained in Step A03 is centrifuged at 28°C with a relative centrifugal force of 2000g for 15 minutes. After centrifugation, the content of insoluble impurities in the oil phase is ≤0.20wt%, thus obtaining the flaxseed oil matrix of this embodiment. The total content of flaxseed oil matrix in the final product of this embodiment consists of two parts: the flaxseed oil matrix directly added in Step S3 and the flaxseed oil matrix contained in the nano-assembly concentrate. Both exist in the final product in the form of flaxseed oil matrix with an insoluble impurity content of ≤0.20wt%.

[0175] The flaxseed oil phospholipid-enriched phase of this embodiment is prepared through the following steps. The raw material used in step B01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0176] Step B01, Raw material preparation: 100 parts by weight of flaxseed oil base; 0.03 parts by weight of citric acid; 1.5 parts by weight of deionized water; 2.5 parts by weight of ethanol.

[0177] Step B02, Degumming: Before degumming, citric acid is dissolved in deionized water to prepare an aqueous phase of citric acid. Then, the aqueous phase of citric acid is added to the oil phase. The mixture is stirred mechanically with a paddle at 150 rpm for 12 minutes under nitrogen protection at 47°C.

[0178] Step B03, separation: Centrifuge for 28 minutes at a centrifugation temperature of 22℃ and a relative centrifugal force of 5800g to separate the gel phase.

[0179] Step B04, washing and post-treatment: Wash the colloidal phase of this embodiment once with ethanol of this embodiment, contact at 32°C for 12 min, and then centrifuge at 1200g for 6 min to remove the ethanol washing liquid; after washing, dry at 37°C and vacuum degree of -0.082MPa for 1.5 h.

[0180] Step B05, Quality Control: A flaxseed oil phospholipid enriched phase with a total phosphorus content of 1.19 wt%, a moisture content of 1.80 wt%, and an ethanol residue of ≤0.05 wt% was obtained.

[0181] The flaxseed oil unsaponifiable concentrate of this embodiment is obtained through the following steps. The raw material used in step C01 is flaxseed oil matrix, and its insoluble impurity content does not exceed 0.20 wt%.

[0182] Step C01, Raw material preparation: 100 parts by weight of flaxseed oil base; 100 parts by weight of ethanol; 10 parts by weight of potassium hydroxide; 55 parts by weight of deionized water; 100 parts by weight of ethyl acetate.

[0183] Step CO2, Saponification: Potassium hydroxide is added to ethanol and fully dissolved to form an alcoholic saponification solution. The alcoholic saponification solution is then added to the oil phase and reacted at 60°C under nitrogen protection for 1.5 hours.

[0184] Step C03, Extraction: After cooling to 32°C, the total amount of deionized water and ethyl acetate in this embodiment is added in three portions for liquid-liquid extraction. After each addition, the mixture is thoroughly mixed and contacted for 20 minutes. Phase separation is achieved by centrifugation at a relative centrifugal force of 1500g for 12 minutes. The upper organic phase is collected, and the operation is repeated until the total amount of ethyl acetate is exhausted.

[0185] Step C04, washing and concentration: collect the organic phase and wash it with deionized water until the pH of the washing solution is 7.0, then concentrate it for 2.0 h at 40 °C and a vacuum of -0.090 MPa.

[0186] Step C05, Quality Control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 55.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

[0187] The nano-assembly concentrate in this embodiment is prepared through the following steps:

[0188] Step D01, Raw material preparation: Based on a total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, 85.7 parts by mass of flaxseed oil phospholipid enriched phase and 14.3 parts by mass of flaxseed oil unsaponifiable concentrate were prepared at a mass ratio of 6:1, and 80 parts by mass of flaxseed oil matrix were added as a continuous oil phase, for a total system mass of 180 parts by mass.

[0189] Step D02, pre-dispersion: high shear dispersion at 7500 rpm for 12 min under nitrogen protection at 43℃.

[0190] Step D03, Nanoassembly: Using a probe-type ultrasonic instrument, ultrasonic treatment was performed in pulse mode at 40kHz and 450W for 5 minutes. During the ultrasonic process, the system temperature was controlled to not exceed 45℃ using a cooling method.

[0191] Step D04, degassing and filtration: Degas for 8 minutes at 27℃ and a vacuum of -0.082MPa, then filter through a 0.22μm filter.

[0192] Step D05, Quality Control: A nano-assembly concentrate with a particle size D50 of 24 nm, a polydispersity index of 0.27, a total phosphorus content (calculated as P) of 0.57 wt% (derived from the 1.19 wt% total phosphorus in the phospholipid-enriched phase in Step B05 and its proportion in the total formulation of 85.7 / 180), and a moisture content of 0.86 wt% (derived from the 1.80 wt% moisture in the phospholipid-enriched phase in Step B05 and its proportion of 85.7 / 180) was obtained. The particle size D50 and polydispersity index of the nano-dispersions in the nano-assembly concentrate were determined by dynamic light scattering method. The particle size D50 is the median particle size of the intensity-weighted distribution. During the determination, the sample was diluted with n-hexane as the test medium, the determination temperature was 25 ± 0.5℃, and the number of parallel determinations was not less than 3. The average value of each determination result was taken as the final detection value. The nano-assembly concentrate in this embodiment is a nano-aggregate dispersion system with flaxseed oil as the continuous phase, formed by non-covalent intermolecular interactions between phospholipids in the flaxseed oil phospholipid enriched phase and tocopherols and sterols in the unsaponifiable concentrate of flaxseed oil. The sample obtained after solvent extraction to separate the free oil phase from the nano-assembly concentrate and the flaxseed oil phospholipid enriched phase were subjected to Fourier transform infrared spectroscopy (FTIR) measurements. In the comparative spectra, the characteristic peak of the P=O stretching vibration of phosphate esters was located at 1220-1260 cm⁻¹. - The characteristic peaks of the nano-assembled concentrate sample showed a shift in position compared to the corresponding peaks in the phospholipid-rich phase of flaxseed oil. This shift can serve as one of the auxiliary characterization evidences for the non-covalent intermolecular interactions between the polar head groups of phospholipids and the tocopherol and sterol unsaponifiable components.

[0193] The high antioxidant flaxseed oil in this embodiment is prepared through the following steps:

[0194] S1. Prepare the flaxseed oil matrix according to the methods described in steps A01 to A04 above;

[0195] S2. Prepare the nano-assembly concentrate according to the methods described in steps D01 to D05 above;

[0196] S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed at mass percentages of 98.15 wt% and 1.85 wt% respectively, so that the sum of their mass percentages is 100 wt%. The amount of the 1.85 wt% nano-assembly concentrate added is determined based on the measured total phosphorus content (as P) of the nano-assembly concentrate provided in step S2, so that the total phosphorus content (as P) of the final product is within the range of 20-120 mg / kg. The mixture is mechanically stirred at 250 rpm for 20 min at 32°C under nitrogen protection, filtered through a filter material with a pore size of 0.45 μm, and then filled with nitrogen and packaged in light-proof containers to obtain the high antioxidant flaxseed oil of this embodiment. The total residual amount of ethyl acetate and ethanol in the final product is quantitatively verified by headspace gas chromatography to ensure that the low residual solvent meets the food safety boundary.

[0197] The product obtained in this embodiment is suitable for high-end markets with extremely stringent requirements for alpha-linolenic acid protection. It can be applied to ultra-high quality extra virgin functional flaxseed oil, high-end medicinal and edible health food special oils, medical nutritional ingredient oils, and high-end infant complementary food oils and excipients. It is particularly suitable for the industrial production of high-premium functional oil products that require long shelf life, strict alpha-linolenic acid protection, and high alpha-linolenic acid content.

[0198] Comparative Example 1: Basically the same as Example 1, except that the amount of nano-assembly concentrate added is 0.2 wt% based on the total mass of the final product formulation, and other conditions remain unchanged.

[0199] Comparative Example 2: Basically the same as Example 1, except that the amount of nano-assembly concentrate added is 2.2 wt% based on the total mass of the final product formulation, and other conditions remain unchanged.

[0200] Comparative Example 3: Basically the same as Example 1, except that the mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiables enriched phase in the nano-assembly concentrate is 2:1, and other conditions remain unchanged.

[0201] Comparative Example 4: Basically the same as Example 1, except that the mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiable concentrate in the nano-assembly concentrate is 10:1, and other conditions remain unchanged.

[0202] Comparative Example 5: It is basically the same as Example 1, except that the ultrasonic power of the probe-type ultrasonic instrument in step D03 is 120W, and other conditions remain unchanged.

[0203] Comparative Example 6: It is basically the same as Example 1, except that the ultrasonic power of the probe-type ultrasonic instrument in step D03 is 520W, and other conditions remain unchanged.

[0204] Comparative Example 7: Basically the same as Example 1, except that the filter pore size in step D04 is 5 μm, and other conditions remain unchanged.

[0205] Comparative Example 8: It is basically the same as Example 1, except that the oxygen content in the top space of the packaging measured immediately after sealing is 3.0 vol%. Other conditions remain unchanged.

[0206] Comparative Example 9: Basically the same as Example 1, except that the content of insoluble impurities in the flaxseed oil matrix is ​​0.45 wt%, and other conditions remain unchanged.

[0207] Performance testing:

[0208] The relationship between oxygen exposure in the headspace and oxidative stability of packaged samples was quantified using light-protected filling. Higher oxygen content in the headspace facilitates the initiation of the auto-oxidation chain reaction, and an accelerated oxidation induction period characterizes the antioxidant level. Oxygen levels in the headspace after sealing were measured at 25°C (n=3), followed by oxidative stability time at 110°C. The Rancimat flow rate was set to 10 L / h. Data are expressed as mean ± standard deviation and correlation regression analysis was performed.

[0209] Fatty acid methyl esters were separated by capillary gas chromatography, and the peak area corresponded to the content. This was used to determine the mass fraction of α-linolenic acid and verify batch-to-batch fluctuations. After preparing fatty acid methyl esters, α-linolenic acid was quantified using gas chromatography-flame ionization detector (GC-FID). A column temperature programming method and external standard method were employed, with three parallel determinations performed. Mass fraction, relative standard deviation, and retention time comparison data were output.

[0210] After dilution or pretreatment as required, the phosphorus emission intensity was determined by ICP-OES and the concentration was calculated. The total phosphorus content was used to characterize the phospholipid loading level. A phosphorus standard curve was established and blank correction was performed. The determination was repeated in triplicate. The results are expressed in mg / kg and the standard deviation and limit of detection are given.

[0211] The hydrodynamic particle size distribution of the nano-assembly concentrate and its subsequent oil sample (diluted with n-hexane) was determined using dynamic light scattering at 25 ± 0.5 °C. D50 and polydispersity index reflected particle size and dispersion uniformity. D10 / D50 / D90 and polydispersity index were measured, and repeated at 0, 30, and 60 days to assess long-term stability. Each measurement was performed in parallel at least three times. Data are expressed as mean ± standard deviation, and the rate of change over time was calculated.

[0212] Acid value was determined by the consumption of potassium hydroxide titration, and peroxide value was determined by iodometric titration to obtain peroxide content. Both methods can evaluate free fatty acids and the initial degree of oxidation. The operating temperature was 25℃, and the determinations were performed in triplicate. Data are expressed as mean ± standard deviation and were checked for consistency with the oxidation stabilization time.

[0213] Flaxseed oil base and finished oil were diluted with solvent, filtered, washed, dried, and weighed. The mass fraction of insoluble impurities was calculated to verify the contribution of insoluble impurity control to clarity, turbidity, and filterability for bottling. Triple parallel determinations were performed using standard-specified filter media and drying conditions. Results were expressed as mass fractions, and relative standard deviations were calculated.

[0214] Moisture content in phospholipid-rich phases, unsaponifiable concentrates, nano-assembly concentrates, and finished oils was determined using the Karl Fischer method. Headspace gas chromatography was used to quantify ethanol / ethyl acetate residues, ensuring low moisture and low residual solvent levels meet food safety boundaries. Equilibration temperature and time were set according to the method, and measurements were performed in triplicate. Data are expressed as mean ± standard deviation, and a pass / fail criterion is provided.

[0215] Kinematic viscosity was obtained by measuring flow time using a capillary viscometer, and dynamic viscosity was calculated by combining this with density measurement to evaluate the suitability of low-viscosity processing windows for low-temperature applications. Measurements were performed at 40℃ with a temperature control accuracy of ±0.02℃. Each sample was measured in triplicate. Data are expressed as mean ± standard deviation, and outliers were removed according to statistical criteria.

[0216] Figure 1 To illustrate the differential and cumulative particle size distribution of the concentrated nanoparticle assembly solutions from Example 1, Comparative Examples 5 and 7, dynamic light scattering was used with n-hexane as the dilution medium. Three parallel measurements were performed on the three samples at 25 ± 0.5 °C. The horizontal axis is a logarithmic coordinate to fully represent the particle size distribution in the range of 1 to 3000 nm. The left vertical axis represents the normalized percentage of differential intensity, and the right vertical axis represents the percentage of cumulative distribution. The solid line represents the differential distribution curve, and the dashed line represents the cumulative distribution curve. In all three samples, the mass ratio of flaxseed oil phospholipid-rich phase to unsaponifiable flaxseed oil concentrate was 5:1. Example 1 uses a 300W probe for ultrasound combined with a 0.45μm terminal filter. Comparative Example 5 reduces the ultrasound power to 120W. Comparative Example 7 increases the terminal filter pore size to 5μm. The D50 of Example 1 is 50nm and the polydispersity index is 0.18. The D50 of Comparative Example 5 is increased to 120nm and the polydispersity index is increased to 0.36. The D50 of Comparative Example 7 is increased to 160nm and the polydispersity index is increased to 0.48. This demonstrates that suitable ultrasonic energy input and precise terminal filtration are the decisive process conditions for forming a nano-aggregate dispersion system with concentrated particle size and uniform distribution.

[0217] Figure 2The graph shows the evolution of the particle size difference distribution of the concentrated nano-assembly solution in Example 1 over storage time. The same batch of samples was retested on day 0, day 30, and day 60 using dynamic light scattering method. Each time point was measured in parallel at least three times. The horizontal axis is the logarithmic coordinate of particle size, and the vertical axis is the normalized differential intensity percentage. The three superimposed curves correspond to different storage times. D50 slowly increased from 50 nm to 55 nm, and the peak shape and peak width remained basically consistent. The polydispersity index was below 0.20 throughout the storage period, which proves that the nano-aggregate dispersion system constructed by non-covalent intermolecular interactions with flaxseed oil matrix as the continuous phase has excellent long-term particle size stability during the 60-day storage period.

[0218] Figure 3 The stability curves of D50 particle size change with storage time for the nano-assembly concentrates of Example 1, Comparative Example 5, and Comparative Example 7 are shown. Dynamic light scattering method was used to remeasure the values ​​on day 0, day 30, and day 60. The data are expressed as mean plus or minus standard deviation, n=3. The only differences in the preparation process of the three groups of samples are ultrasonic power and terminal filter pore size. The D50 of Example 1 increased by only about 5 nm in 60 days, while the D50 of Comparative Example 5 and Comparative Example 7 increased by about 38 nm and 78 nm, respectively. The polydispersity index increased synchronously with storage time, which proves that suitable ultrasonic assembly conditions and strict terminal filter control can give the nano-dispersion system long-term dimensional stability on the basis of small initial particle size. However, deviations in process parameters will cause the aggregates to continue to increase with storage time and affect the stability of the dispersion system.

[0219] Figure 4 The phospholipid-rich phase of flaxseed oil was compared with the nano-assembly concentrates of Examples 1, 3, and 4 at 1150–1310 cm⁻¹. - ¹The normalized infrared spectral overlay of the P=O stretching vibration of phosphate esters in the specified interval was analyzed using Fourier transform infrared spectroscopy on the sample obtained after solvent extraction to remove the free oil phase. The solvent extraction was... Figure 4 Sample pretreatment steps: The nano-assembly concentrate sample was mixed with anhydrous acetone at a mass-to-volume ratio of 1:10 (g / mL), shaken at room temperature for 10 min, and then centrifuged at a relative centrifugal force of 4000g for 10 min. The supernatant was discarded. The extraction was repeated twice under the above conditions, for a total of three extractions. The resulting precipitate was used for infrared spectroscopy. After normalization, the spectra were superimposed, and the characteristic peak positions were marked with a vertical reference line. The characteristic peak of P=O in the phospholipid-rich phase of flaxseed oil was located at 1247 cm⁻¹. - ¹, In Example 1, the mass ratio of flaxseed oil phospholipid-enriched phase to unsaponifiable flaxseed oil concentrate in the nano-assembly concentrate was 5:1, corresponding to a peak shift to 1232 cm⁻¹. - ¹, Peak displacement is 15cm -¹, while in Comparative Example 3 the mass ratio was 2:1 and in Comparative Example 4 the mass ratio was 10:1, and the corresponding peak displacements decreased to 6 cm. - ¹ and 2cm - ¹, It is demonstrated that when the mass ratio of flaxseed oil phospholipid-enriched phase to flaxseed oil unsaponifiable concentrate is controlled within the range of 3:1 to 8:1, the polar head groups of phospholipids can form the strongest non-covalent intermolecular interaction with tocopherol and sterol unsaponifiable components, and the peak shift can be used as an auxiliary spectroscopic characterization basis for judging the degree of nano-assembly.

[0220] Figure 5 The scatter plots are independent repeated measurements of the oxidation stability time of high antioxidant flaxseed oil in Examples 1, 1, and 8, along with the mean plus or minus the standard deviation. Rancimat measurements were performed at 110°C and 10 L / h according to ISO 6886:2016, with each group repeated three times. The scatter plots represent the independent measurements, the horizontal line represents the group mean, and the error bars represent the standard deviation. In Example 1, the amount of nano-assembly concentrate added was 1.0 wt%, and the headspace oxygen content was 0.5 vol%. In Comparative Example 1, the amount of nano-assembly concentrate added was only 0.2 wt%, and the headspace oxygen content in Comparative Example 8 reached 3.0 vol%. The mean time for Example 1 was 6.0 h, significantly higher than the 3.5 h for Comparative Example 1 and the 4.8 h for Comparative Example 8. This demonstrates that sufficient nano-assembly concentrate and effectively controlled headspace oxygen content have an inseparable and synergistic decisive role in improving the oxidation stability time of high antioxidant flaxseed oil.

[0221] Figure 6 The graph shows the high-performance liquid chromatography (HPLC) results of the content of tocopherol homologues in the basic flaxseed oil, Comparative Example 1, and Example 1. The external standard method of reversed-phase HPLC was used to quantify α-tocopherol, γ-tocopherol, and δ-tocopherol, respectively. Each group was measured in triplicate, and the mean values ​​were taken. Data are expressed in mg / kg. Stacked columns represent the composition of each homologue, and the superimposed line represents the total tocopherol content. The total tocopherol content of the basic flaxseed oil was 257 mg / kg. In Comparative Example 1, due to the addition of only 0.2 wt% of the nano-assembly concentrate, the total tocopherol content was only [amount missing]. The total tocopherol content increased to 277 mg / kg, while in Example 1, by adding 1.0 wt% of a nano-assembly concentrate with an unsaponifiable content of 50 wt%, the total tocopherol content increased to 383 mg / kg, an increase of approximately 49%. The contents of α-tocopherol, γ-tocopherol, and δ-tocopherol all increased significantly at the same time. This demonstrates that an appropriate amount of nano-assembly concentrate can effectively load the tocopherol antioxidant active components in the unsaponifiable concentrate of linseed oil into the final product oil phase, providing a direct and quantifiable active material basis for achieving high oxidative stability time.

[0222] Figure 7This is a transmission electron microscope (TEM) image of the nano-assembly concentrate from Example 1. The basic parameters are: the morphology and internal structure of the nano-assemblies were observed using TEM and cross-validated with the particle size D50 (50 nm) and polydispersity index (PDI) of 0.18 obtained by dynamic light scattering. The variable parameters are: the influence of sample preparation methods such as negative staining or freeze-drying on shell contrast and particle size statistics, and the influence of electron beam dose on structure preservation. The conclusion is that discrete particles mainly in the tens of nanometers were observed, with shell contrast characteristics and a narrow distribution trend consistent with DLS. This proves that the nano-assembly concentrate forms stable nanoscale aggregates and provides structural basis for the effective organization of antioxidant components in the final product.

[0223] Figure 8 This is a scanning electron microscope (SEM) image of the nano-assembly concentrate from Example 1. The basic parameters are: the sample is a nano-dispersion enriched sample obtained by solvent extraction to separate the free oil phase from the nano-assembly concentrate, which is then dried and conductively treated before SEM observation. The particle size D50 of the nano-assembly concentrate is 50 nm and the polydispersity index is 0.18. The variable parameters are: the repetition of the process of high-shear dispersion at 5500 rpm for 20 min and ultrasonication at 30 kHz and 300 W for 10 min, as well as the effect of different sampling dilution ratios on the deposition dispersion state. The conclusion is that the deposition distribution is generally uniform at low magnification and no micron-sized hard impurities are observed. At medium and high magnification, assembly units mainly of tens of nanometers can be resolved, accompanied by a small amount of secondary aggregation characteristics. This proves that filtration and centrifugation can effectively remove large insoluble impurities, and that high shear and ultrasonication can form narrowly distributed nano-assemblies, thus verifying the correctness of the process path.

[0224] Figure 9 This is a macroscopic optical photograph of the high antioxidant flaxseed oil from Example 1. The basic parameters are: the sample composition is 99.0 wt% flaxseed oil matrix and 1.0 wt% nano-assembly concentrate, packaged in a light-proof container filled with nitrogen, with an oxygen content of 0.5 vol% in the top space of the packaging; the variable parameters are: the amount of nano-assembly concentrate added is adjusted according to the total phosphorus content (P) to keep the total phosphorus of the final product between 20 and 120 mg / kg, and the changes in color and clarity due to different storage times. The conclusion is that the sample has a uniform and clear light golden-yellow oil phase with no visible layering or obvious suspended matter, and is consistent with a low peroxide value of 2.8 meq / kg and an acid value of 1.1 mg KOH / g. This indicates that a stable final product with a low oxidation level can be obtained under nitrogen protection and the synergy of the nano-assembly system, thus supporting the rationality of the scheme.

[0225] Table 1. Oxidation and Composition Related Indicators

[0226]

[0227] Table 2. Indicators Related to Dispersion and Processing

[0228]

[0229] As can be seen from the performance of the examples and comparative examples in Tables 1 and 2, the examples are superior in key antioxidant quality indicators such as oxidation stabilization time, peroxide value, and acid value, while maintaining a high α-linolenic acid content. Comparative Example 1 suffered from insufficient total phosphorus and antioxidant component loading due to the low amount of nano-assembly concentrate added, resulting in a significant decrease in stability. Comparative Examples 3 / 5 / 7 suffered from a significant increase in D50 and PDI due to improper assembly ratio or ultrasonic / filtration conditions, making the dispersion system prone to instability and accelerating oxidation. Comparative Examples 8 and 9 respectively demonstrated the amplification effect of oxygen exposure and impurities carrying pro-oxidative factors, further verifying the comprehensive advantages of this scheme in synergistic loading, nano-dispersion, and oxygen exposure control.

[0230] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high-oxidation-resistance linseed oil, characterized in that, Measured by mass percentage of the final product formulation components, including: The flaxseed oil matrix comprises 98.0-99.7 wt% flaxseed oil, wherein the content of insoluble impurities in the flaxseed oil matrix is ​​≤0.20 wt%. 0.3-2.0wt% nano-assembly concentrate; The sum of the mass percentages of each formulation component is 100wt%. The nano-assembly concentrate is formed by flaxseed oil phospholipid enriched phase, flaxseed oil unsaponifiable concentrate and flaxseed oil matrix. The mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiable concentrate in the nano-assembly concentrate is 3:1-8:

1. The flaxseed oil matrix is ​​a continuous oil phase. The particle size D50 of the nano-assembly concentrate is 20-80 nm, and the polydispersity index is 0.05-0.

30. Based on phosphorus (P), the total phosphorus content in high antioxidant flaxseed oil is 20-120 mg / kg, the α-linolenic acid mass fraction is 45.0-70.0 wt%, and the oxidative stability time measured at 110℃ according to ISO 6886:2016 is 4.0-8.0 h. Flaxseed oil matrix is ​​prepared through the following steps: A01. Raw material preparation: 100 parts by weight of flaxseed; nitrogen is used as a protective gas; A02. Pretreatment: Clean and remove impurities from the flaxseeds, and adjust the moisture content to 4.0-8.0 wt%. A03. Pressing: Press at 35-55℃ under nitrogen protection for 10-40 minutes; A04. Clarification: Centrifuge the obtained pressed oil at 25-45℃ for 10-30 min. If the content of insoluble impurities in the oil phase obtained after centrifugation is still higher than 0.20 wt%, then filter it again to obtain flaxseed oil matrix with insoluble impurity content ≤0.20 wt%. The nano-assembly concentrate is prepared through the following steps: D01. Raw material preparation: Based on the total mass of 100 parts by mass of flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate, flaxseed oil phospholipid enriched phase and flaxseed oil unsaponifiable concentrate are prepared at a mass ratio of 3:1-8:1, and 50-300 parts by mass of flaxseed oil matrix are added as continuous oil phase. D02. Pre-dispersion: High-shear dispersion at 3000-8000 rpm for 10-30 min under nitrogen protection at 35-45℃; D03. Nanoassembly: Using a probe-type ultrasonic instrument, ultrasonic treatment is carried out in continuous or pulse mode for 5-15 minutes at 20-40kHz and 100-500W. Cooling is used during the ultrasonic process to control the system temperature to not exceed 45℃. D04. Degassing and filtration: Degas for 5-20 minutes at 25-40℃ and a vacuum of -0.06 to -0.095 MPa, then filter through a 0.22-0.45 μm filter; D05. Quality control: Obtain a nano-assembly concentrate with a particle size D50 of 20-80 nm, a polydispersity index of 0.05-0.30, a total phosphorus content of 0.10-1.19 wt% (based on P), and a moisture content of 0.09-2.96 wt%.

2. The high-oxidation-resistance linseed oil according to claim 1, characterized in that, The phospholipid-rich phase of flaxseed oil was prepared through the following steps: B01. Raw material preparation: 100 parts by weight of any one of flaxseed oil base and flaxseed oil; 0.02-0.20 parts by weight of citric acid; 1-5 parts by weight of deionized water; and 2-6 parts by weight of ethanol in total. B02. Degumming: Stir for 10-30 minutes at 45-60℃ under nitrogen protection; B03. Separation: Centrifuge for 10-30 minutes at a relative centrifugal force of 3000-6000g to separate the colloidal phase; B04. Washing and post-treatment: Wash the colloidal phase 1-3 times with the ethanol, each time at 30-45°C for 10-20 min, and then dry at 35-45°C and vacuum degree of -0.080 to -0.095 MPa for 1-4 h; B05. Quality control: Obtain flaxseed oil phospholipid-rich phase with a total phosphorus content of 0.20-2.00wt% and a moisture content of 0.50-5.00wt%.

3. The high oxidative stability linseed oil according to claim 1, characterized in that, Unsaponifiable concentrate of flaxseed oil was obtained through the following steps: C01. Raw material preparation: 100 parts by weight of any one of flaxseed oil base and flaxseed oil; 60-140 parts by weight of ethanol; 5-15 parts by weight of potassium hydroxide; 20-100 parts by weight of deionized water; and 60-150 parts by weight of ethyl acetate. CO2. Saponification: The ethanol and potassium hydroxide are mixed and then added to the oil phase, and the mixture is reacted at 50-65°C under nitrogen protection for 0.5-2.0 h. CO3. Extraction: After cooling to 20-40℃, add the total amount of deionized water and ethyl acetate in 2-4 portions for liquid-liquid extraction, with each contact lasting 10-30 minutes; C04. Washing and concentration: Collect the organic phase and wash it with deionized water until the pH of the washing solution is 6.0-8.

0. Then concentrate it for 1-3 hours at 30-45℃ and vacuum degree of -0.080 to -0.095MPa. C05. Quality control: Obtain flaxseed oil unsaponifiable concentrate with an unsaponifiable content of 20.0-80.0 wt%, residual alkali ≤0.05 wt%, and total residual ethanol and ethyl acetate ≤0.50 wt%.

4. The high-oxidation-resistance linseed oil according to claim 1, characterized in that, The amount of nano-assembly concentrate added is 0.5-1.5 wt% based on the total mass of the final product formulation, and the mass ratio of flaxseed oil phospholipid enriched phase to flaxseed oil unsaponifiable concentrate is 4:1-6:

1.

5. The high oxidative stability linseed oil of claim 1, wherein, The particle size D50 of the nano-assembly concentrate is 25-60 nm, the polydispersity index is 0.10-0.25, and the total phosphorus content of the high antioxidant flaxseed oil is 30-100 mg / kg (calculated as P).

6. The high oxidative stability linseed oil of claim 1, wherein, The high antioxidant flaxseed oil is packaged in a light-proof container, and the oxygen content in the top space of the package measured immediately after sealing at 25°C is 0.1-1.0 vol.

7. The high oxidative stability linseed oil of claim 1, wherein, The flaxseed oil with high antioxidant properties has an acid value of 0.2-2.0 mgKOH / g and a peroxide value of 0.5-5.0 meq / kg.

8. A process for the preparation of high oxidative stability linseed oil as claimed in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Provides flaxseed oil as a base; S2. Provides nano-assembly concentrate; S3. The flaxseed oil matrix provided in step S1 and the nano-assembly concentrate provided in step S2 are mixed according to the final product formulation component mass percentages of 98.0-99.7wt% and 0.3-2.0wt%, respectively, so that the sum of the two mass percentages is 100wt%. The mixture is mechanically stirred at 50-300rpm for 10-30min under nitrogen protection at 25-35℃. After filtration through a filter material with a pore size of 0.45-5μm, the mixture is filled with nitrogen to obtain flaxseed oil with high antioxidant properties.

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