Vitamin E-rich linseed oil for enhancing linolenic acid activity and preparation method thereof

Abstract

The invention provides linseed oil rich in vitamin E and capable of enhancing linolenic acid activity and a preparation method of the linseed oil, and belongs to the technical field of edible oil processing. The preparation method of the flaxseed oil comprises the following steps: mechanically polishing and degumming flaxseeds, and then carrying out microwave thermal refining and low-temperature squeezing to obtain virgin flaxseed oil and a squeezed cake; adsorbing and deacidifying the primary oil through modified diatomite to obtain refined oil; carrying out ethanol solution ultrasonic extraction and supercritical CO2 extraction on the pressed cake to obtain a high-purity vitamin E extract; and finally, mixing the extract with the refined linseed oil to obtain the linseed oil. Through the whole-process low-temperature, physical adsorption and efficient extraction and purification process, the retention rate and enrichment degree of vitamin E are remarkably improved, meanwhile, nutritional ingredients such as alpha-linolenic acid are effectively protected, use of synthetic antioxidants is avoided, and the product has the advantages of being high in oxidation stability, good in safety, excellent in sensory quality and the like and is suitable for industrial production. The edible oil is suitable for being used as a nutritional supplement, edible oil or food additive.

Description

Technical Field

[0001] This invention relates to the field of edible oil processing technology, specifically to a flaxseed oil rich in vitamin E that enhances the activity of linolenic acid and its preparation method. Background Technology

[0002] Flaxseed oil is a highly nutritious plant oil, especially known for its rich content of alpha-linolenic acid (ALA), which can reach over 50%. ALA, an essential Omega-3 fatty acid, has positive effects on cardiovascular health and anti-inflammation, and is hailed as "the fish oil of the land."

[0003] However, flaxseed oil faces two major challenges in actual production and application: First, it has extremely poor oxidative stability. The high proportion of polyunsaturated fatty acids in flaxseed oil has a highly reactive molecular structure, making it very sensitive to factors such as light, heat, and oxygen. It is extremely prone to oxidative rancidity, leading to a rancid odor, decreased nutritional value, and the formation of harmful substances. This results in a short shelf life for flaxseed oil and imposes stringent requirements on packaging and storage conditions.

[0004] Secondly, a significant amount of natural antioxidants are lost during processing. Vitamin E is the most important natural antioxidant in oils, effectively slowing down the oxidation process. However, in traditional flaxseed oil extraction processes, high-temperature pressing and refining processes including degumming, deacidification, decolorization, and deodorization are often used to increase oil yield and clarity. These drastic physical and chemical treatments severely damage and remove the original vitamin E in flaxseeds, resulting in insufficient natural antioxidant content in the finished oil and a weak self-defense system.

[0005] The contradiction between the need to protect nutrients and the loss of those protective components has led to a common dilemma for existing flaxseed oil products: their core nutrient (alpha-linolenic acid) urgently needs protection, while the natural component that can protect it (vitamin E) is largely lost during processing. To address stability issues, manufacturers often have to add synthetic antioxidants, but this contradicts consumers' pursuit of natural and clean-label health products.

[0006] Therefore, developing a flaxseed oil and its preparation method that can retain and even enrich natural vitamin E to the maximum extent, thereby possessing strong antioxidant capabilities without relying on synthetic additives, is of great practical significance and technical value for improving product quality, extending shelf life, and meeting market demand. Summary of the Invention

[0007] The purpose of this invention is to provide a flaxseed oil rich in vitamin E that enhances the activity of linolenic acid and a method for preparing the same. The flaxseed oil provided by this invention has a high content of natural vitamin E and contains no synthetic antioxidants.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid, comprising: mechanically grinding and degumming flaxseeds to obtain degummed flaxseed grains; subjecting the degummed flaxseed grains to microwave conditioning and low-temperature pressing to obtain virgin flaxseed oil and press cake; subjecting the virgin flaxseed oil to deacidification to obtain refined flaxseed oil; crushing the press cake, mixing it with an ethanol solution, ultrasonically extracting, filtering, and concentrating under reduced pressure to obtain a crude extract, and then subjecting it to supercritical CO2 extraction to obtain an extract rich in vitamin E; and mixing the flaxseed oil with the extract to obtain flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid.

[0009] Preferably, the mechanical grinding and degumming adopts a sand roller degumming machine with a sand roller speed of 800-1200 r / min and a grinding time of 20-40 min.

[0010] Preferably, the microwave conditioning temperature is 35-45℃, the power is 200-400W, and the time is 3-8min.

[0011] Preferably, the low-temperature pressing temperature is 45-55℃, the pressure is 18-22MPa, and the time is 70-90min.

[0012] Preferably, the deacidification is performed using physical adsorption, with modified diatomaceous earth as the adsorbent. The amount of modified diatomaceous earth used is 1.5-2.5% of the mass of virgin flaxseed oil, the adsorption temperature is 48-52℃, and the adsorption time is 40-80 min.

[0013] Preferably, the volume fraction of the ethanol solution is 72%-78%, and the mass-to-volume ratio of the pressed cake to the ethanol solution is 1:(10-15)g / mL.

[0014] Preferably, the ultrasonic extraction power is 350-450W, the temperature is 52-58℃, the number of extractions is 1-3, and the extraction time for each extraction is 30-70min.

[0015] Preferably, the supercritical CO2 extraction is performed at a pressure of 30-35 MPa, a temperature of 40-45°C, a CO2 flow rate of 20-25 L / h, and a time of 2-3 h.

[0016] The present invention also provides a flaxseed oil rich in vitamin E and with enhanced linolenic acid activity obtained according to the above preparation method.

[0017] The present invention also provides an application of the flaxseed oil rich in vitamin E and enhanced with linolenic acid activity as described above in food, the application including use as a nutritional supplement, edible oil or food additive.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid: flaxseeds are mechanically milled and degummed, then subjected to microwave conditioning and low-temperature pressing to obtain virgin flaxseed oil and pressed cake; the virgin oil is deacidified by modified diatomaceous earth adsorption to obtain refined oil; the pressed cake is subjected to ultrasonic extraction with ethanol solution and supercritical CO2 extraction to obtain a high-purity vitamin E extract; finally, the extract is mixed with refined flaxseed oil to obtain flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid.

[0019] This invention efficiently enriches natural vitamin E, achieving endogenous antioxidant effects on oils: by utilizing the resources of pressed cake, it not only significantly increases the vitamin E content of the final product, giving it a stronger intrinsic antioxidant capacity, but also effectively delays the oxidative rancidity of oils, avoiding the addition of synthetic antioxidants, and conforming to the healthy consumption trend of clean labels.

[0020] This invention preserves core nutrients and inherent flavor to the maximum extent: The gentle processing conditions throughout effectively inhibit the oxidative decomposition of heat-sensitive polyunsaturated fatty acids such as alpha-linolenic acid and the formation of trans fatty acids, ensuring the alpha-linolenic acid content in the product. Simultaneously, physical adsorption deacidification precisely removes undesirable components such as free fatty acids, while adsorbing less of beneficial substances such as vitamin E and sterols, jointly guaranteeing that the finished oil possesses excellent nutritional value, a refreshing flavor, a light yellow color, and good transparency.

[0021] This invention features strong process synergy, combining high efficiency and economy: each process step is closely linked and mutually reinforcing. Mechanical degumming lays the foundation for subsequent uniform conditioning and efficient pressing; microwave conditioning improves oil extraction efficiency and creates conditions for low-temperature pressing; deep extraction of the pressed cake enables high-value comprehensive utilization of the raw materials. This invention's technical approach improves product quality while also increasing resource utilization, demonstrating promising prospects for industrial application.

[0022] The flaxseed oil prepared by this invention has a high vitamin E content, good oxidative stability, comprehensive nutrition, and is natural and safe, making it suitable as a nutritional supplement, edible oil, or food additive. Detailed Implementation

[0023] This invention provides a method for preparing flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid, comprising: mechanically grinding and degumming flaxseeds to obtain degummed flaxseed grains; subjecting the degummed flaxseed grains to microwave conditioning and low-temperature pressing to obtain virgin flaxseed oil and press cake; subjecting the virgin flaxseed oil to deacidification to obtain refined flaxseed oil; crushing the press cake, mixing it with an ethanol solution, ultrasonically extracting, filtering, and concentrating under reduced pressure to obtain a crude extract, and then subjecting it to supercritical CO2 extraction to obtain an extract rich in vitamin E; and mixing the flaxseed oil with the extract to obtain flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid.

[0024] In this invention, the mechanical grinding and degumming preferably employs a sand roller degumming machine, with a preferred sand roller speed of 800-1200 r / min, more preferably 1000 r / min, and a preferred grinding time of 20-40 min, more preferably 30 min. The gum residue hinders the smooth flow of oil during pressing, leading to a decrease in oil yield and increasing the risk of subsequent oil oxidation. Mechanical grinding and degumming removes the gum residue from the surface of the seeds, preventing gum residue from affecting oil quality. It also creates uniform raw material conditions for subsequent microwave conditioning and low-temperature pressing, ensuring the retention of nutrients in subsequent processes. This is a fundamental step in improving oil extraction efficiency and stability.

[0025] In this invention, the microwave conditioning temperature is preferably 35-45℃, more preferably 40℃, the power is preferably 200-400W, more preferably 300W, and the time is preferably 3-8min, more preferably 5min. Microwave penetration enables uniform heating and moisture control of flaxseeds (to the appropriate pressing moisture level). Compared to traditional hot air conditioning, microwaves avoid localized high temperatures that destroy vitamin E, while slight cell wall disruption makes oil extraction easier. Precise temperature control and short processing time maintain seed integrity, reduce nutrient loss, lay the foundation for efficient oil extraction through low-temperature pressing, and ensure the initial content of α-linolenic acid and natural vitamin E in the virgin oil.

[0026] In this invention, the preferred temperature for low-temperature pressing is 45-55℃, more preferably 50℃; the preferred pressure is 18-22 MPa, more preferably 20 MPa; and the preferred time is 70-90 min, more preferably 80 min. The low-temperature environment inhibits the oxidation of polyunsaturated fatty acids and the thermal decomposition of vitamin E, avoiding nutrient loss and trans fatty acid formation caused by high temperatures. Appropriate pressure and time balance the oil yield (ensuring virgin oil production) and oil quality. Simultaneously, the pressed cake obtained after separation retains a good amount of residual vitamin E, providing high-quality raw materials for subsequent extract preparation. This achieves efficient oil extraction and resource utilization of by-products, a key process for ensuring the core nutritional value of the product.

[0027] In this invention, the deacidification is preferably performed using physical adsorption, preferably with modified diatomaceous earth as the adsorbent. The amount of modified diatomaceous earth used is preferably 1.5-2.5% of the mass of virgin flaxseed oil, more preferably 2%. The adsorption temperature is preferably 48-52℃, more preferably 50℃, and the adsorption time is preferably 40-80 min, more preferably 60 min. The preparation method of the modified diatomaceous earth of this invention preferably includes: diatomaceous earth is crushed, sieved, pretreated with hydrochloric acid, and then reacted sequentially with an L-lysine aqueous solution and a tannic acid aqueous solution by heating to obtain modified diatomaceous earth. Specifically, the process includes: pulverizing diatomaceous earth through a 150-250 mesh sieve, mixing it with 8-12 times its mass of a 4-7% hydrochloric acid solution, stirring at 55-63℃ and 150-250 r / min for 1.5-2.5 h, filtering, washing the precipitate, and drying to obtain pretreated diatomaceous earth; mixing the pretreated diatomaceous earth with a 3%-5% L-lysine aqueous solution at a mass ratio of 1:(8-10), adjusting the pH to 7.5-8, and stirring at 50-60℃ and 120-180 r / min. The mixture was stirred at 180 r / min for 3-4 hours, filtered, and the precipitate was washed three times with deionized water, dried, and pulverized through a 250-350 mesh sieve to obtain lysine diatomaceous earth. Lysine diatomaceous earth was then mixed with a 1.5%-2.5% tannic acid aqueous solution at a mass ratio of 1:10-15, and stirred at 40-50℃, pH 5-6, and 180 r / min for 2-3 hours. The mixture was filtered, and the precipitate was washed three times with deionized water, dried, and pulverized through a 250-350 mesh sieve to obtain modified diatomaceous earth.

[0028] This invention utilizes hydrochloric acid pretreatment to efficiently remove impurities such as carbonates and iron oxides, as well as surface-soluble salts, from diatomaceous earth ore. Simultaneously, it reacts with hydroxyl groups on the diatomaceous earth surface, increasing the number of active sites and optimizing specific surface area and porosity. L-lysine achieves directional grafting by forming stable chemical bonds with the hydroxyl groups on the pretreated diatomaceous earth surface through its amino group, reducing interfacial tension with oils and increasing contact area and compatibility. Its amino group specifically adsorbs free fatty acids through electrostatic attraction, exhibiting low affinity for beneficial components such as vitamin E and sterols, thus achieving targeted deacidification and ensuring that the refined oil meets acid value standards without nutrient loss. Tannic acid forms a composite active layer through hydrogen bonds and hydrophobic interactions with the amino group of L-lysine via its phenolic hydroxyl group, increasing the density of adsorption active sites. Its phenolic hydroxyl structure also possesses antioxidant properties, which can help inhibit the oxidative decomposition of α-linolenic acid. Furthermore, it optimizes surface charge distribution, enhancing the adsorption selectivity and capacity for free fatty acids and improving deacidification efficiency. The modified diatomaceous earth prepared by the method of this invention not only has a high specific surface area, excellent interfacial compatibility and targeted adsorption performance, but also can accurately remove free fatty acids from flaxseed oil under mild conditions, retain core nutrients such as vitamin E and α-linolenic acid to the maximum extent, avoid the use of synthetic additives, and improve the oxidative stability and sensory quality of oil, providing a key guarantee for the preparation of high-quality flaxseed oil.

[0029] During modification, the amino group of L-lysine forms a stable structure with the hydroxyl group on the surface of diatomaceous earth. The hydrophilicity of L-lysine reduces the interfacial tension between diatomaceous earth and oil, increases the contact area, and improves the adsorption efficiency. It specifically adsorbs free fatty acids through electrostatic attraction without adsorbing target nutrients, ensuring that the acid value of refined oil meets the standards, improving the stability and food safety of oil, and laying a pure foundation for subsequent mixed extracts.

[0030] In this invention, the volume fraction of the ethanol solution is preferably 72%-78%, more preferably 75%, and the mass-to-volume ratio of the pressed cake to the ethanol solution is preferably 1:(10-15) g / mL, more preferably 1:10 g / mL. The ultrasonic extraction power is preferably 350-450W, more preferably 400W, the temperature is preferably 52-58℃, more preferably 55℃, the number of extractions is preferably 1-3 times, more preferably 2 times, and the extraction time for each extraction is preferably 30-70 min, more preferably 50 min. Ethanol can directionally dissolve vitamin E; ultrasonic vibration enhances mass transfer efficiency, shortens extraction time, and increases the vitamin E dissolution rate, avoiding the inefficiency and high-temperature loss of traditional extraction; multiple extractions and filtrations can fully collect vitamin E, providing a high-content crude extract for subsequent purification and enrichment, and achieving efficient recovery of vitamin E from byproducts.

[0031] In this invention, the pressure of the supercritical CO2 extraction is preferably 30-35 MPa, more preferably 32 MPa; the temperature is preferably 40-45℃, more preferably 42℃; the CO2 flow rate is preferably 20-25 L / h, more preferably 23 L / h; and the time is preferably 2-3 h, more preferably 2.5 h. The strong solubility and selectivity of supercritical CO2 can separate impurities (such as pigments and small molecule organic matter) from the crude extract, purifying it to obtain a high-purity vitamin E extract. This enables targeted enrichment and purification of vitamin E, providing high-quality raw materials for subsequent vitamin E fortification of oils and fats, and is a core guarantee for the product's vitamin E-rich characteristics.

[0032] The present invention also provides a flaxseed oil rich in vitamin E and with enhanced linolenic acid activity obtained according to the above preparation method.

[0033] The present invention also provides an application of the flaxseed oil rich in vitamin E and enhanced with linolenic acid activity as described above in food, the application including use as a nutritional supplement, edible oil or food additive.

[0034] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] Unless otherwise specified, the following embodiments are all conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] Example 1 (1) Pretreatment and mechanical grinding and degumming 10 kg of high-quality flaxseeds were selected and subjected to wind separation and magnetic separation to remove impurities such as dust, stones, and metal particles, resulting in uniform and undamaged flaxseed raw materials. Flaxseeds were degummed using a sand roller degumming machine. The sand roller speed was set to 1000 r / min and the sanding time was 30 minutes. During the sanding process, the glue powder was separated in real time through a 1.5 mm sieve to obtain degummed flaxseed grains.

[0038] (2) Microwave conditioning Degummed flax seeds were fed into a microwave conditioning device with a microwave power of 300W and a temperature of 40℃ for 5.5 minutes. After conditioning, the moisture content of the flax seeds was 5wt%, the seeds were uniform in shape, and there was no local overheating.

[0039] (3) Low-temperature pressing The conditioned flaxseeds were fed into a spiral low-temperature press, and the pressing temperature was set to 50℃ and the pressure to 20MPa. The press was pressed for 80 minutes to obtain virgin flaxseed oil and press cake.

[0040] (4) Physical adsorption deacidification Modified diatomaceous earth (2% of the mass of virgin flaxseed oil) was added to virgin flaxseed oil. The system temperature was set at 50℃, and intermittent stirring was used (stirring for 15 minutes and stopping for 5 minutes, repeating 3 times). The total adsorption time was 60 minutes. After adsorption, the modified diatomaceous earth was removed by plate and frame filtration to obtain refined flaxseed oil. The modified diatomaceous earth is prepared as follows: diatomaceous earth is pulverized through a 200-mesh sieve and mixed with 10 times its mass of a 5% hydrochloric acid solution. The mixture is stirred at 60℃ and 200 r / min for 2 hours, filtered, and the precipitate is washed three times with deionized water and dried to a water content of 2 wt% to obtain pretreated diatomaceous earth. The pretreated diatomaceous earth is then mixed with a 4% L-lysine aqueous solution at a mass ratio of 1:9, the pH is adjusted to 7.8, and the mixture is stirred at 55℃ and 160 r / min. The reaction was carried out for 3.5 hours, filtered, and the precipitate was washed three times with deionized water, dried to a water content of 3 wt%, and pulverized through a 300-mesh sieve to obtain lysine-modified diatomaceous earth. The lysine-modified diatomaceous earth was mixed with a 2.0% tannic acid aqueous solution at a mass ratio of 1:12, and stirred at 45℃, pH value of 5.5, and 180 r / min for 2.5 hours. The mixture was filtered, and the precipitate was washed three times with deionized water, dried to a water content of 2 wt%, and pulverized through a 300-mesh sieve to obtain modified diatomaceous earth.

[0041] (5) Press cake extraction and processing The pressed cake was crushed and passed through a 100-mesh sieve to obtain pressed cake powder. A 75% ethanol solution was added to the pressed cake powder at a material-to-liquid ratio of 1:12 g / mL, and the mixture was stirred thoroughly. The mixture was placed in an ultrasonic extraction device, with the ultrasonic power set to 400W and the temperature at 55℃. Extraction was performed twice, each time for 50 minutes. The extracts were filtered, and the two extracts were combined. Solid impurities were removed by filtration through a ceramic membrane (0.8 μm pore size). The filtrate was concentrated under reduced pressure and then freeze-dried under vacuum until the water content was 2 wt%, yielding a crude extract rich in vitamin E.

[0042] (6) Supercritical CO2 extraction The crude extract was fed into a supercritical CO2 extraction device, and the pressure was set to 32 MPa, the temperature to 42 °C, and the CO2 flow rate to 23 L / h. The extraction was carried out for 2.5 h to obtain an extract rich in vitamin E.

[0043] (7) Mixing Refined flaxseed oil was mixed with the extract, and the mixture was stirred at 35°C and 350 r / min for 1.2 h. The mixture was then filtered through a 0.22 μm microfiltration membrane to obtain flaxseed oil rich in vitamin E and with enhanced linolenic acid activity.

[0044] Example 2 (1) Pretreatment and mechanical grinding and degumming 10 kg of high-quality flaxseeds were selected and subjected to wind separation and magnetic separation to remove impurities such as dust, stones, and metal particles, resulting in uniform and undamaged flaxseed raw materials. Flaxseeds were degummed using a sand roller degumming machine. The sand roller speed was set to 800 r / min and the sanding time was 40 minutes. During the sanding process, the glue powder was separated in real time through a 1.5 mm sieve to obtain degummed flaxseed grains.

[0045] (2) Microwave conditioning Degummed flax seeds were fed into a microwave conditioning device with a microwave power of 200W and a temperature of 35℃ for 8 minutes. After conditioning, the moisture content of the flax seeds was 4wt%, and the seeds were uniform in shape with no local overheating.

[0046] (3) Low-temperature pressing The conditioned flaxseeds were fed into a spiral low-temperature press, and the pressing temperature was set to 45℃, the pressing pressure to 18MPa, and the pressing time to 90min to obtain virgin flaxseed oil and pressed cake.

[0047] (4) Physical adsorption deacidification Modified diatomaceous earth (1.5% of the mass of virgin flaxseed oil) was added to virgin flaxseed oil. The system temperature was set at 48℃, and intermittent stirring was used (stirring for 15 minutes, stopping for 5 minutes, repeating twice). The total adsorption time was 40 minutes. After adsorption, the modified diatomaceous earth was removed by plate and frame filtration to obtain refined flaxseed oil. The modified diatomaceous earth is prepared as follows: diatomaceous earth is pulverized through a 150-mesh sieve and mixed with 8 times its mass of a 4% hydrochloric acid solution. The mixture is stirred at 57℃ and 150 r / min for 2.5 h, filtered, and the precipitate is washed three times with deionized water and dried to a water content of 3 wt% to obtain pretreated diatomaceous earth. The pretreated diatomaceous earth is then mixed with a 3% L-lysine aqueous solution at a mass ratio of 1:8, the pH is adjusted to 7.5, and the mixture is stirred at 50℃ and 130 r / min. The mixture was stirred and reacted at 4°C for 4 hours, filtered, and the precipitate was washed three times with deionized water, dried to a water content of 2 wt%, and pulverized through a 250-mesh sieve to obtain lysine diatomaceous earth. Lysine diatomaceous earth was mixed with a 1.5% tannic acid aqueous solution at a mass ratio of 1:10, and stirred and reacted at 40°C, pH 5, and 150 r / min for 2 hours. The mixture was filtered, and the precipitate was washed three times with deionized water, dried to a water content of 3 wt%, and pulverized through a 250-mesh sieve to obtain modified diatomaceous earth.

[0048] (5) Press cake extraction and processing The pressed cake was crushed and passed through an 80-mesh sieve to obtain pressed cake powder. A 72% ethanol solution was added to the pressed cake powder at a material-to-liquid ratio of 1:10 g / mL, and the mixture was stirred thoroughly. The mixture was placed in an ultrasonic extraction device, with the ultrasonic power set to 350W and the temperature at 52℃. Extraction was performed three times, each time for 35 minutes. The extracts were filtered, and the three extracts were combined. Solid impurities were removed by filtration through a ceramic membrane (0.8 μm pore size). The filtrate was concentrated under reduced pressure and then freeze-dried under vacuum until the water content reached 3 wt%, yielding a crude extract rich in vitamin E.

[0049] (6) Supercritical CO2 extraction The crude extract was fed into a supercritical CO2 extraction device, with a pressure of 30 MPa, a temperature of 40 °C, and a CO2 flow rate of 20 L / h. Extraction was carried out for 3 hours to obtain an extract rich in vitamin E.

[0050] (7) Mixing Refined flaxseed oil was mixed with the extract, and the mixture was stirred at a temperature of 32℃ and a stirring speed of 300r / min for 1.5h. The mixture was then filtered through a 0.22μm microfiltration membrane to obtain flaxseed oil rich in vitamin E and with enhanced linolenic acid activity.

[0051] Example 3 (1) Pretreatment and mechanical grinding and degumming 10 kg of high-quality flaxseeds were selected and subjected to wind separation and magnetic separation to remove impurities such as dust, stones, and metal particles, resulting in uniform and undamaged flaxseed raw materials. Flax seeds were degummed using a sand roller degumming machine. The sand roller speed was set to 1200 r / min and the sanding time was 20 minutes. During the sanding process, the glue powder was separated in real time through a 1.5 mm sieve to obtain degummed flax seed kernels.

[0052] (2) Microwave conditioning Degummed flax seeds were fed into a microwave conditioning device with a microwave power of 400W and a temperature of 45℃ for 3 minutes. After conditioning, the moisture content of the flax seeds was 6wt%, the seeds were uniform in shape, and there was no local overheating.

[0053] (3) Low-temperature pressing The conditioned flaxseeds were fed into a spiral low-temperature press, and the pressing temperature was set to 55℃ and the pressure to 22MPa. The press was pressed for 70 minutes to obtain virgin flaxseed oil and press cake.

[0054] (4) Physical adsorption deacidification Modified diatomaceous earth (2.5% of the mass of virgin flaxseed oil) was added to virgin flaxseed oil. The system temperature was set at 52℃, and intermittent stirring was used (stirring for 15 minutes and stopping for 5 minutes, repeating 4 times). The total adsorption time was 80 minutes. After adsorption, the modified diatomaceous earth was removed by plate and frame filtration to obtain refined flaxseed oil. The modified diatomaceous earth is prepared as follows: diatomaceous earth is passed through a 250-mesh sieve and mixed with 12 times its mass of a 7% hydrochloric acid solution. The mixture is stirred at 62℃ and 250 r / min for 1.5 h, filtered, and the precipitate is washed three times with deionized water and dried to a water content of 3 wt% to obtain pretreated diatomaceous earth. The pretreated diatomaceous earth is then mixed with a 5% L-lysine aqueous solution at a mass ratio of 1:10, the pH is adjusted to 8, and the mixture is stirred at 58℃ and 180 r / min. The mixture was stirred and reacted at 3h for 3 hours, filtered, and the precipitate was washed three times with deionized water, dried to a water content of 4wt%, and pulverized through a 350-mesh sieve to obtain lysine-modified diatomaceous earth. Lysine-modified diatomaceous earth was mixed with a 2.5% tannic acid aqueous solution at a mass ratio of 1:15, and stirred and reacted at 50℃, pH 6, and 200r / min for 3 hours. The mixture was filtered, and the precipitate was washed three times with deionized water, dried to a water content of 3wt%, and pulverized through a 350-mesh sieve to obtain modified diatomaceous earth.

[0055] (5) Press cake extraction and processing The pressed cake was crushed and passed through a 120-mesh sieve to obtain pressed cake powder. An ethanol solution with a volume fraction of 78% was added to the pressed cake powder at a material-to-liquid ratio of 1:15 g / mL and mixed evenly. The mixture was placed in an ultrasonic extraction device, and the ultrasonic power was set to 450W and the temperature to 58℃ for 70 min. Solid impurities were removed by filtration through a ceramic membrane (pore size 0.8μm). The filtrate was concentrated under reduced pressure and freeze-dried under vacuum to a water content of 3wt% to obtain a crude extract rich in vitamin E.

[0056] (6) Supercritical CO2 extraction The crude extract was fed into a supercritical CO2 extraction device, and the pressure was set to 35 MPa, the temperature to 45 °C, and the CO2 flow rate to 25 L / h. The extraction was carried out for 2 hours to obtain an extract rich in vitamin E.

[0057] (7) Mixing Refined flaxseed oil was mixed with the extract, and the mixture was stirred at 38°C and 400 r / min for 1 hour. The mixture was then filtered through a 0.22 μm microfiltration membrane to obtain flaxseed oil rich in vitamin E and with enhanced linolenic acid activity.

[0058] Comparative Example 1 The difference from Example 1 is that the sanding and degumming in step (1) is omitted, and the flax seeds after wind and magnetic separation are directly subjected to microwave conditioning in step (2). The parameters of subsequent steps (3)-(7) are completely consistent with those of Example 1.

[0059] Comparative Example 2 The difference from Example 1 is that in step (2), a hot air drying device is used instead of microwave conditioning, the temperature is set at 40°C and the drying time is 20 min, so that the moisture content of flaxseed is reduced to 5 wt%.

[0060] Comparative Example 3 The difference from Example 1 is that the low-temperature pressing in step (3) is replaced with high-temperature pressing, and the pressing temperature is set to 120°C, the pressure to 20MPa, and the pressing time to 60min.

[0061] Comparative Example 4 The difference from Example 1 is that the modified diatomaceous earth in step (3) is replaced with unmodified diatomaceous earth.

[0062] Comparative Example 5 The difference from Example 1 is that the modified diatomaceous earth in step (3) is replaced with lysine diatomaceous earth, and the tannic acid aqueous solution modification step is omitted.

[0063] Comparative Example 6 The difference from Example 1 is that step (6) supercritical CO2 extraction is omitted, and the vitamin E-rich crude extract obtained in step (5) is directly used for mixing in step (7).

[0064] Experimental Example 1 The following parameters were tested in the flaxseed oils of Examples 1-3 and Comparative Examples 1-5: the content of core nutritional parameters (α-linolenic acid, vitamin E, saturated fatty acids, and polyunsaturated fatty acids); the quality and safety parameters (acid value, peroxide value, and trans fatty acid content); and the physicochemical properties (odor, taste, color, and transparency).

[0065] (1) Detection and results of core nutritional parameters The detection method for vitamin E content refers to GB 5009.82-2016 (Method 1), the detection method for α-linolenic acid (C18:3) content refers to GB 5009.168-2016 (Method 3), and the detection method for saturated fatty acids and polyunsaturated fatty acids refers to GB 5009.168-2016 (Method 1).

[0066] The results of the core nutritional parameters of flaxseed oil in Examples 1-3 and Comparative Examples 1-5 are shown in Table 1.

[0067] Table 1. Core nutritional parameters of flaxseed oil in each group

[0068] Table 1 shows that the vitamin E and α-linolenic acid contents of Examples 1-3 were significantly higher than those of the comparative examples, indicating that the process described in this invention has significant advantages in preserving and enriching natural nutrients. Comparative Example 1, due to the lack of mechanical degumming, resulted in residual gum affecting subsequent extraction efficiency, leading to a significant decrease in vitamin E and α-linolenic acid contents. Comparative Example 2 used hot air conditioning instead of microwave treatment, resulting in vitamin E loss due to uneven heating and localized high temperatures. Comparative Example 3 used high-temperature pressing, causing oxidation of unsaturated fatty acids and thermal decomposition of vitamin E, resulting in the most severe nutrient loss. Comparative Example 4 used unmodified diatomaceous earth, which had poor adsorption selectivity, affecting oil purity and nutrient retention. Furthermore, the poor interfacial compatibility between diatomaceous earth and oil easily caused local microenvironment instability during adsorption, accelerating the oxidative decomposition of a small amount of polyunsaturated fatty acids. Comparative Example 5, lacking tannic acid modification, relied solely on the amino group of L-lysine for electrostatic adsorption without additional antioxidant protection, resulting in slight loss of some vitamin E during deacidification. Comparative Example 6 did not undergo supercritical CO2 purification, and residual impurities in the crude extract led to a slight decrease in vitamin E content. Overall, the combined process of this invention effectively achieves the enrichment of vitamin E and the high retention of α-linolenic acid in flaxseed oil.

[0069] (2) Testing and test results of quality and safety parameters The detection method for acid value (KOH) is based on GB 5009.229-2025 (Method I), the detection method for peroxide value is based on GB 5009.227-2023 (Method I), and the detection method for trans fatty acids is based on GB 5009.257-2016.

[0070] The quality and safety parameters of flaxseed oil in Examples 1-3 and Comparative Examples 1-5 are shown in Table 2.

[0071] Table 2 Quality and safety parameters of flaxseed oil in each group

[0072] Note: The limit of quantitation for non-detection is 0.024% (based on fat content).

[0073] In Table 2, the acid value and peroxide value of Examples 1-3 were all at low levels, and trans fatty acids were not detected, indicating that the products have good oxidative stability and food safety. In contrast, Comparative Example 1 had an increased acid value and peroxide value due to incomplete degumming; Comparative Example 3 had a significantly increased peroxide value and detected trans fatty acids due to oil oxidation caused by high-temperature pressing; Comparative Example 4 had a high acid value because the adsorbent was not modified and had limited specific surface area and surface active sites, resulting in low adsorption capacity and adsorption rate for free fatty acids, and could not completely remove free fatty acids from flaxseed oil; Comparative Example 5, with lysine-modified diatomaceous earth, could only adsorb free fatty acids through the electrostatic attraction of amino groups, with limited adsorption efficiency and capacity, and could not completely remove free fatty acids from the oil, and lacked the antioxidant protection of tannins, resulting in slight oxidation of the oil during processing; Comparative Example 6 had a slightly higher acid value and peroxide value due to the lack of supercritical purification and residual impurities. The results show that the physical adsorption deacidification, low-temperature pressing and supercritical purification processes used in this invention have a synergistic effect in controlling oil rancidity, inhibiting oxidation and preventing the formation of harmful substances.

[0074] (3) Detection of physicochemical properties and test results The odor and taste of flaxseed oil are tested according to GB / T 5525-2008, the color is tested according to GB / T 5009.37-2003, and the transparency (20℃) is tested according to GB / T 5525-2008.

[0075] The physicochemical properties of flaxseed oil in Examples 1-3 and Comparative Examples 1-5 are shown in Table 3.

[0076] Table 3 Physicochemical properties of flaxseed oil in each group

[0077] Table 3 shows that the flaxseed oils of Examples 1-3 performed well in terms of odor, taste, color, and transparency, exhibiting a typical flaxseed oil flavor, a uniform light yellow color, and a clear and transparent appearance. Comparative Example 1 suffered from slight turbidity and off-odor due to incomplete degumming; Comparative Example 3 developed a burnt smell and a darker, uneven color due to high-temperature pressing; Comparative Example 4 showed poor hydrophilic-hydrophobic balance on the surface of unmodified diatomaceous earth, resulting in high interfacial tension with the oil and easy particle aggregation, leading to decreased transparency. Furthermore, the unmodified diatomaceous earth had poor adsorption capacity for trace polar impurities in the oil, failing to effectively purify the oil system and thus affecting the sensory consistency of the oil; Comparative Example 5 showed insufficient hydrophilic-hydrophobic balance on the surface of lysine-modified diatomaceous earth, resulting in relatively high interfacial tension with the oil, causing some adsorbent particles to easily aggregate slightly, and limiting its adsorption capacity for trace impurities, resulting in a small amount of suspended particles remaining in the filtered oil, manifesting as slight turbidity. These results demonstrate that the present invention effectively preserves the sensory quality and physical state of oils through mechanical degumming, microwave conditioning, low-temperature pressing, and efficient adsorption, meeting the sensory standards for high-quality edible oils.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method of preparing vitamin E enriched flaxseed oil enhanced linolenic acid activity, characterized by, The application comprises the following steps: The flaxseed is mechanically polished and degummed to obtain degummed flaxseed kernels; the degummed flaxseed kernels are subjected to microwave conditioning treatment, and low-temperature pressing to obtain crude flaxseed oil and pressed cakes; the crude flaxseed oil is subjected to deacidification treatment to obtain refined flaxseed oil; the pressed cakes are crushed, mixed with an ethanol solution, subjected to ultrasonic extraction, filtered, and concentrated under reduced pressure to obtain a crude extract, which is subjected to supercritical CO2 extraction to obtain an extract rich in vitamin E; The flaxseed oil is mixed with the extract to obtain flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid; The deacidification is performed by using a physical adsorption method, and modified diatomite is used as an adsorbent; the amount of the modified diatomite is 1.5-2.5% of the mass of the crude flaxseed oil, the adsorption temperature is 48-52℃, and the adsorption time is 40-80 min; the preparation method of the modified diatomite comprises the following steps: diatomite is crushed and sieved, pretreated with hydrochloric acid, and then subjected to heating reaction with L-lysine aqueous solution and tannic acid aqueous solution in sequence to obtain modified diatomite; The volume fraction of the ethanol solution is 72-78%, and the mass-volume ratio of the pressed cakes to the ethanol solution is 1:(10-15) g / mL; The ultrasonic extraction is performed at a power of 350-450 W and a temperature of 52-58℃, and the extraction is performed for 1-3 times, and each extraction is performed for 30-70 min.

2. The production method according to claim 1, characterized by, The mechanical polishing and degumming are performed by using a sand roller degumming machine, the sand roller rotates at a speed of 800-1200 r / min, and the polishing time is 20-40 min.

3. The preparation method according to claim 1, characterized in that, The microwave conditioning is performed at a temperature of 35-45℃, a power of 200-400 W, and for 3-8 min.

4. The method of claim 1, wherein, The low-temperature pressing is performed at a temperature of 45-55℃, a pressure of 18-22 MPa, and for 70-90 min.

5. The preparation method according to claim 1, characterized in that, The supercritical CO2 extraction is performed at a pressure of 30-35 MPa, a temperature of 40-45℃, a CO2 flow rate of 20-25 L / h, and for 2-3 h.

6. Flaxseed oil rich in vitamin E and enhancing the activity of linolenic acid, which is prepared by the preparation method of any one of claims 1-5.

7. Use of vitamin E enriched linseed oil according to claim 6 for enhancing the activity of linolenic acid in foodstuffs, characterized in that, The application comprises the use as a nutritional supplement, edible oil or food additive.

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