Rapeseed oil and preparation method thereof

Abstract

The invention relates to rapeseed oil and a preparation method thereof, and belongs to the technical field of edible oil processing, physical refining of the rapeseed oil is realized through the process steps of raw material screening, low-temperature drying, double-screw squeezing, natural settling, centrifugal filtering, low-temperature crystallization dewaxing and the like, and chemical refining is not used in the whole process. Natural nutritional ingredients and antioxidant substances in the oil are effectively reserved, the clarity, stability and sensory quality of the oil are improved, and the method is suitable for production and processing of high-quality edible oil.

Description

Technical Field

[0001] This invention relates to the field of edible oil processing technology, and more specifically, to a rapeseed oil and its preparation method. Background Technology

[0002] Rapeseed oil is a vegetable oil extracted from rapeseed and widely used in daily cooking and food processing. Due to its relatively balanced fatty acid composition, rich in unsaturated fatty acids and natural antioxidants, it has gained increasing popularity among consumers in recent years. Traditional rapeseed oil production methods mainly include high-temperature pressing and chemical refining. While these methods offer advantages in oil yield and production efficiency, they often involve high-temperature treatment or the use of chemical reagents, which can easily lead to the loss of natural nutrients in the oil and even produce byproducts harmful to human health. As consumers increasingly focus on food safety and nutritional health, the market demands higher-quality, natural rapeseed oil products with low processing losses. This has driven the development of rapeseed oil production technology towards low-temperature physical processing and green refining. Shortcomings of existing technologies:

[0003] (1) The processing technology of rapeseed oil on the market generally has the problem of damaging the natural components of the oil. Many traditional processes use high temperature treatment during the pressing process, which leads to the loss of a large amount of natural antioxidants such as vitamin E and polyphenols in the oil, reducing the nutritional value and stability of the oil and affecting its quality performance during storage and use.

[0004] (2) In the existing rapeseed oil production process, chemical refining methods are often used to remove impurities and undesirable components from the crude oil, such as alkali refining, decolorization, and deodorization. Although these chemical treatments can improve the appearance and physicochemical properties of the oil, they may also introduce chemical residues and damage the natural flavor and active ingredients of the oil, affecting its positioning as a healthy edible oil.

[0005] (3) Existing technologies often rely on high-temperature treatment or the addition of filter aids to improve efficiency in dewaxing and filtration processes. This not only increases energy consumption and costs, but may also negatively affect the taste and transparency of the oil. The lack of a physical refining method that can efficiently remove impurities, waxes and other undesirable components while maintaining the natural characteristics of the oil has become one of the technical bottlenecks restricting the development of high-quality rapeseed oil.

[0006] (4) The existing rapeseed oil production process does not have a refined screening and pretreatment of raw materials, and fails to fully consider the impact of raw material quality on the final oil quality. For example, the maturity, impurity content and moisture content of rapeseed are not systematically controlled, resulting in unstable pressing efficiency and large fluctuations in the quality of finished oil, which makes it difficult to meet the requirements of high-end markets for product consistency and stability.

[0007] Therefore, a rapeseed oil and its preparation method are proposed to address the above problems. Summary of the Invention

[0008] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide rapeseed oil and its preparation method to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a rapeseed oil and its preparation method, comprising the following steps:

[0010] S1. Select mature, non-GMO rapeseed with no mold as raw material. Clean it in multiple stages through a vibrating screen and air separation device to remove foreign objects such as stones, metal impurities, straw and dust, and obtain clean rapeseed.

[0011] S2. The rapeseed is put into a low-temperature drying equipment and dried at a temperature range of 45℃ to 60℃ for 40 to 70 minutes to control the moisture content of the rapeseed to between 6% and 8%.

[0012] S3. The dried rapeseed is physically pressed using a twin-screw press at a pressing temperature not exceeding 90℃. The pressing pressure is controlled between 6MPa and 10MPa, and the pressing time is 10 to 20 minutes to obtain initially separated crude oil.

[0013] S4. Allow the crude oil to settle naturally in an environment of 20°C to 25°C for 36 to 48 hours to remove large particulate impurities.

[0014] S5. A horizontal screw centrifuge is used to centrifuge and filter the settled crude oil at a speed of 3000 to 5000 rpm and a temperature below 30°C to remove suspended impurities.

[0015] S6. The filtered oil is left to stand at 5°C to 10°C for 18 to 24 hours to allow the waxy components to crystallize and precipitate. The oil is then dewaxed using a diatomaceous earth filter to obtain a clear and transparent rapeseed oil with well-preserved nutrients. The entire preparation process does not use any chemical refining process and relies solely on physical means to purify the oil.

[0016] Furthermore, the low-temperature drying process employs a hot air circulating drying device. This device features a multi-layer mesh belt conveyor structure, with the hot air temperature set between 50°C and 55°C. The rapeseed is continuously heated during the conveying process, resulting in uniform evaporation of moisture. The drying time is controlled between 40 and 60 minutes, ensuring that the moisture content of the rapeseed remains stable between 6.5% and 7.5%. This effectively avoids the damage to the natural oils and nutrients in the rapeseed caused by high-temperature treatment, while also providing optimal moisture conditions for subsequent pressing processes.

[0017] Furthermore, the pressing chamber of the twin-screw press is equipped with an adjustable temperature control system. During the pressing process, the chamber temperature is maintained at no more than 90°C through cooling water circulation. The pressing screw adopts a twin-screw structure design. The first section of the screw is used to initially compress the rapeseed and release some oil. The second section of the screw further applies high pressure, so that the pressing pressure reaches 8MPa to 10MPa, thereby increasing the oil yield and reducing the amount of residual oil in the cake. The entire pressing process is completed under low temperature, high pressure and short time conditions, effectively preserving the natural antioxidant components and vitamin E content in the oil.

[0018] Furthermore, the natural sedimentation step is carried out in a sealed stainless steel sedimentation tank. The bottom of the sedimentation tank is equipped with a conical slag collection structure. During the sedimentation process, large particles of impurities in the crude oil sink to the bottom of the tank under the action of gravity. The sedimentation time is 40 to 48 hours, and the sedimentation temperature is controlled between 22°C and 25°C to avoid uneven oil stratification or resuspension of impurities due to temperature fluctuations. The clear oil in the upper layer after sedimentation is discharged through the bottom oil outlet and enters the next centrifugal filtration stage.

[0019] Furthermore, the horizontal screw centrifuge used in the centrifugal filtration step is equipped with a differential speed control system, which maintains a stable differential speed between the drum and the screw, with the rotation speed controlled between 3500 and 4500 rpm, and the filtration temperature maintained within the range of 25°C to 30°C. During the centrifugation process, suspended particles and fine impurities in the oil are effectively separated and discharged, resulting in preliminarily clarified oil. This step improves the transparency of the oil and reduces the load on subsequent dewaxing treatment.

[0020] Furthermore, the low-temperature crystallization dewaxing step is carried out in a constant-temperature crystallization tank. The oil is left to stand in an environment of 5°C to 8°C for 20 to 24 hours, allowing the waxy components to slowly crystallize and precipitate. After crystallization, it is finely filtered through a diatomaceous earth filter. The filter layer is composed of multiple layers of diatomaceous earth with a pore size controlled between 0.5 and 2.0 micrometers, thereby effectively removing wax, gum, and other fine impurities, and finally obtaining a light yellow, clear, transparent, and highly stable finished rapeseed oil.

[0021] The technical effects and advantages of this invention are as follows:

[0022] Compared with existing technologies, this invention provides a rapeseed oil and its preparation method. Through multiple processes including raw material selection, low-temperature drying, double-screw pressing, natural sedimentation, centrifugal filtration, and low-temperature crystallization dewaxing, rapeseed oil is efficiently and gently purified and refined without relying on chemical refining. The entire process mainly uses physical methods, fully preserving the natural nutrients and antioxidants in the oil and avoiding the damage to oil quality caused by high temperatures and chemical reagents. In terms of technical implementation, low-temperature drying is used to control the moisture content of rapeseed, providing a stable material basis for subsequent pressing. The double-screw press increases the oil yield and reduces cake residue under controlled temperature and pressure conditions. The combination of natural sedimentation and centrifugal filtration effectively removes various impurities, and low-temperature crystallization dewaxing further improves the clarity and stability of the oil. Through the organic combination of the above process steps, not only is the sensory quality and nutritional value of rapeseed oil improved, but its storage stability and market applicability are also enhanced, thereby meeting the production needs of high-quality edible oil while ensuring food safety. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the rapeseed oil preparation process of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] As attached Figure 1 As shown, (1) a rapeseed oil and its preparation method, comprising the following steps:

[0027] S1. Select mature, non-GMO rapeseed with no mold as raw material. Clean it in multiple stages through a vibrating screen and air separation device to remove foreign objects such as stones, metal impurities, straw and dust, and obtain clean rapeseed.

[0028] S2. The rapeseed is put into a low-temperature drying equipment and dried at a temperature range of 45℃ to 60℃ for 40 to 70 minutes to control the moisture content of the rapeseed to between 6% and 8%.

[0029] S3. The dried rapeseed is physically pressed using a twin-screw press at a pressing temperature not exceeding 90℃. The pressing pressure is controlled between 6MPa and 10MPa, and the pressing time is 10 to 20 minutes to obtain initially separated crude oil.

[0030] S4. Allow the crude oil to settle naturally in an environment of 20°C to 25°C for 36 to 48 hours to remove large particulate impurities.

[0031] S5. A horizontal screw centrifuge is used to centrifuge and filter the settled crude oil at a speed of 3000 to 5000 rpm and a temperature below 30°C to remove suspended impurities.

[0032] S6. The filtered oil is left to stand at 5°C to 10°C for 18 to 24 hours to allow the waxy components to crystallize and precipitate. Dewaxing is then completed using a diatomaceous earth filter, ultimately yielding a clear, transparent rapeseed oil with well-preserved nutrients. The entire preparation process does not use any chemical refining processes, relying solely on physical methods for oil purification. The rapeseed oil preparation method of this invention includes several key steps such as raw material screening, low-temperature drying, double-screw pressing, natural sedimentation, centrifugal filtration, and low-temperature crystallization dewaxing. First, non-GMO rapeseed is selected as the raw material, and impurities are removed through multi-stage cleaning equipment to ensure the purity of the raw material. Then, the rapeseed undergoes low-temperature drying to control its moisture content within a suitable range, thereby improving subsequent pressing efficiency and reducing oil oxidation. The dried rapeseed is then physically pressed in a double-screw press to extract crude oil under low-temperature and high-pressure conditions. After natural sedimentation to remove large particles of impurities, the crude oil undergoes further centrifugal filtration to remove suspended impurities. Finally, it is left to crystallize at a low temperature and dewaxed using a diatomaceous earth filter to obtain the finished oil. The entire process relies entirely on physical methods to purify the oil, without using any chemical refining processes, thus preserving the natural nutrients and flavor compounds in rapeseed oil to the greatest extent possible.

[0033] (2) The low-temperature drying process employs a hot air circulating drying device. This device has a multi-layer mesh belt conveyor structure, and the hot air temperature is set between 50°C and 55°C. The rapeseed is continuously heated during transport, and the moisture is evenly evaporated. The drying time is controlled between 40 and 60 minutes, ensuring the rapeseed's moisture content remains stable between 6.5% and 7.5%. This effectively avoids the damage to the natural oils and nutrients in the rapeseed caused by high-temperature treatment, while providing optimal moisture conditions for subsequent pressing processes. In this invention, the low-temperature drying step uses a hot air circulating drying device. This device evenly heats the rapeseed with circulating hot air, maintaining the hot air temperature within a suitable range to ensure effective evaporation of moisture during heating, while avoiding damage to the oil structure and nutrients caused by high temperatures. The rapeseed moves slowly through the multi-layer mesh belt structure during transport, making the entire drying process more uniform and stable. The drying time is controlled within a reasonable range to ensure the rapeseed's moisture content remains stable within the optimal range, providing a good raw material condition for subsequent pressing processes. This drying method not only increases the oil yield but also effectively improves the consistency of the finished oil quality.

[0034] (3) The pressing chamber of the twin-screw press is equipped with an adjustable temperature control system. During the pressing process, the chamber temperature is maintained below 90°C through cooling water circulation. The pressing screw adopts a twin-screw structure design. The first section of the screw is used to initially compress the rapeseed and release some oil. The second section of the screw further applies high pressure, making the pressing pressure reach 8MPa to 10MPa, thereby increasing the oil yield and reducing the residual oil in the cake. The entire pressing process is completed under low temperature, high pressure, and short time conditions, effectively preserving the natural antioxidant components and vitamin E content in the oil. In this invention, a twin-screw press is used to physically press the rapeseed. During the pressing process, the temperature of the pressing chamber is controlled to not exceed the safe upper limit through a cooling water circulation system, ensuring that the oil is extracted under low temperature conditions and avoiding the loss of nutrients due to high temperature. The pressing screw adopts a twin-screw structure design. The first section is used to initially compress the rapeseed and release some oil. The second section further applies high pressure, making the pressing pressure reach a suitable range, thereby increasing the oil yield and reducing the residual oil in the cake. The entire pressing process is completed under low temperature, high pressure, and short time conditions, which effectively preserves the natural antioxidants and vitamin E content in the oil, thereby improving the nutritional value and stability of the finished oil.

[0035] (4) The natural sedimentation step is carried out in a sealed stainless steel sedimentation tank. The bottom of the sedimentation tank is equipped with a conical slag collection structure. During the sedimentation process, large particles of impurities in the crude oil settle to the bottom of the tank under the action of gravity. The sedimentation time is 40 to 48 hours, and the sedimentation temperature is controlled between 22°C and 25°C to avoid uneven oil stratification or resuspension of impurities due to temperature fluctuations. The clear oil in the upper layer after sedimentation is discharged through the bottom oil outlet and enters the next centrifugal filtration stage. In the natural sedimentation step, the crude oil is introduced into a sealed stainless steel sedimentation tank for settling treatment. The bottom of the sedimentation tank is equipped with a conical slag collection structure to facilitate impurity deposition and subsequent cleaning. During this process, large particles of impurities in the crude oil settle to the bottom of the tank under the action of gravity. The sedimentation time is set within an appropriate range to ensure that the impurities settle fully. The sedimentation temperature is controlled within a relatively stable range, which helps the impurities settle quickly and avoids uneven oil stratification or resuspension of impurities due to temperature fluctuations. The settled upper layer of clear oil is discharged through the bottom oil outlet and enters the next centrifugal filtration stage, thereby effectively removing large particulate impurities and providing a good foundation for subsequent fine filtration.

[0036] (5) The horizontal screw centrifuge used in the centrifugal filtration step is equipped with a differential speed control system. A stable differential speed is maintained between the drum and the screw, with the rotation speed controlled between 3500 and 4500 rpm. The filtration temperature is maintained within the range of 25°C to 30°C. During centrifugation, suspended particles and fine impurities in the oil are effectively separated and discharged, resulting in preliminarily clarified oil. This step improves the transparency of the oil and reduces the load on subsequent dewaxing. In this invention, a horizontal screw centrifuge is used to centrifuge and filter the settled crude oil. The centrifuge is equipped with a differential speed control system to maintain a stable differential speed between the drum and the screw, thereby achieving efficient impurity separation. During centrifugation, suspended particles and fine impurities in the oil are effectively separated and discharged, resulting in preliminarily clarified oil. This step improves the transparency of the oil and reduces the load on subsequent dewaxing, while effectively removing residual cake residue and gum components from the oil, improving the sensory quality and physicochemical indicators of the finished oil. The filtration temperature is maintained within a suitable range to avoid adverse effects of high temperature on the oil.

[0037] (6) The low-temperature crystallization dewaxing step is carried out in a constant-temperature crystallization tank. The oil is left to stand in an environment of 5°C to 8°C for 20 to 24 hours, allowing the wax components to slowly crystallize and precipitate. After crystallization, it is finely filtered through a diatomaceous earth filter. The filter layer consists of multiple layers of diatomaceous earth with a pore size controlled between 0.5 and 2.0 micrometers, thereby effectively removing wax, gum, and other fine impurities, ultimately obtaining a light yellow, clear, transparent, and highly stable finished rapeseed oil. In the low-temperature crystallization dewaxing step, the oil is introduced into a constant-temperature crystallization tank and left to stand in a suitable temperature environment for a certain period of time, allowing the wax components to slowly crystallize and precipitate, forming a visible crystal structure. After crystallization, the oil is finely filtered through a diatomaceous earth filter. The filter layer consists of multiple layers of diatomaceous earth with a pore size controlled within a suitable range, thereby effectively removing wax, gum, and other fine impurities. This dewaxing process does not require the addition of any chemical additives and is completed entirely by physical means, ultimately obtaining a light yellow, clear, transparent, and highly stable finished rapeseed oil, meeting the market demand for high-quality edible oil.

[0038] Implementation Process Two: Low-Temperature Physical Pressing Method for Preparing High-Quality Rapeseed Oil

[0039] This process employs low-temperature physical pressing, combined with natural sedimentation, centrifugal filtration, and low-temperature crystallization dewaxing, to produce rapeseed oil that retains its nutrients well, has a clear color, and high stability. The entire process consists of six main steps:

[0040] Step 1: Raw material screening and cleaning

[0041] First, fresh, mold-free, non-GMO, mature rapeseed is selected as raw material and undergoes multi-stage cleaning using a vibrating screen and an air separator. The vibrating screen removes larger impurities such as stones and straw, while the air separator uses airflow to blow away lighter impurities such as dust and leaf fragments. The purpose of this step is to ensure the purity of the raw material and prevent excessive impurities from affecting the quality of the oil during subsequent processing. The cleaned rapeseed should be free of visible foreign matter, with an impurity content of less than 0.1%.

[0042] Step 2: Low-temperature drying treatment

[0043] After cleaning, the rapeseed is fed into a hot air circulating dryer for low-temperature drying. The equipment features a three-layer mesh belt conveyor system, ensuring the rapeseed is continuously heated during transport. The hot air temperature is controlled between 50°C and 55°C, and the drying time is set to 50 minutes. The main purpose of this step is to control the moisture content of the rapeseed between 6.5% and 7.5%, providing optimal moisture conditions for subsequent pressing. Excessive moisture content leads to a decrease in oil yield, while insufficient moisture causes the rapeseed to become brittle, increasing the amount of cake residue during pressing.

[0044] Step 3: Low-temperature double-helix pressing

[0045] After drying, the rapeseed enters a twin-screw press for physical pressing. The press is equipped with a cooling water circulation system to control the pressing temperature to no more than 90℃, preventing high temperatures from damaging the natural nutrients in the oil. The press screw uses a twin-screw structure; the first stage initially compresses the raw material, releasing some oil; the second stage further pressurizes the material, reaching a pressing pressure of 8MPa, with a continuous pressing time of 15 minutes. This step yields crude oil with an oil yield of over 38%, and the residual oil content in the oil cake is controlled below 6%.

[0046] Step 4: Natural sedimentation and initial separation of impurities

[0047] The crude oil obtained from pressing is transferred to a sealed stainless steel settling tank and left to stand for 40 hours at 22°C to 25°C. During this process, large particles of impurities in the crude oil settle to the bottom of the tank due to gravity, while a clearer oil layer remains on top. The bottom of the settling tank has a conical slag collection structure for easy cleaning later. This step reduces the burden on subsequent centrifugal filtration and improves overall filtration efficiency.

[0048] Step 5: Horizontal screw centrifuge for fine filtration

[0049] After settling, the oil enters a horizontal screw centrifuge for centrifugal filtration. The centrifuge is equipped with a differential speed control system, maintaining a stable speed difference between the drum and the screw, keeping the rotation speed controlled at 4000 rpm. The filtration temperature is controlled at 28℃. Under these conditions, suspended impurities, fine cake residue, and gum in the oil are effectively separated and discharged. After centrifugal filtration, the oil's transparency is significantly improved, and its turbidity decreases, providing a good foundation for subsequent dewaxing treatment.

[0050] Step 6: Low-temperature crystallization and dewaxing

[0051] The filtered oil is then introduced into a constant-temperature crystallization tank and left to stand at 7°C for 22 hours, allowing the waxy components in the oil to slowly crystallize and precipitate. After crystallization, the oil undergoes fine filtration through a diatomaceous earth filter. The filter layer consists of multiple layers of diatomaceous earth with a pore size controlled at approximately 1.0 micrometer, effectively removing waxes and gums. The final rapeseed oil is light yellow in color, clear and transparent, with an acid value not exceeding 0.4 mg KOH / g, a peroxide value not exceeding 4.5 mmol / kg, a vitamin E content not less than 65 mg / 100g, and an erucic acid content less than 1.8%.

[0052] Implementation Process 3: All-Natural Rapeseed Oil Refining Process Based on Physical Separation

[0053] This process emphasizes entirely physical processing, without using any chemical reagents, preserving the natural flavor and nutrients of the oil, making it suitable for the high-end edible oil market. The process includes raw material pretreatment, low-temperature pressing, three-stage physical refining (sedimentation, centrifugation, and dewaxing), and finished product testing.

[0054] Step 1: Raw material pretreatment and moisture adjustment

[0055] Non-GMO rapeseed is selected as raw material. First, metallic impurities are removed using a magnetic separator, followed by removal of stones, straw, dust, and other foreign matter through a vibrating screen and air separator. The pre-treated rapeseed then enters a drying system, where it is dried at 50°C for 50 minutes using a hot air circulating dryer, reducing the initial moisture content from 12% to approximately 7%. The key to this step is controlling the moisture content to ensure efficient oil extraction during pressing while preventing high temperatures from damaging the oil quality.

[0056] Step 2: Low-temperature double-screw pressing to extract crude oil

[0057] The dried rapeseed is then pressed in a twin-screw press. The pressing temperature is controlled below 90℃, the pressing pressure is set to 9MPa, and the pressing time is maintained at 15 minutes. During the pressing process, the cooling water circulation system operates continuously to ensure a stable temperature in the pressing chamber. This step yields crude oil with an oil yield of up to 39%, and the residual oil content in the oil cake is controlled below 5.5%. The crude oil contains a certain amount of impurities, moisture, and gums, requiring further refining.

[0058] Step 3: Natural sedimentation removes large particles of impurities.

[0059] Crude oil is introduced into a sealed settling tank and left to stand at 23°C for 42 hours. The settling tank has a conical bottom to facilitate impurity deposition and subsequent cleaning. In this step, large particles such as cake residue and sand settle under gravity, while the upper layer of oil remains relatively clear. The turbidity of the oil after settling decreases significantly, providing a good foundation for subsequent centrifugal filtration.

[0060] Step 4: Remove suspended impurities using a horizontal screw centrifuge.

[0061] After settling, the oil enters a horizontal screw centrifuge for centrifugal filtration. The centrifuge operating parameters are set as follows: speed 4200 rpm, temperature controlled at 27℃. Under these conditions, suspended particles, fine impurities, and colloids in the oil are effectively separated and discharged. After centrifugal filtration, the oil's transparency is improved, its color is clearer, and its turbidity meets the requirements of the subsequent dewaxing process.

[0062] Step 5: Low-temperature crystallization and diatomaceous earth dewaxing

[0063] After centrifugation and filtration, the oil enters a constant-temperature crystallization tank and is left to stand at 6°C for 20 hours, allowing the wax in the oil to slowly crystallize and precipitate. Once crystallization is complete, the oil undergoes dewaxing through a diatomaceous earth filter. The filter layer consists of three layers of diatomaceous earth with a pore size controlled within 1.5 micrometers. This step effectively removes wax, gum, and other fine impurities, ultimately yielding a clear, transparent, and refreshing rapeseed oil.

[0064] Step 6: Finished Product Inspection and Packaging

[0065] After dewaxing, the finished oil undergoes physicochemical testing, including acid value, peroxide value, vitamin E content, erucic acid content, and color. Qualified oils are then fed into a sterile filling line, quantitatively filled into glass or food-grade plastic bottles, labeled, sealed, and boxed. No chemical refining processes are used throughout the entire process, ensuring the product is natural, healthy, and safe, suitable for high-end home kitchens and food processing.

[0066] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", and "linkage" should be interpreted broadly, and can be mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0067] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0068] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapeseed oil and its preparation method, characterized in that, Includes the following steps: S1. Select mature, non-GMO rapeseed with no mold as raw material. Clean it in multiple stages through a vibrating screen and air separation device to remove foreign objects such as stones, metal impurities, straw and dust, and obtain clean rapeseed. S2. The rapeseed is put into a low-temperature drying equipment and dried at a temperature range of 45℃ to 60℃ for 40 to 70 minutes to control the moisture content of the rapeseed to between 6% and 8%. S3. The dried rapeseed is physically pressed using a twin-screw press at a pressing temperature not exceeding 90℃. The pressing pressure is controlled between 6MPa and 10MPa, and the pressing time is 10 to 20 minutes to obtain initially separated crude oil. S4. Allow the crude oil to settle naturally in an environment of 20°C to 25°C for 36 to 48 hours to remove large particulate impurities. S5. A horizontal screw centrifuge is used to centrifuge and filter the settled crude oil at a speed of 3000 to 5000 rpm and a temperature below 30°C to remove suspended impurities. S6. The filtered oil is left to stand at 5°C to 10°C for 18 to 24 hours to allow the waxy components to crystallize and precipitate. The oil is then dewaxed using a diatomaceous earth filter to obtain a clear and transparent rapeseed oil with well-preserved nutrients. The entire preparation process does not use any chemical refining process and relies solely on physical means to purify the oil.

2. The method for preparing rapeseed oil according to claim 1, characterized in that, The low-temperature drying process employs a hot air circulating drying device. This device features a multi-layer mesh belt conveyor structure, with the hot air temperature set between 50°C and 55°C. The rapeseed is continuously heated during the conveying process, resulting in uniform evaporation of moisture. The drying time is controlled between 40 and 60 minutes, ensuring that the moisture content of the rapeseed remains stable between 6.5% and 7.5%. This effectively avoids the damage to the natural oils and nutrients in the rapeseed caused by high-temperature treatment, while also providing optimal moisture conditions for subsequent pressing processes.

3. The method for preparing rapeseed oil according to claim 1, characterized in that, The twin-screw press is equipped with an adjustable temperature control system in its pressing chamber. During the pressing process, the chamber temperature is maintained at no more than 90°C through cooling water circulation. The pressing screw adopts a twin-screw structure design. The first section of the screw is used to initially compress the rapeseed and release some oil. The second section of the screw further applies high pressure, so that the pressing pressure reaches 8MPa to 10MPa, thereby increasing the oil yield and reducing the amount of residual oil in the cake. The entire pressing process is completed under low temperature, high pressure and short time conditions, effectively preserving the natural antioxidant components and vitamin E content in the oil.

4. The method for preparing rapeseed oil according to claim 1, characterized in that, The natural sedimentation step is carried out in a sealed stainless steel sedimentation tank. The bottom of the sedimentation tank is equipped with a conical slag collection structure. During the sedimentation process, large particles of impurities in the crude oil sink to the bottom of the tank under the action of gravity. The sedimentation time is 40 to 48 hours, and the sedimentation temperature is controlled between 22°C and 25°C to avoid uneven oil stratification or resuspension of impurities due to temperature fluctuations. The clear oil in the upper layer after sedimentation is discharged through the bottom oil outlet and enters the next centrifugal filtration stage.

5. The method for preparing rapeseed oil according to claim 1, characterized in that, The horizontal screw centrifuge used in the centrifugal filtration step is equipped with a differential speed control system, which maintains a stable differential speed between the drum and the screw, with the rotation speed controlled between 3500 and 4500 rpm and the filtration temperature maintained between 25°C and 30°C. During the centrifugation process, suspended particles and fine impurities in the oil are effectively separated and discharged, resulting in preliminarily clarified oil. This step improves the transparency of the oil and reduces the load on subsequent dewaxing treatment.

6. The method for preparing rapeseed oil according to claim 1, characterized in that, The low-temperature crystallization dewaxing step is carried out in a constant temperature crystallization tank. The oil is left to stand in an environment of 5°C to 8°C for 20 to 24 hours, allowing the wax components to slowly crystallize and precipitate. After crystallization, it is finely filtered through a diatomaceous earth filter. The filter layer is composed of multiple layers of diatomaceous earth with a pore size controlled between 0.5 and 2.0 micrometers, thereby effectively removing wax, gum and other fine impurities, and finally obtaining a light yellow, clear and transparent finished rapeseed oil with high stability.

Images