Low-temperature physical rapeseed oil squeezing method

Abstract

The invention belongs to the technical field of production of fat oil from raw materials, and particularly relates to a low-temperature physical extraction method of rapeseed oil. The low-temperature physical rapeseed oil squeezing method comprises the following steps: S1, removing impurities from rapeseeds, and sequentially performing germination treatment, microwave treatment and steam explosion treatment to obtain pretreated rapeseeds; and S2, performing low-temperature physical squeezing on the pretreated rapeseeds, and performing standing for impurity removal to obtain the rapeseed oil. By combining multiple physical treatment means, low-temperature physical extraction of the rapeseed oil is realized, and the oil yield is effectively improved.

Description

Technical Field

[0001] This invention belongs to the technical field of producing fatty oils from raw materials, and specifically relates to a low-temperature physical pressing method for rapeseed oil. Background Technology

[0002] Rapeseed oil, as a mainstream product in the edible oil market, occupies an important position in the oil and fat industry. It is a high-quality edible oil with a unique fatty acid profile, high in unsaturated fatty acids such as oleic acid and linoleic acid. Furthermore, rapeseed oil is rich in lipid byproducts such as polyphenols, tocopherols, phytosterols, and carotenoids. These lipid byproducts act as natural antioxidants, helping to scavenge free radicals, quench reactive oxygen species (ROS), inhibit oxidases, and chelate the interaction between transition metals and biological membranes. The body has a very high rate of digestion and absorption of rapeseed oil. Consuming rapeseed oil in a daily diet can enhance immunity, delay aging, soften blood vessels, and prevent cardiovascular and cerebrovascular diseases.

[0003] The choice of rapeseed oil extraction technology is closely related to factors such as the quality of rapeseed raw materials, finished rapeseed oil and by-products, production conditions, technological scale, environmental protection, and the comprehensive utilization value of oilseeds. Cold pressing is an oil extraction technology that directly presses oilseeds that have not been steamed, roasted or rolled into buds at a low temperature between room temperature and 65°C using a low-temperature oil press. Because cold pressing uses a completely physical and mechanical low-temperature oil extraction method, it avoids the contact between edible oil and organic solvents, acids, alkalis, activated clay, and high temperatures found in commonly used oil extraction methods. Cold-pressed oil does not undergo any refining treatment, thus preserving as many nutrients in rapeseed oil as possible and avoiding potential contact contamination and solvent residues.

[0004] Chinese patent (publication number CN113105938B) discloses a method for producing cold-pressed rapeseed oil rich in antioxidants. This invention first treats rapeseed with high-temperature steam, then ventilates and dries it before roasting it with infrared heating. After roasting, the rapeseed is cooled to room temperature and pressed to obtain cold-pressed rapeseed oil. This invention fully utilizes the penetrating effect of high-temperature steam to improve the fluidity of antioxidants and promote the formation of sinapic acid derivatives. The process is simple, safe, and environmentally friendly, significantly increasing the antioxidant content of the rapeseed oil and resulting in oil with good oxidative stability. However, this patented technology requires roasting the rapeseed under a medium-wave infrared lamp during the pressing process, and the oil yield also needs improvement.

[0005] Therefore, there is an urgent need for a low-temperature physical extraction method for rapeseed oil that can achieve low-temperature physical extraction of rapeseed oil without the use of medium-wave infrared lamps for heating, and effectively improve the oil yield. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a low-temperature physical extraction method for rapeseed oil. The method involves pre-treating rapeseed by sequentially performing germination, microwave, and steam explosion treatments after removing impurities. The pre-treated rapeseed is then subjected to low-temperature physical extraction, followed by static impurity removal to obtain rapeseed oil. This method achieves low-temperature physical extraction of rapeseed oil and effectively increases the oil yield by combining multiple physical treatment methods without using medium-wave infrared lamps for heating.

[0007] This invention provides a method for low-temperature physical extraction of rapeseed oil, comprising the following steps: S1. After removing impurities from the rapeseed, it is subjected to germination treatment, microwave treatment and steam explosion treatment in sequence to obtain pretreated rapeseed. S2. The pretreated rapeseed is subjected to low-temperature physical pressing, and then allowed to stand to remove impurities, in order to obtain rapeseed oil.

[0008] As a preferred technical solution of the present invention, the germination treatment in step S1 is as follows: first, the rapeseed is soaked in deionized water, then transferred to a constant temperature and humidity chamber for germination, and then dried to obtain germination-treated rapeseed.

[0009] As a preferred technical solution of the present invention, the specific steps of the germination treatment in step S1 are as follows: soak the rapeseed in deionized water for 4-6 hours, filter to remove water, then spread it evenly on a tray, germinate in a constant temperature and humidity chamber for 70-80 hours, and dry at 50-60℃ to obtain the germination-treated rapeseed.

[0010] As a preferred technical solution of the present invention, the soaking time in step S1 can be, for example, 4h, 4.5h, 5h, 5.5h or 6h.

[0011] As a preferred technical solution of the present invention, the germination time in step S1 can be, for example, 70h, 72h, 74h, 76h, 78h or 80h.

[0012] As a preferred technical solution of the present invention, the drying temperature in step S1 can be, for example, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C.

[0013] As a preferred embodiment of the present invention, the conditions of the constant temperature and humidity chamber are: temperature of 23~27℃ and humidity of 75~85%.

[0014] This invention first soaks rapeseed in deionized water to allow the seeds to absorb sufficient moisture, breaking dormancy, activating enzyme systems, and preparing for germination; then, it removes excess water by draining and filtering in trays to prevent water accumulation that could lead to seed rot due to lack of oxygen; next, it prevents the seed surface from drying out in a high-humidity environment, maintaining the moisture required for metabolism to ensure germination; finally, it dries the seeds to fix the nutrients produced during germination for storage or subsequent crushing / extraction processing.

[0015] As a preferred technical solution of the present invention, the specific steps of microwave treatment in step S1 are as follows: microwave the germinating rapeseed at 700~800W for 8~10 minutes to obtain microwave-treated rapeseed.

[0016] As a preferred technical solution of the present invention, the microwave processing power in step S1 can be, for example, 700W, 720W, 740W, 760W, 780W or 800W.

[0017] As a preferred technical solution of the present invention, the microwave processing time in step S1 can be, for example, 8 min, 9 min, or 10 min.

[0018] This invention microwaves rapeseed and controls the microwave power to 700-800W. This avoids both incomplete cell wall destruction due to excessively low power and excessively high power that could lead to surface carbonization, increase impurities, and affect oil quality and yield.

[0019] As a preferred technical solution of the present invention, the steam explosion treatment in step S1 is as follows: the microwave-treated rapeseed is transferred to an intermittent steam explosion instrument, saturated steam is introduced for steam explosion, and the rapeseed is naturally dried to obtain pretreated rapeseed.

[0020] As a preferred technical solution of the present invention, the specific steps of the steam explosion treatment in step S1 are as follows: the microwave-treated rapeseed is placed in the material chamber of the intermittent steam explosion device, saturated steam is introduced, and the pressure is maintained at 0.4~0.8MPa for 1~3 minutes. The pressure is released instantaneously, and the explosion treatment is completed. The rapeseed is then naturally dried to obtain pretreated rapeseed.

[0021] As a preferred technical solution of the present invention, the pressure of the steam explosion treatment in step S1 can be, for example, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa or 0.8MPa.

[0022] As a preferred technical solution of the present invention, the steam explosion treatment time in step S1 can be, for example, 1 min, 2 min, or 3 min.

[0023] As a preferred embodiment of the present invention, the moisture content of the pretreated rapeseed is less than 7%.

[0024] The steam explosion treatment of this invention completely tears the fragile cell walls of rapeseed oil into fragments through the instantaneous pressure release "explosion" effect. Compared with other methods, the energy of steam explosion is greater and more uniform, thereby effectively increasing the oil yield.

[0025] As a preferred technical solution of the present invention, the conditions for low-temperature physical pressing in step S2 are: pressing temperature of 45~55℃, pressing pressure of 20~30MPa, and pressing time of 30~40min.

[0026] As a preferred technical solution of the present invention, the extraction temperature in step S2 can be, for example, 45°C, 47°C, 49°C, 51°C, 53°C or 55°C.

[0027] As a preferred technical solution of the present invention, the extraction pressure in step S2 can be, for example, 20MPa, 22MPa, 24MPa, 26MPa, 28MPa or 30MPa.

[0028] As a preferred embodiment of the present invention, the extraction time in step S2 can be, for example, 30 min, 32 min, 34 min, 36 min, 38 min, or 40 min. As a preferred embodiment of the present invention, the total impurity content of the rapeseed oil after standing and removing impurities in step S2 is less than 0.3%.

[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention first activates the endogenous enzymes of rapeseed oil through germination treatment, degrades the chemical components of cell wall and breaks dormancy; then, microwave treatment causes micro-explosions inside the cells, initially destroys the structure, quickly inactivates lipases and prevents oil hydrolysis; finally, the huge force of pressure relief in steam explosion is used to completely disintegrate the softened seeds, thereby maximizing the cell breakage rate. Through the three-level synergistic effect of "germination + microwave + steam explosion", the oil yield of rapeseed is significantly increased.

[0030] (2) The germination treatment of the present invention can break the dormancy of seeds, activate metabolism and increase the content of nutrients. At the same time, the endogenous enzymes of seeds are activated during germination, which degrade the cell walls and protein matrix that encapsulate the oil body, thereby releasing the oil body from the tight cell structure and destroying the binding force between oil and protein and fiber, thus effectively increasing the oil yield during mechanical pressing or solvent extraction.

[0031] (3) The present invention breaks through the cell wall and oil membrane structure of rapeseed by microwave treatment, so that the oil outflow channel is fully opened and the oil is more easily squeezed out during pressing, thereby improving the oil extraction rate. Detailed Implementation

[0032] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention. Example

[0033] This embodiment provides a method for low-temperature physical extraction of rapeseed oil, including the following steps: S1. Soak rapeseed in deionized water for 6 hours, filter to remove water, then spread it evenly on a tray and germinate in a constant temperature and humidity chamber (temperature 27℃, humidity 85%) for 70 hours. Dry at 60℃ to obtain germination-treated rapeseed. Microwave the germination-treated rapeseed at 800W for 8 minutes to obtain microwave-treated rapeseed. Place the microwave-treated rapeseed in the material chamber of an intermittent steam explosion apparatus, introduce saturated steam, maintain a pressure of 0.8MPa for 1 minute, release the pressure instantaneously, and air dry after the explosion treatment to obtain pre-treated rapeseed.

[0034] S2. The pretreated rapeseed is subjected to low-temperature physical pressing at a temperature of 55°C, a pressing pressure of 30 MPa, and a pressing time of 30 min. After standing to remove impurities, rapeseed oil is obtained. Example

[0035] This embodiment provides a method for low-temperature physical extraction of rapeseed oil, including the following steps: S1. Soak rapeseed in deionized water for 4 hours, filter to remove water, then spread evenly on a tray and germinate in a constant temperature and humidity chamber (temperature 23℃, humidity 75%) for 80 hours, then dry at 50℃ to obtain germination-treated rapeseed; microwave the germination-treated rapeseed at 700W for 10 minutes to obtain microwave-treated rapeseed; place the microwave-treated rapeseed in the material chamber of an intermittent steam explosion apparatus, introduce saturated steam, maintain at a pressure of 0.4MPa for 3 minutes, release the pressure instantaneously, and after completing the explosion treatment, air dry to obtain pre-treated rapeseed.

[0036] S2. The pretreated rapeseed is subjected to low-temperature physical pressing at a temperature of 45°C, a pressing pressure of 20 MPa, and a pressing time of 40 min. After standing to remove impurities, rapeseed oil is obtained. Example

[0037] This embodiment provides a method for low-temperature physical extraction of rapeseed oil, including the following steps: S1. Soak rapeseed in deionized water for 5 hours, filter to remove water, then spread evenly on a tray and germinate in a constant temperature and humidity chamber (temperature 25℃, humidity 80%) for 75 hours, then dry at 55℃ to obtain germination-treated rapeseed; microwave the germination-treated rapeseed at 750W for 9 minutes to obtain microwave-treated rapeseed; place the microwave-treated rapeseed in the material chamber of an intermittent steam explosion apparatus, introduce saturated steam, maintain a pressure of 0.6MPa for 2 minutes, release the pressure instantaneously, and air dry after the explosion treatment to obtain pre-treated rapeseed.

[0038] S2. The pretreated rapeseed is subjected to low-temperature physical pressing at a temperature of 50°C, a pressing pressure of 25 MPa, and a pressing time of 35 min. After standing to remove impurities, rapeseed oil is obtained.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that no germination treatment is performed in step S1.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that the humidity of the germination treatment in step S1 is changed to 40%.

[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that microwave processing is not performed in step S1.

[0042] Comparative Example 4 The difference between this comparative example and Example 1 is that the power of microwave processing in step S1 is changed to 200W.

[0043] Comparative Example 5 The difference between this comparative example and Example 1 is that the power of microwave processing in step S1 is changed to 1500W.

[0044] Comparative Example 6 The difference between this comparative example and Example 1 is that steam explosion treatment is not performed in step S1.

[0045] The quality indicators of rapeseed oil were tested in accordance with the requirements of GB / T 1536-2021 Rapeseed Oil.

[0046] Table 1 Test Results

[0047] This invention first activates the endogenous enzymes of rapeseed oil through germination treatment, degrades the chemical components of the cell wall, and breaks dormancy; then, microwave treatment causes micro-explosions inside the cells, initially destroying the structure, rapidly inactivating lipases, and preventing oil hydrolysis; finally, the enormous force of pressure relief in the steam explosion is used to completely disintegrate the softened seeds, maximizing the cell breakage rate. Through the synergistic effect of these three methods, the oil yield of rapeseed is significantly increased (Examples 1-3).

[0048] Compared with Example 1, step S1 does not involve germination treatment, thus lacking the effect of germination treatment, resulting in a lower oil yield (Comparative Example 1). Compared with Example 1, the humidity of the germination treatment in step S1 is changed to 40%. The low humidity leads to a poor germination effect, resulting in a lower oil yield (Comparative Example 2). Compared with Example 1, step S1 does not involve microwave treatment, thus lacking the effect of microwave treatment, resulting in a lower oil yield (Comparative Example 3). Compared with Example 1, the power of the microwave treatment in step S1 is changed to 200W. The low power leads to incomplete cell wall destruction, resulting in a lower oil yield (Comparative Example 4). Compared with Example 1, the power of the microwave treatment in step S1 is changed to 1500W. The high power leads to surface carbonization and loss, resulting in a lower oil yield (Comparative Example 5). Compared with Example 1, step S1 does not involve steam explosion treatment, thus lacking the effect of microwave treatment, resulting in a lower oil yield (Comparative Example 6).

Claims

1. A method for low-temperature physical extraction of rapeseed oil, characterized in that, Includes the following steps: S1. After removing impurities from the rapeseed, it is subjected to germination treatment, microwave treatment and steam explosion treatment in sequence to obtain pretreated rapeseed. S2. The pretreated rapeseed is subjected to low-temperature physical pressing, and then allowed to stand to remove impurities, in order to obtain rapeseed oil.

2. The method for low-temperature physical extraction of rapeseed oil according to claim 1, characterized in that, The germination treatment in step S1 is as follows: first, the rapeseed is soaked in deionized water, then transferred to a constant temperature and humidity chamber for germination, and then dried to obtain germination-treated rapeseed.

3. The method for low-temperature physical extraction of rapeseed oil according to claim 2, characterized in that, The specific steps of the germination treatment in step S1 are as follows: soak rapeseed in deionized water for 4-6 hours, filter to remove water, then spread evenly on a tray, germinate in a constant temperature and humidity chamber for 70-80 hours, and dry at 50-60℃ to obtain germination-treated rapeseed.

4. The method for low-temperature physical extraction of rapeseed oil according to claim 3, characterized in that, The conditions of the constant temperature and humidity chamber are: temperature 23~27℃, humidity 75~85%.

5. The method for low-temperature physical extraction of rapeseed oil according to claim 1, characterized in that, The specific steps of microwave treatment in step S1 are as follows: microwave the germinating rapeseed at 700~800W for 8~10 minutes to obtain microwave-treated rapeseed.

6. The method for low-temperature physical extraction of rapeseed oil according to claim 1, characterized in that, The steam explosion treatment in step S1 is as follows: the microwave-treated rapeseed is transferred to an intermittent steam explosion apparatus, saturated steam is introduced for steam explosion, and the rapeseed is naturally dried to obtain pretreated rapeseed.

7. The method for low-temperature physical extraction of rapeseed oil according to claim 6, characterized in that, The specific steps of the steam explosion treatment in step S1 are as follows: the microwave-treated rapeseed is placed in the material chamber of the intermittent steam explosion device, saturated steam is introduced, and the pressure is maintained at 0.4~0.8MPa for 1~3 minutes. The pressure is released instantaneously, and the explosion treatment is completed. The rapeseed is then air-dried to obtain pretreated rapeseed.

8. The method for low-temperature physical extraction of rapeseed oil according to claim 7, characterized in that, The moisture content of the pretreated rapeseed is less than 7%.

9. The method for low-temperature physical extraction of rapeseed oil according to claim 1, characterized in that, The conditions for low-temperature physical pressing in step S2 are: pressing temperature of 45~55℃, pressing pressure of 20~30MPa, and pressing time of 30~40min.

10. The method for low-temperature physical extraction of rapeseed oil according to claim 1, characterized in that, After standing and removing impurities in step S2, the total impurity content of the rapeseed oil is less than 0.3%.

Images