Sesame oil preparation method and device based on low-temperature cold pressing-ultrasonic synergistic extraction

Abstract

The invention relates to the technical field of sesame oil processing, in particular to a sesame oil preparation method and device based on low-temperature cold pressing-ultrasonic synergistic extraction. The preparation method comprises the following steps: cleaning and screening a sesame raw material, loosening a cell wall microfiber network through microwave non-thermal puffing, inducing ice crystals to pierce a lipoprotein complex through cryogenic circulation phase change stress to dissociate an ultrastructure of a cell matrix, and performing three-stage temperature-control variable-pressure extraction to complete low-temperature separation of grease. In addition, residual meal is subjected to polar synergistic carrying by an azeotropic mixed solvent, grease is stripped and embedded through transient high-pressure micro-jet, phospholipid micelle phase separation is achieved through disc centrifugation of mixed oil, free fatty acid is removed through molecular distillation free path difference, finally, sesame oil preparation is completed through ceramic membrane interception, and therefore the oil yield of the sesame oil is increased.

Description

Technical Field

[0001] The invention relates to the technical field of sesame oil processing, in particular to a sesame oil preparation method and device based on low-temperature cold pressing-ultrasonic wave synergistic extraction. Background Art

[0002] Sesame oil, also known as sesame oil, is a commonly used edible oil primarily derived from the pressing of sesame seeds. It is rich in nutrients, including fatty acids, vitamin E, sesame seeds, minerals, and protein. Sesame oil is also rich in minerals such as calcium, phosphorus, iron, and magnesium, which play a positive role in promoting growth and development, preventing osteoporosis and bone and joint diseases, and supporting intellectual development.

[0003] For example, CN114806700A discloses a method for preparing sesame oil, comprising: frying sesame raw materials at 230-260° C. for 2-8 minutes to obtain a first material; frying the sesame raw materials at 120-170° C. for 15-40 minutes to obtain a second material; mixing the first material and the second material in a mass ratio of 1:7-7:8 after smoke conditioning, squeezing, and collecting crude oil; and settling the crude oil and performing solid-liquid separation to obtain sesame oil.

[0004] In the aforementioned method for preparing sesame oil, the frying temperature during the first frying process far exceeds that typically used for frying oilseed seeds, which severely denatures and coagulates the sesame protein. This excessively denatured protein forms a tight network that encapsulates and absorbs some of the oil. This makes it difficult to effectively squeeze out the encapsulated oil during the subsequent pressing process, even after the cells are destroyed, significantly reducing the oil yield of the sesame raw material. Summary of the Invention

[0005] The purpose of the present invention is to avoid the problem that the protein denaturation wraps the oil due to excessively high temperature during frying, so that the wrapped part of the oil cannot be effectively squeezed out in the subsequent pressing process, thereby affecting the oil yield of the sesame raw material.

[0006] The purpose of the present invention is to provide a sesame oil preparation method and device based on low-temperature cold pressing-ultrasonic synergistic extraction. After the sesame raw materials are washed and dehydrated, low-temperature cold pressing combined with ultrasonic synergistic extraction is used to reduce the difficulty of oil extraction, thereby improving the oil yield of the sesame raw materials.

[0007] To achieve the above objectives, one of the objectives of the present invention is to provide a method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction, comprising the following steps:

[0008] Step S1: placing the sesame raw material into a carrying device and washing it in a washing box to remove impurities and then screening to remove the empty grains;

[0009] The sesame raw material is dried with hot air at 40-50°C until the moisture content is ≤5%, and then subjected to microwave treatment and freeze-thaw cycle treatment;

[0010] Step S2: using a twin-screw low-temperature press to perform pressure gradient cold pressing on the sesame raw material treated above to obtain crude oil and cold-pressed cake;

[0011] The cold-pressed cake is crushed and sieved to form homogeneous particles, and the moisture content is adjusted to ≤4%, and then the particles are mixed with an azeotropic mixed solvent;

[0012] Step S3: transferring the above-mentioned mixed system to a temperature-controlled ultrasonic reactor, first subjecting it to 20-40 kHz ultrasonic induction treatment, and maintaining the temperature at 45-50° C. during the induction treatment. Immediately after terminating the ultrasonic treatment, vacuum belt filtration is performed to separate and extract the mixed oil and defatted meal;

[0013] The mixed oil is then subjected to vacuum distillation to obtain extracted oil, and the crude oil and the extracted oil are mixed to obtain crude refined oil;

[0014] Step S4: centrifuging the crude oil with a high-speed self-cleaning disc centrifuge to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane to remove suspended colloids and crystalline lipids to obtain sesame oil.

[0015] As a further improvement of the technical solution, in step S1, the microwave treatment is to intermittently treat the sesame raw material at 300-500W for 4-7 minutes;

[0016] The freeze-thaw cycle treatment was as follows: the sesame raw material was frozen at -25--22°C for 2 h and then thawed at room temperature, which was repeated 3 times.

[0017] As a further improvement of the present technical solution, in step S2, the pressure gradient cold pressing is performed at 5-15 rpm in three stages of 25-35°C, 45-70°C and 80-100°C, to finally obtain crude oil and cold-pressed cake.

[0018] As a further improvement of the present technical solution, in step S2, the azeotropic mixed solvent is obtained by mixing n-hexane and ethanol in a volume ratio of 4:1.

[0019] As a further improvement of the present technical solution, in step S3, the ultrasonic power density during the ultrasonic induction treatment is 500-1000W / m 3 .

[0020] As a further improvement of the present technical solution, in step S3, the temperature during the reduced pressure distillation is 40-50°C.

[0021] As a further improvement of the present technical solution, in step S4, the filtration pore size of the ceramic membrane is 0.3-0.8 μm.

[0022] A second object of the present invention is to provide a device for the above-mentioned method for preparing sesame oil based on low-temperature cold pressing and ultrasonic extraction, wherein the cleaning box includes a box body and a motor disposed at the bottom of the box body, and a pipe for water input / output is disposed on the surface of the box body;

[0023] The carrying device includes a water passing frame and a linkage structure arranged at the bottom of the water passing frame. The water passing frame is used to place the sesame raw material in the water passing frame. The linkage structure is connected to the box body for sliding up and down, and the bottom end of the linkage structure is connected to the motor for driving the water passing frame to move;

[0024] The motor drives the linkage structure to move downward, so that the linkage structure drives the water-passing frame to move downward into the water. In the process of driving the water-passing frame to move downward, the linkage structure also drives the water-passing frame to move back and forth horizontally.

[0025] As a further improvement of the present technical solution, a cleaning chamber is provided in the box body, a first sliding rod is provided on the inner wall surface of the cleaning chamber, the linkage structure includes a lifting frame and a waterproof cover provided at the bottom of the lifting frame, the two ends of the lifting frame are connected to the first sliding rod for up and down sliding, the lifting frame is connected to the bottom surface of the cleaning chamber through the waterproof cover, and a bottom cover is provided at the middle bottom of the lifting frame, and correspondingly, the drive shaft of the motor is threadedly connected to the inner wall of the bottom cover.

[0026] As a further improvement of the present technical solution, a top plate is rotatably connected to the middle of the upper surface of the top of the lifting frame, a bayonet is provided in the middle of the bottom of the top plate, and the bottom end of the bayonet is engaged with the drive shaft. A second sliding rod is provided on both sides of the top of the lifting frame, and the two ends of the water frame are horizontally slidably connected to the second sliding rod. A plate groove is provided on the bottom surface of the water frame, and a disk shaft is correspondingly provided on the upper surface of the top plate, and the disk shaft is slidably connected to the plate groove.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. In this sesame oil preparation method and device based on low-temperature cold pressing and ultrasonic synergistic extraction, after the sesame raw materials are cleaned and screened, the cell wall microfiber network is relaxed by microwave non-thermal expansion, and then ice crystals are induced to pierce the lipoprotein complex through deep cold cycle phase change stress to achieve cell matrix ultrastructure dissociation. Then, the oil is extracted through three-stage temperature-controlled variable pressure extraction to complete low-temperature precipitation.

[0029] In addition, the residual meal is carried by polarity synergistically in an azeotropic mixed solvent, and the embedded oil is stripped by transient high-pressure microjet. The mixed oil is then subjected to disc centrifugation to achieve phospholipid micelle phase separation, and the free fatty acids are removed by molecular distillation free path differential. Finally, the preparation of sesame oil is completed by ceramic membrane interception, thereby improving the oil yield of sesame oil.

[0030] 2. In the sesame oil preparation method and device based on low-temperature cold pressing-ultrasonic coordinated extraction, the lifting frame is driven by the driving shaft of the motor to move downward along the first sliding rod, and the lifting frame then drives the water frame to move downward and immerse in water. The driving shaft also drives the top plate to rotate through the bayonet pin engaged with the top plate. When the top plate rotates, the water frame is driven by the plate shaft to move horizontally back and forth along the second sliding rod, so that water can rinse the sesame raw material in the water frame, further improving the cleaning efficiency of the sesame raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the present invention;

[0032] Figure 2 It is a schematic diagram of the overall structure of the device of the present invention;

[0033] Figure 3 Schematic diagram of the overall cross-sectional structure of the device of the present invention;

[0034] Figure 4 This is a cross-sectional schematic diagram of the structural coordination of the cleaning box and the load-bearing device of the present invention;

[0035] Figure 5 It is a cross-sectional schematic diagram of the cooperation between the water-passing frame and the linkage structure of the present invention;

[0036] Figure 6 It is a schematic diagram of the water flow frame and linkage structure activities of the present invention.

[0037] The meaning of each number in the figure is:

[0038] 1. Cleaning box; 11. Box body; 111. Cleaning chamber; 112. First sliding rod; 12. Motor;

[0039] 2. Carrying device; 21. Water-passing frame; 211. Plate groove; 22. Linkage structure; 221. Lifting frame; 222. Waterproof cover; 223. Bottom cover; 224. Top plate; 225. Pin; 226. Second sliding rod; 227. Plate shaft. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] See also Figure 1-6 As shown, the present invention aims to provide a method for preparing sesame oil based on low-temperature cold pressing-ultrasonic coordinated extraction, comprising the following steps:

[0042] Step S1: placing the sesame raw material into the carrying device 2 and washing it in the washing box 1 to remove impurities and then screening to remove the empty grains;

[0043] The sesame raw material is dried with hot air at 40-50°C to a moisture content of ≤5% (avoiding high temperature baking to reduce volatile loss), microwave-treated, and then subjected to a freeze-thaw cycle;

[0044] Microwave treatment involves intermittently treating the sesame raw materials at 300-500W for 4-7 minutes to promote cell wall loosening;

[0045] The freeze-thaw cycle treatment is to freeze the sesame raw material at -25--22℃ for 2h and then thaw it at room temperature, repeating this three times to use ice crystals to pierce the cell structure.

[0046] Step S2: Using a twin-screw low-temperature press (temperature controlled ≤ 60° C.), the sesame raw material treated above is subjected to pressure gradient cold pressing to obtain crude oil and cold-pressed cake, wherein the pressure gradient cold pressing is performed at 5-15 rpm (low speed to reduce frictional heat generation) in three stages of pressing at 25-35° C., 45-70° C., and 80-100° C., to finally obtain crude oil and cold-pressed cake;

[0047] The cold-pressed cake is crushed and sieved (particle size ≤ 0.5 mm) to form homogeneous particles to increase the solvent-accessible surface area, and the moisture content is adjusted to ≤ 4% to weaken the hydrogen bonding force and optimize the solvent penetration path. The particles are then mixed with an azeotropic mixed solvent, which is obtained by mixing n-hexane and ethanol in a volume ratio of 4:1. Among them, n-hexane provides a non-polar dissolution field and efficiently extracts triglycerides; ethanol destroys lipoprotein complexes, dissociates bound residual oil and inhibits phospholipid dissolution.

[0048] Step S3: transferring the above-mentioned mixed system to a temperature-controlled ultrasonic reactor, first subjecting it to 20-40kHz ultrasonic induction treatment, and the ultrasonic power density during the ultrasonic induction treatment is 500-1000W / m3, providing non-thermal energy input, and instantaneously collapsing the microbubbles generated by the ultrasound, generating local high-pressure shock waves and high-temperature hot spots, completely disintegrating the residual cell walls and protein network structure, and forming cavitation microjets to impact the solid phase surface, continuously stripping and adsorbing the oil, and maintaining the temperature at 45-50°C (20°C lower than the boiling point of the solvent) during the induction treatment, ensuring that the oil viscosity is at a low value to optimize fluidity and avoiding degradation of heat-sensitive components. After terminating the ultrasound, vacuum belt filtration is immediately performed to separate and extract the mixed oil and defatted meal;

[0049] The mixed oil is then subjected to reduced pressure distillation at 40-50° C. to obtain extracted oil, ≥99% of the solvent is recovered (for recycling), and the crude oil and the extracted oil are mixed to obtain crude refined oil.

[0050] Step S4: centrifuging the crude oil in a high-speed self-cleaning disc centrifuge (≥8000 rpm) to achieve continuous separation of the phospholipid-colloid phase to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane with a pore size of 0.3-0.8 μm to remove suspended colloids and crystalline lipids to obtain sesame oil.

[0051] In the present invention, the cleaning box 1 mentioned above includes a box body 11 and a motor 12 arranged at the bottom of the box body 11. The surface of the box body 11 is provided with a pipe for water input / output;

[0052] The carrying device 2 includes a water frame 21 and a linkage structure 22 arranged at the bottom of the water frame 21. The water frame 21 is used to place the sesame raw material. The linkage structure 22 is located in the box body 11 and is connected to the box body 11 for sliding up and down. The bottom end of the linkage structure 22 is connected to the motor 12 for driving the water frame 21 to move.

[0053] The sesame raw material is put into the filter net, and then the filter net is placed in the water frame 21. Water is filled into the box body 11 through the pipe set on the surface of the box body 11. Then, the motor 12 drives the linkage structure 22 to move downward, so that the linkage structure 22 drives the water frame 21 to move downward into the water. In the process of driving the water frame 21 to move downward, the linkage structure 22 also drives the water frame 21 to move back and forth horizontally, thereby facilitating the water to flush the sesame raw material in the water frame 21 and ensuring the cleaning effect of the sesame raw material.

[0054] Specifically, a cleaning chamber 111 is opened in the box body 11, and a first sliding rod 112 is provided on the inner wall surface of the cleaning chamber 111. The linkage structure 22 includes a lifting frame 221 and a waterproof cover 222 provided at the bottom of the lifting frame 221. The two ends of the lifting frame 221 are connected to the first sliding rod 112 for up and down sliding. The lifting frame 221 is connected to the bottom surface of the cleaning chamber 111 through the waterproof cover 222, and a bottom cover 223 is provided at the bottom middle part of the lifting frame 221. Correspondingly, the top end of the driving shaft of the motor 12 is located in the bottom cover 223 and is threadedly connected to the inner wall of the bottom cover 223.

[0055] The driving shaft of the motor 12 drives the lifting frame 221 to move downward along the first sliding rod 112, and the lifting frame 221 then drives the water frame 21 to move downward and immerse into the water. Figure 6As shown by the middle arrow a, water comes into contact with the sesame raw material, thereby being able to remove impurities in the sesame raw material. Furthermore, in order to improve the cleaning effect, a top plate 224 is rotatably connected to the middle of the upper surface of the top of the lifting frame 221, and a pin 225 is provided in the middle of the bottom of the top plate 224. The bottom end of the pin 225 is inserted into the top of the drive shaft and engaged with the drive shaft. A second sliding rod 226 is provided on both sides of the top of the lifting frame 221, and the two ends of the water frame 21 are horizontally slidably connected to the second sliding rod 226. A plate groove 211 is provided on the bottom surface of the water frame 21, and a disk shaft 227 is correspondingly provided on the upper surface of the top plate 224. The disk shaft 227 is located in the plate groove 211 and is slidably connected to the plate groove 211.

[0056] The driving shaft of the motor 12 rotates in the bottom sleeve 223, and when the lifting frame 221 moves up and down along the first sliding rod 112 through the bottom sleeve 223 connected by thread, the driving shaft also drives the top plate 224 to rotate through the bayonet pin 225 engaged with the top plate 224. When the top plate 224 rotates, it drives the water frame 21 to move horizontally back and forth along the second sliding rod 226 through the disk shaft 227, as shown in FIG. Figure 6 As shown by the middle arrow b, water can rinse the sesame raw materials in the water frame 21, further improving the cleaning efficiency of the sesame raw materials.

[0057] The following specific examples are used to further illustrate the method for preparing sesame oil based on low-temperature cold pressing-ultrasonic coordinated extraction provided by the present invention.

[0058] Example 1

[0059] This embodiment proposes a method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction, and the specific steps are as follows:

[0060] Step S1: Put the sesame raw material into the carrying device 2 and wash it in the washing box 1 to remove impurities, and then screen to remove the empty grains (the details of the washing box 1 and the carrying device 2 are not repeated in this embodiment).

[0061] The sesame raw material is dried by hot air at 40°C until the moisture content is less than or equal to 5%, treated by microwave, and then subjected to a freeze-thaw cycle.

[0062] The microwave treatment was performed on the sesame raw material at 500 W for 4 minutes.

[0063] The freeze-thaw cycle treatment was performed by freezing the sesame raw material at -22°C for 2 h and then thawing it at room temperature, which was repeated three times.

[0064] Step S2: Using a twin-screw low-temperature press (temperature controlled ≤ 60°C), the sesame raw material treated above is subjected to pressure gradient cold pressing to obtain crude oil and cold-pressed cake, wherein the pressure gradient cold pressing is performed at 5 rpm in three stages of 35°C, 45°C and 100°C, to finally obtain crude oil and cold-pressed cake.

[0065] The cold-pressed cake is crushed and sieved (particle size ≤ 0.5 mm) to form homogeneous particles, and the moisture content is adjusted to ≤ 4%. The particles are then mixed with an azeotropic mixed solvent, which is obtained by mixing n-hexane and ethanol in a volume ratio of 4:1.

[0066] Step S3: The mixed system is transferred to a temperature-controlled ultrasonic reactor and first subjected to 20kHz ultrasonic induction treatment with an ultrasonic power density of 1000W / m 3 In addition, the temperature was maintained at 45°C during the induction treatment, and vacuum belt filtration was immediately performed after the ultrasonic treatment was terminated to separate and extract the mixed oil and defatted meal.

[0067] The mixed oil is then subjected to reduced pressure distillation at 40-50°C to obtain extracted oil, and the crude oil and the extracted oil are mixed to obtain crude refined oil.

[0068] Step S4: centrifuging the crude oil in a high-speed self-cleaning disc centrifuge (≥8000 rpm) to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane with a pore size of 0.8 μm to remove suspended colloids and crystalline lipids to obtain sesame oil.

[0069] Example 2

[0070] This embodiment proposes a method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction, and the specific steps are as follows:

[0071] Step S1: Put the sesame raw material into the carrying device 2 and wash it in the washing box 1 to remove impurities, and then screen to remove the empty grains (the details of the washing box 1 and the carrying device 2 are not repeated in this embodiment).

[0072] The sesame raw material is dried by hot air at 45°C until the moisture content is less than or equal to 5%, treated by microwave, and then subjected to a freeze-thaw cycle.

[0073] The microwave treatment was performed on the sesame raw material at 400 W for 5 min.

[0074] The freeze-thaw cycle treatment was performed by freezing the sesame raw material at -23°C for 2 h and then thawing it at room temperature, which was repeated three times.

[0075] Step S2: Using a twin-screw low-temperature press (temperature controlled ≤ 60°C), the sesame raw material treated above is subjected to pressure gradient cold pressing to obtain crude oil and cold-pressed cake, wherein the pressure gradient cold pressing is performed at 10 rpm in three stages of 30°C, 60°C and 90°C, to finally obtain crude oil and cold-pressed cake.

[0076] The cold-pressed cake is crushed and sieved (particle size ≤ 0.5 mm) to form homogeneous particles, and the moisture content is adjusted to ≤ 4%. The particles are then mixed with an azeotropic mixed solvent, which is obtained by mixing n-hexane and ethanol in a volume ratio of 4:1.

[0077] Step S3: The mixed system is transferred to a temperature-controlled ultrasonic reactor and first subjected to 30kHz ultrasonic induction treatment with an ultrasonic power density of 800W / m 3 In addition, the temperature was maintained at 48°C during the induction treatment, and vacuum belt filtration was immediately performed after the ultrasonic treatment was terminated to separate and extract the mixed oil and defatted meal.

[0078] The mixed oil is then subjected to reduced pressure distillation at 45°C to obtain extracted oil, and the crude oil and the extracted oil are mixed to obtain crude refined oil.

[0079] Step S4: centrifuging the crude oil in a high-speed self-cleaning disc centrifuge (≥8000 rpm) to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane with a pore size of 0.5 μm to remove suspended colloids and crystalline lipids to obtain sesame oil.

[0080] Example 3

[0081] This embodiment proposes a method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction, and the specific steps are as follows:

[0082] Step S1: Put the sesame raw material into the carrying device 2 and wash it in the washing box 1 to remove impurities, and then screen to remove the empty grains (the details of the washing box 1 and the carrying device 2 are not repeated in this embodiment).

[0083] The sesame raw material is dried by hot air at 50° C. until the moisture content is less than or equal to 5%, treated by microwave, and then subjected to a freeze-thaw cycle.

[0084] The microwave treatment was performed on the sesame raw material at 300W for 7 minutes.

[0085] The freeze-thaw cycle treatment was performed by freezing the sesame raw material at -25°C for 2 h and then thawing it at room temperature, which was repeated three times.

[0086] Step S2: Using a twin-screw low-temperature press (temperature controlled ≤ 60°C), the sesame raw material treated above is subjected to pressure gradient cold pressing to obtain crude oil and cold-pressed cake, wherein the pressure gradient cold pressing is performed at 15 rpm in three stages of 25°C, 70°C and 80°C, to finally obtain crude oil and cold-pressed cake.

[0087] The cold-pressed cake is crushed and sieved (particle size ≤ 0.5 mm) to form homogeneous particles, and the moisture content is adjusted to ≤ 4%. The particles are then mixed with an azeotropic mixed solvent, which is obtained by mixing n-hexane and ethanol in a volume ratio of 4:1.

[0088] Step S3: The mixed system is transferred to a temperature-controlled ultrasonic reactor and first subjected to 40kHz ultrasonic induction treatment with an ultrasonic power density of 500W / m 3 In addition, the temperature was maintained at 50°C during the induction treatment, and vacuum belt filtration was immediately performed after the ultrasonic treatment was terminated to separate and extract the mixed oil and defatted meal.

[0089] The mixed oil is then subjected to reduced pressure distillation at 40-50°C to obtain extracted oil, and the crude oil and the extracted oil are mixed to obtain crude refined oil.

[0090] Step S4: centrifuging the crude oil in a high-speed self-cleaning disc centrifuge (≥8000 rpm) to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane with a pore size of 0.3 μm to remove suspended colloids and crystalline lipids to obtain sesame oil.

[0091] Sesame oil was prepared according to the method provided in Examples 1-3 above. Then, a pretreated sesame sample (moisture ≤ 5%) was taken and the absolute oil content Wo was determined by Soxhlet extraction (solvent: petroleum ether, boiling range 30-60° C.) according to GB5009.6-2016 National Food Safety Standard Determination of Fat in Food. The residual oil content Mw of the defatted meal was then determined, and the oil yield was calculated using the following formula:

[0092]

[0093] Where η is the oil yield, Wo is the absolute oil content of the sesame sample, Mw is the residual oil content of the defatted meal, and Mo is the total mass of the sesame feed. The calculation results are recorded in Table 1.

[0094] Table 1 Oil yield of Examples 1-3

[0095] Example 1 Example 2 Example 3 Oil yield / % 98.2 98.7 98.5

[0096] As shown in Table 1, according to the preparation methods provided in Examples 1-3, the oil yield of the sesame raw materials is higher than 98.2%, indicating that the preparation method provided by the present invention has a high oil yield.

[0097] In the present invention, after washing and screening, the sesame raw materials are subjected to microwave non-thermal expansion to relax the cell wall microfiber network, and then subjected to deep cold cycle phase change stress induction to cause ice crystals to pierce the lipoprotein complex, thereby achieving the dissociation of the cell matrix ultrastructure. The oil is then extracted through three-stage temperature-controlled variable pressure extraction to complete the low-temperature precipitation of the oil.

[0098] In addition, the residual meal is carried by polarity synergistically in an azeotropic mixed solvent, and the embedded oil is stripped by transient high-pressure microjet. The mixed oil is then subjected to disc centrifugation to achieve phospholipid micelle phase separation, and the free fatty acids are removed by molecular distillation free path differential. Finally, the preparation of sesame oil is completed by ceramic membrane interception, thereby improving the oil yield of sesame oil.

[0099] Example 4

[0100] In the present invention, intermittent microwaves of 300-500W can cause selective vibrational breakage of the β-1,4-glycosidic bonds in the sesame cell walls, promote the separation of hemicellulose and lignin, form nanoscale gap channels between cellulose microfibrils, significantly enhance the permeability of the cell walls, and thus improve the oil yield of sesame.

[0101] In order to prove that the microwave treatment power of 300-500 W is one of the important factors for the method provided by the present invention to have a high oil yield, this example, based on the above Example 1, set the microwave treatment power to 100 W, 200 W, 300 W, 400 W, 500 W, 600 W or 700 W, then prepared sesame oil, and calculated the sesame oil yield according to the above method. The test results are shown in Table 2.

[0102] Table 2 Effect of different microwave treatment powers on sesame oil yield

[0103] Microwave processing power / W 100 200 300 400 500 600 700 Oil yield / % 93.5 94.3 98.2 98.5 98.5 93.9 94.0

[0104] According to Table 2, when the microwave treatment power is 100 W, 200 W, 600 W or 700 W, that is, not 300-500 W, the oil yield of sesame is lower than the oil yield of sesame when the microwave treatment power is 300-500 W. Therefore, it can be seen that the microwave treatment power of 300-500 W is one of the important factors that enable the method provided by the present invention to have a higher oil yield.

[0105] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction, characterized in that: The following steps are involved: Step S1: placing the sesame raw material into the carrying device (2) and washing it in the washing box (1) to remove impurities, and then screening to remove the empty grains; The sesame raw material is dried with hot air at 40-50°C until the moisture content is ≤5%, and then subjected to microwave treatment and freeze-thaw cycle treatment; Step S2: using a twin-screw low-temperature press to perform pressure gradient cold pressing on the sesame raw material treated above to obtain crude oil and cold-pressed cake; The cold-pressed cake is crushed and sieved to form homogeneous particles, and the moisture content is adjusted to ≤4%, and then the particles are mixed with an azeotropic mixed solvent; Step S3: transferring the above-mentioned mixed system to a temperature-controlled ultrasonic reactor, first subjecting it to 20-40 kHz ultrasonic induction treatment, and maintaining the temperature at 45-50° C. during the induction treatment. Immediately after terminating the ultrasonic treatment, vacuum belt filtration is performed to separate and extract the mixed oil and defatted meal; The mixed oil is then subjected to vacuum distillation to obtain extracted oil, and the crude oil and the extracted oil are mixed to obtain crude refined oil; Step S4: centrifuging the crude oil with a high-speed self-cleaning disc centrifuge to obtain degummed oil, and then distilling the degummed oil to obtain distilled oil; then filtering the distilled oil through a ceramic membrane to remove suspended colloids and crystalline lipids to obtain sesame oil.

2. The method for preparing sesame oil based on low-temperature cold pressing-ultrasonic synergistic extraction according to claim 1, characterized in that: In step S1, the microwave treatment is to intermittently treat the sesame raw material at 300-500W for 4-7 minutes; The freeze-thaw cycle treatment was as follows: the sesame raw material was frozen at -25--22°C for 2 h and then thawed at room temperature, which was repeated 3 times.

3. The method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction according to claim 1, characterized in that: In step S2, the pressure gradient cold pressing is performed at 5-15 rpm in three stages of 25-35° C., 45-70° C., and 80-100° C., to finally obtain crude oil and cold-pressed cake.

4. The method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction according to claim 1, characterized in that: In step S2, the azeotropic mixed solvent is obtained by mixing n-hexane and ethanol in a volume ratio of 4:

1.

5. The method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction according to claim 1, characterized in that: In step S3, the ultrasonic power density during the ultrasonic induction treatment is 500-1000W / m 3 .

6. The method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction according to claim 1, characterized in that: In step S3, the temperature during the reduced pressure distillation is 40-50°C.

7. The method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction according to claim 1, characterized in that: In step S4, the filtration pore size of the ceramic membrane is 0.3-0.8 μm.

8. A device for preparing sesame oil using the method for preparing sesame oil based on low-temperature cold pressing and ultrasonic synergistic extraction as described in any one of claims 1 to 7, characterized in that: The cleaning box (1) comprises a box body (11) and a motor (12) arranged at the bottom of the box body (11); a pipe for water input / output is arranged on the surface of the box body (11); The carrying device (2) comprises a water passing frame (21) and a linkage structure (22) arranged at the bottom of the water passing frame (21), wherein the water passing frame (21) is used for placing the sesame raw material on the water passing frame (21), the linkage structure (22) is connected to the box body (11) in an upward and downward sliding manner, and the bottom end of the linkage structure (22) is connected to the motor (12) in a transmission manner for driving the water passing frame (21) to move; The motor (12) drives the linkage structure (22) to move downward, so that the linkage structure (22) drives the water passing frame (21) to move downward into the water, and in the process of driving the water passing frame (21) to move downward, the linkage structure (22) also drives the water passing frame (21) to move back and forth in the horizontal direction.

9. The device for preparing sesame oil according to claim 8, characterized in that: A cleaning chamber (111) is provided in the box body (11), and a first sliding rod (112) is provided on the inner wall surface of the cleaning chamber (111). The linkage structure (22) comprises a lifting frame (221) and a waterproof cover (222) provided at the bottom of the lifting frame (221). Both ends of the lifting frame (221) are connected to the first sliding rod (112) in an up-and-down sliding manner. The lifting frame (221) is connected to the inner bottom surface of the cleaning chamber (111) through the waterproof cover (222), and a bottom cover (223) is provided at the middle bottom of the lifting frame (221). Correspondingly, the driving shaft of the motor (12) is threadedly connected to the inner wall of the bottom cover (223).

10. The device for preparing sesame oil according to claim 9, characterized in that: The middle part of the upper surface of the top of the lifting frame (221) is rotatably connected with a top plate (224), the middle part of the bottom of the top plate (224) is provided with a bayonet (225), the bottom end of the bayonet (225) is engaged with the driving shaft, and second sliding rods (226) are provided on both sides of the top of the lifting frame (221), and the two ends of the water frame (21) are horizontally slidably connected to the second sliding rods (226). The bottom surface of the water frame (21) is provided with a plate groove (211), and a disk shaft (227) is correspondingly provided on the upper surface of the top plate (224), and the disk shaft (227) is slidably connected to the plate groove (211).

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