Preparation process of high oleic peanut oil and high oleic peanut oil

Abstract

The present application relates to the field of edible oils, and specifically discloses a preparation process for high-oleic peanut oil and high-oleic peanut oil. A preparation process for high-oleic peanut oil comprises the following steps: raw material selection: selecting peanut kernels with an oleic acid content of 75% or more; cleaning: removing immature kernels, damaged kernels, moldy kernels, stones, and metals from the peanut kernels; removing red skins: roasting the peanut kernels to a moisture content of 4-5.5%, cooling to room temperature, removing the red skins, and obtaining peanut kernels and peanut red skins; pressing: stir-frying the peanut kernels and pressing them to obtain crude oil and peanut cakes, which are then cooled; pre-coating: mixing oil, diatomaceous earth, and perlite, and then circulating pre-coating on a filter device after mixing; filtering: filtering the crude oil using the pre-coated filter device and nitrogen-filling and filling. The preparation process for high-oleic peanut oil of the present application has the advantages of few filtration passes, less use of filtration raw materials, and good low-temperature resistance and difficulty in stratification of the high-oleic peanut oil produced.

Description

Technical Field

[0001] The present application relates to the technical field of edible oils, and more specifically, to a preparation process of high-oleic peanut oil and the high-oleic peanut oil. Background Art

[0002] Peanuts are a major oilseed, grain, and cash crop in my country and around the world. Peanut seeds contain 40-56% oil, of which approximately 80% are oleic and linoleic fatty acids. High-oleic peanut oil, because the oleic acid molecule has one less unsaturated bond than the linoleic acid molecule, is chemically more stable and less susceptible to oxidation and the resulting rancidity. Consuming high-oleic peanuts is beneficial to human health, improving serum lipoprotein profiles, helping to manage weight and blood sugar, reducing the risk of cardiovascular disease and metabolic disorders, and enhancing cognitive function. High-oleic peanut oil also produces less smoke and requires less cooking time. Consequently, high-oleic peanuts have been a popular choice among growers, processors, and consumers since their introduction.

[0003] In the prior art, the Chinese invention patent application document with application number CN2015104701560 discloses a high oleic peanut oil, which uses high oleic peanut oil as raw material and is produced through three steps of screening, baking, pressing, cooling and low-temperature filtration.

[0004] With respect to the above-mentioned related technologies, the inventors found that the above peanut oil preparation method requires multiple filtrations to achieve the effects of peanut degumming, moderate dewaxing and defatting. The number of filtration passes is large and the amount of filtration raw materials used needs to be reduced. Summary of the Invention

[0005] In order to simplify the filtration method of peanut oil, reduce the number of filtration passes, and reduce the amount of filtration raw materials used, the present application provides a preparation process of high oleic peanut oil and high oleic peanut oil.

[0006] In a first aspect, the present application provides a process for preparing high oleic peanut oil, which adopts the following technical solution:

[0007] A preparation process for high oleic peanut oil comprises the following steps:

[0008] Raw material selection: Choose peanut kernels with an oleic acid content of more than 75%;

[0009] Cleaning: remove immature, broken, moldy, pebbles and metals from peanut kernels;

[0010] Removing the red skin: roasting the peanut kernels until the moisture content is 4-5.5%, cooling to room temperature, and removing the red skin to obtain peanut kernels and peanut red skin;

[0011] Pressing: Stir-fry the peanuts and press them to obtain crude oil and peanut cakes. Cool the crude oil to 15-20°C in 20-40 minutes. Pre-coating: Mix oil, diatomaceous earth and perlite in a mass ratio of 1:0.5-1:0.3-0.5 for 20-30 minutes. After mixing, circulate pre-coating on the filter equipment for 1.5-2 hours.

[0012] Filtration: Filter the crude oil using pre-coated filter equipment and fill with nitrogen.

[0013] By adopting the above technical solution and using peanut kernels with a high oleic acid content as raw materials, the prepared peanut oil has a high oleic acid content, good nutritional value, and meets the health needs of the human body. After being pressed, it is quickly cooled to lock the flavor factors and prevent the flavor factors from volatilizing, resulting in a weak aroma of the peanut oil. After the oil, diatomaceous earth and perlite are evenly mixed, they are pre-circulated and coated in a filtering device, thereby forming a filtering layer in the filtering device. When the crude oil is filtered, the content of phospholipids, colloidal impurities, other impurities, etc. can be reduced, making the peanut oil clear and transparent, reducing insoluble impurities, and reducing the number of filtration times and the amount of filtering raw materials used, thereby improving production efficiency.

[0014] Optionally, the pre-coating layer has a thickness of 1-1.5 cm.

[0015] By adopting the above technical solution, a mixture of oil, diatomaceous earth and perlite is coated inside the filtering equipment, and the coating thickness formed is 1-1.5 cm. When filtering the crude oil, insoluble impurities in the crude oil can be better removed, the turbidity of the crude oil can be reduced, and the clarity can be improved.

[0016] Oils and fats contain waxy compounds, and finished oils will crystallize after being stored for a period of time, manifesting as needle-shaped crystals, silk-like crystals, granular crystals, and trace amounts of cloudiness. As the temperature drops, sediment forms in the oil, gradually becoming turbid and viscous. The precipitates increase, slowly forming a colloidal state, affecting the appearance of high-oleic peanut oil, worsening its fluidity, decreasing its digestibility and absorption rate, and worsening its palatability and odor. Some consumers will have doubts when purchasing high-oleic peanut oil in winter, which affects its sales volume in winter. By adopting the above technical solution, the crude oil is quenched, crystallized and precipitated at low temperatures, and then filter aids and peanut oil are used as crystal seeds to promote crystallization in the crude oil, thereby facilitating filtration and dewaxing, improving the low-temperature stability of the high-oleic peanut oil, making it less likely to stratify at low temperatures, and making it clear and bright when sold in winter.

[0017] Optionally, the stirring speed during the crystallization is 60-80 r / min.

[0018] By adopting the above technical solution, the stirring speed is slow during crystallization, and the collision between the precipitated crystals and the wax molecules to be precipitated cannot occur, so the crystallization is slow. If the stirring speed is too fast during crystallization, the crystallized wax will be broken, which is also not conducive to crystallization.

[0019] Optionally, the amount of the seed crystals added is 0.05-0.1% of the total weight of the crude oil, and the mass ratio of the filter aid to the peanut oil in the seed crystals is 1:0.1-0.5.

[0020] By adopting the above technical solution and adding an appropriate amount of seed crystals, the wax in the crude oil is crystallized, which facilitates the removal of the wax, improves the low-temperature stability of the peanut oil, and prevents stratification.

[0021] Optionally, the method further comprises the following steps: cooling the filtered crude oil to 8-12° C. and filtering it with a composite membrane, wherein the composite membrane comprises a PAN membrane layer, a mesoporous diatomaceous earth-molecular sieve composite adsorption layer and a PAN membrane layer.

[0022] By adopting the above technical solution, the filtered crude oil is cooled to 8-12°C to reduce the solubility of the wax, and then the wax particles or wax molecular clusters showing polarity in the oil are captured. The PAN membrane layer is blocked by the wax particles or wax molecular clusters, and the wax crystal particles and wax molecular clusters escaping from the PAN membrane are intercepted by the mesoporous diatomaceous earth-molecular sieve composite adsorption layer. The tiny particles enter the curved and slender pores of the composite adsorption layer and are tightly attached to the surface of the pores under the extrusion and collision caused by the flow of the crude oil, thereby being intercepted. The wax crystal particles and wax molecular clusters escaping from the mesoporous diatomaceous earth-molecular sieve composite adsorption layer are again intercepted by the final PAN membrane, thereby greatly improving the dewaxing effect and improving the low-temperature stability of the peanut oil.

[0023] Optionally, the PAN membrane layer is a PAN membrane liquid-phase grafted with N-vinyl pyrrolidone.

[0024] By adopting the above technical solution, the hydrophilic monomer N-vinyl pyrrolidone is grafted onto the PAN membrane through the liquid phase, and the polar monomer is grafted onto the PAN membrane. When the crude oil is filtered, the wax particles or wax molecular clusters in the crude oil are more easily retained by the PAN membrane, thereby achieving a better dewaxing effect.

[0025] Optionally, the mesoporous diatomite-molecular sieve composite adsorption layer is pretreated as follows: the mesoporous diatomite-molecular sieve composite adsorption layer is mixed with an oxidized polyethylene wax emulsion, immersed for 5-10 minutes under a negative pressure of 0.05-0.08 MPa, and dried.

[0026] By adopting the above technical solution, the oxidized polyethylene wax has good polarity, so that the polar oxidized polyethylene wax is loaded inside and on the surface of the mesoporous diatomaceous earth-molecular sieve composite adsorption layer, thereby capturing polar wax particles and wax molecular clusters in the crude oil during crude oil filtration.

[0027] Optionally, the peanut skin is used to prepare peanut skin polyphenols, and the specific preparation method is as follows: the peanut skin is dried and crushed, and then extracted with n-hexane for 20-24 hours, ethanol is added, the temperature is raised to 60-65°C, stirred for 10 minutes, and microwave extracted with 480-500W for 30-40 seconds, centrifuged, and the supernatant is the peanut skin polyphenols. The material-liquid ratio of ethanol to peanut skin is 1:35-40.

[0028] By adopting the above technical solution, peanut red skin, as the main by-product in the peanut processing process, is rich in polyphenols and has strong antioxidant activity, which can be recycled and save resources.

[0029] Optionally, the peanut cake is used to prepare peanut protein powder, and the specific method is: crush the peanut cake and sieve it, add distilled water, adjust the pH to 8-8.5, extract at 60-65°C for 60-70 minutes, cool to room temperature and centrifuge, take the supernatant, adjust the pH to 4-4.5, let it stand for 30-40 minutes, centrifuge, wash the resulting precipitate, and vacuum dry it.

[0030] Peanut cake is a byproduct of peanut oil extraction. It contains approximately 40-50% peanut protein and a full range of amino acids, resulting in high nutritional value. However, most peanut cake is currently used to make feed or simply thrown away, resulting in a waste of resources. By adopting the above technical solution, peanut protein isolate is prepared from the peanut cake obtained after extraction. After extraction, the protein is deformed and its structure changes, and a large number of groups on both sides of the peptide chain backbone are inactivated, which reduces the lipophilicity of the peanut protein isolate. The resulting peanut protein powder has a high digestibility and is easily absorbed and utilized by the human body.

[0031] Optionally, the pressing temperature is 100-120° C., the pressure is 30-50 MPa, and the pressing time is 40-120 min.

[0032] By adopting the technical solution, crude oil and peanut cake are obtained by high-temperature pressing, and the high-temperature pressing makes the peanut oil have a high oil yield and a rich aroma.

[0033] Optionally, in the step of removing the red coating, the baking temperature is 60-70°C.

[0034] By adopting the above technical solution and low-temperature baking, the moisture in the peanut kernel can be slowly evaporated, and the activity of natural protein and other nutrients rich in peanuts can be maintained to the greatest extent, the removal rate of peanut red skin is high, and energy consumption can be reduced.

[0035] In a second aspect, the present application provides a high oleic peanut oil, which adopts the following technical solution:

[0036] The invention discloses high oleic peanut oil, which is prepared by a preparation process of high oleic peanut oil.

[0037] By adopting the above technical solution, the peanut oil prepared by the above preparation process has the advantages of fewer filtration times, good clarity and transparency, and is not easy to delaminate at low temperatures.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. Since the present application adopts peanut kernels with high oleic acid content as raw materials for oil extraction, the oleic acid content in the prepared peanut oil is high, and before filtering, the filtering equipment is pre-coated with a mixture of oil, diatomaceous earth and perlite to form a pre-coating layer in the filtering equipment, thereby improving the filtering efficiency, reducing the number of filtering passes and the amount of filtering raw materials used, reducing labor costs and energy consumption, and improving production efficiency. Peanut skins and peanut cakes can be used to prepare peanut skin polyphenols and peanut protein isolate, utilizing waste and improving resource utilization.

[0040] 2. In this application, the peanut oil is preferably crystallized at low temperature and then dewaxed to improve the low temperature resistance of the peanut oil to prevent the peanut oil from stratifying at low temperatures and affecting the sales appearance.

[0041] 3. In this application, a composite membrane composed of a PAN membrane, a mesoporous diatomaceous earth-molecular sieve composite adsorption layer and a PAN membrane is preferably used to filter the low-temperature crude oil, which can further capture tiny wax particles and wax molecular clusters. In addition, the mesoporous diatomaceous earth-molecular sieve composite adsorption layer and the PAN membrane are pretreated separately to make both have polar surfaces, thereby enhancing the retention of wax particles and wax molecular clusters by the mesoporous diatomaceous earth-molecular sieve composite adsorption layer and the PAN membrane, improving the low-temperature stability of peanut oil, and preventing low-temperature sealing. DETAILED DESCRIPTION

[0042] Preparation Example 1 of Peanut Protein Isolate

[0043] Preparation Example 1: Grind the peanut cake and pass it through an 80-mesh sieve, add distilled water, adjust the pH to 8.5, extract at 60°C for 60 minutes, cool to room temperature and centrifuge, take the supernatant, adjust the pH to 4.5, let it stand for 30 minutes, centrifuge at 1000 rpm for 10 minutes, wash the resulting precipitate, vacuum dry, and pass through a 20-mesh sieve.

[0044] Preparation Example 2 of Peanut Red Skin Polyphenols

[0045] Preparation Example 2: Roast peanut kernels at 70°C to a moisture content of 5.5%, quickly cool to room temperature, and remove the red skin to obtain peanut red skin;

[0046] The peanut skins were dried and crushed, then extracted with n-hexane for 24 hours, 80% ethanol by volume was added, the temperature was raised to 60°C, and the mixture was stirred at a constant temperature for 10 minutes. The mixture was extracted with a microwave at 480W for 40 seconds and centrifuged. The supernatant was the peanut skin polyphenols, and the material-liquid ratio of ethanol to peanut skin was 1:40.

[0047] Example

[0048] Example 1: A process for preparing high oleic peanut oil, comprising the following steps:

[0049] S1. Raw material selection: Select peanut kernels with an oleic acid content of more than 75%;

[0050] S2. Cleaning: Remove immature, damaged, moldy, stone-like, and metal-containing peanut kernels to ensure that the peanut kernels are full, free of damage, insects, and contain few impurities.

[0051] S3, removing peanut skins: roasting the peanut kernels at 70°C to a moisture content of 5.5%, rapidly cooling to room temperature, removing the peanut skins to obtain peanut kernels and peanut skins, and preparing peanut skin polyphenols from the peanut skins according to the method of Preparation Example 2;

[0052] S4, pressing: stir-fry the peanuts at 200° C. for 20 min and then press to obtain crude oil and peanut cake, and prepare peanut protein powder from the peanut cake according to the method in Preparation Example 1. Cool the crude oil to 15° C. over 20 min, press at a temperature of 120° C., a pressure of 30 MPa, and a pressing time of 120 min;

[0053] S5, pre-coating: Grease, diatomaceous earth and perlite were mixed in a mass ratio of 1:1:0.3 for 20 minutes. After mixing, the plate and frame filter was pre-coated in a cycle for 2 hours. The pre-coating thickness was 1.5 cm. The grease was peanut oil.

[0054] S6. Filtration: Filter the crude oil using pre-coated filtering equipment and fill with nitrogen.

[0055] Example 2: A process for preparing high oleic peanut oil, comprising the following steps:

[0056] S1. Raw material selection: Select peanut kernels with an oleic acid content of more than 75%;

[0057] S2. Cleaning: Remove immature, damaged, moldy, stone-like, and metal-containing peanut kernels to ensure that the peanut kernels are full, free of damage, insects, and contain few impurities.

[0058] S3, removing peanut skins: roasting the peanut kernels at 60°C to a moisture content of 4%, rapidly cooling to room temperature, removing the peanut skins to obtain peanut kernels and peanut skins, and preparing peanut skin polyphenols from the peanut skins according to the method of Preparation Example 2;

[0059] S4, pressing: stir-fry the peanuts at 200° C. for 20 min and then press to obtain crude oil and peanut cake. The peanut cake is prepared into peanut protein powder according to the method of Preparation Example 1. The crude oil is cooled to 20° C. over 40 min, and the pressing temperature is 100° C., the pressure is 50 MPa, and the pressing time is 40 min.

[0060] S5, pre-coating: Grease, diatomaceous earth and perlite were mixed in a mass ratio of 1:0.5:0.5 for 20 minutes. After mixing, the plate and frame filter was pre-coated in a cycle for 1.5 hours. The thickness of the pre-coating layer was 1 cm. The grease was peanut oil.

[0061] S6. Filtration: Filter the crude oil using a pre-coated plate and frame filter and fill with nitrogen.

[0062] Example 3: A preparation process for high oleic peanut oil, which differs from Example 1 in that, in step S4, the crude oil cooled to 15°C is rapidly cooled to 6°C within 1 minute, seed crystals are added, and the mixture is stirred and crystallized at 6°C at a speed of 60 r / min for 24 hours, and then the temperature is raised to 15°C. The seed crystals are made by mixing a filter aid and peanut oil in a mass ratio of 1:0.5, the filter aid is diatomaceous earth, and the amount of seed crystals added is 0.1% of the total weight of the crude oil.

[0063] Example 4: A process for preparing high oleic peanut oil, which differs from Example 1 in that, in step S4, the crude oil cooled to 20°C is rapidly cooled to 8°C within 1 min, seed crystals are added, and the mixture is stirred and crystallized at 8°C at a speed of 80 r / min for 18 hours, and then the temperature is raised to 20°C. The seed crystals are made by mixing a filter aid and peanut oil in a mass ratio of 1:0.1, the filter aid is diatomaceous earth, and the amount of seed crystals added is 0.05% of the total weight of the crude oil.

[0064] Example 5: A process for preparing high oleic peanut oil, which differs from Example 1 in that the crude oil filtered in step S5 is cooled to 8°C and filtered using a composite membrane, wherein the composite membrane includes a PAN membrane layer, a mesoporous diatomaceous earth-molecular sieve composite layer and a PAN membrane layer.

[0065] The composite membrane was prepared by mixing mesoporous diatomite and molecular sieve and pressing at a pressure of 0.05 MPa for 5 seconds to obtain a mesoporous diatomite-molecular sieve composite layer with a thickness of 3 cm. The mesoporous diatomite particle size was 300 nm, and the molecular sieve was Siliclite-1.

[0066] The PAN membranes were respectively attached to both sides of the mesoporous diatomite-molecular sieve composite layer and pressed at a pressure of 0.01 MPa for 3 seconds to obtain a composite membrane.

[0067] Example 6: A preparation process for high oleic peanut oil. The difference from Example 5 is that the mesoporous diatomaceous earth-molecular sieve composite layer is pretreated as follows: the mesoporous diatomaceous earth-molecular sieve composite adsorption layer is mixed with the oxidized polyethylene wax emulsion, immersed for 5 minutes under the action of a negative pressure of 0.08 MPa, and dried. The mass ratio of the mesoporous diatomaceous earth-molecular sieve composite layer to the oxidized polyethylene wax emulsion is 1:0.3.

[0068] Example 7: A preparation process of high oleic peanut oil. The difference from Example 5 is that the PAN membrane layer is a PAN membrane liquid-phase grafted with N-vinyl pyrrolidone. The specific liquid-phase grafting method is: the PAN membrane is irradiated with 50W plasma for 60s under a pressure of 15Pa, and the N-vinyl pyrrolidone monomer with a concentration of 5wt% is subjected to two freeze-thaw cycle degassing treatments with liquid nitrogen. Then, the N-vinyl pyrrolidone monomer is introduced into a reaction chamber, and the reaction chamber is placed on a constant temperature shaker for grafting reaction. The grafting reaction time is 4h, and the reaction temperature is 50°C.

[0069] Example 8: A process for preparing high oleic peanut oil, which differs from Example 5 in that:

[0070] The mesoporous diatomite-molecular sieve composite layer was pretreated as follows: the mesoporous diatomite-molecular sieve composite adsorption layer was mixed with an oxidized polyethylene wax emulsion, immersed for 5 minutes under a negative pressure of 0.08 MPa, and dried. The mass ratio of the mesoporous diatomite-molecular sieve composite layer to the oxidized polyethylene wax emulsion was 1:0.3.

[0071] The PAN membrane layer is a PAN membrane liquid-phase grafted with N-vinyl pyrrolidone. The specific liquid-phase grafting method is as follows: the PAN membrane is irradiated with 50W plasma for 60s under a pressure of 15Pa, and the N-vinyl pyrrolidone monomer with a concentration of 5wt% is subjected to two freeze-thaw cycle degassing treatments with liquid nitrogen. Then, the N-vinyl pyrrolidone monomer is introduced into the reaction chamber, and the reaction chamber is placed on a constant temperature shaker for grafting reaction. The grafting reaction time is 4h and the reaction temperature is 50°C.

[0072] Example 9: A process for preparing high oleic peanut oil, which differs from Example 1 in that:

[0073] In step S4, the crude oil cooled to 20° C. is rapidly cooled to 8° C. within 1 minute, seed crystals are added, and the mixture is stirred and crystallized at 8° C. at a speed of 80 r / min for 18 hours, and then the temperature is raised to 20° C. The seed crystals are prepared by mixing a filter aid and peanut oil in a mass ratio of 1:0.1, the filter aid is diatomaceous earth, and the amount of seed crystals added is 0.05% of the total weight of the crude oil;

[0074] The crude oil filtered in step S5 is cooled to 8° C. and filtered with a composite membrane, wherein the composite membrane includes a PAN membrane layer, a mesoporous diatomaceous earth-molecular sieve composite layer and a PAN membrane layer. The mesoporous diatomaceous earth-molecular sieve composite layer is pretreated as follows: the mesoporous diatomaceous earth-molecular sieve composite adsorption layer is mixed with an oxidized polyethylene wax emulsion, immersed for 5 minutes under a negative pressure of 0.08 MPa, and dried. The mass ratio of the mesoporous diatomaceous earth-molecular sieve composite layer to the oxidized polyethylene wax emulsion is 1:0.3; the PAN membrane layer is liquid-phase grafted with N-vinyl pyrrolidone on the PAN membrane. The specific liquid-phase grafting method is as follows: the PAN membrane is irradiated with a 50W plasma for 60 seconds under a pressure of 15 Pa, and a 5wt% N-vinyl pyrrolidone monomer is subjected to two freeze-thaw cycle degassing treatments with liquid nitrogen. Then, the N-vinyl pyrrolidone monomer is introduced into a reaction chamber, and the reaction chamber is placed on a constant temperature shaker for a grafting reaction. The grafting reaction time is 4 hours and the reaction temperature is 50° C. The composite membrane was prepared by mixing mesoporous diatomite and molecular sieve and pressing at a pressure of 0.05 MPa for 5 seconds to obtain a mesoporous diatomite-molecular sieve composite layer with a thickness of 3 cm. The mesoporous diatomite had a particle size of 300 nm and the molecular sieve was Siliclite-1.

[0075] The PAN membranes were respectively attached to both sides of the mesoporous diatomite-molecular sieve composite layer and pressed at a pressure of 0.01 MPa for 3 seconds to obtain a composite membrane.

[0076] Comparative Example

[0077] Comparative Example 1: A preparation process for high oleic peanut oil. The difference from Example 1 is that the plate and frame filter is not pre-coated, and the crude oil is filtered using the plate and frame filter without pre-coating.

[0078] Comparative Example 2: A preparation process of high oleic peanut oil, which differs from Example 1 in that diatomaceous earth is not added during pre-coating.

[0079] Comparative Example 3: A production process for organic peanut oil, comprising the following steps:

[0080] Cleaning, stone removal, grading and color sorting of organic peanuts produced in the selected base;

[0081] Roasting: Using an ozone generator to remove aflatoxin and other harmful bacteria in the raw materials, the ozone concentration is 80 mg / L, the temperature is controlled at 30°C, the stirring speed is 100 rpm, and the treatment time is 30 minutes; the pretreated peanut raw materials are roasted at 100°C for 15 minutes, and then 1 times the weight of water is added to beat the roasted peanuts into a pulp to prepare peanut pulp, and then the enzymatic hydrolysis product is heat-treated at 150°C for 20 minutes, cooled, and centrifuged; 1% by weight of a composite protease is added to the peanut pulp, and enzymatic hydrolysis is carried out, and the pH is adjusted to 7.2 to obtain an enzymatic hydrolysis product; the composite protease is prepared by: Alcalase protease (Novozymes), Flavourzyme flavor enzyme (Novozymes), and fructose in a weight ratio of 1:1:3;

[0082] Pressing: The temperature of the twin-screw oil press is controlled at 90°C and the screw speed is 15 rpm to obtain virgin peanut oil; the virgin peanut oil is coarsely filtered through a leaf filter to obtain coarse filtered peanut oil;

[0083] Filtering crude oil: filtering the coarse crude oil to obtain filtered crude oil;

[0084] Primary cooling: The temperature of the filtered crude oil sent from the press workshop is generally 60℃. In order to save energy, it is first cooled with tap water at 30rpm until the temperature drops to close to room temperature.

[0085] Add filter aid: the amount of filter aid added is about 0.1% of the weight of the oil, and the filter aid is prepared in a weight ratio of perlite: diatomaceous earth: activated carbon = 2:1:1;

[0086] Second cooling: Use frozen brine to cool the peanut oil to 10℃ under low-speed stirring, then keep it warm and let it settle for 48 hours;

[0087] Filtration: After settling for 48 hours, the crude oil is pumped into a plate and frame filter press for filtration, and the resulting finished oil can be packaged.

[0088] Performance testing

[0089] 1. Peanut oil quality test: The peanut oils prepared in Examples 1-3 and Comparative Examples 1-3 were sampled and tested according to GB / T1534 "Peanut Oil". The test results are recorded in Table 1.

[0090] Table 1 Quality inspection of high oleic peanut oil

[0091]

[0092] From the data in Table 1, it can be seen that the use of a mixture of diatomaceous earth, grease and perlite to pre-coat the plate and frame filter can reduce the content of insoluble impurities in the finished product after filtration, and can achieve the effect of multiple filtration. This shows that the pre-coated plate and frame filter can effectively reduce the insoluble impurities in the crude oil, reduce the number of filtration passes, reduce the use of filtration materials, reduce labor costs and energy consumption, and improve efficiency.

[0093] In Comparative Example 1, diatomaceous earth, grease and perlite were not used to pre-coat the plate and frame filter. In Comparative Example 2, diatomaceous earth was not used during pre-coating. Compared with Example 1, the content of insoluble impurities in the high oleic peanut oil prepared in Comparative Example 1 and Comparative Example 2 increased.

[0094] 2. Low-temperature stratification performance test of peanut oil: 10 ml of oil sample was taken from each of the high oleic peanut oil prepared in Examples 1-10 and the peanut oil prepared in Comparative Example 3 as a test sample. Five samples were taken from each Example. The samples were kept warm at 4°C for 72 hours. Whether the samples were stratified was measured. If stratification occurred, the height of the lower crystal precipitate was measured. The test results were recorded in Table 2 by taking the average of the five test values.

[0095] Table 2 Low temperature stratification effect of high oleic peanut oil

[0096] project Whether to layer Height of lower crystal precipitation / ml Example 1 yes 7.5 Example 2 yes 7.6 Example 3 yes 5.4 Example 4 yes 5.6 Example 5 yes 5.0 Example 6 yes 3.6 Example 7 yes 3.9 Example 8 yes 1.5 Example 9 no No precipitation Comparative Example 3 no Completely solidified

[0097] It can be seen from the data in Table 2 that the high oleic peanut oil prepared in Example 1 and Example 2 has stratification at the bottom of the sample under a low temperature environment of 4°C, and the volume of the lower layer of crystal precipitation accounts for a large proportion; in Example 3 and Example 4, after the high oleic peanut oil is frozen, seed crystals are added to facilitate crystallization, thereby dewaxing, and the low-temperature resistance of the high oleic peanut oil prepared in this way is improved, and the stratification phenomenon is not obvious in a low-temperature environment; and in Example 5, an organic membrane-inorganic membrane-organic membrane is used for low-temperature filtration, and the volume of the lower layer of crystal precipitation of the high oleic peanut oil prepared in this way is reduced at 4°C compared with Example 1; Compared with Example 5, Example 6 uses an oxidized polyethylene wax emulsion to treat the mesoporous diatomaceous earth-molecular sieve composite adsorption layer, and the obtained The adsorption capacity of the mesoporous diatomaceous earth-molecular sieve is enhanced, and the dewaxing effect is improved; compared with Example 5, Example 7 is a composite membrane prepared by liquid-phase grafting of the hydrophilic monomer N-vinyl pyrrolidone on the PAN membrane, which has a better dewaxing effect on the crude oil; compared with Example 5, Example 8 not only pre-treats the mesoporous diatomaceous earth-molecular sieve composite adsorption layer, but also grafts N-vinyl pyrrolidone on the PAN membrane. In Example 8, the stratification of peanut oil under low temperature environment is further improved, and the volume of the lower layer precipitation is further reduced; in Example 9, not only crystal seeds are used for crystallization filtration, but the filtered crude oil is also subjected to organic membrane-inorganic membrane-organic membrane filtration and degumming. The obtained peanut oil does not produce precipitation at low temperature and remains clear and transparent.

[0098] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A preparation process for high oleic peanut oil, characterized in that: The following steps are involved: Raw material selection: Choose peanut kernels with an oleic acid content of more than 75%; Cleaning: remove immature, broken, moldy, pebbles and metals from peanut kernels; Removing the red skin: roasting the peanut kernels until the moisture content is 4-5.5%, cooling to room temperature, and removing the red skin to obtain peanut kernels and peanut red skin; Pressing: Stir-fry the peanuts and press them to obtain crude oil and peanut cakes. Cool the crude oil to 15-20℃ in 20-40 minutes; Pre-coating: Mix grease, diatomaceous earth and perlite in a mass ratio of 1:0.5-1:0.3-0.5 for 20-30 minutes. After mixing, circulate pre-coating on the filter equipment for 1.5-2 hours. After the crude oil is cooled to 15-20°C, it is subjected to the following pretreatment and then filtered: The crude oil cooled to 15-20°C is rapidly cooled to 6-8°C within 1 minute, and seed crystals are added. The seed crystals are made of filter aid and peanut oil. The seed crystals are stirred and crystallized at 6-8°C for 18-24 hours, and then heated to 15-20°C. The amount of seed crystals added is 0.05-0.1% of the total weight of the crude oil. The mass ratio of filter aid to peanut oil in the seed crystals is 1:0.1-0.5; Filtration: Filter the crude oil with a pre-coated filter device, cool the filtered crude oil to 8-12°C, and filter it with a composite membrane. The composite membrane includes a PAN membrane layer, a mesoporous diatomaceous earth-molecular sieve composite adsorption layer and a PAN membrane layer, and then fill it with nitrogen.

2. The preparation process of high oleic peanut oil according to claim 1, wherein: The thickness of the pre-coating layer is 1-1.5 cm.

3. The preparation process of high oleic peanut oil according to claim 1, wherein The stirring speed during the crystallization is 60-80 r / min.

4. The preparation process of high oleic peanut oil according to claim 1, wherein The PAN film layer is a PAN film liquid-phase grafted with N-vinyl pyrrolidone.

5. The preparation process of high oleic peanut oil according to claim 1, wherein The mesoporous diatomite-molecular sieve composite adsorption layer is pretreated as follows: the mesoporous diatomite-molecular sieve composite adsorption layer is mixed with oxidized polyethylene wax emulsion, immersed for 5-10 minutes under a negative pressure of 0.05-0.08 MPa, and dried.

6. The preparation process of high oleic peanut oil according to claim 1, characterized in that: The pressing temperature is 100-120° C., the pressure is 30-50 MPa, and the pressing time is 40-120 min.

7. A high oleic peanut oil, characterized in that The peanut oil is prepared by the preparation process of the high oleic peanut oil according to any one of claims 1 to 6.

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