High-nutrition flavored peanut oil and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and discloses high-nutrition flavored peanut oil and a preparation method thereof.The method comprises the following steps that S1, peanut skin, peanut kernels and optional peanut plants are mixed, and a solid mixture is obtained; mixing the solid mixture with a first solvent, sequentially carrying out first extraction and first solid-liquid separation, mixing a solid phase obtained by the first solid-liquid separation with a second solvent, sequentially carrying out second extraction and second solid-liquid separation, and mixing a liquid phase obtained by the first solid-liquid separation with a liquid phase obtained by the second solid-liquid separation to obtain mixed supernate; taking a solid phase obtained by the second solid-liquid separation as peanut mixed powder for later use; the first solvent and the second solvent are respectively and independently polar solvents or moderate polar solvents, and the first solvent and the second solvent are different; s2, concentrating the mixed supernatant to obtain a concentrated solution; and S3, squeezing the peanut mixed powder, and mixing the obtained grease with the concentrated solution.

Description

Technical Field

[0001] The present invention relates to the technical field of food oil processing, and particularly relates to a highly nutritious flavored peanut oil and a preparation method thereof. Background Art

[0002] Peanuts are an important oil crop, ranking fourth among the world's major oil crops in terms of production. China is a major peanut-growing country. From 2021 to 2022, China's peanut production was approximately 18.31 million tons, accounting for about 36.36% of the global peanut production. At the same time, China is also the largest peanut consumer, with about 55% of peanuts being used for oil extraction. Peanut oil accounts for about 23% of domestic vegetable oils and is one of the important flavored edible vegetable oils in China, deeply loved by consumers for its rich and strong flavor.

[0003] In recent years, influenced by factors such as the improvement of living standards, consumers are not only concerned about the flavor of peanut oil but also pay more attention to its "nutritional" properties. Peanuts are a plant with extremely high nutritional value. For example, peanut skins are rich in polar compounds such as proanthocyanidins with anti-inflammatory effects, and parts such as peanut roots and peanut shells are rich in various medium-polar compounds such as luteolin and resveratrol with antioxidant effects. Peanut fruits and other parts are rich in non-polar compounds such as vitamin E and phytosterols. However, in the actual processing and production process, parts such as peanut roots and peanut skins are mostly discarded as waste, resulting in serious waste of resources and nutrients. Additionally, it should be noted that parts such as peanut skins are directly exposed to the external environment and are easily infected by harmful substances such as aflatoxin, causing the enrichment and transfer of harmful substances to peanut oil.

[0004] Research on the Key Technologies for Quality Control of Aromatic Peanut Oil (Yang Min, Cereals and Foods Industry, 2019, 6: 26) determined the optimal roasting temperature and roasting time by studying the effects of roasting temperature and time of peanut kernels during roasting on the production of benzo[a]pyrene and nutritional elements (vitamin E, sterols, and squalene) in aromatic peanut oil, and obtained the optimal process parameters for the production of aromatic peanut oil. The peanut oil prepared by this method has a relatively low content of nutritional elements.

[0005] CN116869050A discloses a preparation method of peanut oil rich in plant polyphenols. This method prepares peanut oil rich in plant polyphenols through ultrafine pulverization of peanut skins, water extraction ultrasonic cell disruption treatment, heating and stirring with peanut oil, and centrifugal extraction. Among them, some polyphenolic substances soluble in water are extracted by water extraction, and the content of some polyphenolic compounds in the obtained peanut oil is relatively high, while the contents of resveratrol, vitamin E, etc. are relatively low.

[0006] In summary, the existing preparation processes of flavored peanut oil mainly focus on optimizing process parameters such as frying time and frying temperature to enhance the flavor of peanut oil, but do not consider improving the nutritional components of flavored peanut oil. The content of micronutrients in the prepared peanut oil is low and the types of nutrient elements are single. Summary of the Invention

[0007] The object of the present invention is to overcome the problems existing in the prior art that the nutrients and flavor in peanut oil cannot be both present, the content of micronutrient elements in peanut oil is low, and the types of nutrient elements are single. The present invention provides a highly nutritious flavored peanut oil and a preparation method thereof. The peanut oil prepared by this method is rich in various nutrient elements and has a good flavor.

[0008] To achieve the above object, in the first aspect of the present invention, a preparation method of nutritious peanut oil is provided. The method comprises the following steps:

[0009] S1. Mix peanut skins, peanut kernels and optional peanut plants to obtain a solid mixture; mix the solid mixture with a first solvent and perform first extraction and first solid-liquid separation in sequence. Mix the solid phase obtained from the first solid-liquid separation with a second solvent and perform second extraction and second solid-liquid separation in sequence. Mix the liquid phase obtained from the first solid-liquid separation with the liquid phase obtained from the second solid-liquid separation to obtain a mixed supernatant, and reserve the solid phase obtained from the second solid-liquid separation as peanut mixed powder; the first solvent and the second solvent are each independently a polar solvent or a medium-polar solvent and the first solvent and the second solvent are different;

[0010] S2. Concentrate the mixed supernatant to obtain a concentrated solution;

[0011] S3. Press the peanut mixed powder to obtain oil and mix it with the concentrated solution.

[0012] In the second aspect of the present invention, a preparation method of highly nutritious flavored peanut oil is provided. The method comprises the following steps:

[0013] (1) Subject the peanut raw material to pre-baking, frying and pressing in sequence to obtain strongly fragrant peanut oil;

[0014] (2) Mix the nutritious peanut oil prepared by the method of the first aspect of the present invention with the strongly fragrant peanut oil and optional emulsifier to obtain a composite peanut oil.

[0015] In the third aspect of the present invention, a composite peanut oil prepared by the method of the present invention is provided.

[0016] By the above technical solutions, the technical solutions of the present invention at least achieve the following beneficial effects:

[0017] (1) By using the method of the present invention, various nutrient elements can be extracted simultaneously from different parts of peanuts, enriching the types of nutrient elements in peanut oil and further enhancing the nutritional value of peanut oil;

[0018] (2) By using the method of the present invention, the loss of nutrient elements can be effectively reduced, and the content of nutrient elements in peanut oil can be further increased;

[0019] (3) The peanut oil prepared by using the method of the present invention does not contain harmful substances, has high nutritional value and rich aroma;

[0020] (4) By using the method of the present invention, different parts of peanuts can be fully utilized, resource waste can be reduced, and the comprehensive utilization of peanut plants can be realized. Specific embodiments

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] The first aspect of the present invention provides a method for preparing nutritious peanut oil, and the method includes the following steps:

[0023] S1. Mix peanut skins, peanut kernels and optional peanut plants to obtain a solid mixture; mix the solid mixture with a first solvent and perform first extraction and first solid-liquid separation in sequence. Mix the solid phase obtained from the first solid-liquid separation with a second solvent and perform second extraction and second solid-liquid separation in sequence. Mix the liquid phase obtained from the first solid-liquid separation with the liquid phase obtained from the second solid-liquid separation to obtain a mixed supernatant. Reserve the solid phase obtained from the second solid-liquid separation as peanut mixed powder; the first solvent and the second solvent are each independently a polar solvent or a medium-polar solvent and the first solvent and the second solvent are different;

[0024] S2. Concentrate the mixed supernatant to obtain a concentrated solution;

[0025] S3. Press the peanut mixed powder, and mix the obtained oil with the concentrated solution.

[0026] In the present invention, the order of mixing the solid mixture with the polar solvent and the medium-polar solvent is not particularly limited. In addition to first mixing the solid mixture (peanut red skin, peanut kernels, and optionally peanut plants) with the polar solvent for the first extraction and the first solid-liquid separation according to the method of the present invention, and then mixing the solid phase obtained from the first solid-liquid separation with the medium-polar solvent for the second extraction and the second solid-liquid separation, it is also possible to first mix the solid mixture (peanut red skin, peanut kernels, and optionally peanut plants) with the medium-polar solvent for the first extraction and the first solid-liquid separation, and then mix the solid phase obtained from the first solid-liquid separation with the polar solvent for the second extraction and the second solid-liquid separation.

[0027] In the present invention, the peanut kernels in the solid mixture can also be replaced with peanut raw materials (peanut kernels with red skin). If peanut raw materials are mixed with peanut red skin, the peanut raw materials provide the peanut red skin, and the amount of peanut red skin can be reduced accordingly.

[0028] In the present invention, the peanut red skin is obtained by roasting and winnowing the peanut raw materials to separate the peanut kernels and the seed coat.

[0029] Preferably, the conditions for roasting include: the roasting temperature is 80-120°C, and the roasting time is 5-20 min. The separation of the peanut kernels and the seed coat is carried out in a winnowing machine.

[0030] To improve the extraction efficiency of the nutrient elements in the solid mixture, preferably, in S1, the solid mixture also includes a crushing treatment, and the conditions of the crushing treatment are such that the particle size of the crushed material is 5-100 mesh. "Mesh" refers to the mesh number of the sieve through which the crushed material obtained after the crushing treatment of the solid mixture can pass, that is, the particle size of the crushed material is 0.15 mm-4 mm.

[0031] In the present invention, there is no particular requirement for the method of the crushing treatment, and a crusher of model Xulang A230 can be used for crushing.

[0032] According to some embodiments of the present invention, in S1, the first extraction and the second extraction are each independently ultrasonic extraction.

[0033] Preferably, the conditions for ultrasonic extraction include: the ultrasonic power is 200-500 W, preferably 450 W-500 W; the ultrasonic temperature is 25-40°C.

[0034] In the present invention, there is no particular limitation on the time of ultrasonic extraction, which can be adjusted according to the actual situation. Preferably, the time of ultrasonic extraction is 20-60 min.

[0035] According to some embodiments of the present invention, in S1, the mass ratio of peanut red skin, peanut kernels, and peanut plants is 1:(3 - 50):(1 - 30), preferably 1:(3 - 50):(25 - 30).

[0036] According to some embodiments of the present invention, wherein the peanut plants are selected from at least one of peanut roots, peanut shells, peanut stems, and peanut leaves. Preferably, the peanut plants are a mixture of peanut roots, peanut stems, and peanut leaves, wherein the weight ratio of peanut roots, peanut stems, and peanut leaves is 1:(1 - 40):(1 - 30).

[0037] According to some embodiments of the present invention, in S1, the polar solvent is selected from solvents with a polarity not less than that of acetone, preferably at least one of ethylene glycol, methanol, water, and acetonitrile, preferably water and / or methanol; the medium-polarity solvent is selected from solvents with a polarity not greater than that of ethanol, preferably at least one of dichloromethane, ether, ethanol, and butanol, preferably ethanol and / or butanol.

[0038] According to some embodiments of the present invention, in S1, the mass ratio of the solid mixture to the polar solvent is 1:(1 - 20), preferably 1:(6 - 10); the mass ratio of the solid mixture to the medium-polarity solvent is 1:(1 - 20), preferably 1:(1 - 4).

[0039] According to some embodiments of the present invention, in S2, the concentration conditions are such that the evaporation rate of the solvent in the mixed supernatant is ≥60%.

[0040] In the present invention, the concentration method uses vacuum low-temperature concentration. Preferably, the concentration conditions include: the vacuum degree is -0.09 MPa - 0 MPa; the temperature is 20 - 80 °C.

[0041] Preferably, in S2, the method further includes an adsorption treatment. In the present invention, the order of concentration and adsorption treatment is not particularly limited, but in order to improve production efficiency, preferably, the mixed supernatant is concentrated and then subjected to adsorption treatment.

[0042] Preferably, the adsorption treatment method includes: mixing the concentrated solution with an adsorbent.

[0043] Preferably, the adsorbent is selected from at least one of resin, activated carbon, bentonite, and activated clay.

[0044] Preferably, based on the mass of the concentrated solution, the dosage of the adsorbent is 0.05 wt% - 5 wt%.

[0045] Preferably, the adsorption treatment time is 20 - 40 min.

[0046] According to some embodiments of the present invention, in S3, the temperature of the pressing is 50 - 100 °C.

[0047] In the present invention, the pressing method includes pressing the peanut mixed powder in a hydraulic press to obtain crude peanut oil. The temperature of the pressing refers to the temperature of the pressing chamber controlled by the hydraulic press during the extrusion process. The hydraulic press is purchased from Shandong Qiangxing Machinery Equipment Co., Ltd., and the product model is HC500 - B.

[0048] In the present invention, preferably, the method further includes performing hydration, sedimentation, and fine filtration on the oil obtained after pressing, wherein the hydration, sedimentation, and fine filtration are all performed before the oil is mixed with the concentrated solution.

[0049] In the present invention, the hydration method includes mixing the crude peanut oil obtained after pressing with a hydration agent to obtain semi - clear oil.

[0050] Preferably, the hydration agent is selected from water and / or sodium chloride; the mass concentration of the sodium chloride is 0.5 wt% - 10 wt%.

[0051] Preferably, based on the mass of the crude peanut oil, the dosage of the hydration agent is 0.5 wt% - 2.5 wt%.

[0052] Preferably, the temperature of the hydration is 20 - 35 °C.

[0053] In the present invention, the sedimentation method includes allowing the semi - clear oil to stand in a temporary storage tank for 36 - 48 h, draining the oil sludge, and obtaining semi - finished oil.

[0054] In the present invention, the fine filtration method includes performing first - stage filtration and second - stage filtration on the semi - finished oil through a cardboard filter and a bag filter respectively. Preferably, the pore size of the cardboard filter is 0.2 μm - 20 μm; the pore size of the bag filter is 0.5 μm - 2 μm.

[0055] Preferably, the filtration pressure of the first - stage filtration and the second - stage filtration is independently 0.1 MPa - 2 MPa.

[0056] The second aspect of the present invention provides a method for preparing a highly nutritious flavored peanut oil, the method comprising the following steps:

[0057] (1) Pre - roasting, roasting, and pressing the peanut raw materials in sequence to obtain strongly - flavored peanut oil;

[0058] (2) Mixing the nutritious peanut oil prepared by the method of the first aspect of the present invention with the strongly - flavored peanut oil and an optional emulsifier to obtain a composite peanut oil.

[0059] According to some embodiments of the present invention, in step (1), the conditions of the pre-roasting and frying are such that the peanut skin removal rate of the peanut raw material is ≥50%, preferably ≥80%.

[0060] Preferably, in step (1), the conditions of the pre-roasting and frying include: the roasting and frying temperature is 80 - 120 °C.

[0061] In the present invention, there is no particular limitation on the roasting and frying time for the pre-roasting and frying. Preferably, the roasting and frying time is 5 - 20 min.

[0062] According to some embodiments of the present invention, in step (1), the conditions of the frying include: the frying temperature is 130 - 200 °C, and the frying time is 15 - 45 min.

[0063] In the present invention, the pressing of the peanut raw material is carried out using a screw oil press purchased from Shandong Qiangxing Machinery Equipment Co., Ltd., with the model of HC500 - B.

[0064] In the present invention, the method further includes subjecting the crude oil obtained after pressing the peanut raw material to hydration, sedimentation, and fine filtration treatments. Among them, the methods and process parameters of the hydration, sedimentation, and fine filtration treatments are the same as those described above, and will not be elaborated here.

[0065] According to some embodiments of the present invention, in step (2), the emulsifier is selected from at least one of polyglycerol fatty acid ester, sodium stearoyl lactate, calcium stearoyl lactate, and sucrose fatty acid ester.

[0066] According to some embodiments of the present invention, in step (2), the mass ratio of the nutritious peanut oil to the strongly fragrant peanut oil is 1:(0.1 - 20), preferably 1:(5 - 10).

[0067] Preferably, the addition amount of the emulsifier is 0.5 wt% - 1 wt% of the total mass of the nutritious peanut oil and the strongly fragrant peanut oil.

[0068] In the present invention, to simplify the hydration, sedimentation, and fine filtration processes of the crude oil, in a specific embodiment provided by the present invention, the crude oil obtained after pressing the peanut mixed powder (the peanut mixed powder obtained after solid-liquid separation after the peanut skin, peanut kernel, and peanut plant are successively extracted with polar solvents and medium-polar solvents) is mixed with the crude oil obtained after pressing the peanut raw material, and then subjected to hydration, sedimentation, and fine filtration treatments. The obtained mixed oil is then mixed with the concentrated liquid to prepare a highly nutritious flavored peanut oil.

[0069] The third aspect of the present invention provides a composite peanut oil prepared by the method of the present invention.

[0070] According to a particularly preferred embodiment of the present invention, a method for preparing a highly nutritious flavored peanut oil is provided, and the method comprises the following steps:

[0071] S1. Pre-roast the peanut raw materials at 90 - 120 °C for 10 - 20 min, perform air separation treatment by an air separator, separate to obtain peanut kernels and peanut red skins, and the removal rate of red skins is ≥80%;

[0072] S2. Roast the peanut kernels at 150 - 200 °C for 20 - 45 min, and perform pressing by a screw oil press to obtain the first crude oil;

[0073] S3. Mix peanut red skins, peanut kernels and peanut plants (the peanut plants include peanut roots, peanut stems and peanut leaves, and the mass ratio of peanut roots, peanut stems and peanut leaves is 1:(5 - 40):(1 - 30)) according to a mass ratio of 1:(40 - 50):(25 - 30), and crush the obtained solid mixture to 50 - 100 meshes; mix the crushed solid mixture with water according to a mass ratio of 1:(6 - 10), and perform first ultrasonic extraction and first solid-liquid separation in sequence to obtain a first supernatant and a first solid phase; mix the first solid phase and ethanol (the mass ratio of ethanol to the solid mixture is (10 - 20):1), and perform second ultrasonic extraction and second solid-liquid separation in sequence to obtain a second supernatant and a second solid phase; finally, combine the first and second supernatants to obtain a mixed supernatant, and reserve the second solid phase as peanut mixed powder;

[0074] Among them, the conditions of the first ultrasonic extraction and the second ultrasonic extraction are each independently that the ultrasonic power is 460 - 500 W, the ultrasonic temperature is 30 - 40 °C, and the ultrasonic time is 40 - 60 min;

[0075] S4. Concentrate the mixed supernatant at 60 - 80 °C under a vacuum degree of -0.09 MPa to -0.05 MPa, so that the solvent evaporation rate in the mixed supernatant is ≥80%; add activated clay accounting for 0.5 - 5 wt% of the weight of the mixed supernatant to the evaporated supernatant, perform adsorption treatment for 20 - 40 min, and filter to obtain a concentrated solution;

[0076] S5. Perform low-temperature pressing on the peanut mixed powder at 55 - 65 °C to obtain a second crude oil, mix the first crude oil in S2 and the second crude oil, and perform hydration (add an NaCl solution accounting for 1.5 - 2.5 wt% of the total mass of the first crude oil and the second crude oil, and the mass concentration of the NaCl solution is 0.5 - 10 wt%), sedimentation (stand still in a storage tank for 36 - 48 h), and fine filtration (filter through a cardboard filter and a bag filter) treatment in sequence to obtain an oil, and then mix it with the concentrated solution in S4 to obtain a composite peanut oil;

[0077] Among them, the mass ratio of the first crude oil to the total mass of the second crude oil and the concentrated solution is (5 - 10):1;

[0078] S6. Add polyglycerol fatty acid esters with a mass of 0.5 wt% - 1 wt% of the oil mass to the above compound peanut oil, and compound to obtain a finished product of flavored peanut kernel oil with appropriate flavor and high nutritional quality.

[0079] The present invention will be described in detail below through examples.

[0080] In the following examples, the screw oil press was purchased from Shandong Qiangxing Machinery Equipment Co., Ltd., and the product model was HC500 - B.

[0081] In the following examples and comparative examples, unless otherwise specified, the ethanol solvent refers to 94.9% anhydrous ethanol.

[0082] Unless otherwise specified, the materials are commercially available products.

[0083] Example 1

[0084] S1. Preheat and stir - fry the peanut raw materials at 90 °C for 10 min, and perform air - separation treatment using an air - separator to separate peanut kernels and peanut red skins, with a red - skin removal rate of 90%;

[0085] S2. Stir - fry the peanut kernels at 150 °C for 20 min, and perform pressing using a screw oil press to obtain the first crude oil;

[0086] S3. Mix peanut red skins, peanut kernels, and peanut plants (peanut plants include peanut roots, peanut stems, and peanut leaves, and the mass ratio of peanut roots, peanut stems, and peanut leaves is 1:5:1) according to a mass ratio of 1:40:30, and crush the obtained solid mixture to 50 meshes; mix the crushed solid mixture with water according to a mass ratio of 1:10, and perform the first ultrasonic extraction and the first solid - liquid separation in sequence to obtain the first supernatant and the first solid phase; mix the first solid phase with ethanol (the mass ratio of ethanol to the solid mixture is 10:1) and perform the second ultrasonic treatment and the second solid - liquid separation in sequence to obtain the second supernatant and the second solid phase; finally, combine the first and second supernatants to obtain a mixed supernatant, and use the second solid phase as peanut mixed powder for standby;

[0087] Among them, the conditions of the first ultrasonic extraction and the second ultrasonic extraction are each independently an ultrasonic power of 460 W, an ultrasonic temperature of 30 °C, and an ultrasonic time of 40 min;

[0088] S4. Concentrate the mixed supernatant at 60 °C and a vacuum degree of - 0.05 MPa so that the solvent evaporation rate in the mixed supernatant is 90%; add activated clay with a mass of 0.5 wt% of the weight of the evaporated supernatant to the evaporated supernatant, perform adsorption treatment for 20 min, and filter to obtain a concentrated solution;

[0089] S5. The peanut mixed powder is cold-pressed at 60°C to obtain the second crude oil. The first crude oil in S2 and the second crude oil are mixed and then subjected to hydration (adding a NaCl solution with a mass of 1.5 wt% of the total mass of the first crude oil and the second crude oil, and the mass concentration of the NaCl solution is 10 wt%), sedimentation (standing in a storage tank for 36 h), and fine filtration (filtering through a cardboard filter and a bag filter) in sequence to obtain the oil, which is then mixed with the concentrate in S4 to obtain the compound peanut oil;

[0090] Among them, the mass ratio of the first crude oil to the total mass of the second crude oil and the concentrate is 5:1;

[0091] S6. Add polyglycerol fatty acid ester with a mass of 0.5 wt% of the oil mass to the above compound peanut oil, and compound to obtain the finished product of flavored peanut oil with appropriate flavor and high nutritional quality.

[0092] Example 2

[0093] According to the method of Example 1, the difference is that in S2, the peanut kernels are roasted at 130°C for 15 min.

[0094] Example 3

[0095] According to the method of Example 1, the difference is that in S2, the peanut kernels are stir-fried at 200°C for 35 min.

[0096] Example 4

[0097] According to the method of Example 1, the difference is that in S3, peanut red skins, peanut kernels, and peanut plants (the peanut plants include peanut roots, peanut stems, and peanut leaves, and the mass ratio of peanut roots, peanut stems, and peanut leaves is 1:5:1) are mixed at a mass ratio of 1:10:30.

[0098] Example 5

[0099] According to the method of Example 1, the difference is that in S3, the solid mixture obtained by mixing peanut red skins, peanut kernels, and peanut plants is ground to 100 meshes.

[0100] Example 6

[0101] According to the method of Example 1, the difference is that in S3, the mass ratio of the polar solvent (water), the medium polar solvent (ethanol), and the solid mixture is 1:1.

[0102] Example 7

[0103] According to the method of Example 1, the difference is that in S3, the polar solvent is a water-methanol solution (the volume ratio of water to methanol in the polar solvent is 1:1), and the medium polar solvent is ethanol.

[0104] Example 8

[0105] According to the method of Example 1, the difference is that in S3, the ultrasonic power is 400 W and the ultrasonic time is 50 min.

[0106] Example 9

[0107] According to the method of Example 1, the difference is that in S4, the supernatant is concentrated at -0.05 MPa and 40 °C, so that the evaporation rate of the solvent in the supernatant is 99.9%.

[0108] Example 10

[0109] According to the method of Example 1, the difference is that in S3, the mixed supernatant is concentrated at 60 °C, so that the evaporation rate of the solvent in the mixed supernatant is 40%.

[0110] Example 11

[0111] According to the method of Example 1, the difference is that in S3, the supernatant is only concentrated and no activated clay is added for adsorption treatment. Specifically: in S3, the supernatant is concentrated at 60 °C, so that the evaporation rate of the solvent in the supernatant is 90%, and a concentrated solution is obtained. The other steps are the same as those in Example 1, and compound peanut oil is obtained.

[0112] Example 12

[0113] According to the method of Example 1, the difference is that in S3, peanut skins, peanut kernels and peanut plants (peanut plants include peanut roots, peanut stems and peanut leaves) are mixed in a mass ratio of 1:90:1, and the other steps are the same as those in Example 1, and compound peanut oil is obtained.

[0114] Example 13

[0115] According to the method of Example 1, the difference is that in S1, the pre-roasting condition makes the removal rate of peanut skins of the peanut raw material 35%, and the other steps are the same as those in Example 1, and compound peanut oil is obtained.

[0116] Comparative Example 1

[0117] According to the method of Example 1, the difference is that the nutrients in peanut skins, peanut kernels, and peanut plants are extracted separately. Specifically: in S3, a polar solvent and a medium-polarity solvent are respectively added to the peanut skins for the first extraction and the second extraction to obtain the supernatant and solid phase of the extracted peanut skins; a polar solvent and a medium-polarity solvent are respectively added to the peanut kernels for the first extraction and the second extraction to obtain the supernatant and solid phase of the extracted peanut kernels; a polar solvent and a medium-polarity solvent are respectively added to the peanut plants for the first extraction and the second extraction to obtain the supernatant and solid phase of the extracted peanut plants; the obtained supernatants are mixed, and the solid phases are mixed, and compound peanut oil is prepared according to the method of Example 1.

[0118] Comparative Example 2

[0119] According to the method of Example 1, the difference is that in S3, only a polar solvent (water) is added to the solid mixture for ultrasonic extraction.

[0120] Comparative Example 3

[0121] According to the method of Example 1, the difference is that in S3, only a medium-polarity solvent (ethanol) is added to the solid mixture for ultrasonic extraction.

[0122] Comparative Example 4

[0123] According to the method of Example 1, the difference is that in S3, only an ethanol solution (the volume ratio of water to ethanol in the ethanol solution is 10:1) is added to the solid mixture for ultrasonic extraction.

[0124] Test Example

[0125] The compound peanut oil prepared in the above examples and comparative examples is tested for the content of peanut oil nutrients, the content of harmful substances, and sensory indicators, and the results are shown in Tables 1 and 2.

[0126] Testing the content of nutrients in peanut oil: Resveratrol in peanut oil is determined with reference to "GB / T 24903-2010 Cereals, oils and foodstuffs inspection - Determination of resveratrol in peanuts - High performance liquid chromatography method"; Phytosterols in peanut oil are determined according to "GB / T 25223-2010 Animal and vegetable fats and oils - Determination of sterol composition and total sterols - Gas chromatography method"; Nicotinic acid in peanut oil is determined according to "GB / T5009.89-2016 National food safety standard - Determination of niacin and nicotinamide in foods".

[0127] The contents of procyanidins, catechins, caffeic acid, and ferulic acid in peanut oil are determined by high performance liquid chromatography. The specific determination method is as follows:

[0128] (1) Chromatographic conditions: Chromatographic column: Agilent 5TC-C18 (250×4.6 mm); Column temperature: 27 °C; Flow rate: 0.6 mL / min; Injection volume: 5.0 μL; Wavelength: 280 nm; Mobile phase A: Methanol; Mobile phase B: 1.0% glacial acetic acid solution; Gradient elution program: 0 - 10 min, 10% A; 10 - 15 min, 50% A; 15 - 25 min, 100% A; 25 - 30 min, 10% A.

[0129] (2) Preparation of standard solutions: Accurately weigh 2.5 mg of each standard of procyanidins, catechins, caffeic acid, and ferulic acid respectively, dissolve with methanol and make up the volume to 25 mL in a brown volumetric flask to prepare a mixed standard stock solution with a mass concentration of 100 mg / L. Gradually dilute the mixed standard stock solution with methanol to obtain mixed standard series solutions of 1 mg / L, 10 mg / L, 20 mg / L, 50 mg / L, and 100 mg / L, shake well, and store in a refrigerator at 4 °C for standby.

[0130] (3) Sample pretreatment: Take 2.5 g in a 50 mL stoppered Erlenmeyer flask, add 25 mL of 85% ethanol solution respectively, perform ultrasonic-assisted extraction at 30 °C for 30 min. After the extract is centrifuged at 3000 r / min for 5 min, transfer the supernatant to a round-bottom flask. Repeat the above operation for the residue, combine the two supernatants, evaporate to nearly dry in a rotary evaporator, dissolve with methanol and make up the volume to 10 mL in a brown volumetric flask. Take 2 mL of this solution, purify it through an Oasis PRiME HLB solid-phase extraction column, and filter it through a 0.22 μm organic microporous filter membrane.

[0131] Determination of the content of harmful substances in peanut oil: Determine aflatoxin in peanut oil according to "GB / T 5009.22 National Food Safety Standard - Determination of Aflatoxins B and G in Foods"; Determine phthalates in peanut oil with reference to "GB / T 5009.271 National Food Safety Standard - Determination of Phthalates in Foods".

[0132] Testing of sensory indicators in peanut oil: Establish a 10-person sensory evaluation group for peanut oil to evaluate the preference and appearance of peanut oil. Under the standard sensory evaluation test environment, require the evaluators to score the preference of the randomly numbered samples, with the score range being 1 - 15 points, where 1 - 5 points represent very dislike, 6 - 10 points represent general like, and 11 - 15 points represent very like; At the same time, the evaluators need to evaluate the appearance clarity of peanut oil.

[0133] The content of flavor substances in peanut oil is determined by the following method:

[0134] (1) Pretreatment conditions: Add 5 g of peanut oil sample into a 20 mL headspace vial, add 1 μL of 2-methyl-3-heptanone (concentration 41 mg / mL) as the internal standard, mix and seal for storage; place the sample in a constant temperature water bath to equilibrate for 20 min, set the water bath temperature to 55 °C, then insert the solid-phase microextraction fiber head (CAR / DVB / PDMS) for headspace adsorption for 40 min. After the adsorption is completed, insert the extraction head into the gas chromatography injection port and desorb at 250 °C for 5 min.

[0135] (2) GC conditions: The temperature programming is set with an initial temperature of 40 °C, maintaining the temperature for 3 min, first heating at 5 °C / min to 200 °C, then heating at 15 °C / min to 230 °C, and maintaining the temperature for 3 min; the carrier gas is helium, the constant flow rate is set to 1.6 mL / min, the injection port temperature is set to 250 °C, and the split ratio is set to non-split.

[0136] (3) MS conditions: The type of ion source is electron impact, the electron energy is 70 eV, the transfer line temperature is 280 °C, the ion source temperature is maintained at 230 °C, the quadrupole temperature is set to 150 °C, the mass scanning range m / z is 40 - 250, and the solvent delay is 3 min.

[0137] (4) Identification method: Process through the GC-MS chemical workstation, and quantitatively calculate the relative total content of flavor compounds in strong-flavor peanut oil by the internal standard method; use 2-methyl-3-heptanone as the internal standard (the internal standard substance does not exist in the sample itself, and the internal standard and other substances do not affect each other's peak emergence), and calculate the total concentration of unknown compounds through the relationship between peak area and concentration.

[0138] Peanut oil flavor description test: Refer to the standard "GB / T 16291.1 - 2012 Sensory analysis - General guidelines for the selection, training and management of assessors - Part 1: Preferred assessors" to form a 10-person peanut oil evaluation group to describe the most prominent sensory attribute descriptors and intensities of the flavor in peanut oil.

[0139] Table 1

[0140]

[0141]

[0142] Table 2

[0143]

[0144]

[0145] Comparing Examples 1-9 with Examples 10-13, it can be seen that the peanut oil prepared by the preferred method of the present invention is rich in nutritional elements, with less loss, contains no harmful substances, and has a strong aroma.

[0146] Compared with the examples, in Comparative Example 1, polar solvents and medium-polar solvents were used to separately extract the nutrients in peanut skins, peanut kernels, and peanut plants, resulting in relatively large losses of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the prepared peanut oil, and the contents of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the peanut oil were relatively low; in Comparative Example 2, only a polar solvent (water) was added to the solid mixture (peanut skins, peanut kernels, and peanut plants) for ultrasonic extraction, resulting in relatively large losses of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the prepared peanut oil, and the contents of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the peanut oil decreased significantly; in Comparative Example 3, only a medium-polar solvent (ethanol) was added to the solid mixture (peanut skins, peanut kernels, and peanut plants) for ultrasonic extraction, resulting in relatively large losses of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the prepared peanut oil, and the contents of the nutritional elements (proanthocyanidins, resveratrol, catechins, caffeic acid, ferulic acid, niacin, and phytosterols) in the peanut oil decreased significantly. In Comparative Example 4, only an ethanol solution was added to the solid mixture (peanut skins, peanut kernels, and peanut plants) for ultrasonic extraction, resulting in relatively large losses of resveratrol, catechins, caffeic acid, and ferulic acid, the nutritional elements in the prepared peanut oil.

[0147] In summary, the peanut oil prepared by the method of the present invention is rich in various nutritional elements, has high nutritional value, and has a strong aroma.

[0148] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing nutritious peanut oil, characterized in that: The method comprises the following steps: S1. Mix peanut skins, peanut kernels and optional peanut plants to obtain a solid mixture; mix the solid mixture with a first solvent, perform a first extraction and a first solid-liquid separation in sequence, mix the solid phase obtained by the first solid-liquid separation with a second solvent, perform a second extraction and a second solid-liquid separation in sequence, mix the liquid phase obtained by the first solid-liquid separation with the liquid phase obtained by the second solid-liquid separation to obtain a mixed supernatant, and use the solid phase obtained by the second solid-liquid separation as a peanut mixed powder for later use; the first solvent and the second solvent are each independently a polar solvent or a medium-polar solvent and the first solvent and the second solvent are different; S2, concentrating the mixed supernatant to obtain a concentrated solution; S3, squeezing the peanut mixed powder, and mixing the obtained oil with the concentrated liquid.

2. The method according to claim 1, wherein: In S1, the first extraction and the second extraction are each independently ultrasonic extraction; Preferably, the conditions for ultrasonic extraction include: ultrasonic power of 200-500W, preferably 450W-500W; ultrasonic temperature of 25-40°C; ultrasonic time of 20-60min; And / or, in S1, the solid mixture further includes a pulverization process, and the pulverization process is performed under conditions such that the particle size of the pulverized material is 5-100 mesh.

3. The method according to claim 1 or 2, wherein: In S1, the mass ratio of the peanut skin, peanut kernel and peanut plant is 1:(3-50):(1-30), preferably 1:(3-50):(25-30).

4. The method according to any one of claims 1 to 3, wherein: In S1, the peanut plant is selected from at least one of peanut roots, peanut shells, peanut stems and peanut leaves, preferably a mixture of peanut roots, peanut stems and peanut leaves in a weight ratio of 1:(1-40):(1-30); and / or, in S1, the polar solvent is selected from solvents having a polarity not less than that of acetone, preferably at least one of ethylene glycol, methanol, water and acetonitrile; And / or, in S1, the medium polar solvent is selected from solvents with polarity no greater than that of ethanol, preferably at least one of dichloromethane, ether, ethanol and butanol; And / or, in S1, the mass ratio of the solid mixture to the polar solvent is 1:(1-20); And / or, in S1, the mass ratio of the solid mixture to the medium-polarity solvent is 1:(1-20).

5. The method according to any one of claims 1 to 4, wherein: In S2, the concentration condition is such that the evaporation rate of the solvent in the mixed supernatant is ≥ 60%; Preferably, the concentration conditions include: vacuum degree of -0.09MPa-0MPa; temperature of 20-80°C.

6. The method according to any one of claims 1 to 5, wherein: In S2, the method further comprises an adsorption treatment, wherein the adsorption treatment comprises: mixing the concentrated liquid with an adsorbent; Preferably, the adsorbent is selected from at least one of resin, activated carbon, bentonite and activated clay; Preferably, based on the mass of the concentrated liquid, the amount of the adsorbent used is 0.05wt%-5wt%.

7. The method according to any one of claims 1 to 6, wherein: In S3, the pressing temperature is 50-100°C.

8. A method for preparing highly nutritious flavored peanut oil, characterized in that: The method comprises the following steps: (1) pre-roasting, frying and pressing the peanut raw materials in sequence to obtain fragrant peanut oil; (2) The nutritious peanut oil prepared by the method described in any one of claims 1 to 7 is mixed with the fragrant peanut oil and an optional emulsifier to obtain a composite peanut oil.

9. The method according to claim 8, wherein: In step (1), the pre-roasting conditions are such that the peanut red skin removal rate of the peanut raw material is ≥50%, preferably ≥80%; And / or, in step (1), the pre-frying conditions include: the frying temperature is 80-120°C; And / or, in step (1), the frying conditions include: frying temperature of 130-200° C., frying time of 15-45 min; And / or, in step (2), the emulsifier is selected from at least one of polyglycerol fatty acid esters, sodium stearoyl lactylate, calcium stearoyl lactylate and sucrose fatty acid esters; And / or, in step (2), the mass ratio of the nutritious peanut oil to the fragrant peanut oil is 1:(0.1-20), preferably 1:(5-10); Preferably, the added amount of the emulsifier is 0.5wt%-1wt% of the total mass of the nutritious peanut oil and the fragrant peanut oil.

10. The composite peanut oil prepared according to the method of claim 8 or 9.

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