Method for physically removing aflatoxin in edible oil

Abstract

The invention relates to the technical field of edible oil production, and discloses a method for physically removing aflatoxin in edible oil, which comprises the following steps: S1, preparing newly squeezed edible oil; and S2, filtering the newly squeezed edible oil obtained in the step S1 by using a ceramic membrane to obtain the aflatoxin-removed edible oil. Edible oil without aflatoxin can be obtained only through two steps, no other treatment operation is included between squeezing operation and filtering operation, and therefore the method is simple and convenient, meanwhile, the aflatoxin removal effect is good, and 99% of aflatoxin B1 can be removed; based on the method, further research finds that aflatoxin G1 with the toxicity only second to that of aflatoxin B1 can be removed in a targeted manner after filtered edible oil is subjected to low-intensity, specific-wavelength and short-time ultraviolet radiation, meanwhile, other pollutants are not introduced, and the method has progressive significance for improving the safety of the edible oil.

Description

Technical Field

[0001] The invention relates to the technical field of edible oil production, and in particular to a method for physically removing aflatoxin from edible oil. Background Art

[0002] Aflatoxins (AFT) are a type of highly toxic furanoid toxins produced by Aspergillus flavus, Aspergillus parasiticus and Penicillium strains when they contaminate crops. The main components are oxazinone and furanoid rings. There are more than 20 types of aflatoxins discovered so far, the most common of which are AFB1, AFB2, AFG1 and AFG2. Among them, AFB1 is the most toxic, 68 times that of arsenic, and AFG1 is the second most toxic. Aflatoxins have a strong destructive effect on human and animal liver tissues. In severe cases, they can cause liver cancer or even death. In 1993, the Cancer Research Institute of the World Health Organization (WHO) classified aflatoxins as Class I carcinogens.

[0003] Aflatoxin is widely found in a variety of oil crops such as peanuts, corn, soybeans, sesame, and rapeseed, which seriously endangers human life and health. Peanuts and corn are most susceptible to aflatoxin contamination during planting and transportation, especially in the southern region with a hot and humid climate, where the contamination is more serious. Aflatoxin has a stable structure and cannot be destroyed during general food processing. It is also difficult to dissolve in water and not easy to wash off. Therefore, the use of peanuts, corn and other raw materials contaminated with aflatoxin to produce edible oils can easily cause excessive aflatoxin content in the oil. According to my country's GB2761-2017 "National Food Safety Standard Limits of Fungal Toxins in Food", the content of aflatoxin B1 in peanut oil and corn oil shall not exceed 20ug / kg, and the content of aflatoxin B1 in other edible oils shall not exceed 10ug / kg.

[0004] At present, the methods for removing aflatoxins from edible oil mainly include chemical, physical and biological methods. Chemical methods usually use strong oxidants to destroy the structure of aflatoxins, which is easy to produce new pollution and bad flavors. Biological methods mainly use microorganisms and their enzymes to adsorb and degrade aflatoxins, which are costly and limited in large-scale application. Physical methods include ultraviolet and adsorption. Although ultraviolet degradation can effectively remove the aflatoxins content in edible oil, excessive irradiation intensity and long irradiation time may produce new toxins with equal or higher toxicity than AFB1, and will destroy nutrients. Adsorption methods may cause adsorbent residues and cause secondary contamination of oil samples.

[0005] For example, in the patent publication number CN117701335A, a detoxifying enzyme is added to the vegetable oil, and after the reaction, the enzyme is killed at high temperature and centrifuged to obtain a detoxified oil. In the patent publication number CN108094834, the edible oil is directly placed under a UV lamp for high-intensity irradiation to degrade aflatoxin in the oil sample. In the patent publication number CN117121953A, montmorillonite adsorption is combined with ultraviolet irradiation to remove aflatoxin in peanut oil. On the whole, these technical methods cannot remove aflatoxin in edible oil without affecting other nutrients in the oil sample, cannot guarantee the good quality of edible oil, have high cost, and are relatively difficult to operate. Therefore, a new green, simple to operate, and efficient process for removing aflatoxin in edible oil is provided, which is promoted and used to ensure the safety of edible oil for consumers.

[0006] Therefore, there is an urgent need to improve and innovate the removal method of aflatoxin in edible oil, and to propose a method that can control the extremely low content of aflatoxin in edible oil while ensuring that other nutrients are not affected. Summary of the invention

[0007] In order to solve the above-mentioned existing problems, the present invention discloses a method for physically removing aflatoxin from edible oil. Freshly pressed edible oil is prepared, and the freshly pressed edible oil is filtered using a ceramic membrane. The edible oil from which aflatoxin has been removed can be obtained in only two steps. No other processing operations are involved between the pressing and filtering operations. Therefore, the method is simple and has a good aflatoxin removal effect, and 99% of aflatoxin B1 can be removed. Based on the above method, further research has found that low-intensity, specific wavelength and short-time ultraviolet irradiation of the filtered edible oil can specifically remove aflatoxin G1, which is second only to aflatoxin B1 in toxicity, and no other pollutants are introduced. This has progressive significance for improving the safety of edible oil.

[0008] In one aspect, the present invention provides a method for physically removing aflatoxin from edible oil, comprising the following steps: S1, preparing freshly pressed edible oil; S2, filtering the freshly pressed edible oil obtained in step S1 using a ceramic membrane to obtain edible oil from which aflatoxin has been removed.

[0009] First of all, in the "preparation of freshly pressed edible oil", the concept of "preparation" only refers to the preparation of edible oil by pressing, and does not cover other steps of processing the edible oil. "Freshly pressed edible oil" includes any crude edible oil obtained by pressing, such as peanut crude oil, corn crude oil and soybean crude oil; step S2 is to use a ceramic membrane to filter the freshly pressed edible oil obtained in step S1, which means that after the crude edible oil is squeezed out, it is directly sent to the ceramic membrane for filtration, and no other processing operation is performed before it is sent to the ceramic membrane for filtration.

[0010] In the prior art, ceramic membranes are used for degumming (removing phospholipids) in the process of preparing edible oil. For example, patent CN106520365A discloses a processing technology for a low-aflatoxin strong-flavor peanut oil, which discloses the following technical scheme: "A processing technology for a low-aflatoxin strong-flavor peanut oil, comprising the following steps: Step 1, removing the outer red skin of peanuts, and then crushing the peanut kernels and rolling them into peanut embryo slices; Step 2, placing the peanut embryo slices in a flat dryer for baking; Step 3, extruding and puffing the baked peanut embryo slices obtained in Step 2; Step 4, low-temperature pressing the peanut material obtained in Step 3 to obtain crude oil; Step 5, adding acid to the crude oil, stirring, standing and stratifying, removing the water layer, and washing the oil layer with water, and then removing the water layer; Step 6, Peanut oil is rapidly cooled to 1-3°C, bentonite is added, stirred, and then filtered by cold pressing to remove solids; in step 7, diatomaceous earth is added to the peanut oil obtained in step 6, and then sent to a ceramic membrane for filtration and degumming; in step 8, the degummed peanut oil is subjected to vacuum deodorization to obtain a fragrant peanut oil. "In summary, its technical scheme can be summarized as "peeling and crushing-baking-extrusion puffing-low temperature pressing-acid washing and liquid separation-bentonite stirring-ceramic membrane degumming-vacuum deodorization". Although the ceramic membrane degumming process is used, according to its specification, "by adding an acidic process, impurities are effectively removed and the content of aflatoxin can be reduced". The actual process for removing aflatoxin is to add acid, which is still a traditional chemical detoxification method. Under this scheme, the ceramic membrane does not have the function of removing aflatoxin.

[0011] The core innovation of the present invention is that it breaks the technical prejudice that existing ceramic membranes are only used for degumming, discovers for the first time a new use of ceramic membranes for removing aflatoxins, and proposes a new set of physical methods for removing aflatoxins from edible oils, which can be summarized as "pressing-ceramic membrane filtration". There are no other steps between the pressing and ceramic membrane filtration steps, and 99% of aflatoxin AFB1 can be removed in just two simple steps.

[0012] The present invention prefers the process of hot pressing. Hot pressing is a concept opposite to low-temperature pressing. Low-temperature pressing is usually performed in an environment below 60°C, while hot pressing is usually performed in an environment above 100°C. Low-temperature pressing can reduce the production of aflatoxin, but there are many impurities and microorganisms in the oil, and the oil yield is low. Hot pressing can break the cell structure, produce a large oil yield, and the oil is clarified with few impurities, but more aflatoxin will be produced during the hot pressing process. However, by adopting the method of the present invention, the oil obtained by hot pressing is directly added to the ceramic membrane tube for filtration, so that the aflatoxin produced during the hot pressing process can be removed. Therefore, hot pressing combined with the ceramic membrane filtration of the present invention can achieve a large oil yield and low aflatoxin at the same time. However, the present invention does not exclude low-temperature pressing. If pickling, bentonite stirring and other processes are not performed, the low-temperature pressed oil can also achieve a good aflatoxin removal effect by using the ceramic membrane filtration of the present invention.

[0013] It is worth noting that, compared with the existing ceramic membrane degumming technology, the ceramic membrane in the present invention does not require the addition of filter aids such as diatomaceous earth during filtration; the reason why the traditional process needs to add diatomaceous earth is that too many impurities are introduced in the early steps of low-temperature pressing, acid washing, bentonite stirring, etc. Direct filtration will seriously block the ceramic membrane, and the adsorption effect of diatomaceous earth is helpful for filtration; the tubular ceramic membrane used in the present invention for filtration adopts the principle of cross-flow filtration, and the detoxified edible oil penetrates the ceramic membrane outward in a direction perpendicular to the membrane surface, and the aflatoxin molecules are subjected to shear force, move in a direction parallel to the membrane, and wash away blockages on other membranes.

[0014] On the other hand, the research and development team of the present invention speculates that the principle of ceramic membrane filtration may be: aflatoxin molecules are subjected to shear force and transmembrane resistance. During the movement along the direction parallel to the membrane, due to their intramolecular conjugated system, molecules may produce - Accumulation produces a clumpy adsorption structure on a macro scale, which is more difficult to pass through the ceramic membrane.

[0015] Patent CN106520365A records the use of ceramic membrane filtration without adding diatomaceous earth, which has a negative effect. The reason is that it uses acid washing to remove aflatoxin, and the early steps of low-temperature pressing, acid washing, bentonite stirring, etc. introduce too many impurities. The ceramic membrane cannot play a role in such a complex system.

[0016] In some embodiments, in step S2, the ceramic membrane is a tubular ceramic membrane.

[0017] In some embodiments, in step S2, the operating pressure is pressurized at 0.05-1.5 MPa.

[0018] In some embodiments, in step S2, the pore size of the ceramic membrane is 10-140 nm.

[0019] In some embodiments, in step S2, the operating temperature is 30-60°C.

[0020] The above are only the preferred ranges for operating pressure, pore size of ceramic membrane and operating temperature in single factor adjustment, and cannot play a limiting role; it does not exclude that two or more variables leaving the above ranges can achieve equivalent or even better technical effects.

[0021] In some embodiments, in step S1, the freshly pressed edible oil is freshly pressed peanut oil, and the preparation method of the freshly pressed peanut oil is: taking peanuts that mature in the current year, and sequentially washing, drying, shelling, removing red skin, screening and physically pressing; the temperature of the physical pressing is greater than or equal to 100°C.

[0022] In another aspect, the present invention provides a method for removing aflatoxin from edible oil by ceramic membrane filtration in combination with ultraviolet irradiation, comprising the following steps: S1, preparing freshly pressed edible oil; S2, filtering the freshly pressed edible oil obtained in step S1 using a ceramic membrane to obtain filtered edible oil; S3, using ultraviolet light to irradiate the filtered edible oil obtained in step S2 to obtain edible oil from which aflatoxin has been removed.

[0023] Similarly, step S3 uses ultraviolet light to irradiate the filtered edible oil obtained in step S2, which means that after the ceramic membrane is filtered, the filtered edible oil is directly placed under ultraviolet light for irradiation, and no other processing operations are performed after filtration and before irradiation.

[0024] The present invention unexpectedly discovered that after using a ceramic membrane to filter freshly pressed edible oil, ultraviolet irradiation of the filtered edible oil has no obvious effect on the removal of AFB1, AFB2 and AFG2, but has a significant removal effect on AFG1. AFG1 is an aflatoxin whose toxicity is second only to AFB1. Therefore, the combination of ceramic membrane filtration and ultraviolet irradiation is very meaningful for further removing it and improving the safety of edible oil.

[0025] Although there are currently a large number of processes focusing on the removal of aflatoxins by ultraviolet irradiation, proving that high-intensity ultraviolet irradiation can remove aflatoxin AFB1, there has been no research involving the removal of aflatoxins by ceramic membranes, let alone any research on ultraviolet irradiation of edible oil filtered by ceramic membranes. The present invention finds that after filtering freshly pressed edible oil with a ceramic membrane, the filtered edible oil is then subjected to low-intensity, characteristic wavelength, and short-time ultraviolet irradiation, which can specifically remove AFG1 without introducing other pollutants.

[0026] In some embodiments, in step S3, the intensity of the ultraviolet light is 300-600 μW / cm 2 .

[0027] In some embodiments, in step S3, the wavelength of the ultraviolet light is 200-275 nm and / or 315-400 nm.

[0028] In some embodiments, in step S3, the irradiation time is 10-20 minutes.

[0029] The above are only the preferred ranges for ultraviolet light intensity, ultraviolet light wavelength and irradiation time in single factor adjustment, and cannot play a limiting role; it does not exclude that two or more variables leaving the above ranges can achieve equivalent or even better technical effects.

[0030] In another aspect, the present invention provides edible oil prepared according to any one of the above methods.

[0031] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The present invention discloses a method for physically removing aflatoxin from edible oil. Freshly pressed edible oil is prepared, and the freshly pressed edible oil is filtered using a ceramic membrane. The edible oil from which aflatoxin is removed can be obtained in only two steps. No other processing operation is involved between the pressing and filtering operations. Therefore, the method is simple and convenient. At the same time, the aflatoxin removal effect is good, and 99% of aflatoxin B1 can be removed. 2. Based on the above method, further research found that low-intensity, specific wavelength and short-time ultraviolet irradiation of filtered edible oil can remove aflatoxin G1, which is second only to aflatoxin B1 in toxicity, without introducing other pollutants, which has progressive significance for improving the safety of edible oil; 3. Through principle research and experimental verification, suitable process parameters were found. Aflatoxin removal was carried out under the preferred process parameters of the present invention. On the one hand, various types of aflatoxins can be removed to the greatest extent, and on the other hand, the original quality and flavor of edible oil can be retained to the greatest extent; 4. The application scope of the method of the present invention has been expanded through experimental verification. Aflatoxin can be removed from various types of edible oils with low cost, good effect and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : Schematic diagram of the filtering operation of the tubular membrane filtration equipment; wherein, 1- outlet pressure gauge, 2- inlet pressure gauge, 3- feed tank, 4- variable feed pump, 5- first valve, 6- second valve, 7- third valve. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific examples, which are only used to explain the present invention and are not intended to limit the scope of the present invention. The materials, reagents, etc. used in the following examples are reagents and materials available from commercial sources unless otherwise specified.

[0034] The main instruments and equipment used in the following examples are as follows: Ceramic membrane purification device (Shanghai Xiangming Biotechnology Co., Ltd.); CSP1090 variable feed pump (Sichuan Chengdu Xinweicheng Technology Co., Ltd.); electronic balance (Sartorius); UV lamp (Zhejiang Qili Company); UV intensity detector (General Electric Company, USA); high performance liquid chromatograph (Waters Singapore Company, USA); C18 chromatographic column (250mm×4.6mm, 5um); UV-visible spectrophotometer (Metrohm, Switzerland); muffle furnace (Shanghai Jinghua Technology Instrument Co., Ltd.); electric constant temperature water bath (Gongyi Jinghua Instrument Co., Ltd.); electric constant temperature drying oven (Olaybo). Example 1: A method for physically removing aflatoxin from peanut oil

[0035] After a lot of theoretical analysis and experimental demonstration, the research and development team of the present invention innovatively proposed a method for physically removing aflatoxin from peanut oil, which is as follows: Peanuts that matured that year were washed and dried at 50°C for 3.5 hours, shelled and peeled, passed through a 100-mesh sieve, and put into a press for physical pressing at a temperature of 120°C to obtain crude peanut oil (newly pressed peanut oil); This embodiment adopts Figure 1 The tubular membrane filtration equipment shown in the figure includes a ceramic membrane tube assembly and a feed tank 3; the pore size of the ceramic membrane tube is 140 nm, the length of the membrane tube is 25 cm, and the membrane filtration area is 0.0043 m 2 ; Pressure gauges are connected to both ends of the ceramic membrane tube assembly, and the inlet pressure gauge 2 and the outlet pressure gauge 1 respectively detect the inlet pressure and outlet pressure of the membrane assembly during operation; the outlet of the feed tank 3 is connected to a variable feed pump 4, which can adjust the driving pressure so that the crude peanut oil in the tank enters the membrane filtration system.

[0036] Before filtration, the ceramic membrane tube was cleaned by alternating hot deionized water, 2% NaOH and 0.5% HNO3 until the pure water flow rate was restored to 0.2 L / min.

[0037] At 30°C, the variable feed pump is pressurized to 0.05MPa and the crude peanut oil is filtered at a flow rate of 1.5L / h. The variable feed pump provides energy to adjust the pressure of the peanut oil in the liquid tank through a throttle valve and then transport it to the ceramic membrane tube assembly for cross-flow filtration. The peanut oil filtered out from both sides of the ceramic membrane tube flows into the purified oil tank through a valve, and the unpurified crude peanut oil flows back into the liquid tank through a valve, and peanut oil is continuously added to the membrane filtration system to keep the volume of peanut oil in the membrane filtration system constant at 2L during the entire treatment process; the peanut oil product obtained by filtration is collected.

[0038] According to the above operation steps, 10 batches of peanut oil products were repeatedly sampled, and the contents of aflatoxins AFB1, AFB2, AFG1, and AFG2 in crude peanut oil and peanut oil products were determined by referring to the HPLC-post-column derivatization method (method 3) in GB5009.22-2016. The average value within 10 batches was calculated, and the removal efficiency was the ratio of the peanut oil product to the crude peanut oil in reducing the aflatoxin content. The results are shown in Table 1.

[0039] .

[0040] The results showed that filtering crude peanut oil with ceramic membrane tubes can effectively reduce the content of various aflatoxins in peanut oil. Among them, the removal rate of aflatoxin AFB1 was the highest, at 99.0%. The AFB1 content in peanut oil products was only 0.77ug / kg, which is in line with the current national standards (GB2761-2017).

[0041] The possible reason is that at the microscopic level, aflatoxin molecules are subject to transmembrane resistance and shear force when passing through the tubular membrane. The chemical structure of aflatoxin is conjugated oxazinone and bifuran ring. Transmembrane resistance and shear force drive the intermolecular - Accumulation produces a clumpy adsorption structure on a macro scale, which is more difficult to pass through the ceramic membrane.

[0042] The quality of peanut oil products was further tested. The phospholipid content was determined by referring to the molybdenum blue colorimetric method (first method) in GB5537-2008, the acid value was determined by referring to the cold solvent indicator titration method (first method) in GB5009.229-2016, the peroxide value was determined by referring to the indicator titration method (first method) in GB5009.227-2023, and the color was determined by referring to the Robin colorimeter method in GBT22460-2008. The results are shown in Table 2.

[0043] .

[0044] The results show that the peanut oil product prepared according to this embodiment not only has a low aflatoxin content, but also has a low phospholipid content, a low acid value, a low peroxide value and a good color, and its quality is also excellent. The reason is that the ceramic membrane also has the effects of degumming, deacidification, decolorization and impurity removal on peanut oil. Example 2: Comparative test of tubular membrane filtration

[0045] In order to further study the reasons why ceramic membrane filtration achieves good detoxification effects and to study the optimal detoxification process parameters, this embodiment is based on the method of Example 1, and adjusts the filtration operating pressure, the pore size of the ceramic membrane tube, and the filtration operating temperature.

[0046] First, the operating pressure (pressurization) of the filtration was adjusted by adjusting the variable feed pump and the throttle valve. The operating pressure was based on the reading of the pressure gauge at the inlet end of the ceramic membrane tube assembly. The rest was carried out in the same manner as in Example 1. Only the removal efficiency of aflatoxin B1 was calculated. The aflatoxin removal efficiency under different operating pressures is shown in Table 3.

[0047] .

[0048] The results showed that the aflatoxin removal efficiency was higher when the operating pressure was lower. The main reason was that transmembrane resistance and shear force were the driving forces for molecular accumulation. When the operating pressure was lower, transmembrane resistance and shear force were less offset by the transmembrane pressure difference, making molecular accumulation more likely to occur, which was beneficial to the removal of aflatoxin.

[0049] Subsequently, this embodiment tests the effect of the pore size of the ceramic membrane tube on the aflatoxin removal efficiency by replacing ceramic membrane tube assemblies with different pore sizes. The rest is carried out in the same manner as in Example 1, and only the removal efficiency of aflatoxin B1 is calculated. The aflatoxin removal efficiency under different ceramic membrane tube pore sizes is shown in Table 4.

[0050] .

[0051] The results showed that ceramic membrane tubes with pore sizes between 10-140nm have a high aflatoxin B1 removal effect, while larger pore sizes are not conducive to detoxification. The reason is that the transmembrane resistance and shear force provided by large-pore ceramic membranes are lower, which is not conducive to molecular accumulation, making aflatoxin B1 molecules easier to pass through.

[0052] Finally, the temperature control system of the adjustment device was used to perform tubular membrane filtration at different operating temperatures. The rest was carried out in the same manner as in Example 1. Only the removal efficiency of aflatoxin AFB1 was calculated. The aflatoxin removal efficiency at different operating temperatures is shown in Table 5.

[0053] .

[0054] The results showed that the operating temperature should be in the range of 30-60℃. Temperatures below or above this range are not conducive to detoxification. The reason may be that low temperature is not conducive to the formation of accumulation, while high temperature can easily destroy accumulation. At the same time, temperature also has a certain impact on the quality and flavor of peanut oil products. The original good quality and flavor can be maintained to the greatest extent within the range of 30-60℃.

[0055] In summary, the preferred conditions are an operating pressure of 0.05-1.5MPa, a pore size of the ceramic membrane tube of 10-140nm and an operating temperature of 30-60°C; however, the above is only a single factor test, and it does not exclude that good results can be achieved when two or three of the above three factors are not within the above range. Example 3: Method for removing aflatoxin from peanut oil by tubular membrane filtration combined with ultraviolet irradiation

[0056] Based on the method for physically removing aflatoxin from peanut oil described in Example 1, the research and development team of the present invention conducted further research and found that under certain conditions of ultraviolet irradiation, aflatoxin in peanut oil can be further removed without introducing new toxic substances and retaining the nutrients and flavor of peanut oil.

[0057] Based on the method of Example 1, after collecting the peanut oil product obtained by tubular membrane filtration, the peanut oil product was placed under ultraviolet light at 300 μm / cm 2 The peanut oil was irradiated for 15 min at a light intensity of 250 nm and a distance of 25 cm from the UV lamp to obtain detoxified peanut oil.

[0058] Ten batches of detoxified peanut oil were sampled repeatedly, and the contents of aflatoxins AFB1, AFB2, AFG1, and AFG2 in crude peanut oil and detoxified peanut oil were determined by referring to the HPLC-post-column derivatization method (method 3) in GB5009.22-2016. The average value within the 10 batches was calculated, and the removal efficiency was the ratio of the detoxified peanut oil to the crude peanut oil in reducing the aflatoxin content. The results are shown in Table 6.

[0059] .

[0060] The results showed that short-term, low-intensity ultraviolet irradiation of peanut oil after ceramic membrane filtration had no significant effect on the removal of AFB1, AFB2 and AFG2, but significantly reduced the content of aflatoxin AFG1, suggesting that tubular membrane filtration and ultraviolet irradiation may have a certain degree of synergistic effect on the removal of AFG1, especially on AFG1, and the removal efficiency was significantly increased from 94.0% to 99.2%. The toxicity of AFG1 is second only to AFB1. It can be seen that ceramic membrane filtration combined with ultraviolet irradiation can further significantly reduce the content of toxic aflatoxin in peanut oil.

[0061] In order to study the working principle of ceramic membrane filtration combined with ultraviolet irradiation, this example attempts to first irradiate the freshly squeezed peanut oil with ultraviolet light, and then filter it with ceramic membrane. The parameters are the same as those in the above method, but the final aflatoxin content results are basically consistent with the results of Example 1, proving that only by first filtering with ceramic membranes and then irradiating with ultraviolet light can the effect of removing AFG1 be achieved. The reason may be that the mechanism of ultraviolet irradiation is mainly to induce structural changes in certain molecules in the form of electronic transitions. Tubular membrane filtration may filter out certain molecules in the system that were originally mainly affected by ultraviolet irradiation, making AFG1 a new acting molecule, inducing AFG1 to undergo non-toxic degradation. Other possible synergistic mechanisms are not excluded here.

[0062] The quality of the detoxified peanut oil was further tested by determining the phospholipid content by referring to the molybdenum blue colorimetric method (first method) in GB5537-2008, determining the acid value by referring to the cold solvent indicator titration method (first method) in GB5009.229-2016, determining the peroxide value by referring to the indicator titration method (first method) in GB5009.227-2023, and determining the color by referring to the Robin colorimeter method in GBT22460-2008. The results are shown in Table 7.

[0063] .

[0064] Compared with Example 1, after tubular membrane filtration, the peanut oil was subjected to short-term, low-intensity ultraviolet irradiation, which had no obvious effect on the phospholipid content, acid value, peroxide value and color, and the detoxified peanut oil still maintained high quality.

[0065] Ultraviolet radiation may introduce benzopyrene, so the benzopyrene content of detoxified peanut oil was tested in accordance with GB 5009.27-2016, and the results showed that no benzopyrene was detected in the detoxified peanut oil. Example 4: Comparative test of ultraviolet irradiation conditions

[0066] In Example 3, short-time, low-intensity ultraviolet irradiation was selected for the peanut oil obtained based on tubular membrane filtration. In order to further clarify the appropriate parameter range of ultraviolet irradiation, this example investigated the effects of ultraviolet irradiation from three aspects: light intensity, wavelength and irradiation time.

[0067] First, the light intensity was adjusted by setting the UV lamp parameters, and the rest was carried out in the same manner as in Example 3. The results of AFG1 removal efficiency and benzopyrene detection under different light intensities are shown in Table 8.

[0068] .

[0069] The results showed that when the light intensity was 300-600µm / cm 2When the temperature is lower than this range, the removal efficiency of AFG1 is significantly improved; when the temperature is lower than this range, the effect of ultraviolet radiation is not obvious; when the temperature is higher than this range, ultraviolet light may have other effects, converting certain substances into benzopyrene and contaminating peanut oil.

[0070] The wavelength of ultraviolet light was studied again, and the emission wavelength of the ultraviolet lamp was adjusted. The rest was carried out in the same manner as in Example 3. The results of AFG1 removal efficiency and benzopyrene detection at different ultraviolet emission wavelengths are shown in Table 9.

[0071] .

[0072] The results showed that the optimal UV emission wavelength was 200-275nm or 315-400nm. UV light below 200nm may induce other substances to convert into benzopyrene, while UV light between 275nm and 315nm did not have the effect of removing AFG1. Further experiments found that it had no obvious effect on other aflatoxins.

[0073] Finally, this example conducted a series of irradiation time tests, which showed that the best irradiation time was 10-20 minutes. Too short a time would not be effective in removing AFG1, while too long a time would easily introduce toxic pollutants.

[0074] Similarly, the above experiment obtained the optimal conditions: the light intensity was 300-600µm / cm 2 , the ultraviolet emission wavelength is 200-275nm or 315-400nm and the irradiation time is 10-20min; however, the above is only a single factor test, and it does not exclude that when two or three of the above three factors are not within the above range, good results can also be achieved. Example 5: Comparative test of different methods for removing aflatoxin from peanut oil

[0075] This example selects a variety of traditional detoxification methods and detoxification methods in related patent documents for comparison with the detoxification method of the present invention (Example 1, Example 3). Method 1: Traditional chemical alkali refining detoxification method

[0076] Peanuts that mature in the current year are washed and dried at 50°C for 4 hours, shelled and peeled, and then screened with a 120-mesh sieve, and put into a press for physical pressing to obtain crude peanut oil; the crude peanut oil is heated to 60°C, and 0.2% (w / w, relative to oil) NaOH alkali solution (mass fraction is 9.5%) is added, and the reaction is stirred at 100r / min. When the oil soap is separated, the stirring speed is reduced to 50r / min, and the temperature is raised to the final alkali refining temperature of 85°C. After constant temperature stirring for 10 minutes, it is allowed to stand for 24 hours; the upper layer of oil sample is heated to the washing temperature of 75°C, and washed 2 to 3 times with slightly boiling distilled water, the amount of water used is 15% of the oil mass, until the pH of the oil sample washing wastewater reaches neutral; after washing with water, the oil sample is heated to 90°C on an electric furnace to dehydrate the oil sample to obtain peanut oil. Method 2: Physical adsorption

[0077] Peanuts that matured that year were washed and dried at 60°C for 2.5h, shelled and peeled, and then passed through a 150-mesh sieve, and put into a press for physical pressing to obtain peanut crude oil; montmorillonite powder, activated clay and diatomaceous earth were mixed evenly in a ratio of 50%:35%:15%, 1kg was taken, 250mL of 15% nitric acid solution by volume fraction was added, 50mL of water containing 2.5g of calcium hydroxide was added after mixing, and the mixture was reacted for 0.5h, and repeatedly washed with distilled water until neutral. Then, it was placed in a muffle furnace and burned at 450°C for 4h, and crushed through an 80-mesh sieve to obtain a mixed adsorbent. 2.5% (w / w, relative to oil) of the mixed adsorbent was added to the peanut crude oil, heated to 45°C, stirred for 15min, and then allowed to settle for 24h, and the upper layer of oil was taken out to obtain peanut oil. Method 3: Bioenzymatic hydrolysis

[0078] Peanuts that matured that year were washed and dried at 45°C for 4.5 hours, shelled and peeled, and then passed through a 130-mesh sieve, and put into a press for physical pressing to obtain peanut crude oil; 5% (w / w, relative to oil) soft water with a pH of 7 and 450ppm aflatoxin removal enzyme, which was derived from Bacillus subtilis, were added to the peanut crude oil. The mixture was subjected to a high-speed shear treatment at 8000rpm to increase the oil-water reaction interface, and then stirred at 40°C for 12 hours, and the enzyme was inactivated at high temperature and centrifuged to obtain detoxified peanut oil; 5g of detoxified oil was taken, 20mL of methanol solution was added, vortexed and centrifuged to extract aflatoxin in the peanut oil. Method 4: Pulse light degradation method

[0079] Peanuts that matured that year were washed and dried at 55°C for 3.5 hours. After shelling and removing the red skin, they were sieved with a 140-mesh sieve and put into a press for physical pressing to obtain peanut crude oil. 50g of peanut crude oil was put into a glass plate with a diameter of 10cm, covered with a cut-off optical glass with a diameter of 12cm and a thickness of 2mm, with a transmission limit wavelength of 340nm and a transmittance of 85%. The glass plate containing peanut crude oil was placed in a pulsed strong light sterilization system, and the distance from the lamp to the oil surface was kept at 15cm. The pulsed strong light was turned on, and after 60 pulses of irradiation, detoxified peanut oil was obtained. Method 5: UV irradiation

[0080] Peanuts that matured that year were washed and dried at 60℃ for 3.0h, shelled and peeled, and then passed through a 100-mesh sieve and put into a press for physical pressing to obtain peanut crude oil. The peanut crude oil was placed under ultraviolet light at 1200µw / cm 2 The detoxified oil was obtained by irradiating the mixture for 40 min under a light intensity of .

[0081] A new batch of peanut raw materials was purchased, and peanut oil was produced and aflatoxins were removed according to methods 1-6 and examples 1 and 3, and the removal rates of aflatoxins AFB1 and AFG1 were measured. The results are shown in Table 10.

[0082] .

[0083] The results show that the methods of Example 1 and Example 3 of the present invention achieve the highest removal rates of AFB1 and AFG1. Among the traditional methods, ultraviolet irradiation has the highest removal efficiency, but it is difficult to remove AFG1.

[0084] The phospholipid content was determined by referring to the molybdenum blue colorimetric method (first method) in GB5537-2008, the acid value was determined by referring to the cold solvent indicator titration method (first method) in GB5009.229-2016, the peroxide value was determined by referring to the indicator titration method (first method) in GB5009.227-2023, and the color was determined by referring to the Roben colorimeter method in GBT22460-2008; in addition, 12 sensory evaluators were randomly selected to smell and score the flavor preference (0-10 points) respectively, and the evaluation criteria were: very dislike (1 point), very dislike (2 points), dislike (3 points), not very like (4 points), neither like nor hate (5 points), slightly like (6 points), generally like (7 points), like (8 points), like very much (9 points), like very much (10 points), and the average value was taken as the final flavor score of the oil. The quality of the peanut oil obtained by methods 1-6 and Examples 1 and 3 was determined according to the above method, and the results are shown in Table 11.

[0085] .

[0086] The results showed that the traditional method of removing aflatoxin had a great impact on the quality of peanut oil and damaged the flavor of peanut oil; the peanut oil prepared by the methods of Example 1 and Example 3 had much lower phospholipid content, acid value and peroxide value than those prepared by other methods, had the best color and quality, and could preserve the best flavor. Example 6: Method for removing aflatoxin from other types of edible oils

[0087] Aflatoxins are widely present in various oil crops such as peanuts, corn, soybeans, sesame, rapeseed, etc. Based on the same removal principle, it can be understood that the method of the present invention can not only be used to remove aflatoxins in peanut oil, but theoretically can also remove aflatoxins in other types of edible oils, which is further verified in this example.

[0088] First, corn crude oil (freshly pressed corn oil) and soybean crude oil (freshly pressed soybean oil) are prepared. The preparation method of corn crude oil is as follows: select fresh, dry, and complete corn kernels, remove impurities and broken kernels, wash with clean water, dry naturally, reduce the moisture content to less than 5%, put the corn kernels into a grinder, grind them into fine powder, put them into a press for physical pressing, and the pressing temperature is 120°C to obtain corn crude oil; the preparation method of soybean crude oil is as follows: select fresh, clean, mildew-free, and odor-free soybeans, wash them and dry them, crush the soybeans into granules, heat them to 80°C, put them into a press for physical pressing, and the pressing temperature is 120°C to obtain soybean crude oil.

[0089] Three batches of crude corn oil and crude soybean oil were prepared, and aflatoxins were removed from the crude corn oil and crude soybean oil according to the method of Example 1 to obtain corn oil products and soybean oil products, respectively. The contents of aflatoxin B1 and G1 in the crude corn oil, corn oil products, crude soybean oil and soybean oil products were tested and the average values ​​were calculated. The removal efficiency of aflatoxin B1 and G1 was calculated. The results are shown in Tables 12 and 13.

[0090]

[0091] .

[0092] The results showed that after aflatoxin removal, aflatoxin in corn oil and soybean oil could be effectively removed, and the AFB1 removal efficiency reached more than 99%.

[0093] Three batches of crude corn oil and crude soybean oil were re-prepared, and aflatoxins were removed from the crude corn oil and crude soybean oil according to the method of Example 3 to obtain corn oil products and soybean oil products, respectively. The contents of aflatoxin B1 and G1 in the crude corn oil, corn oil products, crude soybean oil and soybean oil products were tested and the average values ​​were calculated. The removal efficiency of aflatoxin B1 and G1 was calculated. The results are shown in Tables 14 and 15.

[0094]

[0095] .

[0096] The results show that the method of the present invention can also achieve the same effect on corn oil and soybean oil, and ceramic membrane filtration combined with ultraviolet irradiation also has an additional removal effect on AFG1.

[0097] In summary, the experiment verified that the method of the present invention can also be used for other types of edible oils. From a theoretical analysis, the effect of removing aflatoxin is only related to the components in the edible oil, and has nothing to do with the type of oil crops. It can be understood that more types of edible oils can also use the method of the present invention to remove aflatoxin.

[0098] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto, and any equivalent modifications or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention.

Claims

1. A method for physically removing aflatoxin from edible oil, characterized in that: The following steps are involved: S1, preparing freshly pressed edible oil; S2, filtering the freshly pressed edible oil obtained in step S1 using a ceramic membrane to obtain edible oil from which aflatoxin has been removed.

2. The method according to claim 1, characterized in that In step S2, the operating pressure is pressurized to 0.05-1.5 MPa.

3. The method according to claim 1, characterized in that In the step S2, the pore size of the ceramic membrane is 10-140 nm.

4. The method according to claim 1, characterized in that In step S2, the operating temperature is 30-60°C.

5. The method according to claim 1, characterized in that In step S1, the newly pressed edible oil is newly pressed peanut oil, and the preparation method of the newly pressed peanut oil is: taking peanuts that mature in the current year, washing, drying, shelling, removing red skin, screening and physically pressing in sequence; the temperature of the physical pressing is greater than or equal to 100°C.

6. A method for removing aflatoxin from edible oil by ceramic membrane filtration in combination with ultraviolet irradiation, characterized in that: The following steps are involved: S1, preparing freshly pressed edible oil; S2, filtering the freshly pressed edible oil obtained in step S1 using a ceramic membrane to obtain filtered edible oil; S3, using ultraviolet light to irradiate the filtered edible oil obtained in step S2 to obtain edible oil from which aflatoxin has been removed.

7. The method according to claim 6, characterized in that In step S3, the intensity of the ultraviolet light is 300-600 µW / cm2.

8. The method according to claim 6, characterized in that In step S3, the wavelength of the ultraviolet light is 200-275nm and / or 315-400nm.

9. The method according to claim 6, characterized in that In step S3, the irradiation time is 10-20 minutes.

10. Edible oil prepared according to the method according to any one of claims 1 to 9.

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