Method for removing aflatoxin from peanut oil

Abstract

This invention discloses a method for removing aflatoxin from peanut oil, belonging to the field of edible oil production technology. The core steps of this method include: first, activating and modifying sodium-based montmorillonite acid, then compounding it with silica in a specific ratio to form a composite adsorbent, while simultaneously preheating the peanut oil; adding the composite adsorbent to the preheated peanut oil, and completing initial adsorption under specific conditions; subsequently, enhancing the adsorption of aflatoxin by the adsorbent through a three-stage gradient power and temperature microwave-assisted treatment; finally, removing the adsorbent through solid-liquid separation. Vacuum deodorization can be added as needed to enhance the flavor of the peanut oil. This invention not only achieves deep removal of aflatoxin from peanut oil but also reduces the loss of nutrients such as total tocopherols and total sterols; moreover, the equipment used in the process is conventional food processing equipment, with simple parameter control, and can be directly integrated into existing peanut oil production lines, combining safety, economy, and industrial adaptability.

Description

Technical Field

[0001] This invention belongs to the field of edible oil production technology, specifically relating to a method for removing aflatoxin from peanut oil. Background Technology

[0002] Peanut oil, a widely consumed vegetable oil in my country, holds an important position in food processing and culinary arts due to its rich content of unsaturated fatty acids, vitamins, and minerals, as well as its unique flavor and taste. However, with increasing consumer health awareness, the quality and safety requirements for peanut oil are becoming increasingly stringent. Among these, the control of aflatoxin contamination has become a key issue restricting the high-quality development of the peanut oil industry.

[0003] Aflatoxins are highly toxic secondary metabolites produced by fungi such as Aspergillus flavus and Aspergillus parasiticus. They are highly carcinogenic, teratogenic, and mutagenic. Aflatoxin B1 is the most toxic and is classified as a Group 1 carcinogen by the World Health Organization. It severely damages organs such as the liver and kidneys, and long-term intake significantly increases the risk of cancer and can even be life-threatening. In peanut oil production, aflatoxin contamination occurs through various pathways: Firstly, during planting, harvesting, drying, and storage, peanut raw materials are susceptible to aflatoxin contamination due to high temperature and humidity, poor ventilation, or pest infestation, leading to the growth of toxin-producing fungi such as Aspergillus flavus. Secondly, improper control of process parameters and incomplete equipment cleaning during pressing and refining processes can also result in toxin residues or cross-contamination. In addition, aflatoxin is heat-resistant and chemically stable, making it difficult to remove effectively through conventional peanut oil processing techniques (such as ordinary pressing, simple filtration, and traditional refining). Even high-temperature cooking cannot completely destroy its toxicity, posing a serious threat to the safety of peanut oil for consumption.

[0004] To address the aflatoxin contamination problem in peanut oil, various removal methods have been proposed in existing technologies, mainly including physical adsorption, chemical degradation, bioconversion, and membrane separation. Physical adsorption commonly uses adsorbents such as activated carbon, bentonite, and molecular sieves to remove toxins through adsorption. Chinese patent CN107008226A discloses a composite adsorbent that can simultaneously remove aflatoxin and benzo[a]pyrene. This adsorbent is made by acidifying diatomaceous earth with hydrochloric acid and modifying it with sodium dodecyl sulfonate, then compounding it with a mixture of calcite, kaolinite, and sepiolite powders, and adding polystyrene microspheres as a pore-forming agent. The mixture is then sintered to form a spherical adsorbent. This adsorbent enhances its adsorption capacity by increasing interlayer spacing, improving hydrophobicity, and constructing a large-pore structure. It can also be regenerated through water immersion and high-temperature calcination. However, this process involves multiple modification and sintering steps, making the preparation process relatively complex. Furthermore, the amount of adsorbent used needs to be controlled at 1-2% to ensure removal efficiency, which increases production costs to some extent. Chinese patent CN119040067A discloses a composite adsorbent prepared by compounding chitosan, bentonite, and activated carbon in a specific ratio. The dispersibility is improved through the intercalation of chitosan and bentonite, and the synergistic adsorption of the three components enhances the removal efficiency of aflatoxin. This process is mild, and the adsorbent preparation does not require high-temperature sintering, but strict control of the bentonite pretreatment process (boiling, alkali leaching, and multiple drying) and the proportions of each component is necessary. Chinese patent CN113812469A discloses a process combining montmorillonite adsorption and DC electric field sedimentation. It utilizes the adsorption of aflatoxin by montmorillonite, and then accelerates the sedimentation of montmorillonite particles through an electric field, achieving a reduction in adsorbent residue. However, the introduction of electric field equipment increases the initial investment for industrial application, and the control of montmorillonite dispersibility still relies on precise particle size screening and stirring parameter adjustment.

[0005] In summary, while existing physical adsorption technologies have achieved aflatoxin removal in specific scenarios, they still suffer from drawbacks such as complex adsorbent preparation processes, insufficient separation efficiency, and high production costs. A mature technological solution that balances high efficiency, low cost, and ease of industrialization has yet to be established. Therefore, developing an efficient, gentle, and industrially viable method for aflatoxin removal from peanut oil is of significant practical importance and application value for ensuring peanut oil safety, improving product quality, and meeting consumer health needs. Summary of the Invention

[0006] To overcome the shortcomings of existing physical adsorption methods for removing aflatoxin from peanut oil, such as complex adsorbent preparation processes, insufficient separation efficiency, and easy destruction of oil nutrients, the present invention aims to provide a highly efficient, mild, low-cost method suitable for industrial production for removing aflatoxin from peanut oil. This method not only achieves deep removal of aflatoxin but also optimizes the oxidation and hydrolysis indices of peanut oil, effectively preserving its natural nutrients while ensuring the safety and quality of peanut oil for consumption.

[0007] This invention constructs an integrated process for removing aflatoxin from peanut oil through the precise design of composite adsorbents and the synergistic effect of staged microwave-assisted treatment. The core technical solution is as follows: (1) Sodium-based montmorillonite is first acid-activated and modified, and then compounded with silica in a specific ratio to prepare a composite adsorbent; (2) Peanut oil is preheated and then initially adsorbed with the composite adsorbent. By controlling the adsorption temperature, stirring speed and time, the adsorbent and peanut oil are fully contacted and initially combined with aflatoxin; (3) Subsequently, a three-stage gradient power / temperature microwave-assisted treatment is adopted to enhance the adsorption efficiency of the adsorbent for aflatoxin by utilizing the thermal effect of microwaves, avoiding the problem of rapid saturation of adsorbent sites caused by single microwave parameters; (4) Finally, the adsorbent is removed by two-step solid-liquid separation. A vacuum deodorization step can be added to further improve the quality of peanut oil, ultimately achieving efficient removal of aflatoxin and preservation of the nutritional flavor of peanut oil.

[0008] Specifically, the key technical solution of this invention lies in the following core design:

[0009] (1) Optimization of the preparation of composite adsorbent: In view of the problem of low removal efficiency of single adsorbent, the present invention modifies sodium-based montmorillonite by acid activation with dilute hydrochloric acid (solid-liquid ratio 1:6-10 (g:mL), mass fraction 4-6% dilute hydrochloric acid, activation at 55-65℃ for 1.5-3h), and expands the interlayer spacing of montmorillonite and increases the surface active adsorption sites through acidification treatment; then the modified montmorillonite is combined with TRISYL ® Silica is compounded in a mass ratio of 7:3 or 6:4, utilizing the layered adsorption characteristics of montmorillonite and the porous structure of silica to form a synergistic adsorption effect, significantly improving the adsorption capacity for aflatoxin. Meanwhile, the amount of the composite adsorbent added is only 0.3% to 1% of the peanut oil mass, far lower than the 1-2% adsorbent used in existing technologies, significantly reducing production costs.

[0010] (2) Initial adsorption process control: preheat peanut oil to 30-40℃ and stir evenly to make the oil system in a stable flow state; stir and adsorb for 1-2 hours at 80-100℃ and 100-150r / min. This parameter design ensures that the composite adsorbent is evenly dispersed in peanut oil and allows aflatoxin to fully contact the active sites of the adsorbent, laying the adsorption foundation for subsequent microwave-assisted treatment.

[0011] (3) Innovative Design of Three-Stage Microwave-Assisted Processing: Breaking through the limitations of existing microwave processing with a single parameter, this invention adopts a three-stage microwave process with alternating gradient power and temperature: The first stage uses 270-360W power adjusted to 70-80℃ for 2-4 minutes, utilizing medium-power microwaves to accelerate the movement of peanut oil molecules and reduce the binding force between aflatoxin and the oil matrix; the second stage uses 540-630W power at 45-55℃ for 4-6 minutes, using high-power microwaves to enhance the binding efficiency between the adsorbent and the toxin; the third stage uses 180-270W power adjusted to 60-70℃ for 2-4 minutes, gently regulating the state of the oil system and avoiding the reduction of removal efficiency due to rapid saturation of adsorbent sites. Stirring is maintained at 50-100r / min throughout the process to ensure that the microwave thermal effect is uniformly applied to the oil system, ultimately achieving a aflatoxin B1 removal rate of over 98%. It should be noted that the microwave device includes a cooling system, enabling temperature control.

[0012] (4) Refinement of solid-liquid separation and post-treatment: The solid-liquid separation method adopts three steps of "coarse filtration, fine filtration and ultrafine filtration". More than 90% of the composite adsorbent particles are removed by pressurized leaf filter, and then fine filtration is carried out through a 0.5-1μm special organic membrane. Finally, a 0.2μm ceramic membrane filter can be added for ultrafine filtration. The optional vacuum deodorization step can effectively remove odor substances in the oil and further optimize the flavor quality of peanut oil.

[0013] Compared with the prior art, the technical advantages of the present invention are as follows:

[0014] (1) High detoxification efficiency: The present invention achieves a removal rate of more than 98% for aflatoxin B1 through the synergistic effect of composite adsorbent and three-stage microwave, which is far higher than the removal effect of single adsorbent or single / two-stage microwave treatment.

[0015] (2) Low process cost: The composite adsorbent of the present invention has a simple preparation process, does not require high temperature sintering or complex chemical modification, and the addition amount is only 0.3%~1%, which greatly reduces the raw material cost for industrial application.

[0016] (3) Excellent oil quality: While removing toxins, the method of the present invention has a high retention rate of nutrients such as total tocopherols and total sterols, avoiding the problem of nutrient destruction in existing processes.

[0017] (4) Strong industrial adaptability: Each process step of the present invention uses conventional food processing equipment, and the parameter control is simple. It can be directly integrated into the existing peanut oil production line and has the feasibility of large-scale application. Attached Figure Description

[0018] Figure 1 Aflatoxin B1 removal rate.

[0019] Figure 2 Effect of composite adsorbent dosage on aflatoxin B1 adsorption. Detailed Implementation

[0020] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0021] Example 1: Method for removing aflatoxin from peanut oil

[0022] (1) Pretreatment of adsorbent and raw materials:

[0023] Sodium-based montmorillonite was passed through a 200-mesh sieve and then added to a 5% (w / w) dilute hydrochloric acid solution (solid-liquid ratio 1:8). It was activated by stirring at 60°C for 2 hours, filtered, washed with deionized water until neutral, dried at 105°C for 2 hours, cooled, and mixed with silica at a mass ratio of 6:4 to obtain a composite adsorbent. Peanut oil was preheated to 35°C and stirred evenly as the raw material to be treated.

[0024] (2) Initial adsorption:

[0025] Add 0.6% by mass of composite adsorbent to the peanut oil to be treated, stir and adsorb for 1.5 h at 90℃ and 120 r / min, and then let stand.

[0026] (3) Staged microwave-assisted processing:

[0027] The sample was transferred to a microwave device for three-stage microwave treatment: the first stage was treated at 75°C with 270W power for 3 minutes; the second stage was treated at 50°C with 540W power for 5 minutes; and the third stage was treated at 65°C with 180W power for 3 minutes. Throughout the process, the sample was stirred at 80r / min and then allowed to stand for 2 minutes.

[0028] (4) Solid-liquid separation.

[0029] (5) Vacuum deodorization.

[0030] Example 2: Method for removing aflatoxin from peanut oil

[0031] (1) Pretreatment of adsorbent and raw materials:

[0032] Sodium-based montmorillonite was passed through a 200-mesh sieve and then added to a 4% (w / w) dilute hydrochloric acid solution (solid-liquid ratio 1:6). It was activated by stirring at a constant temperature of 55°C for 1.5 hours. After filtration, it was washed with deionized water until neutral and then dried at 100°C for 1.5 hours. After cooling, it was mixed with silica at a mass ratio of 7:3 to obtain a composite adsorbent. Peanut oil was preheated to 30°C and stirred evenly as the raw material to be treated.

[0033] (2) Initial adsorption:

[0034] Add 0.3% by mass of composite adsorbent to the peanut oil to be treated, stir and adsorb for 1 hour at 80℃ and 100r / min, and then let stand.

[0035] (3) Staged microwave-assisted processing:

[0036] Transfer to microwave equipment for three-stage microwave treatment: the first stage is treated at 360W power and 75℃ for 3 minutes; the second stage is treated at 630W power and 50℃ for 5 minutes; the third stage is treated at 270W power and 65℃ for 3 minutes, with stirring maintained at 50r / min throughout the process, and then left to stand for 1 minute.

[0037] (4) Solid-liquid separation.

[0038] (5) Vacuum deodorization.

[0039] Example 3: Method for removing aflatoxin from peanut oil

[0040] (1) Pretreatment of adsorbent and raw materials:

[0041] Sodium-based montmorillonite was passed through a 200-mesh sieve and then added to a 6% (w / w) dilute hydrochloric acid solution (solid-liquid ratio 1:10). It was activated by stirring at 65°C for 3 hours, filtered, washed with deionized water until neutral, dried at 110°C for 3 hours, cooled, and then mixed with silica at a mass ratio of 6:4 to obtain a composite adsorbent. Peanut oil was preheated to 40°C and stirred evenly as the raw material to be treated.

[0042] (2) Initial adsorption:

[0043] Add 1% by mass of composite adsorbent to the peanut oil to be treated, stir and adsorb for 2 hours at 100℃ and 150r / min, and then let stand.

[0044] (3) Staged microwave-assisted processing:

[0045] The sample was transferred to a microwave device for three-stage microwave treatment: the first stage was treated at 75°C with 270W power for 3 minutes; the second stage was treated at 50°C with 540W power for 5 minutes; and the third stage was treated at 65°C with 180W power for 3 minutes. Throughout the process, the sample was stirred at 100r / min and then allowed to stand for 3 minutes.

[0046] (4) Solid-liquid separation.

[0047] (5) Vacuum deodorization.

[0048] Single-factor controlled trial on the removal effect of aflatoxin B1 from peanut oil

[0049] Raw material: Peanut oil pressed from moldy peanuts (aflatoxin B1 content of approximately 50-60 μg / kg, total tocopherol content of approximately 32.27 mg / 100g, and total sterol content of approximately 510.42 mg / 100g).

[0050] Detection indicators and methods

[0051] Aflatoxin B1 removal rate: The removal rate was calculated using the high-performance liquid chromatography-post-column derivatization method according to GB5009.22-2016. The formula is as follows:

[0052] Removal rate (%) = (Content before adsorption - Content after adsorption) / Content before adsorption × 100%;

[0053] Total tocopherol content: High performance liquid chromatography, total tocopherol = α-tocopherol + γ-tocopherol + δ-tocopherol;

[0054] Total sterol content: Same as the total tocopherol detection method, total sterol = stigmasterol + sitosterol + campesterol, calculate retention rate (%) = (content after treatment / content before treatment) × 100%.

[0055] Single-factor controlled trial of the effects of three-stage microwave treatment

[0056] No microwave treatment group: only initial adsorption, without microwave treatment;

[0057] Single-stage microwave processing group A: only the microwave parameters of the first stage in Example 1 (270W, 75℃) were used for processing, and the processing time was 11 minutes.

[0058] Single-stage microwave processing group B: Only the microwave parameters of the first stage in Example 1 (540W, 50℃) were used for processing, and the processing time was 11 minutes.

[0059] Two-stage microwave treatment (Group A): Stage 1: 270W, 75℃, 5min; Stage 2: 180W, 65℃, 6min, with stirring at 80r / min throughout.

[0060] Group B, two-stage microwave treatment: Stage 1: 540W, 50℃, 7min; Stage 2: 180W, 65℃, 4min, with stirring at 80r / min throughout.

[0061] Group C, two-stage microwave treatment: Stage 1: 270W, 75℃, 5min; Stage 2: 540W, 50℃, 6min, with stirring at 80r / min throughout.

[0062] Table 1. Aflatoxin B1 Removal Rate

[0063]

[0064] As shown in Table 1, the aflatoxin B1 removal rate of Examples 1-3 reached over 98%, significantly higher than the group without microwave treatment, the single-stage microwave group, and the two-stage microwave group. This indicates that the three-stage microwave-assisted treatment can greatly enhance the removal effect of the adsorbent on aflatoxin and is the core and key step of this process. The thermal effect of microwaves can intensify the movement of peanut oil molecules, reduce the binding force between aflatoxin and the peanut oil matrix, and make it easier for Aspergillus to contact the active sites of the composite adsorbent, thereby increasing the adsorption rate and adsorption capacity. The three-stage microwave treatment uses power and temperature gradient changes, which can avoid the rapid occupation and saturation of adsorbent surface sites under a single power / temperature. At the same time, the adsorption effect is further enhanced through staged temperature control. It should be noted that the data in this patent are the average values ​​of three parallel experiments.

[0065] Table 2. Total tocopherol and total sterol content in peanut oil

[0066]

[0067] Single-factor controlled experiment on the effect of composite adsorbent

[0068] Single acid activated montmorillonite group: No silica, only the acid activated montmorillonite products are adsorbed, otherwise the same as in Example 1.

[0069] Single silica group: only silica is adsorbed, and other aspects are the same as in Example 1.

[0070] Activated carbon group: The composite adsorbent is replaced with activated carbon, and everything else is the same as in Example 1.

[0071] Acid-activated montmorillonite + activated carbon group: silica is replaced with activated carbon, and the rest is the same as in Example 1.

[0072] The addition amount of all adsorbent-containing groups was fixed at 0.4%.

[0073] Table 3 Aflatoxin B1 Removal Rate

[0074]

[0075] Table 3 shows that the removal rate of the single acid-activated montmorillonite group was only 65.4%, the single silica group was 76.5%, the activated carbon group was 82.3%, and the acid-activated montmorillonite + activated carbon group was 93.6%, all of which were lower than those of the groups in Examples 1-3. This proves that the composite adsorbent of acid-activated sodium-based montmorillonite and silica in a specific ratio has a significant synergistic effect in the removal of aflatoxin.

[0076] Table 4. Total tocopherol and total sterol content in peanut oil

[0077]

[0078] Tables 2 and 4 show that the total tocopherol and total sterol content in Examples 1-3 was higher than that in the group without microwave treatment, the single / two-stage microwave treatment group, and also higher than that in the single silica group, the activated carbon group, and the acid-activated montmorillonite + activated carbon group. Tocopherol is a natural antioxidant in peanut oil, and total sterol is an important functional nutrient. The mild process conditions used in this process can reduce the damage of high temperature to nutrients, and the composite adsorbent has low adsorption selectivity for tocopherol and sterol, which can effectively retain these nutrients. Adsorbents such as activated carbon adsorb some tocopherol and sterol while adsorbing toxins; single / two-stage microwave treatment, due to improper power or temperature and time control, is prone to local overheating of the oil, which destroys the molecular structure of nutrients, thus resulting in poor nutrient retention.

[0079] Experiment on the effect of composite adsorbent dosage on aflatoxin B1 adsorption

[0080] The effect of different amounts of composite adsorbent added on the removal rate of aflatoxin B1 in peanut oil was investigated to determine the optimal range of addition amount of composite adsorbent.

[0081] A single-factor variable method was used, with the amount of composite adsorbent added as the only variable. Other process parameters were the same as in Example 1. Three parallel experiments were conducted for each group to reduce experimental error. The aflatoxin B1 content in peanut oil before and after treatment was determined using the GB5009.22-2016 high-performance liquid chromatography-post-column derivatization method. The calculation formula was: Removal rate (%) = (content before adsorption - content after adsorption) / content before adsorption × 100%.

[0082] Table 5. Removal rate of aflatoxin B1 in peanut oil of each group

[0083]

[0084] Table 5 shows that the amount of composite adsorbent added is significantly correlated with the removal rate of aflatoxin B1, and the optimal range of composite adsorbent addition is 0.3%~1.0%.

Claims

1. A method for removing aflatoxin from peanut oil, characterized in that, The preparation method includes the following steps: (1) Pretreatment of adsorbent and raw materials: Sodium-based montmorillonite acid was activated and modified, and then mixed with silica to prepare a composite adsorbent; peanut oil was preheated to 30-40℃ and stirred evenly as raw material to be treated; (2) Initial adsorption: Add composite adsorbent to the treated peanut oil, stir and adsorb for 1-2 hours at 80-100℃ and 100-150r / min, and let stand; (3) Staged microwave-assisted processing: Transfer to microwave equipment and perform three-stage microwave processing: the first stage is to adjust the power to 70-80℃ at 270-360W for 2-4 minutes; the second stage is to adjust the power to 45-55℃ at 540-630W for 4-6 minutes; the third stage is to adjust the power to 60-70℃ at 180-270W for 2-4 minutes, and then let it stand for 1-3 minutes. (4) Solid-liquid separation; The composite adsorbent is a mixture of acid-activated modified sodium-based montmorillonite and silica in a mass ratio of 7:3 or 6:4; the amount of the composite adsorbent added accounts for 0.3% to 1% of the mass fraction of peanut oil.

2. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The sodium montmorillonite acid activation modification step is as follows: after passing sodium montmorillonite through a 200-mesh sieve, add a 4-6% (w / w) dilute hydrochloric acid solution, wherein the solid-liquid ratio of sodium montmorillonite to dilute hydrochloric acid solution is 1:6-10, and activate by stirring at a constant temperature of 55-65℃ for 1.5-3 hours. After filtration, wash with deionized water until neutral, and then dry at 100-110℃ for 1.5-3 hours and cool.

3. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The three-stage microwave treatment is as follows: the first stage is to treat at 75°C with a power of 270W for 3 minutes; the second stage is to treat at 50°C with a power of 540W for 5 minutes; and the third stage is to treat at 65°C with a power of 180W for 3 minutes.

4. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The three-stage microwave treatment is as follows: the first stage is to treat at 75°C with a power of 360W for 3 minutes; the second stage is to treat at 50°C with a power of 630W for 5 minutes; and the third stage is to treat at 65°C with a power of 270W for 3 minutes.

5. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The three-stage microwave process is maintained at a stirring speed of 50-100 r / min.

6. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The solid-liquid separation process includes: coarse filtration, fine filtration, and ultrafine filtration.

7. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that, The solid-liquid separation is followed by a vacuum deodorization step.

Images