Method for removing aflatoxin in peanut oil

Abstract

The invention provides a method for removing aflatoxin in peanut oil, and relates to the technical field of peanut oil processing. The method for removing the aflatoxin in the peanut oil comprises the following steps: step 1, pretreatment of the peanut oil: heating the peanut oil to 60-70 DEG C, and adding citric acid which is 0.5% of the weight of the peanut oil; step 2, adsorption treatment: controlling the temperature of the pretreated peanut oil at 50-55 DEG C, and adding a composite adsorbent; step 3, filtering and separating: carrying out pressure filtration by using a plate-and-frame filter press at the pressure of 0.3 MPa and the temperature of 50 DEG C, and then carrying out secondary filtration by using a 0.5 mu m ceramic membrane; 4, treatment of the adsorption waste: carrying out solvent extraction on the filtered adsorption waste; and step 5, tail oil recycling: independently storing grease of the extracted tail oil for preparing biological kerosene. Through the design of the composite adsorbent, the optimization of a dynamic mixing process and the establishment of a grease recovery system, the efficient removal of aflatoxin and the cyclic utilization of resources are realized, and the method has remarkable economic benefits and social benefits.

Description

Technical Field

[0001] This invention relates to the field of peanut oil processing technology, specifically to a method for removing aflatoxin from peanut oil. Background Technology

[0002] Aflatoxin is a highly toxic metabolite produced by Aspergillus flavus and is commonly found in moldy grains, nuts, and legumes. It is a known potent carcinogen, causing significant damage, especially to the liver.

[0003] Peanuts inevitably develop a small amount of mold during the daily drying and storage process. While peanuts are screened before oil extraction, due to the large volume of peanuts being pressed, a small amount still inevitably ends up in the oil extraction stage. During oil extraction, a small amount of Aspergillus flavus from these moldy peanuts can enter the peanut oil, contaminating it. After extraction, peanut oil undergoes refining to remove Aspergillus flavus, reducing harmful substances to within national standards.

[0004] In the current process of removing aflatoxin from peanut oil, many methods use adsorption to treat the peanut oil. The adsorption method involves adding materials with adsorption properties to the peanut oil, stirring the adsorption materials to adsorb the harmful substances of aflatoxin, and then filtering out clean peanut oil.

[0005] In actual use, this method does not completely adsorb harmful substances from aflatoxin in peanut oil, resulting in a small amount of harmful substances still remaining in the peanut oil. In actual use, the adsorbent and oil do not come into sufficient contact, leading to large fluctuations in the residual toxin content. After the harmful substances in peanut oil are adsorbed by the adsorbent, the peanut oil needs to be filtered. The remaining adsorbent waste contains a small amount of peanut oil. If it is only processed once, there will not be much waste. However, for peanut oil refineries that produce tens or even hundreds of tons a day, the waste of peanut oil is considerable. We must find a way to solve this problem. Therefore, this invention proposes a method for removing aflatoxin from peanut oil. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for removing aflatoxin from peanut oil, solving the problems of incomplete removal of aflatoxin and excessive waste in existing peanut oil extraction methods.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for removing aflatoxin from peanut oil, comprising the following steps: Step 1: Peanut oil pretreatment: Heat the peanut oil to 60-70℃, add 0.5% citric acid by weight of the oil, stir for 30 minutes, and let it stand to settle for 12 hours; Step 2, Adsorption treatment: Control the temperature of the pretreated peanut oil at 50-55℃, add the composite adsorbent, and mix for 45 minutes with double helix stirring and ultrasonic assistance. Step 3, Filtration and Separation: Pressure filtration is performed using a plate and frame filter press at a pressure of 0.3 MPa and a temperature of 50°C, followed by secondary filtration through a 0.5 μm ceramic membrane; Step 4, Adsorption waste treatment: The filtered adsorption waste is subjected to solvent extraction at a solid-liquid ratio of 1:3, a temperature of 60℃, and a time of 2 hours. The solvent is then recovered by vacuum distillation. Step 5, Reuse of tail oil: The oil extracted from the tail oil is stored separately for the production of bio-kerosene.

[0008] Preferably, the composite adsorbent is composed of modified activated carbon, diatomaceous earth and nano-alumina mixed in a mass ratio of 3:2:1.

[0009] Preferably, the method for preparing the modified activated carbon includes: immersing coconut shell activated carbon in a 1 mol / L nitric acid solution, stirring at 80°C for 2 hours, filtering, washing with water until neutral, and drying at 120°C for 4 hours; Preparation of composite adsorbent: Modified activated carbon, 325 mesh diatomaceous earth and 50 nm nano alumina were mixed in a mass ratio of 3:2:1, and 1% stearic acid was added as a dispersant. The mixture was ball-milled for 2 hours.

[0010] Preferably, in the adsorption treatment step, the rotation speed of the double helix stirrer is 120 r / min, and the frequency of the ultrasonic generator is 40 kHz.

[0011] Preferably, the solvent used for solvent extraction is n-hexane, which is recovered by vacuum distillation at a pressure of -0.09 MPa and a temperature of 35°C.

[0012] Preferably, the adsorbent regeneration method includes: calcining the used adsorbent at 300°C for 2 hours, and then washing it with 0.5 mol / L hydrochloric acid.

[0013] Preferably, the aflatoxin B1 content in the refined peanut oil is controlled below 2 μg / kg, and the aflatoxin B1 content in the tail oil does not exceed 5 μg / kg.

[0014] Preferably, an apparatus for removing harmful substances from peanut oil includes: Pretreatment tank: equipped with heating device, pH adjustment system and online monitoring device; Adsorption tank: equipped with a temperature control system, a double spiral stirrer and an ultrasonic generator; Plate and frame filter press: equipped with pressure regulating device and temperature control system; Solvent extraction apparatus: includes extraction tank, vacuum distillation system and solvent recovery tank; Oil storage tank: Used for the separate storage of tail oil.

[0015] Preferably, the online monitoring device is a near-infrared spectrometer for real-time detection of aflatoxin B1 content.

[0016] Preferably, the adsorbent regeneration system includes a calcination furnace and an acid washing tank, and the performance recovery rate of the regenerated adsorbent is >90%.

[0017] This invention provides a method for removing aflatoxin from peanut oil. It has the following beneficial effects: This invention employs a composite system of modified activated carbon, diatomaceous earth, and nano-alumina to enhance the specific adsorption of aflatoxin through surface functional group modification. A mixing device combining double-helix stirring and ultrasonic assistance is developed to achieve uniform dispersion of the adsorbent in oils. A closed-loop recovery process of hexane solvent extraction-vacuum distillation is established to increase the oil recovery rate in adsorption waste to over 85%. Through combined high-temperature calcination and acid washing, the number of times the adsorbent can be recycled is increased from 3 to over 5 times. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the present invention; Figure 2 This is a schematic diagram of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1:

[0021] like Figure 1-2 As shown in the figure, this invention provides a method for removing aflatoxin from peanut oil, including the following steps: through the design of composite adsorbents, optimization of dynamic mixing processes, and the establishment of an oil recovery system, efficient removal of aflatoxin and resource recycling are achieved, resulting in significant economic and social benefits.

[0022] Step 1: Peanut oil pretreatment: Heat the peanut oil to 60℃, add 0.5% citric acid by weight of the oil, stir for 30 minutes, and let it stand to settle for 12 hours; Step 2, Adsorption treatment: The temperature of the pretreated peanut oil is controlled at 50℃, and a composite adsorbent is added. The mixture is stirred by double helix stirring and ultrasonic-assisted mixing for 45 minutes. The composite adsorbent is composed of modified activated carbon, diatomaceous earth and nano alumina in a mass ratio of 3:2:1. The preparation method of modified activated carbon includes: immersing coconut shell activated carbon in a 1 mol / L nitric acid solution, stirring at 80℃ for 2 hours, filtering, washing with water until neutral, and drying at 120℃ for 4 hours. Coconut shell activated carbon has the characteristics of well-developed pores, good adsorption performance, high strength, easy regeneration, and economic durability. It has low sulfur content and strong resistance to pulverization. However, due to factors such as the geographical limitations of raw materials, the production cost is higher than that of conventional wood-based activated carbon. Products are divided into categories such as high-quality coconut shell activated carbon, activated carbon for gold extraction, and LC-type activated carbon for free chlorine removal. Preparation of composite adsorbent: Modified activated carbon, 325 mesh diatomaceous earth and 50 nm nano alumina are mixed in a mass ratio of 3:2:1, 1% stearic acid is added as a dispersant, and the mixture is ball-milled for 2 hours. In the adsorption treatment step, the double helix stirrer rotates at 120 r / min and the ultrasonic generator frequency is 40 kHz to promote the adsorption of harmful substances. Step 3, Filtration and Separation: Pressure filtration is performed using a plate and frame filter press at a pressure of 0.3 MPa and a temperature of 50°C, followed by secondary filtration through a 0.5 μm ceramic membrane; Step 4, Adsorption waste treatment: The filtered adsorption waste is subjected to solvent extraction at a solid-liquid ratio of 1:3, a temperature of 60℃, and a time of 2 hours. The solvent is then recovered by vacuum distillation. The solvent used for solvent extraction was n-hexane, which was recovered by vacuum distillation at a pressure of -0.09 MPa and a temperature of 35°C. The adsorbent regeneration method includes: calcining the used adsorbent at 300℃ for 2 hours, and then washing it with 0.5mol / L hydrochloric acid; Step 5, Reuse of tail oil: The oil extracted from the tail oil is stored separately for the production of bio-kerosene. Secondary filtration is performed using a 0.5μm ceramic membrane filter to remove trace suspended solids. The aflatoxin B1 content in refined peanut oil is controlled below 2 μg / kg, and the aflatoxin B1 content in tail oil does not exceed 5 μg / kg.

[0023] Example 2:

[0024] Reference Figure 2 As shown, an embodiment of the present invention provides an apparatus for removing harmful substances from peanut oil, comprising: Pretreatment tank: equipped with heating device, pH adjustment system and online monitoring device; Adsorption tank: equipped with a temperature control system, a double spiral stirrer and an ultrasonic generator; Plate and frame filter press: Equipped with a pressure regulating device and a temperature control system, using a plate and frame filter press with a filtration area of ​​20m², a pressure of 0.3MPa, and a temperature of 50℃; Solvent extraction apparatus: includes extraction tank, vacuum distillation system and solvent recovery tank; Oil storage tank: Used for the separate storage of tail oil.

[0025] The online monitoring device is a near-infrared spectrometer, which detects the aflatoxin B1 content in real time.

[0026] The adsorbent regeneration system includes a calcination furnace and an acid washing tank, and the performance recovery rate of the regenerated adsorbent is >90%.

[0027] Example 3:

[0028] Reference Figure 1-2 As shown, this embodiment of the invention provides a method for removing aflatoxin from peanut oil. Raw material: 1000 kg of crude peanut oil, with an aflatoxin B1 content of 15 μg / kg. Pretreatment: Heat to 65℃, add 5kg of citric acid, stir for 30 minutes, and let stand for 12 hours; Adsorption treatment: 3 kg of composite adsorbent was added at 55℃, stirred at 120 r / min + ultrasonic at 40 kHz for 45 minutes. Filtration: Pressure 0.3MPa, temperature 50℃, plate and frame filter press + ceramic membrane filter, to obtain 980kg of refined peanut oil; Adsorption waste treatment: 66 kg of n-hexane, extracted at 60℃ for 2 hours, solvent recovered by vacuum distillation, 18.5 kg of tail oil; Refined peanut oil test: Aflatoxin B1 content 1.8 μg / kg; Tail oil test: Aflatoxin B1 content 4.2 μg / kg.

[0029] Example 4:

[0030] Reference Figure 1-2 As shown, this embodiment of the invention provides a method for removing aflatoxin from peanut oil. Raw material: 5000 kg of crude peanut oil, with aflatoxin B1 content of 18 μg / kg; Pretreatment: Heat to 70℃, add 25kg of citric acid, stir for 30 minutes, and let stand for 12 hours; Adsorption treatment: At 50℃, add 15kg of composite adsorbent, stir at 120r / min + 40kHz ultrasound for 45 minutes. Filtration: Pressure 0.3MPa, temperature 50℃, plate and frame filter press + ceramic membrane filtration, yielding 4920kg of refined peanut oil; Adsorption waste treatment: 330 kg of n-hexane, extracted at 60°C for 2 hours, solvent recovered by vacuum distillation, 93.5 kg of tail oil; Refined peanut oil test: Aflatoxin B1 content 1.9 μg / kg; Tail oil test: Aflatoxin B1 content 4.5 μg / kg.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for removing aflatoxin from peanut oil, characterized in that: Includes the following steps: Step 1: Peanut oil pretreatment: Heat the peanut oil to 60-70℃, add 0.5% citric acid by weight of the oil, stir for 30 minutes, and let it stand to settle for 12 hours; Step 2, Adsorption treatment: Control the temperature of the pretreated peanut oil at 50-55℃, add the composite adsorbent, and mix for 45 minutes with double helix stirring and ultrasonic assistance. Step 3, Filtration and Separation: Pressure filtration is performed using a plate and frame filter press at a pressure of 0.3 MPa and a temperature of 50°C, followed by secondary filtration through a 0.5 μm ceramic membrane; Step 4, Adsorption waste treatment: The filtered adsorption waste is subjected to solvent extraction at a solid-liquid ratio of 1:3, a temperature of 60℃, and a time of 2 hours. The solvent is then recovered by vacuum distillation. Step 5, Reuse of tail oil: The oil extracted from the tail oil is stored separately for the production of bio-kerosene.

2. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: The composite adsorbent is composed of modified activated carbon, diatomaceous earth and nano-alumina mixed in a mass ratio of 3:2:

1.

3. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: The preparation method of the modified activated carbon includes: immersing coconut shell activated carbon in a 1 mol / L nitric acid solution, stirring at 80°C for 2 hours, filtering, washing with water until neutral, and drying at 120°C for 4 hours. Preparation of composite adsorbent: Modified activated carbon, 325 mesh diatomaceous earth and 50 nm nano alumina were mixed in a mass ratio of 3:2:1, and 1% stearic acid was added as a dispersant. The mixture was ball-milled for 2 hours.

4. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: In the adsorption treatment step, the double helix stirrer rotates at 120 r / min and the ultrasonic generator frequency is 40 kHz.

5. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: The solvent used in the solvent extraction was n-hexane, which was recovered by vacuum distillation at a pressure of -0.09 MPa and a temperature of 35°C.

6. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: The adsorbent regeneration method includes: calcining the used adsorbent at 300°C for 2 hours, and then washing it with 0.5 mol / L hydrochloric acid.

7. The method for removing aflatoxin from peanut oil according to claim 1, characterized in that: The aflatoxin B1 content in the refined peanut oil is controlled below 2 μg / kg, and the aflatoxin B1 content in the tail oil does not exceed 5 μg / kg.

8. An apparatus for removing harmful substances from peanut oil, the apparatus being used to implement the method according to any one of claims 1-7, characterized in that: include: Pretreatment tank: equipped with heating device, pH adjustment system and online monitoring device; Adsorption tank: equipped with a temperature control system, a double spiral stirrer and an ultrasonic generator; Plate and frame filter press: equipped with pressure regulating device and temperature control system; Solvent extraction apparatus: includes extraction tank, vacuum distillation system and solvent recovery tank; Oil storage tank: Used for the separate storage of tail oil.

9. The apparatus for removing harmful substances from peanut oil according to claim 8, characterized in that: The online monitoring device is a near-infrared spectrometer, which detects the aflatoxin B1 content in real time.

10. The apparatus for removing harmful substances from peanut oil according to claim 8, characterized in that: The adsorbent regeneration system includes a calcination furnace and an acid washing tank, and the performance recovery rate of the regenerated adsorbent is >90%.

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