Method for removing aflatoxin from peanut meal and preparing high-quality peanut meal

Abstract

The present invention relates to a method for removing aflatoxin from peanut meal and preparing high-quality peanut meal. The method for removing aflatoxin from peanut meal of the present invention comprises: placing peanut meal powder with a water content of ≤8% in a closed container; evacuating the container so that the pressure in the container is ≤10mbar; introducing steam at 110-130°C until the pressure in the container reaches 0.14-0.27MPa, and maintaining the temperature and pressure in the container within the temperature range and pressure range for 10-60 minutes. The method for preparing high-quality peanuts of the present invention also comprises the steps of extracting the steam in the closed container and cooling the temperature after the steam treatment is completed. The method of the present invention can effectively remove aflatoxin from peanut meal and prepare high-quality peanut meal. The present invention also relates to products such as feed, soy sauce, and nutritionally fortified food containing or prepared using the high-quality peanut meal.

Description

Technical Field

[0001] The invention relates to a method for removing aflatoxin from peanut meal and preparing high-quality peanut meal. Background Art

[0002] Peanuts are an important economic and oil crop in my country, with an annual output of more than 17 million tons. The planting area ranks third among my country's oil crops, and its primary output value ranks first among oil crops. Peanuts are not only rich in fat, but also contain essential amino acids and trace functional nutrients for the human body. Studies have found that peanuts have the functions of anti-aging, anti-cancer, prevention of Alzheimer's disease and promotion of growth and development, so they are called "longevity nuts". Nearly 60% of peanuts in my country are used for oil extraction, accounting for about 25% of the output of self-produced vegetable oil.

[0003] Peanut meal is a byproduct of peanut oil extraction. It has rich nutritional value, with a protein content of about 50% and a complete range of amino acids. It is a potential high-quality protein feed. Protein solubility is an important indicator for measuring the processing properties of protein foods. Ordinary peanut meal contains large molecular proteins and less small peptides, and has low protein solubility.

[0004] Aflatoxins are the most toxic biological toxins found so far in contaminated agricultural products. They are highly mutagenic, carcinogenic and teratogenic to humans and animals, among which aflatoxin B1 (AFB1) is the most toxic. However, due to factors such as planting methods, environmental pollution, processing methods and storage methods, the aflatoxin content in peanuts is high. After peanut oil is extracted, most of the aflatoxin is concentrated in the peanut meal, affecting its application as a feed raw material. For example, aflatoxin can easily damage the liver of pigs. Steaming and dry heat are ineffective in removing aflatoxin, so the aflatoxin content in peanut meal should be strictly tested. The national health standard stipulates that the allowable amount of aflatoxin must be less than 0.05 mg / kg.

[0005] CN 104920796 A (“A method for reducing aflatoxin content in feed raw materials”) uses steam explosion technology and calcium oxide alkaline treatment agent to treat moldy feed, which can effectively remove aflatoxin, but high temperature will cause the quality of feed to decline. The technical solution adopted in the document “Research on Degradation of Aflatoxin B1 by Instantaneous Catapult Steam Explosion” (Li Zhimin, Master’s Thesis) can also degrade aflatoxin, but it will have a negative impact on the protein utilization rate of peanut cakes.

[0006] Therefore, there is still a need in the art for high-quality peanut meal and a preparation method thereof. Summary of the invention

[0007] The present invention aims to remove aflatoxins, especially aflatoxin B1, from peanut meal.

[0008] Therefore, the first aspect of the present invention provides a method for removing aflatoxin from peanut meal, the method comprising:

[0009] Place peanut meal powder with a moisture content of ≤8% in a sealed container;

[0010] Evacuate the container to a pressure of ≤10mbar;

[0011] After introducing steam at 110-130°C until the absolute pressure in the container reaches 0.14-0.27MPa, the temperature and pressure in the container are maintained within this temperature and pressure range for 10-60 minutes;

[0012] This removes aflatoxin from peanut meal.

[0013] In one or more embodiments, the temperature of the introduced steam is 110-120°C and the absolute pressure is 0.14-0.20 MPa.

[0014] In one or more embodiments, the temperature and pressure within the vessel are maintained within this temperature range and pressure range for 10-45 minutes.

[0015] In one or more embodiments, the temperature and pressure within the vessel are maintained within this temperature range and pressure range for 15-30 minutes.

[0016] In one or more embodiments, the steam is continuously introduced to maintain the pressure.

[0017] In one or more embodiments, the method is used to remove the content of aflatoxin B1 in peanut meal to less than 10 ppb.

[0018] In one or more embodiments, the method is used to remove more than 80% of aflatoxin B1 in peanut meal, preferably to remove more than 85% of aflatoxin B1 in peanut meal.

[0019] Furthermore, the present invention has found that by further controlling the temperature and treatment time of the steam, and extracting the steam in the container and cooling it down after the steam treatment, aflatoxin in the peanut meal can be effectively removed while not affecting the protein content of the peanut meal, thereby providing high-quality peanut meal.

[0020] Therefore, the second aspect of the present invention provides a method for preparing peanut meal, the method comprising:

[0021] Vacuuming the sealed container to a pressure of ≤10 mbar, wherein peanut meal powder with a moisture content of ≤8% is placed in the sealed container;

[0022] After introducing steam at 110-120° C. until the absolute pressure in the sealed container reaches 0.14-0.20 MPa, the temperature and pressure in the container are maintained within the temperature and pressure range for 10-45 minutes; and

[0023] Extracting the steam in the closed container to reduce the temperature;

[0024] Thereby, peanut meal is prepared.

[0025] In one or more embodiments, extracting the steam from the container is evacuating the steam from the container.

[0026] In one or more embodiments, the standing time is 15-30 minutes.

[0027] In one or more embodiments, the steam is continuously introduced to maintain the pressure.

[0028] In one or more embodiments, the method is used to prepare peanut meal having a protein content of ≥50%, a KOH protein solubility of ≥60%, and an aflatoxin B1 content of ≤10 ppb.

[0029] A third aspect of the present invention provides a high-quality peanut meal, wherein the protein content of the high-quality peanut meal is ≥50%, the protein solubility is ≥60%, and the aflatoxin B1 content is ≤10 ppb.

[0030] In a preferred embodiment, the high-quality peanut meal is prepared by any of the methods described in the second aspect of the present invention.

[0031] The fourth aspect of the present invention provides a feed containing peanut meal, wherein the protein content of the peanut meal is ≥50%, the protein solubility is ≥60%, and the aflatoxin B1 content is ≤10ppb; preferably, the peanut meal is prepared by any method described in the second aspect of the present invention.

[0032] A fifth aspect of the present invention provides a soy sauce, wherein the raw materials for brewing the soy sauce contain the peanut meal described in any embodiment of the present invention.

[0033] A sixth aspect of the present invention provides a food, wherein the raw materials for preparing the food contain the peanut meal described in any embodiment of the present invention; preferably, the food includes a nutritionally fortified food, a fermented food and a protein beverage. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0035] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0036] In this article, all features such as quantity, content and concentration defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions). In this article, unless otherwise specified, percentages are mass percentages.

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] The present invention finds that when peanut meal is processed in a closed container, if the closed container is first evacuated to ≤10 mbar and then high-temperature steam is introduced for processing for a period of time, the aflatoxin content of the obtained peanut meal can be significantly reduced while retaining the nutritional value of the peanut meal.

[0039] It should be understood that in the present invention, the "sealed container" does not mean that the container is completely sealed and completely isolated from the outside world, but means that when it is sealed, it can be isolated from the outside world. As described herein, when the sealed container is used to implement the present invention, the sealed container is connected to the outside world through a pipeline to achieve vacuuming and continuous input of the steam described herein.

[0040] Peanut Meal

[0041] Peanut meal refers to peanut cake obtained by pressing peanut kernels to extract oil, and then solvent extraction to obtain a byproduct. Peanut meal is rich in plant protein and is suitable for use in poultry, livestock and aquatic feed. The present invention is applicable to all kinds of peanut meal.

[0042] Usually, the national standard for peanut meal for feed refers to GB 10382-89. Sensory properties: crumb-like, fresh and consistent yellow-brown or light brown in color, without fermentation, mildew, insect infestation, caking, or peculiar smell.

[0043] The present invention found that both drying and crushing can improve the removal rate of aflatoxin, and drying can also increase the protein content of peanut meal and slow down the deepening of color. Therefore, preferably, before the treatment by the method of the present invention, the peanut meal is first crushed to obtain peanut meal powder. Preferably, the peanut meal powder used in the present invention is a powder that passes through a 20-mesh sieve. Preferably, the moisture content of the peanut meal suitable for the present invention is ≤8%.

[0044] Processing time

[0045] The present invention finds that after the high-temperature steam is introduced, if the placement time under the high-temperature steam is too short, it is not conducive to the removal of aflatoxin, and if the placement time is too long, it is not conducive to the nutrient retention of the peanut meal. Generally, for the purpose of removing aflatoxin, the treatment time can be 10-60 minutes, preferably 10-45 minutes, and more preferably 15-30 minutes. If high-quality peanut meal is to be obtained at the same time, the treatment time of the high-temperature steam is preferably 10-45 minutes, and more preferably 15-30 minutes.

[0046] It should be understood that the processing time described herein refers to the processing time after the steam temperature in the closed container reaches the temperature range described herein.

[0047] It should be understood that the high quality described herein includes: protein content ≥50%, protein solubility ≥60%, and aflatoxin B1 content ≤10 ppb.

[0048] Processing temperature

[0049] The present invention has found that too high a temperature of the high-temperature steam introduced is not conducive to the nutrient retention of the obtained peanut meal. The preferred temperature is not higher than 130°C, preferably in the range of 110-130°C. In order to obtain high-quality peanut meal at the same time, the preferred temperature is 110-120°C.

[0050] It should be understood that steam pressure is proportional to steam temperature, and a certain saturated steam corresponds to a certain absolute pressure. The absolute pressure corresponding to 110°C is about 0.14MPa, the absolute pressure corresponding to 120°C is about 0.20MPa, and the absolute pressure corresponding to 130°C is about 0.27MPa.

[0051] Steam within the temperature range described herein may be continuously introduced until the temperature range described herein is reached in the sealed container. Typically, the steam in the container is saturated at this point, and the temperature may be within the range described herein (e.g., 110-130° C.), and the corresponding absolute pressure is also within the range of 0.14-0.27 MPa. The peanut meal is then placed at this temperature and pressure for the time described herein. During the treatment, the pressure and temperature in the sealed container may be monitored and steam may be introduced at appropriate times to maintain the pressure and temperature in the container within the range described herein. Typically, steam is continuously introduced to maintain the pressure and temperature in the container within the range described herein.

[0052] Vacuum degree

[0053] The present invention has found that if the sealed container is not vacuumed before the high-temperature steam is introduced, it is not conducive to the removal of aflatoxin. Therefore, preferably, in the scheme of the present invention, the vacuum degree in the sealed container is first reduced to below 10 mbar before the high-temperature steam is introduced.

[0054] In addition, the present invention also found that if the steam is not extracted after the high-temperature steam treatment, but the temperature is directly lowered, the steam will condense into the peanut meal, so the color of the peanut meal after absorbing water will darken at high temperature, and the protein content will also decrease. Therefore, in a preferred embodiment, after the high-temperature steam treatment is completed, the steam in the container is extracted and then the temperature is lowered.

[0055] product

[0056] The invention comprises peanut meal prepared by the method described herein, wherein the protein content of the peanut meal is ≥50%, the protein solubility is ≥60%, and the aflatoxin B1 content is ≤10ppb.

[0057] The peanut meal prepared by the method of the invention can be used for preparing feed, brewing soy sauce, preparing nutritionally fortified food, fermented food and protein beverage, etc.

[0058] It is generally believed in the art that the degradation of aflatoxin B1 increases with increasing temperature. Compared with existing methods, the method of the present invention does not require the additional addition of alkali treatment agents (such as CaO or ammonia water), and does not require violent high-temperature reactions (160-250°C) and high-pressure reactions (for example, above 1.2MPa). The present invention can effectively reduce the content of aflatoxin B1 in peanut meal to below 10ppb by utilizing mild reaction temperature and absolute pressure (110-130°C, 0.14-0.27MPa) by vacuum treatment before steam treatment, which is far lower than the upper limit value (50ppb) set in the feed hygiene standards, and the removal rate is above 80%. Moreover, the present invention also ensures that the obtained peanut meal has high quality by vacuum treatment after steam treatment.

[0059] In this article, protein content, KOH protein solubility and aflatoxin B1 content were tested according to the following methods:

[0060] Protein Content:

[0061] KOH protein solubility test: According to GB / T 6432-1994 Kjeldahl nitrogen determination method, the soluble protein (W1) and total crude protein content (W2) in the sample are determined respectively. The KOH protein solubility X is calculated according to the following formula: X = W1 / W2*100%

[0062] The aflatoxin B1 content test was carried out in accordance with GB 5009.22-2016 method.

[0063] The feed hygiene standard refers to GB 13078-2017, and the aflatoxin B1 in peanut cake (meal) used as feed raw material is ≤50ppb.

[0064] The methods, equipment and materials not mentioned in this article are conventional methods and commercially available equipment and materials.

[0065] The following embodiments are illustrative embodiments and are not intended to limit the scope of the present invention.

[0066] Preparation example: Peanut meal pretreatment

[0067] First, the commercially available peanut meal is dried in an oven to a moisture content of ≤8%, then crushed with a universal grinder, and then passed through a 20-mesh sieve, and the sample under the sieve is taken for later use.

[0068] Example

[0069] The pretreated peanut meal prepared in the preparation example is placed in a high-pressure container and treated according to the conditions in the following table: evacuate to a vacuum degree of ≤10 mbar, then introduce steam at the temperature shown, and treat for the time shown in the table. After the treatment, evacuate the steam in the high-pressure container and cool it down to obtain high-quality peanut meal.

[0070] Example Vacuum degree Saturated steam temperature time 1 10mbar 110℃ 30min 2 10mbar 110℃ 45min 3 10mbar 115℃ 30min 4 10mbar 120℃ 10min 5 10mbar 120℃ 20min 6 10mbar 120℃ 30min

[0071] Comparative Example

[0072] The pretreated peanut meal prepared in the preparation example is placed in a high-pressure container and treated according to the conditions in the following table: evacuate to a vacuum degree of ≤10 mbar, then introduce steam at the temperature shown, and treat for the time shown in the table. After the treatment, evacuate the steam in the high-pressure container and cool it down to obtain peanut meal.

[0073] Comparative Example Vacuum degree Saturated steam temperature time 1 10mbar 115℃ 5min 2 10mbar 115℃ 60min 3 10mbar 125℃ 30min 4 10mbar 130℃ 30min

[0074] Comparative Example 5

[0075] Undried peanut meal (water content 10%) was placed in a high-pressure container, first vacuumed to 10 mbar, then introduced with 115° C. saturated steam for 30 min, and then vacuumed and cooled.

[0076] Comparative Example 6

[0077] The uncrushed peanut meal was placed in a high-pressure container, first vacuumed to 10 mbar, then introduced with 115°C saturated steam for 30 minutes, and then vacuumed and cooled.

[0078] Comparative Example 7

[0079] The pretreated peanut meal prepared in the preparation example was placed in a high-pressure container, and directly introduced with 115° C. saturated steam for 30 min without vacuuming, and then vacuumed and cooled.

[0080] Comparative Example 8

[0081] The pretreated peanut meal prepared in the preparation example was placed in a high-pressure container, first evacuated to 10 mbar, introduced with 115° C. saturated steam for 30 min, and then cooled naturally without evacuating to remove the steam.

[0082] Comparative Example 9

[0083] The untreated peanut meal was mixed with CaO in a ratio of 50:1, and the mixed materials were loaded into the explosion cylinder of QB-2000 steam explosion machine (Hebi Gandao Niuwu Energy Company) with a loading factor of 90%. Then the explosion cylinder was sealed and saturated steam at 250°C was introduced. When the pressure in the explosion cylinder reached 3.0MPa, it was maintained for 1min, and then the pneumatic valve of the explosion cylinder was quickly opened within 0.00875s for steam explosion, and the peanut meal after explosion was collected.

[0084] Comparative Example 10

[0085] The peanut meal without pretreatment was placed in an instantaneous ejection steam explosion machine QBS-80B (Hebi Zhengdao Qibao Co., Ltd.) with a blasting pressure of 1.2 MPa and a pressure holding time of 200 s, and the peanut meal after explosion was collected.

[0086] Comparative Example 11

[0087] 100 g of untreated peanut meal was first mixed with 20 ml of 4% ammonia water, and then placed in an instantaneous ejection steam explosion machine QBS-80B (Hebi Zhengdao Qibao Co., Ltd.) with a blasting pressure of 1.2 MPa and a pressure holding time of 200 s. The peanut meal after explosion was collected.

[0088] Sample index test

[0089] The peanut meal in each example and comparative example was tested for protein content, KOH protein solubility, aflatoxin B1 content, and the color was observed and evaluated. The results are shown in the table below.

[0090]

[0091]

[0092] The color of peanut meal is directly related to its quality. Darker color indicates a deeper degree of protein denaturation, which can be expressed by KOH protein solubility. The higher the degree of denaturation, the lower the KOH protein solubility. A high degree of protein denaturation will affect animal absorption and reduce the application value of peanut meal. Aflatoxin is not only related to food safety, but also to the palatability of food. The lower the toxin, the better the palatability.

[0093] As can be seen from the above table, the treatment time of Comparative Example 1 is relatively short, so the content of aflatoxin B1 is basically not reduced. The treatment time of Comparative Example 2 is too long, resulting in a significant decrease in the solubility of KOH protein, and the color of the peanut meal is dark brown. The saturated steam temperature of Comparative Examples 3 and 4 is too high, resulting in a high degree of protein denaturation, a significant decrease in the solubility of KOH protein, and the color becomes dark brown. The peanut meal of Comparative Documents 5 and 6 is not pretreated, the content of aflatoxin B1 is relatively high, and the solubility of KOH protein has also decreased to a certain extent. The results of Comparative Example 7 show that the saturated steam treatment was not vacuumed before, resulting in a high content of aflatoxin B1 and a certain degree of decrease in the solubility of KOH protein. The results of Comparative Example 8 show that the saturated steam treatment was not vacuumed after vacuuming, although it can significantly reduce aflatoxin B1, but the protein content and KOH protein solubility are significantly reduced. The results of Comparative Examples 9-11 show that the use of steam explosion method (temperature between 160-250°C) causes serious protein denaturation, the product is black, and the solubility of KOH protein is extremely low.

[0094] It can also be seen from the above table that the content of aflatoxin B1 in comparative examples 2-4 and 8 is lower than 10 ppb, indicating that aflatoxin B1 can be effectively removed by treating within the temperature range and time described in the present invention.

Claims

1. A method for removing aflatoxin from peanut meal, the method comprising: Place peanut meal powder with a moisture content of ≤8% in a sealed container; Evacuate the container to a pressure of ≤10mbar; After introducing steam at 110-120°C until the absolute pressure in the container reaches 0.14-0.20 MPa, maintain the temperature and pressure in the container within this temperature and pressure range for 10-45 minutes; This removes aflatoxin from peanut meal.

2. The method according to claim 1, characterized in that The temperature and pressure in the container are maintained within this temperature and pressure range for 15-30 minutes.

3. The method according to claim 1 or 2, characterized in that The method is used to remove the content of aflatoxin B1 in peanut meal to below 10 ppb.

4. A method for preparing peanut meal, characterized in that: The method comprises, in sequence: Vacuuming the sealed container to a pressure of ≤10 mbar, wherein peanut meal powder with a moisture content of ≤8% is placed in the sealed container; After introducing steam at 110-120° C. until the absolute pressure in the sealed container reaches 0.14-0.20 MPa, the temperature and pressure in the container are maintained within the temperature and pressure range for 10-45 minutes; and Extracting the steam in the closed container to reduce the temperature; Thereby, peanut meal is prepared.

5. The method according to claim 4, characterized in that The temperature and pressure in the container are maintained within this temperature and pressure range for 15-30 minutes.

6. The method according to claim 4 or 5, characterized in that The method is used for preparing peanut meal with a protein content of ≥50%, a KOH protein solubility of ≥60% and an aflatoxin B1 content of ≤10 ppb.

7. A peanut meal, characterized in that: The protein content of the peanut meal is ≥50%, the KOH protein solubility is ≥60%, and the aflatoxin B1 content is ≤10ppb. The peanut meal is prepared by the method according to any one of claims 4 to 6.

8. A feed containing peanut meal, wherein: The peanut meal as claimed in claim 7.

9. A soy sauce, characterized in that The brewing raw materials of the soy sauce contain the peanut meal described in claim 7.

10. A food, characterized in that The raw materials for preparing the food contain the peanut meal described in claim 7.

11. The food according to claim 10, characterized in that The food includes nutritionally fortified food, fermented food and protein beverage.

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