Detoxification method of flaxseed meal

Abstract

The invention discloses a detoxification method of flaxseed meal, and relates to the technical field of food processing. The detoxification method comprises the following steps: (1) crushing flaxseed meal, introducing water mist while stirring, stopping introducing water mist when the water content of the flaxseed meal is 30-40%, and carrying out microwave treatment and decompression treatment to obtain a primary treatment material; (2) putting the primary treated material into a distillation retort, connecting the distillation retort with an evaporator, firstly adding equal amount of water and 0.5-1.5% ethanol solution into the evaporator, then introducing mixed steam, and carrying out detoxification distillation under a micro-pressure condition; reducing the pressure to normal pressure, adding 0.01-1.5% of acetic acid solution, continuously introducing mixed steam, and performing detoxification distillation under a micro-pressure condition; continuously reducing the pressure to normal pressure, adding 0.001-0.015% of ethanol solution, and introducing mixed steam for detoxification and distillation; and finally, performing decompression treatment. The method not only can efficiently remove hydrocyanic acid, trypsin inhibiting factors and phytic acid, but also can reduce the loss of nutrient substances.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a method for detoxifying flaxseed meal. Background Art

[0002] Flaxseed meal is a byproduct of flaxseed oil extraction. It is rich in nutrients and physiologically active substances such as plant protein, flax gum, dietary fiber, lignans and α-linolenic acid, and has potential utilization value. However, flaxseed meal also contains many anti-nutritional factors and toxic substances, such as cyanogenic glycosides, trypsin inhibitors, phytic acid, etc. Cyanogenic glycosides can form hydrocyanic acid in animals, causing poisoning and death. According to literature reports, the content of hydrocyanic acid in flaxseed is usually 200-300 mg / kg, while the minimum lethal oral dose of hydrocyanic acid is 0.5-3.5 mg / kg, which seriously limits the development and utilization of flaxseed meal.

[0003] At present, there have been many studies on the detoxification of flaxseed meal. Commonly used detoxification methods include boiling, pressure cooking, microbial method, microwave method and solvent extraction method, all of which have certain detoxification effects. Among them, the removal rate of hydrocyanic acid by boiling is the highest, about 97%, the removal rate of pressure cooking is about 64%, the removal rate of microbial method is about 60%, the removal rate of microwave method is about 89%, and the removal rate of solvent extraction is about 85%. Except for the low content of hydrocyanic acid by boiling method, which can meet the use requirements, the hydrocyanic acid content of other treatment methods is still very high, all higher than 10 mg / kg, which cannot meet the requirements of development and utilization. In addition, the boiling method can also remove trypsin inhibitors and phytic acid, but the boiling method is prone to cause the loss and destruction of nutrients such as flax gum, dietary fiber, lignans, α-linolenic acid and protein. Studies have reported that boiling detoxification causes the protein molecules in flaxseed meal to dissociate, and the content of available lysine decreases by 30%.

[0004] In summary, the present invention aims to provide a method for detoxifying flaxseed meal. Summary of the invention

[0005] In view of the above shortcomings, the present invention provides a detoxification method for flaxseed meal, which solves the problems of poor hydrocyanic acid removal effect and serious loss and destruction of nutrients in the current treatment method. The present invention is used to detoxify flaxseed meal, which can not only efficiently remove hydrocyanic acid, trypsin inhibitor and phytic acid, but also reduce the loss of nutrients. The specific technical scheme is as follows:

[0006] A method for detoxifying flaxseed meal comprises the following steps:

[0007] (1) After the flaxseed meal is crushed, water mist is introduced while stirring. When the moisture content of the flaxseed meal is 30-40%, the introduction of water mist is stopped, and then microwave treatment is performed for 3-5 minutes, followed by decompression treatment for 20-30 minutes to obtain a primary treated material;

[0008] (2) The primary treated material is placed in a distillation tank, which is connected to an evaporator. First, water of the same weight as the primary treated material and an ethanol solution of 0.5-1.5% by weight of the primary treated material are added to the evaporator. Then, the mixed vapor in the evaporator is passed into the distillation tank, and detoxification distillation is performed for 1-3 minutes under micro-pressure conditions; then, the pressure is reduced to normal pressure, and an acetic acid solution of 0.01-1.5% by weight of the primary treated material is added to the evaporator, and the mixed vapor is continued to be passed, and detoxification distillation is performed for 3-5 minutes under micro-pressure conditions; the pressure is further reduced to normal pressure, and an ethanol solution of 0.001-0.015% by weight of the primary treated material is added to the evaporator, and the mixed vapor is passed for detoxification distillation for 1-2 minutes; finally, the pressure is reduced for 3-5 minutes to obtain the product.

[0009] Furthermore, in step (1), the microwave power is 200-300 W and the frequency is 600-800 MHz.

[0010] Furthermore, in step (1), the pressure of the decompression treatment is -0.05 to -0.02 MPa, and the temperature is set to 70 to 80°C.

[0011] Furthermore, in step (2), the pressure in the micro-pressure condition is 0.001 to 0.005 MPa.

[0012] Furthermore, in step (2), the mass concentration of the ethanol solution is 40-60%.

[0013] Furthermore, in step (2), the mass concentration of the acetic acid solution is 1 to 3%.

[0014] Furthermore, in step (2), the pressure of the decompression treatment is -0.03 to -0.01 MPa, and the temperature is set to 60 to 70°C.

[0015] Furthermore, in step (2), the amount of the primary treated material in the distillation tank is 100-150 kg; and the steam flow rate of the mixed steam is set to 2-2.5 kg / min.

[0016] The above pressures are all relative pressures.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention can effectively remove hydrocyanic acid, trypsin inhibitors and phytic acid, and can also reduce the loss of nutrients such as flax gum, dietary fiber, lignans, α-linolenic acid, etc. It has been found through testing that after the flaxseed meal is detoxified by the method of the present invention, the hydrocyanic acid removal rate is more than 99%, the trypsin inhibitor content is less than 0.2 mg / g, and the phytic acid removal rate is more than 90%. It can be used for further development and utilization, and has high safety.

[0019] 2. The flaxseed gum in the flaxseed meal of the present invention has a certain water holding capacity. After the flaxseed meal is crushed, water mist is introduced while stirring so that the flaxseed meal can absorb water uniformly. When microwaved, the water in the flaxseed meal is first heated and the temperature rises rapidly, and the glycosidase in the flaxseed meal is activated. When the water content is set to 30-40%, the glycosidase activation speed is faster and the activity is higher. The glycosidase rapidly converts the cyanogenic glycoside into hydrocyanic acid. After the conversion is complete, a decompression treatment is performed. During the decompression process, the hydrocyanic acid is volatilized and removed with the water vapor. When the decompression is performed, the pressure is set to -0.05--0.02MPa. The volatilization speed is faster and the removal is more thorough. The final removal rate of hydrocyanic acid is more than 99%, which can basically achieve complete removal. The decompression treatment temperature is 70-80°C, which will not damage other nutrients. Compared with the traditional boiling method (protein dissociation occurs, lysine loss is about 30%), the pressure cooking method (hot steam at about 120°C, removal rate is about 64, protein loss is large) or the single microwave method (cyanogenic glycoside removal rate is about 89%, and the removal effect is not significant), the method of the present invention has a higher hydrocyanic acid removal rate and a smaller loss of nutrients.

[0020] 3. The present invention uses ethanol and acetic acid as solvents and performs distillation treatment under micro-pressure conditions, which can effectively remove anti-nutritional factors such as trypsin inhibitors and phytic acid in flaxseed meal, and the amount of ethanol and acetic acid used is small, the treatment time is short, and under less solvent and treatment time, the loss of nutrients due to heat is less. At the same time, the final decompression treatment can also reduce the water content of flax gum in flaxseed meal and reduce viscosity, which is convenient for later treatment. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0022] The pressures mentioned below are all relative pressures.

[0023] Example 1

[0024] The detoxification method of flaxseed meal comprises the following steps:

[0025] (1) After the flaxseed meal is crushed, water mist is introduced while stirring. When the moisture content of the flaxseed meal reaches 30%, the introduction of water mist is stopped. Then, the flaxseed meal is subjected to microwave treatment at a power of 200 W and a frequency of 600 MHz for 5 minutes, and then subjected to reduced pressure treatment at 70° C. for 30 minutes. The reduced pressure is -0.05 MPa, thereby obtaining a primary treated material;

[0026] (2) 100 kg of the primary treated material is placed in a distillation tank, which is connected to an evaporator. First, water equal to the weight of the primary treated material and a 40% ethanol solution of 0.5% of the weight of the primary treated material are added to the evaporator, and then the mixed steam in the evaporator is passed into the distillation tank, the steam flow rate is set to 2 kg / min, and detoxification distillation is performed for 3 minutes under a micro-pressure of 0.001 MPa; then the pressure is reduced to normal pressure, and a 1% acetic acid solution of 0.01% of the weight of the primary treated material is added to the evaporator, and the mixed steam is continued to be passed, the steam flow rate is set to 2 kg / min, and detoxification distillation is performed for 5 minutes under a micro-pressure of 0.001 MPa; the pressure is further reduced to normal pressure, and a 40% ethanol solution of 0.001% of the weight of the primary treated material is added to the evaporator, and the mixed steam is passed for detoxification distillation for 2 minutes, and the steam flow rate is set to 2 kg / min; finally, the mixture is decompressed at 60°C and -0.03 MPa for 5 minutes. Vacuum packaging is performed before shipment.

[0027] Example 2

[0028] The detoxification method of flaxseed meal comprises the following steps:

[0029] (1) After the flaxseed meal is crushed, water mist is introduced while stirring. When the moisture content of the flaxseed meal reaches 40%, the introduction of water mist is stopped. Then, the flaxseed meal is subjected to microwave treatment at a power of 300 W and a frequency of 800 MHz for 3 minutes, and then subjected to reduced pressure treatment at 80° C. for 20 minutes. The reduced pressure is -0.02 MPa, and a primary treated material is obtained.

[0030] (2) 150 kg of primary treated material is placed in a distillation tank, which is connected to an evaporator. First, water equal to the weight of the primary treated material and a 60% ethanol solution of 1.5% of the weight of the primary treated material are added to the evaporator, and then the mixed steam in the evaporator is passed into the distillation tank, the steam flow rate is set to 2.5 kg / min, and detoxification distillation is performed at a micro-pressure of 0.005 MPa for 1 minute; then the pressure is reduced to normal pressure, and a 3% acetic acid solution of 1.5% of the weight of the primary treated material is added to the evaporator, and the mixed steam is continued to be passed, the steam flow rate is set to 2.5 kg / min, and detoxification distillation is performed at a micro-pressure of 0.005 MPa for 3 minutes; the pressure is further reduced to normal pressure, and a 60% ethanol solution of 0.015% of the weight of the primary treated material is added to the evaporator, and the mixed steam is passed for detoxification distillation for 1 minute, and the steam flow rate is set to 2.5 kg / min; finally, the mixture is decompressed at 70°C and -0.01 MPa for 3 minutes. Vacuum packaging is performed before shipment.

[0031] Example 3

[0032] The detoxification method of flaxseed meal comprises the following steps:

[0033] (1) After the flaxseed meal is crushed, water mist is introduced while stirring. When the moisture content of the flaxseed meal reaches 35%, the introduction of water mist is stopped. Then, the flaxseed meal is subjected to microwave treatment at a power of 250 W and a frequency of 700 MHz for 4 minutes, and then subjected to reduced pressure treatment at 75° C. for 25 minutes. The reduced pressure is -0.03 MPa, thereby obtaining a primary treated material;

[0034] (2) 120 kg of the primary treated material is placed in a distillation tank, which is connected to an evaporator. First, water equal to the weight of the primary treated material and a 50% ethanol solution of 1% by weight of the primary treated material are added to the evaporator, and then the mixed steam in the evaporator is passed into the distillation tank, the steam flow rate is set to 2.2 kg / min, and detoxification distillation is performed for 2 minutes under a micro-pressure of 0.003 MPa; then the pressure is reduced to normal pressure, and a 2% acetic acid solution of 1% by weight of the primary treated material is added to the evaporator, and the mixed steam is continued to be passed, the steam flow rate is set to 2.2 kg / min, and detoxification distillation is performed for 4 minutes under a micro-pressure of 0.003 MPa; the pressure is further reduced to normal pressure, and a 50% ethanol solution of 0.0012% by weight of the primary treated material is added to the evaporator, and the mixed steam is passed for detoxification distillation for 1.5 minutes, and the steam flow rate is set to 2.2 kg / min; finally, the mixture is decompressed at 65°C and -0.02 MPa for 4 minutes. Vacuum packaging is performed before shipment.

[0035] The detoxification of the flaxseed meal after being treated in Examples 1 to 3 was tested respectively, and the results are shown in Table 1:

[0036] Sample description: Example 1 product sample 1 box, 500g / bag, 500g x 30 bags / box, vacuum packed, outer carton packed, packed in good condition. The samples of Example 2 and Example 3 have the same specifications as Example 1, and the packaging is intact.

[0037] Inspection items:

[0038] Trypsin inhibitor concentration: tested according to GB 5009.224-2016;

[0039] Phytic acid removal rate: Phytic acid removal rate = (phytic acid content of linseed meal before treatment - phytic acid content of linseed meal after treatment) / phytic acid content of linseed meal before treatment × 100%, wherein the phytic acid content is detected with reference to GB 5009.153-2016.

[0040] Hydrogen cyanide removal rate: Hydrogen cyanide removal rate = (hydrogen cyanide content of flaxseed meal before treatment - hydrocyanic acid content of flaxseed meal after treatment) / hydrocyanic acid content of flaxseed meal before treatment × 100%; the hydrocyanic acid content is detected with reference to the second method of GB 5009.36-2023 "National Food Safety Standard Determination of Cyanide in Food".

[0041] Table 1 Detoxification of flaxseed meal after treatment in each embodiment

[0042]

[0043] Table 1 shows that the trypsin inhibitor concentration of the flaxseed meal treated by the method of the present invention is less than 0.2 mg / g, the phytic acid removal rate is more than 90%, and the hydrocyanic acid removal rate is more than 99%, and the detoxification effect is significant. Compared with the flaxseed meal before detoxification (the hydrocyanic acid content of the flaxseed meal before detoxification is 260 mg / kg), the toxic substance hydrocyanic acid has been basically removed, and can be used for further development and utilization, with high safety.

[0044] The changes of amino acids in flaxseed meal before and after treatment in Examples 1 to 3 were detected respectively, and compared with the conventional boiling method. The results are shown in Table 2:

[0045] Each example takes the same batch of flaxseed meal, a part of which is directly extracted with flaxseed meal protein and then used to detect the amino acid content as the amino acid content before treatment, and the other part of flaxseed meal is detoxified by the method of each example, and the flaxseed meal protein is extracted after the treatment and the amino acid content is detected, and the amino acid loss rate = (amino acid content before treatment-amino acid content after treatment) / amino acid content before treatment × 100%. Among them, the flaxseed meal protein is extracted by alkali dissolution and acid precipitation method, and the specific method is to grind the flaxseed meal and then leaching it in an extracting solution with a solid-liquid ratio of 1:30 for 90 minutes, the pH of the extracting solution is 9.5, the extraction temperature is 35°C, centrifuge, add acid to the supernatant to precipitate the protein, filter, take the precipitate, wash, and dry to obtain flaxseed meal protein. After the flaxseed meal protein is extracted, it is detected by an automatic amino acid analyzer.

[0046] Table 2 Changes of amino acids in flaxseed meal before and after detoxification in each example

[0047]

[0048] Table 2 shows that the loss rate of amino acids in detoxification by the method of the present invention is very small. Except for the loss rates of cystine and lysine, which are about 10%, the loss rates of other amino acids can be basically controlled within 0-6%. Some individual amino acids are not even lost, thus ensuring the nutritional value of flaxseed meal, which is superior to conventional methods.

[0049] The changes of lignans and flax gum in flaxseed meal before and after treatment in Examples 1 to 3 were detected respectively, and compared with the conventional water boiling method. The results are shown in Table 3:

[0050] The extraction method of lignans from flaxseed meal was carried out with reference to "Gao Qianqian et al. Study on microwave-assisted extraction process and antioxidant activity of lignans from flaxseed cake. Food Research and Development. 2020, 41(16).".

[0051] The method for extracting flaxseed gum from flaxseed meal was carried out with reference to "Yao Yue et al. Enzymatic method combined with ultrasonic extraction of flaxseed gum. China Oils and Fats. 2022, 47(02)."

[0052] Lignan loss rate = (lignan content before treatment - lignan content after treatment) / lignan content before treatment × 100%.

[0053] Linen gum loss rate = (linen gum content before treatment - linen gum content after treatment) / linen gum content before treatment × 100%.

[0054] Table 3 Changes of lignans and flax gum in flaxseed meal before and after detoxification in each example

[0055] Category / Project Lignan loss rate (%) Linen gum loss rate (%) Example 1 0.78 0.44 Example 2 0.63 0.35 Example 3 0.55 0.33 boiling method 11.5 30.8

[0056] Table 3 shows that the loss rate of lignans and flax gum in flaxseed meal by the detoxification method of the present invention is very low, with almost no loss, which is better than the conventional method.

[0057] Comparative Example 1

[0058] The detoxification process in this comparative example does not include step (1), and the other steps are the same as those in Example 1.

[0059] Comparative Example 2

[0060] In the detoxification step (1) of this comparative example, water mist treatment is not performed, and microwave treatment is performed directly. The other steps are the same as those in Example 1.

[0061] Comparative Example 3

[0062] In the detoxification treatment step (1) of this comparative example, the moisture content of the flaxseed meal after the water mist is introduced is set to 20%, and the other steps are the same as those in Example 1.

[0063] Comparative Example 4

[0064] In the detoxification step (1) of this comparative example, the moisture content of the flaxseed meal after the water mist is introduced is set to 45%, and the other steps are the same as those in Example 1.

[0065] Comparative Example 5

[0066] The detoxification step (1) of this comparative example does not undergo decompression treatment, and the other steps are the same as those of Example 1.

[0067] The removal of hydrocyanic acid in Comparative Examples 1 to 5 was tested, and the results are shown in Table 4:

[0068] Table 4 Detoxification of hydrocyanic acid in flaxseed meal after treatment

[0069] Project / Group Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Hydrocyanic acid removal rate (%) 99.1 72.3 80.2 94.5 92.7 79.6

[0070] Table 4 shows that hydrocyanic acid can be completely removed only by introducing water mist and setting the water content of flaxseed meal to 30-40%, in combination with microwave treatment and reduced pressure treatment.

[0071] Comparative Example 6

[0072] In the detoxification treatment of this comparative example, the "micro-pressure condition" of step (2) was changed to "normal pressure", and the other steps were the same as those in Example 1.

[0073] The detoxification effect of comparative example 6 was tested, and the results are shown in Table 5:

[0074] Table 5 Comparison of test results of each group

[0075]

[0076] The data of Example 1 and Comparative Example 6 in the above table show that the use of micro-pressure conditions during distillation with the addition of ethanol and acetic acid can improve the removal effect of trypsin inhibitors and phytic acid.

[0077] In summary, the present invention can effectively remove hydrocyanic acid, trypsin inhibitors and phytic acid, and can also reduce the loss of nutrients such as flax gum and lignans. It was found through testing that after the flaxseed meal was detoxified by the method of the present invention, the hydrocyanic acid removal rate was more than 99%, the trypsin inhibitor content was less than 0.2 mg / g, and the phytic acid removal rate was more than 90%, which can be used for further development and utilization with high safety.

[0078] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for detoxifying flaxseed meal, characterized in that: The following steps are involved: (1) After the flaxseed meal is crushed, water mist is introduced while stirring. When the moisture content of the flaxseed meal is 30-40%, the introduction of water mist is stopped, and then microwave treatment is performed for 3-5 minutes, followed by decompression treatment for 20-30 minutes to obtain a primary treated material; (2) The primary treated material is placed in a distillation tank, which is connected to an evaporator. First, water of the same weight as the primary treated material and an ethanol solution of 0.5-1.5% by weight of the primary treated material are added to the evaporator. Then, the mixed vapor in the evaporator is passed into the distillation tank, and detoxification distillation is performed for 1-3 minutes under micro-pressure conditions; then, the pressure is reduced to normal pressure, and an acetic acid solution of 0.01-1.5% by weight of the primary treated material is added to the evaporator, and the mixed vapor is continued to be passed, and detoxification distillation is performed for 3-5 minutes under micro-pressure conditions; the pressure is further reduced to normal pressure, and an ethanol solution of 0.001-0.015% by weight of the primary treated material is added to the evaporator, and the mixed vapor is passed for detoxification distillation for 1-2 minutes; finally, the pressure is reduced for 3-5 minutes to obtain the product.

2. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (1), the microwave power is 200-300 W and the frequency is 600-800 MHz.

3. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (1), the pressure of the decompression treatment is -0.05 to -0.02 MPa, and the temperature is set to 70 to 80°C.

4. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (2), the pressure in the micro-pressure condition is 0.001 to 0.005 MPa.

5. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (2), the mass concentration of the ethanol solution is 40-60%.

6. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (2), the mass concentration of the acetic acid solution is 1 to 3%.

7. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (2), the pressure of the decompression treatment is -0.03 to -0.01 MPa, and the temperature is set at 60 to 70°C.

8. The method for detoxifying flaxseed meal according to claim 1, characterized in that: In step (2), the amount of the primary treated material in the distillation tank is 100-150 kg; the steam flow rate of the mixed steam is set to 2-2.5 kg / min.

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