Production method of low-toxin low-viscosity corn steep liquor dry powder with special flavor

Abstract

The invention discloses a production method of low-toxin low-viscosity corn steep liquor dry powder with a special flavor, and belongs to the technical field of biology. According to the method disclosed by the invention, the aspergillus niger spore suspension with a corresponding proportion of 106 cfu / mL is inoculated into the corn steep liquor and is cultured for a period of time at a certain rotating speed and temperature, so that not only is the viscosity of the corn steep liquor effectively reduced, but also the pollution of aflatoxin in the corn steep liquor is remarkably reduced; wherein the degradation rate of the AFB1 can reach 52.14%, the degradation rate of the AFB2 can reach 80.21%, the degradation rate of the AFG1 can reach 86.31%, and the degradation rate of the AFG2 can reach 80.22%. After the fermented corn steep liquor is dried, the protein content and the total amino acid content of the corn steep liquor are improved, and the corn steep liquor can be dried into dry corn steep liquor powder. Technical reference is provided for safe and efficient utilization of the corn steep liquor, the transportation cost of the corn steep liquor is greatly reduced, the product storage life is prolonged, and the use convenience is improved.

Description

Technical Field

[0001] The present application relates to a method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor, belonging to the field of microbial technology. Background Art

[0002] The process of deep processing of corn mainly includes the following steps. First, the corn is soaked in sulfite water to soften the corn tissue and prepare for subsequent separation. Subsequently, a variety of valuable components are separated from the corn, including corn steep liquor, corn germ, corn husk and pure corn starch. Corn steep liquor (CSL) is the main by-product obtained from deep processing of corn and is rich in a variety of chemical nutrients. Concentrated corn steep liquor is obtained by collecting the liquid produced in the production process after using corn steep liquor to produce products such as phytic acid and inositol, combining and concentrating. The protein content of this part is 16-30%, the amino acid content is 8-12%, the reducing sugar content is 5-7%, the vitamin content is 0.7-1mg / L, the total acid content is 8-13%, the lactic acid content is 7-12%, the phosphorus content is 4-4.5%, and the potassium content is 2-2.5%. It is the preferred raw material for animal feed.

[0003] During the storage process, corn will become moldy due to the influence of the external environment and storage conditions, especially the contamination of toxin-producing fungi such as Aspergillus flavus. Common aflatoxins include: AFB1, AFB2, AFG1, AFG2. In the prior art, the degradation of aflatoxins is mostly concentrated on AFB1. For example, Chinese patent CN113373060A discloses an Aspergillus niger that can degrade AFB1. However, aflatoxins AFB1, AFB2, AFG1 and AFG2 often coexist in food and feed, and the degradation of a single toxin cannot completely eliminate the harm of aflatoxins. Therefore, strains that can simultaneously degrade all four aflatoxins can not only improve the degradation efficiency, but also significantly reduce food safety risks, providing a more effective solution for the comprehensive prevention and control of aflatoxin contamination.

[0004] In addition, since concentrated corn syrup contains high concentrations of polysaccharides and lactic acid substances, the concentrated corn syrup has extremely strong viscosity. This high viscosity not only increases the difficulty of the concentration process, but also brings considerable challenges to the drying process. Specifically, high-viscosity substances have poor performance in flow and heat transfer, which makes the flow of concentrated corn syrup in the evaporator slow and affects the evaporation efficiency. At the same time, materials with high viscosity are more likely to form lumps during the drying process, which not only reduces the drying efficiency, but may also lead to a decline in product quality.

[0005] Based on the above statements, providing a method for producing corn slurry dry powder that can simultaneously degrade four aflatoxins, reduce the viscosity of dry powder, and improve the drying efficiency of corn slurry has significant economic benefits, but there is no related research in the prior art. Summary of the invention

[0006] [Technical issues]

[0007] The technical problem to be solved by the present invention is to provide a method for simultaneously degrading aflatoxins AFB1, AFB2, AFG1 and AFG2, reducing the viscosity of corn steep liquor, and increasing the total protein and amino acid content of corn steep liquor.

[0008] [Technical solution]

[0009] To this end, the embodiment of the present invention provides a method for preparing a flavor-detoxified corn slurry powder with reduced viscosity, so as to solve the problem that the prior art cannot effectively detoxify the AFB1, AFB2, AFG1, and AFG2 toxins present in the corn slurry, and consume the residual sugar and lactic acid in the corn slurry, reduce the viscosity of the corn slurry, and solve the problem that the corn slurry has high viscosity and is difficult to dry. At the same time, the fermentation strain achieves the problem of improving the flavor of the corn slurry.

[0010] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0011] The present invention firstly provides a method for preparing corn steep liquor dry powder with reduced aflatoxin content, the method comprising: using corn steep liquor as fermentation raw material and using Aspergillus niger for fermentation; the aflatoxins comprise at least two of aflatoxins AFB1, AFB2, AFG1 and AFG2.

[0012] In one embodiment, the Aspergillus niger includes Aspergillus niger CCTCC NO: M2013703.

[0013] In one embodiment, the aflatoxins include: aflatoxins AFB1, AFB2, AFG1 and AFG2.

[0014] In one embodiment, the method comprises the following steps:

[0015] (1) Preparation of seed culture solution: preparing a spore suspension of Aspergillus niger, inoculating the spore suspension of Aspergillus niger into a culture medium, and culturing to obtain a seed culture solution;

[0016] (2) fermentation: inoculating the seed culture solution obtained in step (1) into corn steep liquor to ferment and obtain a fermented product;

[0017] (3) Preparation of corn steep liquor powder: The fermented product obtained in step (3) is collected and dried to obtain corn steep liquor powder.

[0018] In one embodiment, the concentration of Aspergillus niger spores in the Aspergillus niger spore suspension is not less than 1×10 6 CFU / mL.

[0019] In one embodiment, the step (1) is specifically as follows: inoculating a spore suspension of Aspergillus niger into a culture medium at an inoculation amount of 1% to 3%, and culturing at 25° C. to 35° C. for at least 24 hours to obtain a seed culture solution;

[0020] The step (2) specifically comprises: inoculating the seed culture solution obtained in step (1) into corn steep liquor at an inoculation rate of 5% to 25%, and fermenting at 25° C. to 32° C. for 48 to 72 hours to obtain a fermentation product;

[0021] The step (3) specifically comprises: drying the fermented product obtained in step (2) at 90° C. to 105° C. for 24 h to 48 h, and crushing the product.

[0022] In one embodiment, the corn steep liquor in step (2) is sterilized.

[0023] The invention also provides corn steep liquor dry powder prepared by the method.

[0024] The present invention also provides the use of Aspergillus niger CCTCC NO: M 2013703 in degrading aflatoxins, wherein the aflatoxins include at least two of aflatoxins AFB1, AFB2, AFG1 and AFG2.

[0025] In one embodiment, the aflatoxins include: aflatoxins AFB1, AFB2, AFG1 and AFG2.

[0026] The present invention also provides the method or application of the corn steep liquor dry powder in feed preparation.

[0027] The present invention has the following beneficial effects:

[0028] 1. The method of the present invention can effectively remove AFB1, AFB2, AFG1 and AFG2 in corn steep liquor, the detoxification steps are simple, the detoxification effect is good, and the removal rates reach 52.14%, 80.21%, 86.31% and 80.22% respectively;

[0029] 2. The fermentation strain used in the present invention can change the amino acid composition in corn steep liquor, thereby improving the flavor of corn steep liquor and making it more palatable;

[0030] 3. The viscosity of the corn slurry obtained by the present invention is significantly lower than that before treatment, so the drying device can be directly used to produce corn slurry dry powder, thereby greatly reducing transportation costs, extending the product storage period, and improving ease of use.

[0031] 4. The processing method of the present invention only requires the addition of a small amount of equipment such as a corn slurry processing tank and a supporting stirring device, and the process is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0033] Figure 1 .Comparison of the concentrated and dried state of corn pulp before and after fermentation (A is the state after drying before fermentation; B is the state after drying after fermentation). DETAILED DESCRIPTION

[0034] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the embodiment of the present invention, corn steep liquor is prepared by counter-currently soaking corn particles with a sulfur dioxide solution, and finally pumping out a solution containing 6-7% dry matter in the soaking water, and then using triple-effect vacuum evaporation to concentrate the solution into a concentrated solution containing a certain amount of dry matter, which is called corn steep liquor.

[0036] In the embodiments of the present invention, the so-called "dry matter" refers to the matter remaining after drying the corn steep liquor.

[0037] In the embodiments of the present invention, Aspergillus niger refers to Aspergillus niger CCTCC NO: M2013703, which is disclosed in Chinese Patent CN103937681B.

[0038] Example 1

[0039] A method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor comprises the following steps:

[0040] S1. Activation of Aspergillus niger strain and preparation of seed solution

[0041] Aspergillus niger was taken out from -80℃, revived, inoculated into PDA medium and cultured at 28℃ for 5 days, and then the spores were washed with sterile saline containing Tween 80 to adjust the spore concentration to 1×10 6 CFU / mL, and the Aspergillus niger spore suspension is obtained; the PDB culture medium is pumped into a 5L fermentation tank for sterilization, and after sterilization and cooling, the temperature is raised to 30°C and then kept warm, and 1% Aspergillus niger spore suspension is added at a speed of 500r / min, and the culture time is 24h to obtain the seed culture solution.

[0042] S2, corn steep liquor inoculation and fermentation

[0043] The corn slurry is pumped into a 10L fermentation tank for sterilization. After sterilization and cooling, the temperature is raised to 25°C and then kept warm. At a rotation speed of 800r / min and a ventilation ratio of 1vvm, 5% of the Aspergillus niger seed culture solution in S1 is added and the culture time is 72h to obtain corn slurry with low toxin, low viscosity and special flavor after fermentation.

[0044] S3. Preparation of corn syrup powder

[0045] The low-toxin, low-viscosity corn syrup with special flavor obtained in S2 is evenly distributed in a stainless steel tray and dried in a dry heat forced air drying oven at a drying temperature of 90° C. for 48 hours. The dried material is corn syrup dry powder in a non-sticky block shape.

[0046] Example 2

[0047] A method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor comprises the following steps:

[0048] S1. Activation of Aspergillus niger strain and preparation of seed solution

[0049] Aspergillus niger was taken out from -80℃, revived, inoculated into PDA medium and cultured at 28℃ for 5 days, and then the spores were washed with sterile saline containing Tween 80 to adjust the spore concentration to 1×10 6 CFU / mL, and the Aspergillus niger spore suspension is obtained; the PDB culture medium is pumped into a 5L fermentation tank for sterilization, and after sterilization and cooling, the temperature is raised to 30°C and then kept warm, and 1.5% Aspergillus niger spore suspension is added at a speed of 500r / min, and the culture time is 20h to obtain the seed culture solution.

[0050] S2, corn steep liquor inoculation and fermentation

[0051] The corn slurry is pumped into a 10L fermentation tank for sterilization. After sterilization and cooling, the temperature is raised to 28°C and then kept warm. At a rotation speed of 700r / min and a ventilation ratio of 1vvm, 10% of the Aspergillus niger seed culture solution in S1 is added and the culture time is 66h to obtain corn slurry with low toxin, low viscosity and special flavor after fermentation.

[0052] S3. Preparation of corn syrup powder

[0053] The low-toxin, low-viscosity corn syrup with special flavor obtained in S2 is evenly distributed in a stainless steel tray and dried in a dry heat forced air drying oven at a drying temperature of 95° C. for 36 hours. The dried material is corn syrup dry powder in a non-sticky block shape.

[0054] Example 3

[0055] A method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor comprises the following steps:

[0056] S1. Activation of Aspergillus niger strain and preparation of seed solution

[0057] Aspergillus niger was taken out from -80℃, revived, inoculated into PDA medium and cultured at 28℃ for 5 days, and then the spores were washed with sterile saline containing Tween 80 to adjust the spore concentration to 1×10 6 CFU / mL, and the Aspergillus niger spore suspension is obtained; the PDB culture medium is pumped into a 5L fermentation tank for sterilization, and after sterilization and cooling, the temperature is raised to 30°C and then kept warm, and 2% Aspergillus niger spore suspension is added at a speed of 500r / min, and the culture time is 16h to obtain the seed culture solution.

[0058] S2, corn steep liquor inoculation and fermentation

[0059] The corn slurry is pumped into a 10L fermentation tank for sterilization. After sterilization and cooling, the temperature is raised to 30°C and then kept warm. At a rotation speed of 600r / min and a ventilation ratio of 1vvm, 15% of the Aspergillus niger seed culture solution in S1 is added and the culture time is 60h to obtain corn slurry with low toxin, low viscosity and special flavor after fermentation.

[0060] S3. Preparation of corn syrup powder

[0061] The low-toxin, low-viscosity corn pulp with special flavor obtained in S2 is evenly distributed in a stainless steel tray and dried in a dry heat blast drying oven at a drying temperature of 100°C for 32 hours. The dried material is non-sticky and blocky ( Figure 1 ).

[0062] Example 4

[0063] A method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor comprises the following steps:

[0064] S1. Activation of Aspergillus niger strain and preparation of seed solution

[0065] Aspergillus niger was taken out from -80℃, revived, inoculated into PDA medium and cultured at 28℃ for 5 days, and then the spores were washed with sterile saline containing Tween 80 to adjust the spore concentration to 1×10 6 CFU / mL, and the Aspergillus niger spore suspension is obtained; the PDB culture medium is pumped into a 5L fermentation tank for sterilization, and after sterilization and cooling, the temperature is raised to 30°C and then kept warm, and 2.5% Aspergillus niger spore suspension is added at a speed of 500r / min, and the culture time is 12h to obtain the seed culture solution.

[0066] S2, corn steep liquor inoculation and fermentation

[0067] The corn slurry is pumped into a 10L fermentation tank for sterilization. After sterilization and cooling, the temperature is raised to 32°C and then kept warm. At a rotation speed of 500r / min and a ventilation ratio of 1vvm, 20% of the Aspergillus niger seed culture solution in S1 is added and the culture time is 54h to obtain corn slurry with low toxin, low viscosity and special flavor after fermentation.

[0068] S3. Preparation of corn syrup powder

[0069] The low-toxin, low-viscosity corn syrup with special flavor obtained in S2 is evenly distributed in a stainless steel tray and dried in a dry heat forced air drying oven at a drying temperature of 105° C. for 30 hours. The dried material is corn syrup dry powder in a non-sticky block shape.

[0070] Example 5

[0071] A method for producing low-toxin, low-viscosity corn steep liquor dry powder with special flavor comprises the following steps:

[0072] S1. Activation of Aspergillus niger strain and preparation of seed solution

[0073] Aspergillus niger was taken out from -80℃, revived, inoculated into PDA medium and cultured at 28℃ for 5 days, and then the spores were washed with sterile saline containing Tween 80 to adjust the spore concentration to 1×10 6 CFU / mL, and the Aspergillus niger spore suspension is obtained; the PDB culture medium is pumped into a 5L fermentation tank for sterilization, and after sterilization and cooling, the temperature is raised to 30°C and then kept warm, and 3% Aspergillus niger spore suspension is added at a speed of 500r / min, and the culture time is 12h to obtain the seed culture solution.

[0074] S2, corn steep liquor inoculation and fermentation

[0075] The corn slurry is pumped into a 10L fermentation tank for sterilization. After sterilization and cooling, the temperature is raised to 25°C and then kept warm. At a rotation speed of 500r / min and a ventilation ratio of 1vvm, 25% of the Aspergillus niger seed culture solution in S1 is added and the culture time is 48h to obtain corn slurry with low toxin, low viscosity and special flavor after fermentation.

[0076] S3. Preparation of corn syrup powder

[0077] The low-toxin, low-viscosity corn syrup with special flavor obtained in S2 is evenly distributed in a stainless steel tray and dried in a dry heat forced air drying oven at a drying temperature of 105° C. for 24 hours. The dried material is corn syrup dry powder in a non-sticky block shape.

[0078] The aflatoxin removal effect of the methods of Examples 1-5 was tested:

[0079] Collect the fermented samples, dry them, and then introduce each corn syrup dry powder into a centrifuge tube, add acetonitrile-water solution (70+30) to extract and rinse the fermentation dish and introduce it into the centrifuge tube to avoid the influence of uneven distribution of toxins in the meal on the experimental results; after mixing, ultrasonic treatment for 10 minutes, oscillation for 30 minutes, centrifugation at 8000r / min for 10 minutes, take the supernatant after filtration and pass it through the solid phase purification column, collect the liquid and freeze concentrate it, dissolve the filter membrane with methanol-water solution (50+50), and then detect it on LC-MS / MS. Chromatographic conditions: Chromatographic column: BEH C 18 column (2.1mm×100mm, 1.7μm), mobile phase A is acetonitrile, B is ammonium formate solution, column temperature: 45℃, flow rate: 0.3mL / min, injection volume: 5μL. Elution conditions are shown in Table 1.

[0080] Table 1 Gradient elution table

[0081]

[0082] The above method was used to detect the residual amounts of the four toxins in the samples after aflatoxin removal in Examples 1 to 5, and the corresponding removal rates of the four aflatoxin were calculated. The results are shown in Table 2.

[0083] Table 2. Degradation rates of AFB1, AFB2, AFG1, and AFG2

[0084]

[0085] The protein, amino acid content and dry matter were determined according to standards GB / T 6432-2018, GB / T 18246-2000 and GB / T 22428.4-2008 respectively. The residual sugar concentration was measured using Silman M-100. The results are shown in Table 3.

[0086] Table 3. Changes of total protein, total amino acids, total dry matter and residual sugar before and after fermentation

[0087]

[0088] The volatile compounds produced in Example 3 before and after fermentation of corn steep liquor were detected by headspace solid phase microextraction, and the specific method was to put 3 grams of unfermented and fermented corn germ meal samples into headspace sampling bottles, respectively, and heat for 30 minutes to release volatile substances. Insert the SPME extraction head for adsorption for 30 minutes, and then analyze at the injection port of the gas chromatograph for 15 minutes. GC conditions: The chromatographic capillary column is an Equity-5 column (30m×0.32mm×0.25μm), with high-purity helium (≥99.999%) as the carrier gas, and the flow rate is 2.5mL / min. The injector temperature is 250°C, and there is no split injection. The initial temperature of the oven is 80°C and maintained for 2min, then increased to 200°C at a rate of 15°C / min, maintained for 2min, and then increased to 260°C at 6°C / min, and maintained at 260°C for 5min.

[0089] MS conditions: ionization mode is electron impact source (EI), electron energy is 70eV, detector voltage is -1499V, ion source temperature is 250℃, mass scanning range m / z is 15~350. As shown in Table 4, taking Example 3 as an example, after being treated with Aspergillus niger, the alcohols, acids and esters in corn steep liquor that have a greater contribution to flavor are all increased compared to before fermentation. In addition, using a digital viscometer from Shanghai Yixin, the viscosity was found to be 12.51mPa.s before fermentation (Example 3) and 1.38mPa.s after fermentation.

[0090] Table 4 Classification and proportion of volatile compounds produced before and after corn pulp fermentation

[0091]

[0092] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing corn steep liquor dry powder with reduced aflatoxin content, characterized in that: The method comprises: using corn steep liquor as a fermentation raw material and using Aspergillus niger for fermentation; the aflatoxins comprise: at least two of aflatoxins AFB1, AFB2, AFG1 and AFG2.

2. The method according to claim 1, characterized in that The Aspergillus niger includes Aspergillus niger CCTCC NO:M 2013703.

3. The method according to claim 1, characterized in that The aflatoxins include: aflatoxins AFB1, AFB2, AFG1 and AFG2.

4. The method according to claim 1, characterized in that: The method comprises the following steps: (1) Preparation of seed culture solution: preparing a spore suspension of Aspergillus niger, inoculating the spore suspension of Aspergillus niger into a culture medium, and culturing to obtain a seed culture solution; (2) fermentation: inoculating the seed culture solution obtained in step (1) into corn steep liquor to ferment and obtain a fermented product; (3) Preparation of corn steep liquor powder: The fermented product obtained in step (3) is collected and dried to obtain corn steep liquor powder.

5. The method according to claim 4, characterized in that The concentration of Aspergillus niger spores in the Aspergillus niger spore suspension is not less than 1×10 6 CFU / mL.

6. The method according to claim 5, characterized in that The step (1) specifically comprises: inoculating a spore suspension of Aspergillus niger into a culture medium at an inoculation amount of 1% to 3%, and culturing at 25° C. to 35° C. for at least 24 hours to obtain a seed culture solution; The step (2) specifically comprises: inoculating the seed culture solution obtained in step (1) into corn steep liquor at an inoculation rate of 5% to 25%, and fermenting at 25° C. to 32° C. for 48 to 72 hours to obtain a fermentation product; The step (3) specifically comprises: drying the fermented product obtained in step (2) at 90° C. to 105° C. for 24 h to 48 h, and crushing the product.

7. Corn steep liquor powder prepared by the method according to any one of claims 1 to 6.

8. Use of Aspergillus niger CCTCC NO:M 2013703 in degrading aflatoxin, characterized in that: The aflatoxins include: at least two of aflatoxins AFB1, AFB2, AFG1, and AFG2.

9. The use according to claim 8, characterized in that: The aflatoxins include: aflatoxins AFB1, AFB2, AFG1 and AFG2.

10. Use of the method according to any one of claims 1 to 6, or the corn steep liquor powder according to claim 7 in feed preparation.

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