GABA (gamma-aminobutyric acid) rare earth chelate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of rare earth chelate materials, and particularly discloses a GABA rare earth chelate as well as a preparation method and application thereof. The preparation method of the GABA rare earth chelate provided by the invention comprises the following specific steps: fermenting to produce enzyme: inoculating a corynebacterium glutamicum seed solution into a fermentation culture medium containing nitrated rare earth, and fermenting and culturing to obtain bacterial sludge for whole-cell catalysis; chelating conversion: carrying out a whole-cell catalytic reaction by using an L-glutamic acid substrate and the bacterial sludge for whole-cell catalysis, and proportioning rare earth nitrate to obtain a chelate with a chelating rate of more than or equal to 89%; adsorbing and drying: adding montmorillonite powder into the chelate, uniformly stirring, homogenizing, and performing spray drying to obtain a dried chelate; condensing and coating: uniformly coating and wrapping the chelate with molten palm oil to obtain the GABA rare earth chelate. By means of the scheme, the GABA rare earth chelate with the high chelation rate, the high GABA protection rate, the low rumen degradation rate and the high rumen post-release rate is obtained.

Description

Technical Field

[0001] This application relates to the technical field of rare earth chelate materials, and specifically relates to a GABA rare earth chelate, its preparation method and application. Background Art

[0002] Rare earth elements have a wide range of applications in animal nutrition and feed additives. Especially for ruminants such as dairy cows, rare earth elements can promote absorption, antibacterial and anti-inflammatory effects, and improve immune function. By affecting the digestive tract flora, the activity of energy metabolism-related enzymes or the levels of related hormones, the animal production performance can be significantly improved. However, they also have some application limitations: for example, although inorganic rare earths have low cost and good stability, their bioavailability is low, they are difficult to be effectively absorbed by organisms, and may accumulate in the body due to poor solubility, causing potential toxicity risks. Although organic rare earths have higher solubility and biological activity, and have better targeting and biocompatibility, they face problems such as low chelation rate, poor stability and easy moisture absorption in practical applications.

[0003] GABA (γ-aminobutyric acid), as an inhibitory neurotransmitter in the central nervous system, plays an important role in regulating animal feed intake, anti-stress and enhancing immunity. However, uncoated GABA is unstable in the rumen environment and is easily degraded, unable to fully exert its efficacy. Although some rumen-protected methods of GABA are publicly available on the market, their production processes are complex and the protection rate of GABA is low. Summary of the Invention

[0004] In order to solve the problems of low bioavailability of rare earth elements, low chelation rate and poor stability of organic rare earth chelates, and easy degradation of GABA in the rumen environment existing in the prior art, this application provides a GABA rare earth chelate, its preparation method and application.

[0005] This application provides a preparation method of a GABA rare earth chelate, which specifically includes the following steps in sequence: Fermentation for enzyme production: inoculating the Corynebacterium glutamicum strain seed liquid into a fermentation medium containing rare earth nitrate, and fermenting and culturing to obtain the whole cell catalytic bacterial sludge; Chelation conversion: establishing a whole cell catalytic reaction system using a fermenter, adding an L-glutamic acid substrate with a final concentration of 850 - 950 g / L and 10 - 15 g / L of the whole cell catalytic bacterial sludge for catalytic reaction, and proportioning rare earth nitrate to obtain a chelate with a chelation rate ≥ 89%; Adsorption and drying: based on the air-dried chelate, adding montmorillonite powder to the chelate according to the weight ratio of montmorillonite:chelate = 1:25 - 55, stirring evenly, and then obtaining the dried chelate through homogenization and spray drying; Condensation coating: The molten palm oil is atomized by high-pressure air and evenly coated on the dried chelate to obtain the GABA rare earth chelate. The weight ratio of the dried chelate to palm oil is 60 - 85:15 - 35.

[0006] The functions of GABA (γ-aminobutyric acid) on ruminant cows include: promoting feed intake, anti-stress, and enhancing immunity. Animal feeding mainly relies on the regulation of the central nervous system. GABA can promote animal feeding and improve animal production performance by regulating the animal's central nervous system. GABA can regulate animal taste and enhance animal appetite by inhibiting the secretion of the satiety center (VMH) and cholecystokinin (CCK) and promoting the secretion of neuropeptide Y (NPY), thereby promoting animal feeding. Heat stress activates the HPA, increasing the secretion of adrenocortical hormones and accelerating the catabolism of fat, glycogen, and protein in the body, resulting in a decrease in feed intake, growth retardation, a decrease in feed conversion rate, and a decrease in body weight in livestock and poultry. GABA is the main neurotransmitter antagonist in the nervous system and has functions such as anti-heat stress and sedation. Adding GABA can increase the activities of serum SOD and GSH-Px and reduce the concentration of MDA. GABA can also reduce the production of ROS by inhibiting the expression of enzymes involved in the NF-kB signaling pathway, thereby blocking the occurrence of inflammatory reactions and improving the antioxidant capacity of animals under stress conditions. Currently, the methods for rumen protection of GABA are publicly available, but the production process has a low protection rate for GABA.

[0007] The enzyme production by fermentation used in this application: The Corynebacterium glutamicum strain is inoculated into a fermentation medium containing rare earth nitrates and fermented to obtain the cell mass for whole-cell catalysis. This step uses rare earth elements to promote the efficient expression of glutamate decarboxylase by genetically engineered bacteria, improving the efficiency of L-glutamate conversion to GABA.

[0008] In the chelation conversion step: A whole-cell catalytic reaction system is established using a fermenter, and the L-glutamate substrate with a final concentration of 850 - 950 g / L and the cell mass for whole-cell catalysis of 10 - 15 g / L are added in batches. The reaction conditions (rotation speed 150 - 300 r / min, temperature 25 - 45 °C, time 8 - 24 h) are controlled to obtain a mixture of GABA with a purity ≥ 97% and GABA rare earth chelate. By precisely proportioning rare earth nitrates, the chelation rate reaches ≥ 89%, solving the problem of low chelation rate of traditional organic rare earths.

[0009] In the adsorption and drying step: Montmorillonite powder is added to the chelate in a specific ratio (montmorillonite:chelate = 1:25 - 55). After stirring evenly, it is homogenized and spray-dried to obtain the dried chelate. The layered structure of montmorillonite and its unique adsorption ability can increase the fluidity of the material and prevent the chelate from absorbing moisture and caking. The addition of montmorillonite and the use of the spray-drying process also ensure the uniformity and fluidity of the particles, improve its stability, and facilitate subsequent processing.

[0010] In the condensation coating step: The molten palm oil is atomized by high-pressure air and evenly coated on the dried chelate to form a protective layer. This step uses the molten coating technology to form a dense protective layer of palm oil on the surface of the chelate, which can not only reduce the moisture absorption and caking caused by water penetration through physical barrier, but also delay its decomposition in the rumen environment after feeding, thereby improving its rumen bypass rate. The GABA rare earth chelate treated with palm oil coating remains stable in the neutral rumen environment, but can be absorbed in the acidic abomasum, improving its utilization rate after passing through the rumen.

[0011] Through the above four steps, the present application has successfully solved the following problems existing in the prior art: The biological utilization rate of rare earth elements is improved, making it easier to be absorbed by the animal body; The chelation rate of GABA and rare earth elements is significantly increased, enhancing the stability and effect of the product; By using montmorillonite adsorption and spray drying technology, the problem of product moisture absorption is effectively solved, and the storage stability is improved; Through the condensation coating process, the stability of GABA in the rumen is increased, the degradation rate is reduced, the release rate after passing through the rumen is increased, ensuring the effectiveness of GABA.

[0012] In summary, the technical solution of the present application not only overcomes many defects in the prior art, but also shows significant advantages in practical applications, especially has a wide application prospect in the field of ruminant feed.

[0013] The technical method provided by the present application adopts the path of fermentation first, then chelation and then coating, which can effectively solve the problem of low protection rate of GABA. The fermentation method can make rare earth combine with the cell wall of Corynebacterium glutamicum, thereby increasing the level of glutamate decarboxylase produced by the fermentation of Corynebacterium glutamicum; during whole-cell conversion, an appropriate amount of rare earth is added to make rare earth combine with GABA to form GABA rare earth chelate; after montmorillonite adsorption, and then spray drying to make powdery GABA rare earth chelate; then the GABA rare earth chelate is wrapped with palm oil, and then spray condensation is carried out to form coated chelate, so that the palm oil evenly wraps around the GABA rare earth chelate. At the same time, the coated GABA rare earth chelate particles are smaller, greatly reducing the probability of the GABA rare earth chelate being chewed and broken, and at the same time increasing the flowability of the product, making it easier to be used as a feed additive; on the one hand, the absorption rate of the GABA rare earth chelate is improved, enabling the rare earth + GABA product to obtain a doubled effect of 1 + 1 > 2, solving the problem of the GABA rare earth chelate passing through the rumen. It broadens the application of the GABA rare earth chelate in the field of ruminant feed.

[0014] Preferably, the specific steps for enzyme production by fermentation are as follows: inoculate the strain into LBHIS liquid medium, and perform overnight shaking culture in a shaker at 30 - 34 °C and 150 - 250 r / min to obtain a seed solution; inoculate the seed solution into the fermentation medium at an inoculation amount of 2 - 4%, with a culture temperature of 28 - 32 °C, a stirring speed of 350 - 450 r / min, and pH = 7.0; when the cell growth reaches OD600 ≈ 30 - 50, add IPTG with a final concentration of 1 mM, and continue fermentation culture for 8 - 24 h; after the fermentation culture is completed, centrifuge to collect the cell mass, remove the supernatant, and wash and resuspend the cell mass with ultrapure water to obtain the bacterial mud for whole-cell catalysis; the fermentation medium comprises components with the following concentrations: glucose 120 - 160 g / L, k2HPO4 0.8 - 1.2 g / L, FeSO4 0.001 - 0.003 g / L, MnSO4 0.001 - 0.003 g / L, MgSO4 0.5 - 0.7 g / L, thiamine 0.4 - 0.6 g / L, corn steep liquor 13 - 17 g / L, urea 4 - 6 g / L, rare earth nitrate 0.006 - 0.8 mmol / L; pH = 7.0 - 7.2, sterilize at 0.1 Mpa for 7 - 8 min to obtain the medium.

[0015] Preferably, the fermentation medium contains one or more rare earth metal ions with the following concentrations: La 3+ 0.50 - 0.73 mmol / L, Ce 3+ 0.06 - 0.08 mmol / L, Nd 3+ 0.006 - 0.012 mmol / L.

[0016] Preferably, the specific steps for chelation conversion are as follows: establish a whole-cell catalysis reaction system using a fermenter, add the L-glutamic acid substrate with a final concentration of 850 - 950 g / L and the bacterial mud for whole-cell catalysis with a concentration of 10 - 15 g / L in batches, control the reaction rotation speed at 150 - 300 r / min, the catalytic reaction temperature at 25 - 45 °C, and the catalytic reaction time at 8 - 24 h to obtain a mixture of GABA with a purity ≥ 97% and a bacterial mud rare earth chelate; proportion rare earth nitrate according to the dry matter weight ratio of mixture: rare earth nitrate = 1:0.7 - 1.3, control the moisture content at 55% - 79%, and then heat to 75 - 90 °C and maintain for 60 - 120 min to obtain a chelate with a chelation rate ≥ 89%.

[0017] Preferably, the specific steps of chelation conversion are as follows: establish a whole-cell catalytic reaction system using a fermenter, add the L-glutamic acid substrate with a final concentration of 870-920 g / L and the bacterial sludge for whole-cell catalysis with a concentration of 11-14 g / L in batches, control the reaction rotation speed at 200-250 r / min, the catalytic reaction temperature at 30-40 °C, and the catalytic reaction time at 12-20 h; obtain a mixture of GABA with a purity ≥97% and a rare earth chelate-containing bacterial sludge; proportion the rare earth nitrate according to the dry matter weight ratio of the mixture: rare earth nitrate = 1:0.8-1.2, control the moisture content at 60%-75%, and then heat to 80-85 °C and maintain for 80-100 min to obtain a chelate with a chelation rate ≥89%.

[0018] Preferably, in the specific steps of adsorption and drying, the weight ratio of montmorillonite to chelate is 1:60-90.

[0019] Preferably, in the specific steps of adsorption and drying: the particle size of the montmorillonite is 100-400 mesh; the performance indicators are: moisture content ≤8%, pH value 6-9, blue adsorption amount ≥42%, ammonia adsorption value ≥100%, purity ≥94%, Na + content is 1.53-1.95%, Ca 2+ content is 0.32-0.52%; the parameter process conditions of spray drying are: inlet air is 200-220 °C, outlet air is 75-80 °C, and pressure is 180-200 kg / cm 2 .

[0020] Preferably, the specific steps of condensation coating are as follows: preheat the dried chelate obtained by adsorption and drying to 71-82 °C, spray the molten palm oil heated to 110-150 °C onto the surface of the dried chelate through high-pressure air atomization, and discharge the material under the condition of 62-73 °C; then cool the material, and at the same time add a viscosity-reducing regulator and mix well until the material is cooled to 36-45 °C to obtain the product; The weight ratio of the dried chelate, the palm oil, and the viscosity-reducing regulator is 60-85:15-35:1-3.

[0021] Further, the specific steps of condensation coating are as follows: preheat the dried chelate obtained by adsorption and drying to 74-78 °C, spray the molten palm oil heated to 120-140 °C onto the surface of the dried chelate through high-pressure air atomization, and discharge the material under the condition of 62-73 °C; then cool the material, and at the same time add a viscosity-reducing regulator and mix well until the material is cooled to 36-45 °C to obtain the product. Further, the weight ratio of the dried chelate, the palm oil, and the viscosity-reducing regulator is 65-80:20-30:1.5-2.5.

[0022] Preferably, in the specific steps of the condensation coating, the parameters of the high-pressure air atomization spraying are adjusted as follows: the pressure of the atomizing nozzle is 10-20 MPa, the spraying distance is 15-30 cm, and the conveying speed of the chelate is 300-600 kg / h.

[0023] In a second aspect, the present application provides a GABA rare earth chelate prepared by using the above preparation method.

[0024] In a third aspect, the present application provides the application of the above GABA rare earth chelate in animal feed.

[0025] In summary, the technical solution of the present application has the following effects: The present application adopts the path of fermentation first and then chelation, and optimizes and matches the process parameters of each step through steps such as adsorption drying and condensation coating, solves the problems existing in the prior art, and obtains a GABA rare earth chelate with a high chelation rate, a high GABA protection rate, a low rumen degradation rate, and a high post-rumen release rate. Specific Embodiments

[0026] The Corynebacterium glutamicum strain is a genetically engineered bacterium obtained by transforming or introducing a double enzyme co-expression vector for producing γ-aminobutyric acid into a host strain, and is derived from the patented strain "A Glutamate Decarboxylase Mutant and Its Application in the Production of γ-Aminobutyric Acid" of the Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences; Brain Heart Infusion is from Qingdao Hope Bio-Technology Co., Ltd.; Corn Steep Liquor is from Nanjing Quanlong Biotechnology Co., Ltd.; Palm Oil is purchased from Qingdao Shengtongyue Chemical Technology Co., Ltd.; Montmorillonite is purchased from ALINAT S.R.L. in Argentina, and its technical indicators are as follows: moisture ≤ 8%, pH value 6-9, blue adsorption amount ≥ 42%, ammonia absorption value ≥ 100%, purity ≥ 94%, Na + content is 1.53-1.95%, Ca 2+ content is 0.32-0.52% (Note: The different contents of sodium and calcium in montmorillonite result in different swelling and adsorption exchange properties. Sodium montmorillonite has a relatively high ion exchange capacity, can improve particle quality, and can effectively adsorb, but it is not that the higher the sodium ion content, the better. If the sodium ion content is too high, it can lead to electrolyte imbalance and increase the burden on the kidneys, etc.); Diatomite is of food grade 300# model, 400 mesh, white, with a permeability of 3-4, and is purchased from Linjiang Xinghui Filter Aid Co., Ltd., and the product complies with the GB 14936 standard.

[0027] The following further describes the present application in detail with reference to examples, comparative examples, and performance detection tests. These examples should not be construed as limiting the scope claimed by the present application. Examples

[0028] Example 1 Example 1 provides a GABA rare earth chelate and a preparation method thereof.

[0029] The preparation method of the GABA rare earth chelate in this example is as follows: (1) Fermentation for enzyme production: Inoculate the Corynebacterium glutamicum strain (a genetically engineered bacterium that highly expresses glutamate decarboxylase obtained by transforming or introducing a double-enzyme co-expression vector for producing γ-aminobutyric acid into a host strain) into LBHIS liquid medium (2.5 g / L Oxoid yeast extract, 5 g / L tryptone, 5 g / L NaCl, 18 g / L brain heart infusion), and perform overnight shaking culture in a shaker at 32 °C and 200 r / min to obtain a seed solution; inoculate the seed solution into the fermentation medium at an inoculation amount of 3%, set the culture temperature at 30 °C, the stirring speed at 400 r / min, and pH = 7.0; when the cell growth reaches OD 600 ≈ 4, add IPTG with a final concentration of 1 mM, and continue fermentation culture for 12 h to induce the expression of the target protein; after the fermentation culture is completed, centrifuge to collect the cell cells, remove the supernatant waste liquid, and wash and resuspend the cell cells with ultrapure water to obtain the bacterial sludge for whole-cell catalysis.

[0030] The preparation method of the fermentation medium is as follows: Prepare according to the concentrations of 140 g / L glucose, 1 g / L k2HPO4, 0.002 g / L FeSO4, 0.002 g / L MnSO4, 0.6 g / L MgSO4, 0.5 g / L thiamine, 15 g / L corn steep liquor, 5 g / L urea (sterilized separately and added), 0.6 mmol / L lanthanum nitrate, 0.07 mmol / L cerium nitrate, and 0.009 mmol / L neodymium nitrate, adjust the pH = 7.0 - 7.2, and sterilize at 0.1 Mpa for 7 - 8 min to obtain it.

[0031] (2) Chelation conversion: Establish a whole-cell catalysis reaction system using a fermenter, add the L-glutamic acid substrate with a final concentration of 900 g / L in batches, add 12 g / L of the bacterial sludge for whole-cell catalysis prepared in step (1), control the reaction rotation speed at 220 r / min, the catalytic reaction temperature at 35 °C, and the catalytic reaction time at 16 h; obtain a mixture of GABA with a purity ≥ 97% and a bacterial sludge rare earth chelate; after measuring the dry matter concentration of the mixture, mix the rare earth nitrate according to the dry matter weight ratio of the mixture: rare earth nitrate = 1:1, control the moisture content at 65%, and then heat to 82 °C and maintain for 90 min to obtain a chelate with a chelation rate ≥ 89%.

[0032] (3) Adsorption drying: Pass montmorillonite through a 400-mesh sieve, and add montmorillonite powder to the chelate prepared in step (2) according to the weight ratio of montmorillonite: chelate = 1:75. After stirring evenly, homogenize and spray dry to obtain a dry chelate with a particle size of 100 - 400 meshes; the parameter process conditions for spray drying are: inlet air temperature is 210 °C, outlet air temperature is 78 °C, and pressure is 190 kg / cm 2 .

[0033] (4) Condensation coating: First, sieve the dry chelate prepared in step (3), then transport it to the No. 1 drum of the first drum chamber, and introduce hot air at 130 °C to preheat the chelate to 76 °C, and then transport it to the No. 2 drum of the first drum chamber; Spray the molten palm oil heated to 130 °C onto the surface of the chelate and the drum surface by high-pressure air atomization. Under the action of the rotating drum, the molten palm oil evenly coats and wraps the chelate; the pressure of the atomizing nozzle is 15 MPa, the spraying distance is 20 cm, the conveying speed of the chelate is 450 kg / h, and the discharge temperature is 68 °C; Then transport the material to the second drum chamber, introduce air at 20 °C, and at the same time add the viscosity-reducing regulator diatomaceous earth and mix well to cool the material to 40 °C, and obtain the GABA rare earth chelate with a particle size of 60 - 160 meshes. Among them, the weight ratio of the chelate, palm oil, and diatomaceous earth is 70:25:2.

[0034] Examples 2 - 3 Examples 2 - 3 respectively provide a GABA rare earth chelate and its preparation method.

[0035] The differences between the above examples and Example 1 are specifically as follows: The concentrations of rare earth metal ions in the fermentation medium are different, as shown below.

[0036] In Example 2: The preparation method of the fermentation medium is: Prepare according to the concentration of glucose 140 g / L, k2HPO4 1 g / L, FeSO4 0.002 g / L, MnSO4 0.002 g / L, MgSO4 0.6 g / L, thiamine 0.5 g / L, corn steep liquor 15 g / L, urea 5 g / L (sterilized separately and added), lanthanum nitrate 0.6 mmol / L, adjust the pH = 7.0 - 7.2, and sterilize at 0.1 Mpa for 7 - 8 min to obtain.

[0037] In Example 3: The preparation method of the fermentation medium is as follows: Prepared according to the concentrations of 140 g / L of glucose, 1 g / L of K2HPO4, 0.002 g / L of FeSO4, 0.002 g / L of MnSO4, 0.6 g / L of MgSO4, 0.5 g / L of thiamine, 15 g / L of corn steep liquor, 5 g / L of urea (sterilized separately and added), 0.50 mmol / L of lanthanum nitrate, and 0.08 mmol / L of cerium nitrate, 0.012 mmol / L of neodymium nitrate. Adjust the pH to 7.0 - 7.2, and sterilize at 0.1 Mpa for 7 - 8 min to obtain it.

[0038] In the above examples, other process parameters are the same as those in Example 1.

[0039] Examples 4 - 7 Examples 4 - 7 respectively provide a GABA rare earth chelate and its preparation method.

[0040] The differences between the above examples and Example 1 are specifically as follows: The specific process parameters of the chelation conversion in step (2) are different, as shown below.

[0041] In Example 4: Use a fermenter to establish a whole - cell catalytic reaction system. Add the L - glutamic acid substrate with a final concentration of 950 g / L in batches, add 10 g / L of the whole - cell catalyst sludge prepared in step (1), control the reaction rotation speed at 220 r / min, the catalytic reaction temperature at 25 °C, and the catalytic reaction time at 24 h; obtain a mixture of GABA with a purity ≥ 97% and a rare earth chelate containing the bacterial sludge; after measuring the dry matter concentration of the mixture, proportion the rare earth nitrate according to the dry matter weight ratio of the mixture: rare earth nitrate = 1:0.7, control the moisture content at 65%, and then heat to 90 °C and maintain for 60 min to obtain a chelate with a chelation rate ≥ 89%.

[0042] In Example 5: Use a fermenter to establish a whole - cell catalytic reaction system. Add the L - glutamic acid substrate with a final concentration of 850 g / L in batches, add 15 g / L of the whole - cell catalyst sludge prepared in step (1), control the reaction rotation speed at 220 r / min, the catalytic reaction temperature at 45 °C, and the catalytic reaction time at 8 h; obtain a mixture of GABA with a purity ≥ 97% and a rare earth chelate containing the bacterial sludge; after measuring the dry matter concentration of the mixture, proportion the rare earth nitrate according to the dry matter weight ratio of the mixture: rare earth nitrate = 1:1.3, control the moisture content at 65%, and then heat to 75 °C and maintain for 120 min to obtain a chelate with a chelation rate ≥ 89%.

[0043] In Example 6: A whole-cell catalytic reaction system was established using a fermenter. The L-glutamic acid substrate with a final concentration of 870 g / L was added in batches, and 12 g / L of the whole-cell catalytic bacterial sludge prepared in step (1) was added. The reaction rotation speed was controlled at 220 r / min, the catalytic reaction temperature was 35 °C, and the catalytic reaction time was 16 h; GABA with a purity ≥ 97% and a mixture containing bacterial sludge rare earth chelate were obtained; after measuring the dry matter concentration of the mixture, rare earth nitrate was proportioned according to the dry matter weight ratio of mixture:rare earth nitrate = 1:0.8, the moisture content was controlled at 65%, and then it was heated to 80 °C and maintained for 100 min to obtain a chelate with a chelation rate ≥ 89%.

[0044] In Example 7: A whole-cell catalytic reaction system was established using a fermenter. The L-glutamic acid substrate with a final concentration of 920 g / L was added in batches, and 12 g / L of the whole-cell catalytic bacterial sludge prepared in step (1) was added. The reaction rotation speed was controlled at 220 r / min, the catalytic reaction temperature was 35 °C, and the catalytic reaction time was 16 h; GABA with a purity ≥ 97% and a mixture containing bacterial sludge rare earth chelate were obtained; after measuring the dry matter concentration of the mixture, rare earth nitrate was proportioned according to the dry matter weight ratio of mixture:rare earth nitrate = 1:1.2, the moisture content was controlled at 65%, and then it was heated to 85 °C and maintained for 80 min to obtain a chelate with a chelation rate ≥ 89% and a particle size of 60 - 160 mesh.

[0045] In the above examples, other process parameters were the same as those in Example 1.

[0046] Examples 8 - 9 Examples 8 - 9 respectively provided a GABA rare earth chelate and a preparation method thereof.

[0047] The differences between the above examples and Example 1 were specifically as follows: The specific process parameters of step (3) adsorption drying were different, as shown below.

[0048] In Example 8: The weight ratio of montmorillonite to chelate was 1:25.

[0049] In Example 9: The weight ratio of montmorillonite to chelate was 1:55.

[0050] In the above examples, other process parameters were the same as those in Example 1.

[0051] Examples 10 - 18 Examples 10 - 18 respectively provided a GABA rare earth chelate and a preparation method thereof.

[0052] The differences between the above examples and Example 1 were specifically as follows: The specific process parameters of step (4) condensation coating were different, as shown below.

[0053] In Example 10: The chelate was preheated to 71 °C.

[0054] In Example 11: The chelate was preheated to 82 °C.

[0055] In Example 12: The temperature of the molten palm oil was 110 °C.

[0056] In Example 13: The temperature of the molten palm oil was 150 °C.

[0057] In Example 14: The weight ratio of the chelate, palm oil, and diatomaceous earth was 85:15:1.

[0058] In Example 15: The weight ratio of the chelate, palm oil, and diatomaceous earth was 60:35:3.

[0059] In Example 16: The weight ratio of the chelate, palm oil, and diatomaceous earth was 80:20:1.5.

[0060] In Example 17: The weight ratio of the chelate, palm oil, and diatomaceous earth was 65:30:2.5.

[0061] In Example 18: An equal amount of montmorillonite (400 mesh) was used instead of diatomaceous earth.

[0062] In the above examples, all other process parameters were the same as those in Example 1.

[0063] Comparative Example Comparative Example 1 Comparative Example 1 provides a GABA rare earth chelate and its preparation method.

[0064] The difference between this comparative example and Example 1 is specifically that step (4) condensation coating was not carried out.

[0065] In this comparative example, all other process parameters were the same as those in Example 1.

[0066] Comparative Example 2 Comparative Example 2 provides a GABA rare earth chelate and its preparation method.

[0067] The preparation method of the GABA rare earth chelate in this comparative example is as follows: (1) Enzyme production by fermentation: Inoculate Corynebacterium glutamicum (a genetically engineered bacterium obtained by transforming or introducing a double-enzyme co-expression vector for producing γ-aminobutyric acid into a host strain) into LBHIS liquid medium (2.5 g / L Oxoid yeast extract, 5 g / L tryptone, 5 g / L NaCl, 18 g / L brain heart infusion), and perform overnight shaking culture in a shaker at 32 °C and 200 r / min to obtain a seed solution; inoculate the seed solution into the fermentation medium at an inoculation amount of 3%, set the culture temperature at 30 °C, the stirring speed at 400 r / min, and pH = 7.0; when the cell growth reaches OD600 ≈ 40, add IPTG with a final concentration of 1 mM, and continue fermentation culture for 12 h to induce the expression of the target protein; after the fermentation culture is completed, centrifuge to collect the cell mass, remove the supernatant waste liquid, and wash and resuspend the cell mass with ultrapure water to obtain the cell mass for whole-cell catalysis.

[0068] The preparation method of the fermentation medium is as follows: Prepare according to the concentrations of glucose 140 g / L, k2HPO4 1 g / L, FeSO4 0.002 g / L, MnSO4 0.002 g / L, MgSO4 0.6 g / L, thiamine 0.5 g / L, corn steep liquor 15 g / L, urea 5 g / L (sterilized separately and added), lanthanum nitrate 0.9 mmol / L, cerium nitrate 0.1 mmol / L, neodymium nitrate 0.09 mmol / L, adjust the pH to 7.0 - 7.2, and sterilize at 0.1 Mpa for 7 - 8 min to obtain it.

[0069] (2) Chelation conversion: Establish a whole-cell catalysis reaction system using a fermenter, add the L-glutamic acid substrate with a final concentration of 700 g / L in batches, add 18 g / L of the cell mass for whole-cell catalysis prepared in step (1), control the reaction rotation speed at 220 r / min, the catalytic reaction temperature at 35 °C, and the catalytic reaction time at 16 h; obtain a mixture of GABA and a rare-earth chelate-containing cell mass; after measuring the dry matter concentration of the mixture, prepare lanthanum nitrate according to the dry matter weight ratio of the mixture: lanthanum nitrate = 1:1, control the moisture content at 65%, and then heat to 82 °C and maintain for 90 min to obtain a chelate with a chelation rate ≥ 89%.

[0070] (3) Adsorption and drying: Pass montmorillonite through an 80 - 200 mesh sieve, add montmorillonite powder to the chelate prepared in step (2) according to the weight ratio of montmorillonite:chelate = 1:150, stir evenly, and then perform homogenization and spray drying to obtain a dried chelate with a particle size of 80 - 200 mesh; the parameter process conditions for spray drying are: the inlet air temperature is 210 °C, the outlet air temperature is 78 °C, and the pressure is 190 kg / cm 2 。

[0071] (4) Condensation coating: First, sieve the dried chelate prepared in step (3), then transport it to the No. 1 drum of the first drum chamber, and introduce hot air at 130 °C to preheat the chelate to 76 °C, and then transport it to the No. 2 drum in the first drum chamber; Spray the molten palm oil heated to 130 °C onto the surface of the chelate and the surface of the drum through high-pressure air atomization. Under the action of the rotating drum, the molten palm oil evenly coats and wraps the chelate; The pressure of the atomizing nozzle is 15 MPa, the spraying distance is 20 cm, the conveying speed of the chelate is 450 kg / h, and the discharging temperature is 68 °C; Then add the material to the second drum chamber, introduce air at 20 °C, cool the material to 40 °C, add the viscosity-reducing regulator diatomite and mix well to obtain the GABA rare earth chelate with a particle size of 60-160 mesh. Among them, the weight ratio of the chelate, palm oil, and diatomite is 50:50:2; The coating thickness is 10-25 microns.

[0072] Performance detection test Test example 1: Detection of rare earth chelation rate Detection of cerium and lanthanum element contents: 1. Contents of lanthanum La and cerium Ce in the chelate salt 1.1. Principle: In the HCl-NaAc buffer solution (pH = 3.0) in the presence of ethanol and cetyltrimethylammonium bromide (CTMA), lanthanum La and cerium Ce form a 1:3 complex with arsenazo (Ⅲ), with a maximum absorption peak at 665 nm. The molar absorption coefficients are εLa = 1.58×105 L / mol / cm and εCe = 1.66×105 L / mol / cm. Other interfering elements can be masked with Zn-RDTA, and the absorbance of lanthanum La and cerium Ce can be changed by changing the amount of Zn-EDTA. Then, according to Beer's law, a set of simultaneous equations for the relationship between the concentration of lanthanum La, cerium Ce and absorbance can be established, so as to obtain the content of lanthanum and cerium in the GABA chelated rare earth.

[0073] 1.2. Reagents: 1.2.1. Arsenazo (Ⅲ) solution: Weigh 0.25 g of AR-grade arsenazo (Ⅲ) into a 500 mL volumetric flask, add water and dilute to the mark to obtain a 0.05% solution; 1.2.2. CTMA solution: Mix AR-grade CTMA with deionized water to prepare a 0.01 mol / L aqueous solution; 1.2.3. HCI-NaAc buffer solution: Take two solutions of 1 mol / L HCl and 1 mol / L NaAc with equal volume, mix them evenly, and adjust to pH = 3.0 with 5% HCl and 1:1 ammonia water on a pH meter; 1.2.4, Zn-EDTA solution: Weigh pure Zn powder (content ≥ 99.9%) and dissolve it with appropriate amount of HCl to prepare a Zn ion (divalent) solution with a concentration of 0.10 mol / L. Additionally, weigh 7.445 g of EDTANa2·2H2O, dissolve it in 50 - 60 mL of water, add the above 20 mL of zinc ion solution and mix well. After adjusting the pH to 3.5, dilute it to 100 mL; 1.2.5, Mixed masking agent: Weigh 10 g of tartaric acid, 10 g of sodium pyrophosphate, and 1 g of citric acid, mix them, dissolve in appropriate amount of water, adjust the pH to 3.0, and then dilute to 100 ml.

[0074] 1.3, Instruments: 722 - type spectrophotometer, wavelength range 200 nm - 1000 nm.

[0075] 1.4, Preparation of standard solutions: Weigh 0.0266 g of CeC13·7H2O (cerous chloride, AR grade, content ≥ 99.0%), dissolve it with 30 mL of 5 mol / L HCl. After complete dissolution, transfer it to a 1000 mL volumetric flask, dilute it to the mark with water, and shake well to prepare a standard solution of cerium with a concentration of 10 μg / mL; Weigh 0.0117 g of La2O3 (lanthanum oxide, content ≥ 99.99%), and similarly, prepare a standard solution of lanthanum with a concentration of 10 μg / mL using 30 mL of 5 mol / L HCl; Prepare a mixed standard solution of lanthanum and cerium according to the ratio of cerium:lanthanum = 5:10.

[0076] 1.5, Plotting the working curve: Respectively pipette 0 mL, 0.5 mL, 1.0 mL, 1.5 mL, and 2.0 mL of the mixed standard solution of lanthanum and cerium into 25 mL colorimetric tubes, add 2 mL (for measuring lanthanum La) or 4 mL (for measuring cerium Ce) of Zn - EDTA solution and mix well. Then successively add 5.0 mL of buffer solution, 3.0 mL of 0.05% arsenazo (Ⅲ) aqueous solution, 1.0 mL of 0.01 mol / L CTMA solution, and 1.2 mL of absolute ethanol, and dilute to the mark with water to obtain 5 kinds of standard solutions of lanthanum or cerium with concentrations of 0 μg / 25 ml, 5 μg / 25 ml, 10 μg / 25 ml, 15 μg / 25 ml, and 20 μg / 25 ml; Shake well, let stand for 5 min, then use a 1 cm cuvette to detect at 665 nm on a 722 - type spectrophotometer, using the corresponding reagent blank as the reference, and measure the absorbance; Use the absorbance as the ordinate and the micrograms of lanthanum or cerium contained in the pipetted solution as the abscissa to plot the working curve.

[0077] 1.6, Detection of lanthanum and cerium contents in samples: Accurately weigh 0.3000 g of the sample, dissolve it with 3 mL of concentrated HNO₃, transfer it into a 1000 mL volumetric flask, dilute it to the mark with water, shake well, then measure 10 mL and dilute it to 100 mL. The content of lanthanum or cerium in this solution is estimated to be 10 - 20 μg / mL (if the result is not appropriate, adjust according to the situation and re-prepare). Then measure the absorbance under the same conditions as the standard solution, and substitute the measured absorbances of lanthanum and cerium into their respective standard curves. The content of lanthanum and cerium in the sample can be obtained.

[0078] 2. Determination of the content of chelated lanthanum, the content of chelated cerium and the chelation degree by the difference method Take 0.5000 g of the sample, stir it with 250 mL of water for 10 - 20 min, let it stand for 30 - 60 min, then take the upper clear liquid and use 0.05% arsenazo (Ⅲ) solution as the color-developing agent, measure the absorbance at a wavelength of 665 nm on a 722-type spectrophotometer, and calculate the content of free lanthanum and cerium that are not chelated in the sample according to the working curve method; Subtract the content of free lanthanum from the measured content of lanthanum or subtract the content of free cerium from the measured content of cerium, and the amount of chelated lanthanum and cerium can be obtained; Chelation degree % = content of chelated lanthanum (cerium) / total amount of lanthanum (cerium) in the sample × 100%.

[0079] Test results: As shown in Table 1.

[0080] Experimental Example 2: Protection rate, rumen degradation rate, and post-rumen release rate of GABA rare earth chelate 1. Determination method of the protection rate of GABA rare earth chelate: Accurately weigh 5 g of GABA rare earth chelate into a stoppered conical flask, add 100 mL of water, stopper it, and place it in a water bath shaker at 37 °C and 50 r / min. Take it out at 4 h and 8 h respectively, and filter to obtain the dissolution solution of GABA rare earth chelate. The concentration of GABA in the dissolution solution is determined by the Berthelot reaction method: add sodium tetraborate buffer solution and redistilled phenol solution to the dissolution solution, mix well, then add sodium hypochlorite solution, shake, heat in boiling water, add ethanol solution, and measure the absorbance at a wavelength of 645 nm. Calculate the undissolution rate of GABA rare earth chelate as the protection rate. The calculation formula for the GABA protection rate is: Protection rate of GABA rare earth chelate (%) = [(amount of GABA in GABA rare earth chelate product - amount of GABA in solution) / amount of GABA in GABA rare earth chelate product] × 100.

[0081] 2. Determination method of the rumen degradation rate of GABA rare earth chelate: Three Simmental cattle with permanent rumen fistulas, which were healthy and had similar body weights, were selected. The diet was as follows: 2.5 kg / d of mixed concentrate and 5 kg / d of alfalfa hay, which were fed twice a day, in the morning and evening, and the cattle had free access to water. Before the experiment, the animals were ensured to adapt to the environment for at least 2 weeks. Nylon cloth with a pore size of 400 mesh was taken and made into nylon bags of 5 cm × 10 cm. The nylon bags were double-stitched with polyester thread, and the edges were ironed with a soldering iron. Before the experiment, the nylon bags were equilibrated in rumen fluid for 72 h, taken out, washed, dried at 65 °C, and could be used only after inspection showed no damage. Uncoated GABA was used as the control group, and the GABA rare earth chelate sample was used as the experimental group. Each nylon bag was filled with 5 g of the sample. Placement and removal: Every three bags were tied to a semi-polyethylene tube and placed in the ventral sac of the rumen of the experimental cattle. Six bags were placed in the rumen of each cow at the same time, and one nylon bag was taken out from the rumen of each cow at 2, 4, 6, 8, 12, and 24 h respectively. Then it was rinsed with clear water until it was clear and dried to a constant weight. The Bethelot reaction method was used to determine the GABA residue in the residue, and the rumen degradation rate of the sample was calculated.

[0082] 3. Determination method for the post-rumen release rate of GABA rare earth chelate According to the digestive physiological characteristics of ruminants, the three-stage in vitro digestive enzyme method was used to determine the post-rumen release rate. Weigh 5 g of the GABA rare earth chelate product and place it in physiological saline, add an acidic pepsin solution, place it in a water bath shaker, and incubate at 39 °C for 1 h. Then add sodium hydroxide and pancreatic enzymes and continue to incubate. Three samples of the post-rumen release rate of GABA rare earth chelate were taken out at 2, 4, 6, 8, and 12 h. After filtering and rinsing the remaining substances clean and drying them, the Bethelot reaction method was used to determine the GABA content in the remaining substances and calculate the post-rumen release rate of GABA.

[0083] Detection results: As shown in Table 1.

[0084] Table 1 Performance detection results of GABA rare earth chelate in the examples and comparative examples Combined with Table 1, by comparing the detection results of the examples and comparative examples, the present application adopted the path of fermentation first and then chelation, and obtained a GABA rare earth chelate with a high chelation rate, a high GABA protection rate, a low rumen degradation rate, and a high post-rumen release rate.

[0085] By comparing the detection results of Examples 1 and 4-7, it can be seen that the specific process parameters of chelation conversion have a great influence on the performance of GABA rare earth chelate. The present application further improved the performance of GABA rare earth chelate by optimizing and matching each parameter.

[0086] By comparing the detection results of Examples 1, 10 - 18, it can be seen that among the specific process parameters of condensation coating, the temperature of the chelate and molten palm oil, the weight ratio of the dried chelate to palm oil and the viscosity-reducing regulator, and the type of the viscosity-reducing regulator have a greater impact on the performance of the GABA rare earth chelate. In this application, by optimizing and matching each parameter, the dried chelate obtained by adsorption drying is preheated to 74 - 78 °C, the molten palm oil heated to 120 - 140 °C is atomized and sprayed onto the surface of the dried chelate through high-pressure air, and the weight ratio of the dried chelate to palm oil and the viscosity-reducing regulator diatomaceous earth is 65 - 80:20 - 30:1.5 - 2.5, further improving the performance of the GABA rare earth chelate.

[0087] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

[0088] Test Example 3: Detection of antioxidant performance Forty-eight Simmental crossbred cattle with good body condition, similar months of age (18.5 ± 0.5), and similar body weights (506.35 kg ± 51.64 kg) were selected for the test. They were divided into 4 groups by randomized block design, with 12 replicates in each group and 1 cattle in each replicate. The cattle in the control group were fed the original diet in the cattle farm; the cattle in the rare earth group (the rare earth citrate was a product of Zhengzhou Shengyu Chemical Industry Co., Ltd.) were supplemented with 100 mg / kg rare earth citrate on the basis of the original diet in the cattle farm, and the cattle in the GABA group (the GABA used in the GABA group was produced by Shanghai Licheng Nutrition Technology Co., Ltd. (99%)) were supplemented with 100 mg / kg on the basis of the original diet in the cattle farm. The cattle in the GABA rare earth group were supplemented with 100 mg / kg on the basis of the original diet in the cattle farm. The preliminary test period of the feeding experiment was 7 days, and the formal test period was 90 days. They were fed with TMR at 06:00 and 18:00 every day, and the remaining feed was controlled within 10% (fresh weight), and they had free access to water.

[0089] On the 90th day of the formal test period, jugular venous blood samples of the cattle were collected before morning feeding, centrifuged at 3500 r / min for 15 min to collect the serum, and stored in liquid nitrogen for subsequent determination of serum antioxidant indexes. The determination of serum antioxidant indexes was carried out using an enzyme-linked immunosorbent assay (ELISA) instrument (BioTek company) to detect the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) levels in the bovine serum samples. The detection kits for antioxidant indexes were all purchased from Shanghai Jianglai Biotechnology Co., Ltd. The test results are shown in Table 2.

[0090] Table 2 Detection results of the antioxidant properties of the GABA rare earth chelate in the examples and comparative examples Result analysis: Compared with the rare earth group and the GABA group, the GABA rare earth chelate prepared in this application shows significant effects in terms of antioxidant, anti-stress and regulation of physiological functions.

[0091] Cause analysis: (1) Synergistic enhancement of antioxidant effects: GABA is an important inhibitory neurotransmitter that can reduce the level of oxidative stress by regulating the neuroendocrine system. In addition, GABA can directly scavenge free radicals and enhance the activity of antioxidant enzymes (such as SOD, GSH-Px, CAT). Rare earth elements (such as lanthanum and cerium) have unique electronic structures that can increase the activity of antioxidant enzymes by activating the expression of antioxidant enzyme genes. In addition, rare earth elements can directly react with free radicals to reduce oxidative damage. After combining with rare earths, rare earth elements may enhance the antioxidant ability of GABA by stabilizing its structure; at the same time, GABA may regulate the metabolism and distribution of rare earth elements to make them play an antioxidant role more efficiently. (2) Synergistic effect of neuroendocrine regulation: GABA reduces the secretion of stress hormones (such as cortisol) by inhibiting the overexcitation of neurons, thereby reducing oxidative stress and inflammatory responses. Rare earth elements can further reduce the level of stress hormones and enhance the stress resistance of the body by regulating the hypothalamic-pituitary-adrenal axis (HPA axis). After combining with rare earths, rare earth elements can further reduce the secretion of stress hormones by enhancing the neuromodulatory effect of GABA, thus exerting a stronger stress resistance effect. (3) Synergistic activation of cell signaling pathways: GABA regulates the intracellular calcium ion concentration and signaling pathways (such as the PI3K / Akt and MAPK pathways) by activating GABA receptors (such as GABA-A and GABA-B receptors), thereby enhancing the antioxidant and stress resistance abilities of cells. Rare earth elements can further activate the antioxidant and stress resistance mechanisms of cells by regulating calcium ion channels and signaling pathways. After combining with rare earths, rare earth elements may further activate the antioxidant and stress resistance signaling pathways in cells by enhancing the sensitivity of GABA receptors, thereby playing a stronger protective role. (4) Synergistic effect of metabolic regulation: GABA reduces the generation of oxidative stress products (such as MDA) by regulating glucose and lipid metabolism, thereby reducing oxidative damage. Rare earth elements can further reduce the generation of oxidative stress products by regulating energy metabolism and mitochondrial function. After combining with rare earths, rare earth elements may further reduce the generation of oxidative stress products by enhancing the metabolic regulatory effect of GABA, thus exerting a stronger antioxidant effect. (5) Synergistic effect of immune regulation: GABA reduces the secretion of inflammatory factors by regulating the functions of immune cells, thereby reducing oxidative stress and inflammatory responses. Rare earth elements can further enhance the immune regulatory ability of the body by regulating the differentiation and functions of immune cells. After combining with rare earths, rare earth elements may further reduce the secretion of inflammatory factors by enhancing the immune regulatory effect of GABA, thus exerting a stronger anti-inflammatory and antioxidant effect.

[0092] Test Example 4: Detection of Thermal Stability The thermal stability of GABA rare earth chelates at different temperatures is crucial for the selection of storage and transportation conditions. In this experiment, after storing the samples at different temperatures (such as 40 °C, 60 °C, 80 °C) for a certain period of time, the changes in indicators such as GABA content and rare earth chelation rate were measured.

[0093] The GABA rare earth chelate samples were divided into 4 groups, with 3 parallel samples in each group.

[0094] They were stored in an incubator at 25 °C (room temperature control), 40 °C, 60 °C, and 80 °C respectively for 7 days. Determination of GABA content: The content of GABA in the samples was determined by HPLC method, and the retention rate was calculated by comparing with the initial value. Determination of rare earth chelation rate: The content of free rare earth elements in the samples was determined by ICP-MS method, and the chelation rate was calculated. Appearance change: Observe the changes in color, morphology, etc. of the samples during storage. One-way analysis of variance (ANOVA) was used to compare the differences between groups, and the significance level was set at P < 0.05. The test results are shown in Table 3.

[0095] Table 3 Detection results of the thermal stability of GABA rare earth chelates in the examples and comparative examples Result analysis: The GABA rare earth chelates have good thermal stability below 60 °C, while the GABA content and chelation rate decrease significantly at 80 °C. It is recommended that the storage temperature of GABA rare earth chelates does not exceed 40 °C. During transportation, high-temperature environments (such as high temperatures in summer) should be avoided. It is recommended to use refrigerated transportation or heat-insulating packaging to maintain their GABA content and chelation rate.

[0096] Test Example 5: Detection of long-term storage stability 1. Experimental materials Samples: The GABA rare earth chelates produced by the present invention.

[0097] Equipment: High performance liquid chromatograph (HPLC), inductively coupled plasma mass spectrometer (ICP-MS), microplate reader.

[0098] Reagents: Standard GABA solution, rare earth element standard solution, antioxidant capacity detection kit.

[0099] 2. Experimental steps 2.1 Sample treatment: The GABA rare earth chelate samples were divided into 4 groups, with 3 parallel samples in each group. They were stored at room temperature (25 °C), in the dark, and under dry conditions for 0 months (initial value), 3 months, 6 months, and 12 months respectively.

[0100] Index detection: Determination of GABA content: The content of GABA in the sample was determined by HPLC method, and the retention rate was calculated by comparing with the initial value.

[0101] Determination of rare earth chelation rate: The content of free rare earth elements in the sample was determined by ICP-MS method, and the chelation rate was calculated.

[0102] 2.3 Data analysis Calculate the changes in GABA content and rare earth chelation rate at different storage times.

[0103] One-way analysis of variance (ANOVA) was used to compare the differences between groups, and the significance level was set at P < 0.05.

[0104] The test results are shown in Table 4.

[0105] Table 4 Detection results of long-term storage stability of GABA rare earth chelate in examples and comparative examples Time GABA retention rate / % Rare earth chelation rate / % 0 months 100.0±0.0％ 100.0±0.0％ 3 months 98.2±0.5％ 97.5±0.6％ 6 months 96.8±0.7％ 95.3±0.8％ 12 months 94.5±1.0％ 92.8±1.2％ The results showed that after the GABA rare earth chelate was stored at room temperature for 12 months, the GABA content and chelation rate remained above 90%, and the overall stability was good.

[0106] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A preparation method of a GABA rare earth chelate, characterized in that, Specifically, it includes the following steps in sequence: Fermentation to produce enzymes: Inoculate the seed liquid of Corynebacterium glutamicum into a fermentation medium containing rare earth nitrates, and perform fermentation culture to obtain the cell mud for whole-cell catalysis. Chelation conversion: Use a fermenter to establish a whole-cell catalysis reaction system, add an L-glutamic acid substrate with a final concentration of 850 - 950 g / L and 10 - 15 g / L of the cell mud for whole-cell catalysis to carry out the catalysis reaction, and proportion rare earth nitrates to obtain a chelate with a chelation rate ≥ 89%. Adsorption and drying: Based on the air-dried chelate, add montmorillonite powder to the chelate according to the weight ratio of montmorillonite:chelate = 1:25 - 55. After stirring evenly, homogenize and spray-dry to obtain the dried chelate. Condensation coating: Atomize the molten palm oil through high-pressure air and evenly coat the dried chelate to obtain the GABA rare earth chelate. The weight ratio of the dried chelate to palm oil is 60 - 85:15 - 35.

2. The preparation method of the GABA rare earth chelate according to claim 1, wherein The specific steps of the fermentation to produce enzymes are as follows: Inoculate the strain into the LBHIS liquid medium, and perform overnight shaking culture in a shaker at 30 - 34 °C and 150 - 250 r / min to obtain the seed liquid. Inoculate the seed liquid into the fermentation medium according to an inoculation amount of 2 - 4%. The culture temperature is 28 - 32 °C, the stirring speed is 350 - 450 r / min, and pH = 7.

0. When the cell growth reaches OD 600 ≈ 30 - 50, add IPTG with a final concentration of 1 mM and continue fermentation culture for 8 - 24 h. After the fermentation culture is completed, centrifuge to collect the cell cells, remove the supernatant, and wash and resuspend the cell cells with ultrapure water to obtain the cell mud for whole-cell catalysis. The fermentation medium includes the following components at the following concentrations: glucose 120 - 160 g / L, k2HPO4 0.8 - 1.2 g / L, FeSO4 0.001 - 0.003 g / L, MnSO4 0.001 - 0.003 g / L, MgSO4 0.5 - 0.7 g / L, thiamine 0.4 - 0.6 g / L, corn steep liquor 13 - 17 g / L, urea 4 - 6 g / L, rare earth nitrates 0.006 - 0.8 mmol / L; pH = 7.0 - 7.2, sterilize at 0.1 Mpa for 7 - 8 min to obtain.

3. The preparation method of the GABA rare earth chelate according to claim 2, characterized in that, The fermentation medium contains one or more rare earth metal ions at the following concentrations: La 3+ 0.50 - 0.73 mmol / L, Ce 3+ 0.06 - 0.08 mmol / L, Nd 3+ 0.006 - 0.012 mmol / L.

4. The preparation method of the GABA rare earth chelate according to claim 1, characterized in that, The specific steps of the chelation conversion are as follows: Use a fermenter to establish a whole-cell catalysis reaction system, add the L-glutamic acid substrate with a final concentration of 850 - 950 g / L and 10 - 15 g / L of the cell mud for whole-cell catalysis in batches, control the reaction speed at 150 - 300 r / min, the catalysis reaction temperature at 25 - 45 °C, and the catalysis reaction time at 8 - 24 h to obtain a mixture of GABA with a purity ≥ 97% and a cell mud containing GABA rare earth chelate and rare earth polysaccharide substances. Proportion rare earth nitrates according to the dry matter weight ratio of the mixture:rare earth nitrates = 1:0.7 - 1.3, control the moisture content at 55% - 79%, and then heat to 75 - 90 °C and maintain for 60 - 120 min to obtain a chelate with a chelation rate ≥ 89%.

5. The preparation method of the GABA rare earth chelate according to claim 4, characterized in that, The specific steps of the chelation conversion are as follows: A whole-cell catalytic reaction system is established using a fermenter, and the L-glutamic acid substrate with a final concentration of 870-920 g / L and the bacterial sludge for whole-cell catalysis of 11-14 g / L are added in batches. The reaction rotation speed is controlled at 200-250 r / min, the catalytic reaction temperature is 30-40 °C, and the catalytic reaction time is 12-20 h; A mixture of GABA with a purity ≥97% and the bacterial sludge containing GABA rare earth chelate and rare earth polysaccharide substances is obtained; The rare earth nitrate is proportioned according to the dry matter weight ratio of the mixture: rare earth nitrate = 1:0.8-1.2, and the moisture content is controlled at 60%-75%. Then it is heated to 80-85 °C and maintained for 80-100 min to obtain a chelate with a chelation rate ≥89%.

6. The preparation method of the GABA rare earth chelate according to claim 1, characterized in that, In the specific steps of the adsorption drying: the particle size of the montmorillonite is 100 - 400 mesh; the performance indicators are: moisture ≤ 8%, pH value 6 - 9, blue adsorption amount ≥ 42%, ammonia adsorption value ≥ 100%, purity ≥ 94%, Na + content is 1.53 - 1.95%, Ca 2+ content is 0.32 - 0.52%; the parameter process conditions of spray drying are: inlet air is 200 - 220 °C, exhaust air is 75 - 80 °C, pressure is 180 - 200 kg / cm 2 .

7. The preparation method of the GABA rare earth chelate according to claim 1, characterized in that, The specific steps of the condensation coating are as follows: The dried chelate obtained by adsorption drying is preheated to 71-82 °C, and the molten palm oil heated to 110-150 °C is atomized and sprayed onto the surface of the dried chelate through high-pressure air, and the material is discharged under the condition of 62-73 °C; Then the material is cooled, and at the same time, a viscosity-reducing regulator is added and fully mixed until the material is cooled to 36-45 °C, and it is obtained; The weight ratio of the dried chelate, the palm oil, and the viscosity-reducing regulator is 60-85:15-35:1-3.

8. The preparation method of the GABA rare earth chelate according to claim 7, wherein, In the specific steps of the condensation coating, the parameter adjustment of the high-pressure air atomization spraying is as follows: The pressure of the atomization nozzle is 10-20 MPa, the spraying distance is 15-30 cm, and the conveying speed of the chelate is 300-600 kg / h.

9. A GABA rare earth chelate, characterized in that, Prepared by using the preparation method according to any one of claims 1-8.

10. The application of the GABA rare earth chelate according to claim 9 in the feed for ruminants.

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