Rare earth chelate based on yeast hydrolysate as well as preparation method and application of rare earth chelate

Abstract

The invention relates to the technical field of rare earth chelates, and particularly discloses a rare earth chelate based on yeast hydrolysate as well as a preparation method and application of the rare earth chelate. The preparation method comprises the following steps: adding deionized water into the yeast hydrolysate, and dissolving and dispersing into a suspension with the concentration of 20-35%; the method comprises the following steps: mixing rare earth with weak acid to react for 30-60 minutes to obtain pretreated rare earth; carrying out chelation reaction on the suspension and the pretreated rare earth to obtain a crude chelate; filtering the crude chelate with a ceramic membrane of 80-100 nm to obtain a concentrated solution and a filtrate; and carrying out spray drying on the concentrated solution. The rare earth chelate based on the yeast hydrolysate prepared by the preparation method provided by the invention has relatively high yield and rare earth chelation rate, and the rare earth chelate based on the yeast hydrolysate has relatively high antibacterial activity as an animal feed additive, and can improve the immunity of animals.

Description

Technical Field

[0001] The present application relates to the technical field of rare earth chelates, and more specifically, to a rare earth chelate based on yeast hydrolysate, its preparation method and application. Background Art

[0002] Antibiotics are used as feed growth promoters. Due to the widespread use of antibiotics in livestock and poultry feeds, it causes various pathogenic microorganisms in livestock and poultry to develop drug resistance and secondary infections in livestock and poultry, seriously affecting the health status of livestock and poultry. Moreover, when antibiotics enter the animal body, part of them will be discharged through animal feces, directly polluting the surrounding environment (soil, water source, air, etc.), thus causing serious harm to the environment.

[0003] Rare earth is the general term for seventeen metal elements including lanthanide elements, scandium and yttrium in the periodic table of chemistry. Due to its unique physical and chemical properties such as light, electricity and magnetism, it is widely used in various fields of the national economy and national defense industry. In recent years, people have gradually recognized and confirmed that rare earth has antibacterial effects. Due to its good antibacterial and anti-inflammatory effects, rare earth has been gradually applied to the fields of biomedicine and animal feeds.

[0004] At present, animals have a weak absorption ability for rare earth elements. Most of the absorption of rare earth by animals is in the form of chelates. However, due to the different types of rare earth chelates, there is a large gap in their effects. Summary of the Invention

[0005] The present application provides a rare earth chelate based on yeast hydrolysate, its preparation method and application.

[0006] The rare earth chelate based on yeast hydrolysate prepared by the method of the present application has a high yield and rare earth chelation rate, and the rare earth chelate based on yeast hydrolysate has high antibacterial properties as an animal feed additive and can improve the immunity of animals.

[0007] In the first aspect, the present application provides a preparation method of a rare earth chelate based on yeast hydrolysate, adopting the following technical scheme:

[0008] A preparation method of a rare earth chelate based on yeast hydrolysate, the preparation method specifically includes the following steps:

[0009] (1) Pretreatment of yeast hydrolysate: Add deionized water to the yeast hydrolysate and dissolve and disperse it into a suspension with a concentration of 20-35%;

[0010] (2) Pretreatment of rare earth: Mix the rare earth with a weak acid and react for 30-60 min to obtain the pretreated rare earth;

[0011] (3) Chelation reaction: Chelate the suspension and the pretreated rare earth to obtain a crude chelate;

[0012] The addition amount of the pretreated rare earth is 20-35% of the dry matter weight in the suspension; the conditions of the chelation reaction are: reacting for 125-150 min in an environment with a pH of 3-4 and a temperature of 85-90 °C;

[0013] (4) Purification treatment: Filter the crude chelate with a ceramic membrane of 80-100 nm to obtain a concentrated solution and a filtrate;

[0014] (5) Spray drying: Spray dry the concentrated solution.

[0015] The yield of the rare earth chelate based on yeast hydrolysate prepared in this application is above 85%, and the chelation rates of cerium and lanthanum elements in the rare earth chelate based on yeast hydrolysate can both reach above 89%.

[0016] Yeast hydrolysate is a product obtained by hydrolyzing yeast cells and is rich in various nutrients, mainly including the following categories: 1. Proteins and amino acids. Yeast hydrolysate contains abundant proteins and amino acids, and the protein content is usually not less than 35%. After hydrolysis, the amino acid nitrogen can reach 3%, and the free amino acids are about 10%. Among them, the content of glutamic acid is as high as more than 6%, which has a significant function of attracting food. 2. Carbohydrates and polysaccharides. Yeast hydrolysate contains a large amount of carbohydrates, which are the main energy sources for yeast growth and reproduction. In addition, it is rich in mannan and β-glucan. Among them, mannan accounts for 30% of the dry weight of the cell wall and has the functions of regulating intestinal health and enhancing immunity. 3. Nucleotides. Yeast hydrolysate is rich in ribonucleic acid (RNA), with a content of 3-15%. Its hydrolysis product nucleotides are important genetic materials, which can promote the recovery of intestinal epithelial cells and play an important role in the growth and development of young animals. In addition, flavor nucleotides (such as guanylic acid and inosinic acid) have a fresh flavor and can significantly improve the feed intake of animals. 4. Vitamins and minerals. Yeast hydrolysate contains various B vitamins (such as B1, B2, B6, B12) and minerals (such as calcium, iron, zinc), and these components are crucial for cell metabolism and growth and development. The multi-component synergistic chelation of rare earths by yeast hydrolysate is a complex but efficient process, involving the interaction of multiple components and chemical reactions under specific conditions. Small peptides and amino acids provide abundant functional groups such as carboxyl (-COOH), amino (-NH 2 ) and hydroxyl (-OH), and react with rare earth ions (such as La 3+ , Ce 3+)Form stable coordination bonds to form the core structure of the chelate. Polysaccharides (including β-glucan and mannan oligosaccharides) enhance the stability of the chelate by forming hydrogen bonds or electrostatic interactions with rare earth ions, and at the same time play antibacterial and immunomodulatory roles. Other bioactive substances such as polyphenols can protect rare earth ions from oxidation through antioxidant effects, improving the chelation efficiency and the yield of the finished product.

[0017] The method for preparing rare earth chelates based on yeast hydrolysate in this application is as follows: 1. Adsorption of rare earth ions: Rare earth ions first adsorb with small peptides and amino acids in the yeast hydrolysate to form a preliminary coordination structure. 2. Formation of coordination bonds: Under acidic conditions with a pH of 3-4, the carboxyl and amino groups of small peptides and amino acids form stable coordination bonds with rare earth ions to construct the core of the chelate. 3. Enhancement of hydrogen bonds and electrostatic interactions: Polysaccharide substances further stabilize the chelate through hydrogen bonds and electrostatic interactions, while promoting the uniform distribution of rare earth ions in the solution. 4. Antioxidant protection: Polyphenols prevent rare earth ions from being oxidized during the reaction through antioxidant effects, ensuring the high efficiency of the reaction. That is, small peptides, free amino acids, and small molecules such as β-glucan in the yeast hydrolysate chelate with rare earth respectively, and the synergistic effect among various rare earth chelates can improve the chelation rate and stability of rare earth chelates based on yeast hydrolysate, thereby enhancing the antibacterial effect on animal bodies, and then being able to replace antibiotics as animal feed additives.

[0018] By adopting the above technical solution, when the addition amount of rare earth is 20-35% of the dry matter weight in the suspension, the content of chelated rare earth in the prepared rare earth chelate based on yeast hydrolysate is relatively high; when the addition amount of rare earth is too small, it will also cause some small peptides unable to chelate, thus reducing the content of chelated rare earth in the rare earth chelate based on yeast hydrolysate; when the addition amount of rare earth is too large, some rare earth cannot chelate with small peptides, and when the subsequent free rare earth elements are not completely collected, it will cause waste of rare earth.

[0019] The absorption effect of free rare earth elements by animals is poor, and free rare earth elements will be excreted from the body with animal excreta, which not only causes waste of resources but also pollutes the environment. In this application, by filtering the crude chelate with a ceramic membrane with a particle size of 80-100 nm, the free rare earth elements in the crude chelate can be nanofiltrated, and through the collection of free rare earth, the free rare earth can be recycled, thereby saving resources and reducing production costs, and at the same time being able to improve the chelation rate of chelated rare earth elements in the prepared rare earth chelate based on yeast hydrolysate.

[0020] In this application, by adding deionized water, the autolytic enzymes contained in Saccharomyces cerevisiae can be activated, and the yeast cell wall can be dissolved by the autolytic enzymes, so as to release β-glucan and mannan oligosaccharide. When the concentration of the suspension is too low, the production cost is high; when the concentration of the suspension is too high, the chelation temperature requirement is high, the chelation time is long, and moreover, when the concentration of the suspension is high, the stirring resistance is large and the equipment is easily damaged.

[0021] Optionally, the content of small peptides in the yeast hydrolyzate within the range of 1000 - 4000 Da is greater than 60%.

[0022] In this application, when the content of small peptides in the Saccharomyces cerevisiae hydrolyzate is higher than 60%, more chelation sites can be provided per unit mass of the yeast hydrolyzate, significantly increasing the binding probability of rare earth ions, and the content of chelated rare earths in the rare earth chelate based on the yeast hydrolyzate prepared is relatively high. At the same time, under this ratio condition, small peptides form a composite chelation network with other components in the yeast hydrolyzate (such as β-glucan, nucleotides), enhancing the rare earth binding strength, improving the rare earth chelation rate of the yeast hydrolyzate, and thus enhancing the antibacterial effect on animals.

[0023] Optionally, in the rare earth pretreatment, the weight ratio of the rare earth to the weak acid is (5 - 7):(3 - 5).

[0024] Optionally, the weak acid is any one of acetic acid and lactic acid.

[0025] Optionally, the rare earth is selected from one or more of rare earth carbonates, rare earth nitrates, and rare earth chlorides.

[0026] By adopting the above technical solution, compared with rare earth nitrates and rare earth chlorides, rare earth carbonates have more stable properties and do not produce dangerous gases such as ammonia or chlorine. Rare earth carbonates react with acetic acid to form rare earth acetates. Lanthanum and cerium in rare earth acetates are more soluble in water, and lanthanum and cerium are more likely to chelate with small peptides, free amino acids, etc. in blood peptides in an ionic state.

[0027] Optionally, the specific operation of the spray drying is as follows: homogenize the concentrated solution at a pressure of 30 - 70 Mpa for 5 - 20 min, and then place it under the conditions of an inlet air temperature of 200 - 220 °C, an exhaust air temperature of 75 - 80 °C, and a pressure of 180 - 200 kg / cm 2 for spray drying.

[0028] It has been found through experiments that the best temperature control for the chelation conditions is 85 - 90 °C. When the temperature is too high, the peptide chains are prone to aggregate to form irreversible precipitates (such as β-sheet stacking), resulting in a reduction in effective coordination groups; Ce 3+ may be oxidized to Ce 4 +, thus reducing the chelating ability; when the temperature is too low, the reaction rate is insufficient, the chelating time is prolonged, the peptide chain is not fully unfolded, the chelating sites are insufficiently exposed, and the chelating rate is reduced.

[0029] By homogenizing the concentrated solution, the chelate aggregates can be broken into smaller particles. The increased specific surface area can reduce the moisture diffusion path during drying, reduce the drying time, avoid excessive heat exposure, and increase the stability between the rare earth and the structure of the chelating ligand, thereby ensuring the stability of the rare earth chelate based on yeast hydrolysate during spray drying.

[0030] Optionally, after the spray drying, the obtained rare earth chelate based on yeast hydrolysate is made into particles with a particle size of 1 mm by a double-roll dry granulator to obtain a rare earth chelate product based on yeast hydrolysate.

[0031] In a second aspect, the present application provides a rare earth chelate based on yeast hydrolysate prepared by the above preparation method.

[0032] In a third aspect, the present application provides the use of the above rare earth chelate based on yeast hydrolysate in the field of animal feed.

[0033] Optionally, the rare earth chelate based on yeast hydrolysate is used to prepare livestock and poultry feed.

[0034] Optionally, the addition amount of the rare earth chelate based on yeast hydrolysate is 0.05 - 0.2% of the total weight of the feed.

[0035] The rare earth chelate based on yeast hydrolysate prepared in the present application can exert the function of the yeast hydrolysate itself to enhance immunity. For example, β-glucan can activate macrophages and natural killer cells and enhance the non-specific immune response. Small peptides can act as immunomodulators, promote lymphocyte proliferation and antibody production, and enhance humoral and cellular immunity. Mannan oligosaccharides indirectly enhance the immune system by regulating the intestinal microflora, inhibiting the growth of harmful bacteria, and promoting the proliferation of beneficial bacteria. Rare earth elements (such as cerium, lanthanum, etc.) also have unique antibacterial properties. For example, rare earth compounds bind to negatively charged sites on the bacterial surface, destroying the cell membrane structure; they can also disrupt the cell membrane permeability, resulting in the outflow of cytoplasm and death; they can also inhibit bacterial reproduction by interfering with the replication and transcription processes of harmful bacteria.

[0036] Meanwhile, yeast hydrolysate and rare earth can form stable chelates. This synergistic effect can significantly improve immunity and enhance antibacterial effects because chelation makes rare earth more stable in animals, less prone to oxidation or decomposition, ensuring its continuous release and function. Using yeast hydrolysate as a carrier, rare earth can be directed to the intestine or immune cells, improving utilization efficiency. The combination of yeast hydrolysate and rare earth not only enhances antibacterial activity but also further improves the overall health level of animals through immunomodulatory effects.

[0037] The rare earth chelate based on yeast hydrolysate prepared in this application can replace antibiotics, inhibit the number of harmful bacteria in animals, and improve the immunity of animals. In this application, by feeding laying hens with the rare earth chelate based on yeast hydrolysate as a feed additive, the laying rate and hatching rate of laying hens can be improved, and the incidence rate of laying hens can be reduced.

[0038] In summary, the technical solution of this application has the following beneficial effects:

[0039] (1) In this application, the prepared rare earth chelate based on yeast hydrolysate can increase the content of chelated cerium and chelated lanthanum in the rare earth chelate based on yeast hydrolysate and the yield rate of the rare earth chelate based on yeast hydrolysate. Among them, the yield rate of the rare earth chelate based on yeast hydrolysate is above 95%, and the rare earth chelation rate in the rare earth chelate based on yeast hydrolysate can reach above 88%.

[0040] (2) In this application, by selecting Saccharomyces cerevisiae hydrolysate as the raw material and using the prepared rare earth chelate based on yeast hydrolysate as a feed additive, the effects of inhibiting harmful bacteria and improving immunity in animals can be enhanced. Detailed Embodiments

[0041] Before describing the embodiments of this application in detail, it should be understood that the terms used herein are only for the purpose of describing specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this term belongs.

[0042] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of this application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0043] In the scope disclosed in this application, the endpoints and any values of the scope are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0044] In this application, the term "comprising" or "including" is an open expression, that is, it includes the content specified in this application, but does not exclude other aspects of the content.

[0045] This application provides a method for preparing rare earth chelate based on yeast hydrolysate. The above preparation method specifically includes the following steps:

[0046] (1) Pretreatment of yeast hydrolysate: Add deionized water to the yeast hydrolysate and dissolve and disperse it into a suspension with a concentration of 20 - 35%. Among them, the content of small peptides (1000 - 4000Da) in the yeast hydrolysate is greater than 60%.

[0047] Optionally, the content of small peptides (1000 - 4000Da) in the yeast hydrolysate is 60 - 80%.

[0048] (2) Pretreatment of rare earth: Mix the rare earth with a weak acid and react for 30 - 60 min to obtain the pretreated rare earth.

[0049] Among them, the weight ratio of the rare earth to the weak acid is (5 - 7):(3 - 5). The weak acid can be any one of acetic acid and lactic acid.

[0050] (3) Chelation reaction: Mix the suspension and the pretreated rare earth for chelation reaction to obtain the crude chelate.

[0051] Among them, the addition amount of the rare earth is 20 - 35% of the dry matter weight in the suspension.

[0052] Among them, the chelation conditions are: React for 125 - 150 min in an environment with a pH of 3 - 4 and a temperature of 85 - 90 °C.

[0053] Among them, the rare earth is any one or more of rare earth carbonate, rare earth nitrate, and rare earth chloride.

[0054] In a specific embodiment, the rare earth used is rare earth carbonate.

[0055] (4) Purification treatment: Filter the crude chelate with a ceramic membrane of 80 - 100 nm to obtain a concentrate and a filtrate.

[0056] (5) Spray drying: Spray dry the concentrate to obtain the rare earth chelate based on yeast hydrolysate.

[0057] Among them, the specific operation of spray drying is as follows: homogenize the concentrated solution at a pressure of 30 - 70 Mpa for 5 - 20 min, and then place it under the conditions of an inlet air temperature of 200 - 220 °C, an outlet air temperature of 75 - 80 °C, and a pressure of 180 - 200 kg / cm 2 for spray drying.

[0058] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application and should not be construed as a limitation of this application.

[0059] For those not specified in the embodiments, follow the techniques or conditions described in the literature in this field or follow the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0060] In the following embodiments, the source of the brewer's yeast hydrolyzate used is Henan Anxun Biotechnology Co., Ltd. The crude protein in this brewer's yeast hydrolyzate is ≥ 32%, mannan ≥ 5%, β-glucan ≥ 10%, amino acid nitrogen ≥ 2.0%, and moisture ≤ 8%. During use, before use, it is purified or diluted in advance to obtain brewer's yeast hydrolyzates with different small peptide (1000 - 4000 Da) contents.

[0061] In the following embodiments, the ceramic membranes used are commercially available.

[0062] In the following embodiments, the rare earth used is rare earth carbonate. The composition of the rare earth carbonate is a mixture of 50% lanthanum carbonate and 50% cerium carbonate, and the source is Ganxian Hongjin Rare Earth Co., Ltd.

[0063] The following further elaborates on this application in combination with the embodiments and test results.

[0064] Embodiment

[0065] Embodiment 1

[0066] This embodiment provides a method for preparing a rare earth chelate based on yeast hydrolyzate.

[0067] The above preparation method specifically includes the following steps:

[0068] (1) Pretreatment of yeast hydrolysate: Deionized water was added to the yeast hydrolysate of Saccharomyces cerevisiae and dissolved and dispersed into a suspension with a concentration of 25%. Among them, it was required that the content of small peptides (1000 - 4000 Da) in the yeast hydrolysate of Saccharomyces cerevisiae was 60%.

[0069] (2) Pretreatment of rare earth: Rare earth carbonate and acetic acid were mixed according to a weight ratio of 6:4 and reacted for 30 - 60 min to obtain rare earth acetate.

[0070] (3) Chelation reaction: The suspension and acetic acid were mixed, and a chelation reaction was carried out for 130 min at a pH of 3 - 4 and a temperature of 90 °C to obtain a crude chelate. The addition amount of rare earth acetate was 25% of the dry matter weight in the suspension.

[0071] (4) Purification treatment: The crude chelate was filtered through a 100 nm ceramic membrane to obtain a concentrated solution and a filtrate.

[0072] (5) Spray drying: The concentrated solution was spray - dried to obtain a rare earth chelate based on yeast hydrolysate.

[0073] The concentrated solution was homogenized at a pressure of 65 Mpa for 10 min, and then placed under the conditions of an inlet air temperature of 200 °C, an outlet air temperature of 75 °C, and a pressure of 180 - 200 kg / cm 2 for spray drying to obtain a rare earth chelate based on yeast hydrolysate.

[0074] Examples 2 - 3

[0075] Examples 2 - 3 respectively provided a preparation method of a rare earth chelate based on yeast hydrolysate. The differences between the above - mentioned examples and Example 1 were the content of small peptides in the yeast hydrolysate, as shown in Table 1 specifically, and the remaining steps were the same as those in Example 1.

[0076] Comparative examples

[0077] Comparative examples 1 - 2

[0078] Comparative examples 1 - 2 respectively provided a preparation method of a rare earth chelate based on yeast hydrolysate. The differences between the above - mentioned comparative examples and Example 2 were the content of small peptides in the yeast hydrolysate, as shown in Table 1 specifically, and the remaining steps were the same as those in Example 2.

[0079] Table 1 Partial parameter settings of examples and comparative examples

[0080]

[0081] Examples 4 - 6

[0082] Examples 4-6 respectively provide a method for preparing a rare earth chelate based on yeast hydrolysate. The difference between the above examples and Example 2 lies in the addition amount of rare earth acetate, as specifically shown in Table 1, and the remaining steps are the same as those in Example 2.

[0083] Comparative Examples 3-4

[0084] Comparative Examples 3-4 respectively provide a method for preparing a rare earth chelate based on yeast hydrolysate. The difference between the above comparative examples and Example 2 lies in the addition amount of rare earth acetate, as specifically shown in Table 1, and the remaining steps are the same as those in Example 2.

[0085] Comparative Example 5

[0086] Comparative Example 5 provides a method for preparing a rare earth chelate based on yeast hydrolysate. The difference between the above comparative example and Example 2 lies in the particle size of the ceramic membrane, as specifically shown in Table 1, and the remaining steps are the same as those in Example 2.

[0087] Performance detection test

[0088] The following is to detect the yield and rare earth chelation rate of the rare earth chelates based on yeast hydrolysate prepared in the above examples and comparative examples.

[0089] (1) Contents of chelated cerium, chelated lanthanum and chelation degree

[0090] The detection principle is as follows: In an 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), having a maximum absorption peak at 665 nm, and the molar absorption coefficients are εLa = 1.58×10 5 L / mol / cm, εCe = 1.66×10 5 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 varying the amount of Zn-EDTA used. Then, a set of simultaneous equations for the relationship between the concentrations of lanthanum La and cerium Ce and the absorbance can be established according to Beer's law, so that the contents of lanthanum and cerium in the rare earth chelate based on yeast hydrolysate can be obtained.

[0091] The reagents used are as follows: Arsenazo (III) solution: Weigh 0.25 g of AR-grade Arsenazo (III) into a 500 mL volumetric flask, dilute it with water to the mark, and obtain a 0.05% solution. CTMA solution: Mix AR-grade CTMA with deionized water to prepare a 0.01 mol / L aqueous solution. HCI-NaAc buffer solution: Take equal volumes of 1 mol / L HCl and 1 mol / L NaAc solutions, mix them evenly, and adjust the pH to 3.0 with 5% HCl and 1:1 ammonia water on a pH meter. 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 EDTA Na 2 ·2H 2 0, dissolve it in 50 - 60 mL of water, add the above 20 mL of zinc ion solution, mix well, adjust the pH to 3.5, and then dilute it to 100 mL. 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 it to 100 ml.

[0092] The instrument used is a 722-type spectrophotometer with a wavelength range of 200 nm - 1000 nm.

[0093] Preparation of standard solution: Weigh 0.0266 g of CeC1 3 ·7H,0 (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 with water to the mark, shake well, and prepare a standard solution with a cerium concentration of 10 μg / mL; Weigh 0.0117 g of La 2 O 3 (lanthanum oxide, content ≥ 99.99%), similarly, prepare a standard solution with a lanthanum concentration of 10 μg / mL with 30 mL of 5 mol / L HCl; Prepare a lanthanum and cerium mixed standard solution according to cerium:lanthanum = 5:10.

[0094] Drawing the working curve: 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 respectively. Add 2 mL (for measuring lanthanum La) or 4 mL (for measuring cerium Ce) of Zn-EDTA solution and mix well. Then add 5.0 mL of HCI-NaAc buffer solution, 3.0 mL of 0.05% arsenazo (Ⅲ) aqueous solution, 1.0 mL of CTMA solution with a concentration of 0.01 mol / L, and 1.2 mL of absolute ethanol in sequence. 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 colorimetric cell to detect at 665 nm on a 722-type spectrophotometer, using the corresponding reagent blank as the reference to measure the absorbance; take the absorbance as the ordinate and the microgram number of lanthanum or cerium contained in the pipetted solution as the abscissa to draw the working curve.

[0095] Detection of the total content of lanthanum (cerium) in rare earth chelates based on yeast hydrolysate: Accurately weigh 0.3000 g of the sample, add 3 mL of concentrated HNO 3 After dissolution, transfer it into a 1000-mL volumetric flask, dilute 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 respectively. Then the content of lanthanum and the content of cerium in the sample can be obtained.

[0096] Detection of the content of free lanthanum (cerium) in rare earth chelates based on yeast hydrolysate: Take 0.5000 g of the sample, stir it with 250 mL of water for 10 - 20 min, let stand for 30 - 60 min, then take the upper clear liquid and use 0.05% arsenazo (Ⅲ) solution as the color-developing agent to measure the absorbance at 665 nm wavelength on a 722-type spectrophotometer, and calculate the content of unchelated free lanthanum and cerium in the sample according to the working curve method.

[0097] The content of chelated cerium (chelated lanthanum) in rare earth chelates based on yeast hydrolysate = The total content of lanthanum (cerium) in rare earth chelates based on yeast hydrolysate - The content of free lanthanum (cerium) in rare earth chelates based on yeast hydrolysate.

[0098] Rare earth chelation degree (%) = The content of chelated rare earth (lanthanum, cerium) / The total amount of rare earth (lanthanum, cerium) in the sample × 100%.

[0099] (2) Yield

[0100] The calculation method of the yield is as follows:

[0101] Yield rate (%) = Weight of rare earth chelate based on yeast hydrolysate / (Weight of yeast hydrolysate + Weight of rare earth + Weight of acetic acid) × 100%.

[0102] (III) Test results

[0103] The test results are shown in Table 3 below.

[0104] Table 3 Rare earth content and yield rate in rare earth chelates based on yeast hydrolysate in the examples and comparative examples

[0105]

[0106] As can be seen from Table 3, the rare earth chelation rate of the rare earth chelate based on yeast hydrolysate prepared by the preparation method of the present application can reach more than 88%, and the yield rate can reach more than 95%.

[0107] In addition, since yeast hydrolysate contains not only crude protein (such as small peptides), but also mannan, β-glucan, amino acid nitrogen, etc., when the content of small peptides increases, the proportion of other components will decrease, and when the content of small peptides increases, the proportion of other components will decrease. During the chelation of the suspension with rare earth, not only small peptides will chelate with rare earth, but other components will also chelate with rare earth, and these forms of chelation will promote the improvement of the rare earth chelation rate and the yield rate. Therefore, it is necessary to control the content of small peptides within a certain range to ensure that other components have a certain proportion in the suspension. In this case, through the co-chelating effect of small peptides and other components with rare earth, the formation of rare earth chelates can be promoted, and the rare earth chelation rate and the yield rate can be effectively improved.

[0108] Application of rare earth chelate based on yeast hydrolysate

[0109] The rare earth chelate based on yeast hydrolysate provided in Example 2 of the present application was added to animal feed to verify its application in animal feed.

[0110] 120 laying hens at 1 - 2 weeks old were selected and randomly divided into 6 groups, with 20 hens in each group. A feeding comparison test was carried out using feeds added with different rare earth chelates based on yeast hydrolysate (as shown in Table 4, the addition amount of rare earth chelate based on yeast hydrolysate is the percentage of the weight of laying hen feed). After continuous feeding for 1 month, the growth of the test laying hens was recorded. The ileal contents of 10 laying hens in each group were taken back to the laboratory, and then the numbers of Escherichia coli and Salmonella were detected by the plate counting method. The results are shown in Table 5 below.

[0111] Table 4 Sources and addition amounts of rare earth chelates based on yeast hydrolysate in the application examples

[0112]

[0113]

[0114] Table 5 Statistical data of the growth of laying hens and the number of bacteria in the ileum

[0115]

[0116] As can be seen from Table 5, compared with Application Example 4, the average daily gain, laying rate, and hatching rate of laying hens in Application Examples 1-3 are all increased, and the incidence rate and harmful bacteria in the ileum are decreased. Therefore, the inventor found that the rare earth chelate based on yeast hydrolysate prepared in this application can improve the laying rate and hatching rate of laying hens, and at the same time can reduce the incidence rate of laying hens. And the addition amount of the rare earth chelate based on yeast hydrolysate prepared is 0.05-0.2% of the total weight of the feed, and the effect is the best.

[0117] Compared with Application Examples 1-3, the growth of laying hens in Application Examples 5-6 is poor, and the incidence rate is increased. It can be seen that adding cerium element and lanthanum element to the laying hen feed is beneficial to the growth of laying hens, and the absorption effect of laying hens on the rare earth chelate based on yeast hydrolysate is better than that on cerium element and lanthanum element.

[0118] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing rare earth chelates based on yeast hydrolysate, characterized in that: The preparation method specifically comprises the following steps: (1) Pretreatment of yeast hydrolysate: Add deionized water to the yeast hydrolysate to dissolve and disperse it into a suspension with a concentration of 20-35%; (2) Rare earth pretreatment: Mix the rare earth with a weak acid and react for 30-60 minutes to obtain pretreated rare earth; (3) Chelating reaction: subjecting the suspension to a chelating reaction with the pretreated rare earth to obtain a crude chelate; The amount of the pretreated rare earth added is 20-35% of the weight of the dry matter in the suspension; the conditions of the chelating reaction are: reacting for 125-150 minutes at a pH of 3-4 and a temperature of 85-90°C; (4) Purification treatment: filtering the crude chelate through a 80-100 nm ceramic membrane to obtain a concentrate and a filtrate; (5) Spray drying: spray drying the concentrated solution.

2. The preparation method according to claim 1, characterized in that: The content of small peptides in the range of 1000-4000Da in the yeast hydrolysate is greater than 60%.

3. The preparation method according to claim 1, characterized in that: In the rare earth pretreatment, the weight ratio of the rare earth to the weak acid is (5-7): (3-5).

4. The preparation method according to claim 1, characterized in that: The weak acid is any one of acetic acid and lactic acid.

5. The preparation method according to claim 1, characterized in that: The spray drying operation is as follows: the concentrated liquid is homogenized at a pressure of 30-70 MPa for 5-20 min, and then placed in a vacuum oven with an air inlet temperature of 200-220°C, an exhaust temperature of 75-80°C, and a pressure of 180-200 kg / cm 2 Spray drying was performed under the following conditions.

6. A rare earth chelate based on yeast hydrolysate prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the rare earth chelate based on yeast hydrolysate according to claim 6 in the field of animal feed.

8. The use according to claim 7, characterized in that: The rare earth chelate based on yeast hydrolysate is used for preparing poultry and livestock feed; Optionally, the yeast hydrolyzate-based rare earth chelate is added in an amount of 0.05-0.2% of the total weight of the feed.

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