42 results about "Salting out" patented technology

The invention discloses a high-strength microneedle with directional holes for biological analysis sampling and a preparation method of the high-strength microneedle, and belongs to the technical field of microneedles, the method comprises the following steps: filling a silk fibroin solution into a microneedle mold to form a microneedle preform, the microneedle preform comprising a needle body part and a backing part; performing directional freezing on the microneedle preform to enable ice crystals to directionally grow in the direction from the backing part to the needle body part, and demolding to obtain a frozen blank; the frozen blank is placed in an organic solution of a cross-linking agent, soaked at the low temperature lower than 0 DEG C for ice template low-temperature solvent exchange-cross-linking treatment, taken out and cleaned, then soaked in a salt solution for salting-out treatment strengthening, taken out and cleaned and freeze-dried, and the high-strength microneedle with the directional holes is obtained. The microneedle prepared through the method has high strength and excellent puncture performance, and the skin interstitial fluid collection speed and efficiency are greatly improved.

The invention discloses a preparation method and application of torreya grandis antioxidant emulsion, and relates to the field of food additives. The torreya grandis antioxidant emulsion is prepared by taking torreya grandis oil production waste as a raw material, performing selective degreasing, enzymolysis extraction, acid sedimentation and alkaline salting-out to obtain a torreya grandis antioxidant nutrient substance, and then performing self-assembly composite emulsification. According to the preparation method of the torreya grandis antioxidant emulsion, the used raw materials are purely natural and low in cost, beneficial substances with different polarities in torreya grandis are reserved to a great extent, and finally a natural food additive which is high in nutritional value, strong in antioxidant effect and relatively long in storage life is obtained.

The invention relates to the technical field of bioengineering, in particular to an SOD (superoxide dismutase) impurity removal and purification process which comprises the following steps: extracting SOD enzyme from fresh animal blood, separating high-purity red blood cells through gradient centrifugation, preparing a crude extract by combining hypotonic lysis and freeze thawing strengthening, then selectively precipitating hemoglobin and other heat-sensitive impurity proteins by adopting a gradient temperature rise thermal denaturation method, and purifying to obtain the SOD impurity removal and purification process. The method comprises the following steps: extracting SOD, removing pigments and lipid impurities by using a mixed adsorbent, further enriching SOD by using ammonium sulfate salting-out, and finally obtaining high-purity SOD powder through vacuum freeze drying by combining ion exchange chromatography and ultrafiltration concentration technologies. The method has the advantages of high efficiency, rapidness and low cost, impurities can be effectively removed through a combined process of hypotonic / freeze-thaw cracking, hemoglobin removal through thermal denaturation, ammonium sulfate salting-out, ion exchange chromatography and ultrafiltration concentration, the purity and the recovery rate of the SOD enzyme are remarkably improved, the whole purification process is carried out at 4 DEG C, and the method is suitable for industrial production. The influence of high temperature on the activity of the SOD enzyme is avoided.

The invention provides a preparation method of a terminal-peptide-free bovine type I collagen product. The preparation method comprises the following steps: obtaining a crushed bovine tissue raw material without impurities; the preparation method comprises the following steps: soaking a cattle tissue raw material in acid, and homogenizing to obtain cattle tissue homogenate; protease is added into the bovine tissue homogenate in batches for enzymolysis, the enzymolysis temperature is controlled to be 2-6 DEG C, after salting-out precipitation, pH value adjustment and redissolution are carried out on the bovine type I collagen extracting solution obtained in the middle batch, protease is added again for enzymolysis, salting-out precipitation, pH value adjustment and redissolution are carried out again, and the bovine type I collagen extracting solution is obtained. Repeating for multiple times to obtain a terminal-peptide-free bovine type I collagen solution; adjusting the pH value of the terminal-peptide-free bovine type I collagen solution, salting out, precipitating, centrifuging and washing to obtain terminal-peptide-free bovine type I collagen precipitate; and purifying the terminal-peptide-free bovine type I collagen precipitate to obtain the terminal-peptide-free bovine type I collagen product. According to the telopeptide-free bovine type I collagen product provided by the invention, no residual telopeptide is detected, and the purity is high.

The invention relates to low-fat collagen as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out acidolysis and enzymolysis on a pre-treated product; preheating, centrifuging and salting out the enzymolysis product; after salting out, carrying out secondary centrifugation, taking precipitate, re-dissolving the precipitate in an acetic acid solution, carrying out first pasteurization, and filtering; and carrying out ultrafiltration concentration on the filtered product, and carrying out secondary pasteurization on the concentrated solution to obtain the recombinant collagen. The collagen obtained by the extraction process disclosed by the invention is lower in grease content and lower in bacterial endotoxin content, and the purity, the safety, the thermal stability, the structural integrity, the applicability and the like of the collagen are guaranteed.

The present application relates to the technical field of protein separation and purification, and specifically discloses a method for extracting bovine colostrum immunoglobulin. The method comprises the following steps: centrifugal degreasing: degreasing the bovine colostrum by centrifugation, followed by filtering the intermediate layer to obtain colostrum whey; ammonium sulfate salting out: diluting the colostrum whey, then adding a saturated ammonium sulfate solution, stirring, standing, centrifuging, removing the supernatant A, adding phosphate buffer to the precipitate A, stirring evenly, adding a saturated ammonium sulfate solution, standing, centrifuging, removing the precipitate B, adding a saturated ammonium sulfate solution to the supernatant B, centrifuging, removing the supernatant C, and obtaining the precipitate C; and purification: desalting the precipitate C using a gel column, concentrating it by ultrafiltration, and separating it by column chromatography to obtain the bovine colostrum immunoglobulin.

The invention discloses a salt-tolerant clean fracturing fluid and a preparation method thereof, and the salt-tolerant clean fracturing fluid comprises the following components: an anionic-nonionic surfactant NPEC and a cationic surfactant CTAB, the preparation method comprises the following steps: step a, uniformly mixing an anionic-nonionic surfactant NPEC and a cationic surfactant CTAB according to a ratio; step b, adding water, stirring until the materials are completely dissolved, adjusting the pH value, and performing cooling and aging treatment; and c, adjusting the viscosity and rheological property of the fracturing fluid according to actual requirements by adding NaCl with different concentrations. The fracturing fluid prepared by the invention can effectively cope with the influence of hypersalinity formation water in shallow oil and gas reservoirs; the stability of the fracturing fluid is improved, and performance reduction caused by salting-out is reduced; the method has high salt tolerance, is suitable for development of shallow oil and gas reservoirs, does not need high-temperature crosslinking, and has good economical efficiency and practicability.

The invention relates to a method for purifying erythromycin thiocyanate, which comprises the following steps of: firstly, carrying out decoloration and impurity removal pretreatment on alkalized erythromycin fermentation liquor through combination of activated carbon adsorption and diatomite packed column filtration, then combining an acetone extract salifying primary crystallization method and a crystallization mother liquor salting-out secondary crystallization method, and finally drying to obtain the erythromycin thiocyanate. According to the method, the extraction process of erythromycin thiocyanate is optimized, the yield is increased while the purity of the erythromycin thiocyanate product is effectively improved, the content of erythromycin thiocyanate A reaches 90% or above, and the yield reaches 88% or above.

The present application provides a method for refining cefotaxime sodium, belonging to the technical field of pharmaceutical preparations. The crude cefotaxime hydrochloride is dissolved in a mixed solvent, the pH is adjusted to 2-4, a desalting agent is added for salting out, followed by decolorization, filtration, and the filtrate is retained. The mixed solvent is acetone + alcohol, acetone + alkane, or acetone + alcohol + alkane. The salifying agent is dissolved in the mixed solvent, and the resulting solution is dropped into the filtrate for salting, crystallization, filtration, washing, draining, and vacuum drying to obtain the finished product cefotaxime sodium. Applying the present application to the preparation of cefotaxime sodium not only reduces the impurity content of the product but also helps to reduce the acetone residue, with good product color and high yield.

This invention discloses a method for salting out salmon PDRN. The method includes: adding a soluble salt and an organic solvent to a salmon ooze enzymatic hydrolysate, mixing thoroughly, allowing the mixture to stand and separate into three phases, forming a three-phase salting-out extraction system consisting of an upper phase, an intermediate phase, and a lower phase; collecting the intermediate phase when the organic solvent is hydrophilic, and collecting the lower phase when the organic solvent is hydrophobic; purifying and drying the collected intermediate or lower phase to obtain PDRN powder. This invention uses salmon ooze enzymatic hydrolysate as raw material and extracts salmon PDRN product in one step through salting-out extraction. The PDRN product yield is greater than 5.0%, A260 / A280 is 1.8–2.0, A260 / A230 is ≥2.0, endotoxin content is <0.03 EU / mg, protein content is ≤0.5%, and molecular weight is 200–4000 bp. The method of this invention has the advantages of simple process, low cost, high yield, and high product purity, making it suitable for large-scale industrial production.

The invention relates to the field of bioengineering, in particular to a perch collagen peptide as well as a preparation method and application thereof. The invention provides a preparation method of perch collagen, which comprises the following steps: carrying out acid extraction on pretreated perch scales, hydrolyzing with a first enzyme, filtering, salting out filtrate, centrifuging, collecting precipitate, redissolving, purifying, hydrolyzing with a second enzyme, and heating to obtain the perch collagen, enzymes adopted by the first enzyme hydrolysis and the second enzyme hydrolysis can be the same or different; the enzyme comprises one or more of alkaline protease, papain, subtilisin and pepsin. The collagen peptide extracted from sea bass scales and processed into the sea bass scales is systematically researched and developed, and the collagen peptide has an excellent anti-photoaging effect and high replicability. The collagen peptide is low in molecular weight, high in oxidation resistance and wide in application range, and can be applied to the fields of cosmetics, oral collagen supplements and the like.

The invention relates to the field of collagen preparation, in particular to a preparation method for improving the biological safety of collagen, a product and application. The preparation method comprises the following steps: pretreating raw materials; performing enzymolysis on the pre-treated product, and performing salting-out on the enzymolysis product; after redissolving the precipitate separated out by salting out, filtering by using a diatomite filter; and carrying out ultrafiltration and concentration on the filtered product to obtain the collagen. On the basis of ensuring the purity, the collagen obtained by the extraction process disclosed by the invention is higher in biological safety, sterile, lower in pathogen content and lower in bacterial endotoxin content, and can be ensured to be applied to the medical field.

The invention discloses a natto active substance, natto-flavored konjac jelly and a preparation method thereof, and relates to the technical field of food processing. The preparation method of the natto active substance comprises the following steps: mixing mature natto and normal saline according to a volume ratio of (1-1.1): (2-2.2), extracting for 24-26 hours, centrifugally filtering the obtained extract liquid, and reserving supernate to obtain a crude extract liquid; and mixing the crude extract and an ammonium sulfate solution with the saturation degree of 30% according to the volume ratio of (28-32): (12-15), carrying out primary salting-out, then carrying out primary centrifugal filtration, adding an ammonium sulfate saturated solution into the supernatant obtained by the primary salting-out until the saturation degree is 70-72%, carrying out secondary salting-out, then carrying out secondary centrifugal filtration, and taking the precipitate, thereby obtaining the natto active substance. The preparation method is simple, the natto active substance is extracted from the mature natto through extraction and secondary salting-out, the extraction rate is high, the purity is high, the obtained natto active substance is applied to the jelly, the flavor of the jelly can be increased, and the digestibility of the jelly can be improved.

The invention provides a preparation method of a medical high-transparency collagen solution, which comprises the following steps: S1, taking fresh animal tissues, removing tissues such as hair, fascia, fat and blood meat, slicing, cleaning to remove blood water, washing with water, and freezing and crushing; s2, soaking the crushed materials in a mixed degreasing agent for degreasing; the mixed degreasing agent comprises a cationic surface active agent and lipase, and the cationic surface active agent comprises at least one of a bio-based surface active agent and a quaternary ammonium salt type surface active agent; the bio-based surfactant comprises at least one of rhamnolipid, sophorolipid and trehalose lipid; s3, freezing the degreased material, irradiating, soaking in purified water, filtering, and collecting a swelled material; s4, carrying out enzymolysis on the swelled substance; s5, collecting filtrate after enzymolysis, filtering after salting out, collecting filter residues, and cleaning in a salt solution to obtain a salting-out substance; s6, the salting-out substance is added into pure water to be dissolved, the mass fraction of collagen is controlled to range from 0.01% to 6.5%, then ultrafiltration is conducted, filtrate is collected, low-temperature storage is conducted, and a collagen solution is obtained. The collagen prepared by the preparation method has relatively high transparency, and meanwhile, the structure of the collagen is not damaged in the preparation process, that is, the finally obtained collagen solution still has a complete triple helix structure. And heavy metals or toxic and harmful reagents are not added in the whole extraction process, so that the problem of residues of the heavy metals or the toxic and harmful reagents does not exist, and the application range is widened.

The present invention relates to a highly efficient method for purifying flue gas desulfurization amine liquid, comprising: adding a composite purifier to the regenerated lean agent to be purified, while simultaneously and continuously introducing nitrogen for stripping; after the composite purifier is added, continuing to introduce nitrogen for stripping for at least 3 minutes; after the stripping is completed, cooling the resulting mixed solution to 20-45°C, allowing it to stand for stratification and separation, resulting in a free amine liquid in the upper layer and a brine solution containing sulfate and degradation products in the lower layer. The purification method of the present invention utilizes stripping coupled with salting out to simultaneously and efficiently remove organic amine degradation products and sulfate, achieving a high single-stage purification removal rate. The device is also simple to operate, has low energy consumption, minimizes amine loss, and reduces the discharge of amine-containing wastewater, meeting the new requirements for clean production to achieve the dual carbon goals.

The invention discloses collagen sponge and a preparation method and application thereof. The preparation method comprises the steps of pretreatment, acidolysis, enzymolysis, salting-out, filtration, ultrafiltration and concentration, crosslinking, freeze-drying treatment and the like. The preparation process of the collagen sponge provided by the invention is simple to operate, the water absorption capacity of the prepared collagen sponge product can reach 40-60 times of the self weight, the hemostatic effect is good, the mechanical property is good, the requirements of industrial standards are met, and the application range is wide.

The present application discloses a recombinant sea cucumber peptide with soothing effect, a preparation method thereof and an application thereof, wherein the amino acid sequence with repairing effect is shown in SEQ ID NO. 1. The present application also provides a preparation method of a recombinant sea cucumber peptide, which mainly comprises: gene synthesis; constructing a vector plasmid: integrating the target gene sequence into the vector plasmid, and introducing the plasmid into a competent genetic engineering strain; fermenting and expressing the target product; obtaining a high-purity sea cucumber peptide by purification means (solid-liquid separation, salting out, isoelectric precipitation, chromatography technology, ultrafiltration), and the sea cucumber peptide has excellent water solubility and high purity, and can be widely used in cosmetics.

The invention discloses a holboellia latifolia seed protein extraction method in the technical field of protein extraction, and particularly comprises the following steps: crushing holboellia latifolia seeds, degreasing with n-hexane or petroleum ether, and drying; then, mixing the melon seed powder with a sodium hydroxide solution, and carrying out microwave treatment for 15-20 minutes; after cooling, carrying out pulsed electric field-assisted ultrasonic-assisted enzymolysis, and adding neutral protease; after the enzymolysis is finished, cooling and adding ammonium sulfate powder for salting out; centrifuging the salting-out mixed solution, collecting supernate, passing through an affinity chromatography column, flushing with a phosphate buffer solution with the pH value of 7.0, and eluting protein with an eluent containing sodium chloride with the concentration of 1-1.2 mol / L; and adjusting the pH value of the eluent to 10.5-11.5, centrifuging after extraction, adjusting the pH value of the supernatant to 5, centrifuging and collecting the precipitate. And dissolving the precipitate with a phosphate buffer solution, dialyzing and drying to obtain the holboellia latifolia seed protein. According to the extraction method, the extraction rate and the purity of the holboellia latifolia seed protein can be remarkably improved.

This invention discloses a DAMP4-DiPGLa-H fusion protein DD1, its preparation method, and its applications. DAMP4 and DiPGLa-H are fused using the TEV protease recognition sequence ENLYFQG and the flexible-to-rigid linker sequence GPGS. The corresponding fusion protein DD1 is then expressed intracellularly via a recombinant expression vector. Cells are lysed by heating under high salt conditions, and purified by centrifugation and salting out after cooling. The purified fusion protein DD1 is cleaved using TEV protease, and purified by isoelectric precipitation to obtain the target recombinant protein G-DiPGLa-H. The antibacterial activity of G-DiPGLa-H is then verified.

The present invention relates to the technical field of medical dressing materials, and more specifically to jellyfish collagen sponges and methods for producing the same. Step S1: Adjust the concentration of a jellyfish collagen raw material with a molecular weight of 80 kDa or more with pure water to obtain a collagen solution with a mass concentration of 0.2 to 0.5%. Step S2: Add ethanol to the jellyfish collagen solution, stir, and let stand. Step S3: Obtain a precipitate by centrifugation or obtain a filter cake by suction filtration. Step S4: Freeze-dry under vacuum to obtain a collagen sponge. 60 The present invention includes step S5, which involves radiation sterilization, packaging, and storage. The collagen sponge produced by this invention has a dense structure, the collagen does not denature, it has strong liquid absorption capacity, and it is resistant to deformation and collapse even when exposed to water. The manufacturing method of this invention avoids technical problems such as the inclusion of impurities due to salting out, low pH precipitation efficiency, or low mechanical strength of the collagen sponge.

This invention provides a method for preparing androstane-3,6,17-trione (E,Z)-3-[O-(2-aminoethyl)]oxime hydrochloride, comprising the following steps: benzophenone oxime reacts with 2-chloroethylamine hydrochloride in dimethyl sulfoxide, followed by acid-base adjustment, toluene extraction, hydrolysis with concentrated hydrochloric acid to remove the protecting group, and crystallization to obtain high-purity 2-aminoethylamine hydrochloride; androstane-3,6,17-triol is used as a raw material and oxidized under the catalysis of sodium bromate and ruthenium oxide (IV), quenched, separated, washed with water, and crystallized by solvent replacement with isopropanol to obtain androstane-3,6,17-trione; the 2-aminoethylamine hydrochloride solution is mixed and reacted with the trione in tetrahydrofuran solution at low temperature, followed by salting out, filtration, separation, washing with saturated brine and drying with magnesium sulfate, and purification by solvent replacement, water dissolution and concentration, and cooling crystallization to obtain the high-purity target product. This invention significantly improves the yield of the target product by optimizing reaction conditions, while achieving readily available raw materials, low cost, and industrialized production through traditional chemical reaction pathways.

The invention discloses a preparation method for extracting biologically active small molecule proteins from soybean water. The method comprises the following steps: firstly clarifying, microwave irradiating and concentrating the soybean water in sequence to obtain concentrated soybean water; then freezing the concentrated soybean water, thawing it with microwaves, and subjecting it to ultrasonic oscillation treatment. Under the action of a pulsed magnetic field, the concentrated soybean water is subjected to salting out by ammonium sulfate, and solids are filtered to obtain a salting out product; finally, the salting out product is ultrasonically dispersed in distilled water, subjected to high-pressure spraying treatment, a composite enzyme is added, enzymolysis is performed, enzyme inactivation is performed, and vacuum freeze drying is performed to obtain the product. The invention extracts biologically active small molecule proteins from soybean water, realizes the recycling of waste soybean water, is green and environmentally friendly, and has broad application prospects.

The invention provides a method for separating and purifying fusidic acid through salting-out crystallization. The method comprises the following steps: (1) filtering fermentation liquor: filtering the fermentation liquor; (2) salting-out crystallization: adding salt for crystallization into the filtrate, then adjusting the pH value, and then salting out; (3) dissolving and extracting: adding an extracting solvent into the salting-out substance, adding drinking water for extracting, standing for layering, and collecting an extracted lipid phase; (4) crystallization: concentrating the extracted lipid phase, cooling, stirring and crystallizing, and filtering; (5) recrystallization: adding an extraction solvent into the fusidic acid crude product, concentrating, and cooling for crystallization; and (6) drying: drying to obtain a fusidic acid finished product. The production process is simple, the production cost is low, and industrial production is easier to realize. And the salting-out crystallization step and the recrystallization step use the same extraction solvent, and one solvent is singly used, so that the doping of multiple solvents is reduced, the loss of the solvents is reduced, the recovery is convenient, the recovery rate is high, and the production cost is low.

The present application discloses a recombinant sea cucumber peptide with anti-aging effect, a preparation method and application thereof. The amino acid sequence with anti-aging effect is SEQ ID NO.1. The present application provides a preparation method of the recombinant sea cucumber peptide, which mainly includes: gene synthesis; construction of a vector plasmid: integrating the target gene sequence into the vector plasmid, and introducing the plasmid into a competent genetically engineered bacterial strain; fermentation expression of the target product; obtaining high-purity sea cucumber peptide by purification means (solid-liquid separation, salting out, isoelectric precipitation, chromatography technology, ultrafiltration). This sea cucumber peptide has excellent water solubility and high purity and can be widely used in cosmetics. The present application also provides a preparation method for an anti-aging, lifting and repairing base liquid. This product is gentle and non-irritating to use and has excellent anti-aging effect.

The invention relates to the technical field of antibiotic detection, and particularly discloses a sample treatment method for detecting macrolide antibiotics in a plant source matrix sample. The sample treatment method provided by the invention comprises the following steps: uniformly mixing a plant source matrix sample with a buffer solution, adding acidified acetonitrile, salting out and absorbing water by using a mixed inorganic salt, and purifying by using an adsorbent comprising anhydrous magnesium sulfate, an aliphatic diamine derivative and O-terminated octadecyl bonded silica gel to obtain the treated plant source matrix sample. Through the systematic design of extraction-separation-purification, the chemical properties of the target object and the characteristics of the plant matrix are combined, and the synergistic effect of the buffer solution, acidified acetonitrile, salting-out and multiple adsorbents is utilized, so that matrix interference can be effectively removed, the target object is stable, and efficient extraction of macrolide antibiotics is realized. The method is suitable for detecting the macrolide antibiotics such as lincomycin, tilmicosin and erythromycin in the plant source matrix.

The invention relates to the technical field of bioengineering, in particular to a preparation method of stable natural creatine kinase. Comprising the following steps: removing fascia fat from a pig heart, adding a DK1 buffer solution, and crushing by a meat grinder to obtain an enzyme extracting solution A; adding ammonium sulfate into the crude enzyme extract A for multiple times, adjusting the pH value by using DK2, centrifuging, and taking supernatant to obtain an enzyme extract B; adding solid ammonium sulfate into the enzyme extracting solution B to carry out salting-out precipitation, centrifuging to take precipitate, and dialyzing with DK2 to obtain an enzyme extracting solution C; purifying through an ion exchange column, and sequentially eluting through a DK3 buffer solution to obtain a creatine kinase solution; carrying out concentration dialysis liquid change treatment on creatine kinase by using DK4 to obtain an enzyme extracting solution D; adding a liquid protective agent into the enzyme extracting solution, and carrying out stabilizer research; through the mode, high-activity and high-stability creatine kinase can be obtained, the process repeatability is high, the cost is low, and large-scale production of the process is facilitated.

This invention relates to the field of biomaterials technology, and more particularly to a protein-based tubular hydrogel, its preparation method, and its applications. The hydrogel is prepared from the following raw materials: a skin layer solution and a core layer solution; the skin layer solution comprises a 5-20 wt% aqueous protein solution; and the core layer solution comprises a 20-30 wt% aqueous hydrophilic salt solution. The hydrogel preparation steps include: mixing the skin layer solution and the core layer solution in a receiving bath via coaxial extrusion, followed by solidification to form the hydrogel. This method uses a high-concentration salt solution to induce protein salting out, constructing a tubular hydrogel structure. The addition of polysaccharides or shaping agents enhances the gel's plasticity and stability, preventing deformation and collapse. The resulting tubular material exhibits excellent biocompatibility and mechanical properties, making it suitable for biomedical scaffolds and other applications. Furthermore, the preparation process is simple and inexpensive, indicating broad prospects for industrialization.

The invention relates to the technical field of functional food processing, and discloses a formula and a preparation technology of medicinal and edible walnut milk with the efficacy of improving immunity, and the formula comprises walnut protein isolate, walnut oil, a functional component base material, a composite emulsion stabilizer and water. The method comprises the following steps: carrying out directional enzyme digestion on walnut protein by adopting a targeting compound incision enzyme preparation to generate a peptide fragment; by regulating and controlling the redox potential of the system, the enzymolysis peptide fragment and functional factors in the functional component base material are promoted to form a covalent conjugate; by utilizing the amphipathy newly generated by the conjugate, phase inversion enrichment and purification are carried out by adjusting the pH value to an isoelectric point and combining salting-out, so that substances with bad flavor are efficiently separated; and compounding, homogenizing and sterilizing to obtain a final product. By constructing the walnut peptide-TCM functional factor conjugate, the in-vitro digestion stability of the functional factor is effectively improved; meanwhile, the sensory flavor of the product is remarkably improved through the phase transformation purification step, and the obtained product is high in physical stability and pure in flavor.

This invention relates to the field of oil and gas drilling engineering technology, specifically to a solids-free kill fluid and its preparation method, comprising the following raw materials by weight: 80-100 parts base fluid, 25-35 parts composite additives, 8-12 parts soluble thickener, 6-10 parts liquid phase anti-collapse agent, and 3-5 parts lubricant. In this invention, a high-density system is constructed through additive A of the composite additives, breaking through the specific gravity limit of traditional salt-based weighting agents. Combined with the solubilizing and stabilizing effect of triethanolamine, high-concentration components are prevented from salting out, effectively solving the problem of limited specific gravity increase in traditional solids-free kill fluids. Simultaneously, additive B constructs a liquid-phase cross-linked colloidal network, increasing the system viscosity and forming a liquid plug, effectively blocking the exchange and dilution between the kill fluid and residual wastewater in the wellbore, preventing performance degradation of the kill fluid due to dilution, and reducing material waste caused by replenishing the kill fluid.

This invention belongs to the field of biotechnology. Specifically, it discloses a method for preparing recombinant protein using rice seeds. The method involves dehulling rice seeds to obtain rice flour, which is then enzymatically hydrolyzed using cellulase and neutral protease in a buffer solution. This process efficiently hydrolyzes the cellulose in the rice cell wall and some impurities. The buffer solution reduces protein salting out and increases the dissolution rate of recombinant human lactoferrin. Activated carbon is used to initially adsorb and remove impurities such as natural pigments and phenolic substances from the rice seeds. The mixture is then subjected to chromatography using CM Sepharose FF, SP Sepharose XL, and CM Sepharose FF columns, effectively improving the purity and recovery rate of the recombinant human lactoferrin. Simultaneously, the enzymatic hydrolysis and fractionation chromatography effectively reduce the iron saturation in the recombinant human lactoferrin.