159 results about "Molecular weight cut-off" patented technology

The invention provides a layer-by-layer self-assembled nanofiltration membrane and a preparation method and application thereof.The layer-by-layer self-assembled nanofiltration membrane comprises a base membrane and a self-assembled coating formed on the base membrane, and the self-assembled coating at least comprises an initial alternating coating and a separation alternating coating; the molecular weight cutoff of the base membrane is not less than 500kDa; the initial alternate coating is formed by alternately assembling a large-molecular-weight cationic polyelectrolyte layer and an anionic polyelectrolyte layer, and the separation alternate coating is formed by alternately assembling a small-molecular-weight cationic polyelectrolyte layer and an anionic polyelectrolyte layer; the initial alternating coating is formed on the base membrane, and a high-molecular-weight cationic polyelectrolyte layer in the initial alternating coating adopts cationic polyelectrolyte with the number-average molecular weight not less than 500kDa; and the small-molecular-weight cationic polyelectrolyte layer in the separation alternate coating is cationic polyelectrolyte with the number-average molecular weight not exceeding 100kDa. The layer-by-layer self-assembled nanofiltration membrane provided by the invention has more excellent permeability and micropollutant rejection rate.

The invention discloses a high-salt-rejection and pollution-resistant polyamide reverse osmosis membrane, which is characterized in that an aromatic cationic surfactant containing two benzene ring structures is adopted to regulate and control the interfacial polymerization reaction of a polyamine monomer and a polyacyl chloride monomer, and a high-salt-rejection and pollution-resistant polyamide functional layer is generated on a porous ultrafiltration base membrane. The effective specific surface area of the polyamide functional layer of the reverse osmosis membrane is gt; 1.2, the surface potential gt when the pH is equal to 7; -20 mV; the molecular weight cut-off of the polyamide reverse osmosis membrane is 1t; the molecular weight is 100Da, and the retention rate for 2000ppm of NaCl is gt; the anti-fouling coating has the advantages of good hydrophilicity and excellent anti-fouling performance. The preparation process of the polyamide reverse osmosis membrane is simple and efficient, and has industrial application potential. The polyamide reverse osmosis membrane can be used for purification and treatment of different types of water, and has important application value.

The invention discloses a preparation method and device of a low molecular weight cutoff ultrafiltration membrane, and belongs to the technical field of ultrafiltration membrane preparation. A thermally induced phase separation method and a non-solvent induced phase separation method are combined to prepare the membrane, the relationship between the flux and the retention rate of the ultrafiltration membrane is balanced, high flux is considered while high retention of low-molecular-weight substances is provided, an upper-layer membrane casting solution and a lower-layer membrane casting solution are used for double-layer simultaneous coating, a substrate is coated with the membrane casting solutions, and the membrane is obtained through a dry process section. Phase separation is carried out after entering a coagulating bath, a finished membrane is obtained through cleaning, the obtained membrane is of an integrated structure, the coagulating bath used in the membrane casting process is pure water, and recycling and aftertreatment of the ultrafiltration membrane are facilitated.

The invention discloses a surface-enhanced tryptophan modified nanofiltration membrane as well as a preparation method and application thereof. Belongs to the field of water treatment membrane preparation. The invention aims to solve the technical problems of non-uniform pore size distribution and surface hydrophobicity of the conventional nanofiltration membrane. The method comprises the following steps: adding tryptophan into a piperazine water-phase solution, and carrying out interfacial polymerization with oil-phase trimesoyl chloride to prepare the tryptophan modified nanofiltration membrane. According to the preparation method, the diffusion rate of the piperazine monomer can be adjusted in the interfacial polymerization process by utilizing a similar surfactant structure of tryptophan, meanwhile, the tryptophan has hydrophilicity and can improve the hydrophilicity of the surface of an active layer, and the prepared modified nanofiltration membrane is reduced in molecular weight cut-off, improved in surface hydrophilicity and good in water resistance. The retention rate of organic micro-pollutants is improved, and meanwhile, good anti-pollution performance is achieved.

The invention discloses camel milk polypeptide with xanthine oxidase inhibitory activity and application thereof.The camel milk polypeptide is prepared by taking fresh camel milk as a raw material, conducting low-temperature centrifugation to remove fat, conducting triple enzymolysis through papain, pepsin and trypsin to obtain enzymatic hydrolysate, enabling the enzymatic hydrolysate to pass through an ultrafiltration membrane (the molecular weight cutoff is 10 kDa) to obtain filtrate, and conducting freeze-drying to obtain the camel milk polypeptide. The compound has xanthine oxidase inhibitory activity. The invention also discloses a small molecule polypeptide with xanthine oxidase inhibitory activity. The filtered solution is screened and combined with polypeptides by adopting a xanthine oxidase affinity ultrafiltration method, the activity of the polypeptides is verified through molecular docking and in-vitro enzyme inhibition, four small-molecule polypeptides with xanthine oxidase inhibitory activity are obtained, the sequence of the small-molecule polypeptides is shown as any one of SEQ ID NO.1-4, and the small-molecule polypeptides can be used for preparing drugs with the effect of inhibiting the uric acid level.

The invention discloses an implant-derived exosome which is prepared by the following steps: adding cleaned and crushed colored rice flour into a PBS (Phosphate Buffer Solution) with the pH value of 6-7.4, homogenizing at a high speed, adding alpha-amylase into rice milk, performing enzymolysis for 1-2 hours under the conditions that the pH value is 6-7.4 and the temperature is 90-97 DEG C, filtering, and standing filtrate overnight; carrying out gradient differential centrifugation at 4 DEG C, collecting supernate, filtering, carrying out ultracentrifugation on filtrate at 4 DEG C and 12000-15000g for 1.5-3 hours, and collecting precipitate; and re-suspending the precipitate, enriching by using an MWCO ultrafiltration tube with the molecular weight cut-off of 100kDa, collecting the precipitate at the bottom of the ultrafiltration tube, and re-suspending in a PBS buffer solution, thereby obtaining the product. The exosome can effectively inhibit the generation of inflammatory factors, has a good inhibition effect on various pathogenic bacteria, also has an anti-oxidation effect, and has application prospects in the fields of inflammation resistance, bacteria resistance, oxidation resistance and the like.

The invention relates to protein peptide and polysaccharide efficient separation equipment for sea cucumber peptide processing and a use method of the protein peptide and polysaccharide efficient separation equipment, and particularly relates to the technical field of bioengineering. The sea cucumbers are subjected to two-time enzymolysis by adopting two-time enzyme adding and two-time different hydrolase adding in cooperation with different enzymolysis conditions, a first ultrafiltration membrane with the molecular weight cut-off of 10 KDa is selected for first-time ultrafiltration separation, permeate liquid is protein peptide mixed liquid, cut-off liquid is polysaccharide mixed liquid, and the protein peptide mixed liquid and the polysaccharide mixed liquid are mixed. The protein peptide mixed solution and the polysaccharide mixed solution correspondingly enter corresponding ultrafiltration assemblies to be subjected to multi-stage ultrafiltration, protein peptide and polysaccharide are further separated and purified respectively, and finally the protein peptide mixed solution and the polysaccharide mixed solution enter corresponding spray drying towers to be subjected to spray drying to obtain corresponding protein peptide powder and polysaccharide powder; separation, purification and drying of protein peptide and polysaccharide can be achieved at the same time, and waste of resources is reduced.

The invention belongs to the technical field of nanofiltration membrane separation, and particularly relates to an organic solvent composite nanofiltration membrane as well as a preparation method and application thereof. A cross-linked polyimide ultrafiltration membrane is used as a base membrane, and a polyesteramide separation layer is obtained by polycondensation of a polyacyl chloride monomer and a polyamine monomer on the cross-linked polyimide base membrane. The preparation method comprises the following steps: soaking a naturally aired polyimide ultrafiltration base membrane in a water phase solution containing polyamine, airing, soaking in an organic phase solution containing polyacyl chloride, carrying out interfacial polymerization reaction, and carrying out thermal crosslinking post-treatment on the prepared membrane to obtain the thin-film composite nanofiltration membrane. And hydrophobic trifluoromethyl and hydrophilic phenolic hydroxyl are introduced by utilizing a functional group effect to prepare the thin-film composite nanofiltration membrane with a Janus pore channel structure. The membrane composite nanofiltration membrane can simultaneously improve the permeation flux of polar and non-polar solvents, obviously improves the flux of the non-polar solvent, can maintain low molecular weight cut-off, and has high economic value for separation of an organic solvent system in industry.

The invention discloses application of walnut peptide in preparation of a medicine for treating or preventing cognitive impairment of diabetes mellitus. The preparation process of the walnut peptide is as follows: after walnut protein is subjected to enzymolysis by alkaline protease, the molecular weight cut-off is 1t; and separating by using a 3kDa ultrafiltration tube to obtain the walnut peptide. The walnut peptide can effectively reduce the blood sugar level of a diabetic model mouse, regulate the disorder effect of blood fat, relieve brain tissue oxidative damage and hippocampal neuroinflammation damage of the diabetic model mouse, and improve learning and memory damage. The compound can be used for preparing medicines for treating or preventing cognitive impairment of diabetes mellitus.

The invention provides a preparation method of yak bone collagen peptide, a composition for promoting skeletal development and application of the composition, and relates to the technical field of health food. The preparation method comprises the following steps: carrying out ultrasonic pretreatment on yak bones, and degreasing through supercritical CO2 to obtain a degreased product; mixing the degreased product with a fishy smell removing agent to obtain a fishy smell removing product; the fishy smell removing agent is an aqueous solution of a plant extract; the plant extract is selected from at least one of amomum tsao-ko extract, turmeric extract, green tea extract or momordica grosvenori extract; the fishy smell removal product is subjected to an enzymatic hydrolysis reaction through an immobilized compound enzyme reactor, wherein the compound enzyme is prolyl endopeptidase, papain and ficin; obtaining a crude product; carrying out ultrafiltration by adopting a filter membrane with the molecular weight cut-off of 1kDa, and adsorbing through macroporous resin. The yak bone collagen peptide and the composition prepared by the invention can obviously improve the body length, promote the skeletal development and promote the secretion of growth hormone, and meet the growth requirements of children.

The invention relates to an efficient enrichment method for low-concentration bacteriophages in river and lake water bodies, which remarkably improves the recovery rate and the concentration multiple of the bacteriophages through a multi-stage synergistic technology in combination with physical interception, chemical precipitation and biological targeted adsorption. The method specifically comprises the following steps: pretreatment: removing large particles and suspended solids through gradient filtration and low-speed centrifugation; ultrafiltration concentration: adopting a hollow fiber ultrafiltration membrane with the molecular weight cut-off of 30-100 kDa, and realizing 10-50 times concentration under the pressure of 0.1-0.3 MPa; chemical precipitation strengthening: optimizing synergistic precipitation conditions of PEG and NaCl, and reducing phage inactivation in combination with low-temperature standing; specific adsorption of host bacteria: combining the host bacteria in the logarithmic phase with bacteriophage according to the volume ratio of 1: 100, and carrying out pH regulation and control elution to obtain a high-purity enriched solution. The method has the advantages that the total concentration multiple reaches 500-1000 times, and the recovery rate is gt; the activity retention rate is gt; and the method is suitable for a complex water body environment. Through a multi-technology combination strategy and targeted adsorption design, an efficient tool is provided for environmental monitoring, phage therapy and microbiological research.

The application discloses a fusion protein NGF2 with improved in-vivo half-life and application thereof, and belongs to the technical field of medical biological engineering, and comprises ABD and FGF2, and the gene and protein sequence thereof are respectively composed of the sequences shown in SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:6 and SEQ ID NO:7, and the complete gene and protein sequence thereof is shown in SEQ ID NO:4 and SEQ ID NO:8. The fusion protein NGF2 can keep activity for more than 7 days in an environment of 37 DEG C, and the half-life of the fusion protein in solution is prolonged. In addition, the ABD is combined with HAS to form a complex, and the total molecular weight reaches 90kDa, which is higher than the cut-off molecular weight of glomerular filtration, so that the in-vivo half-life of the fusion protein is effectively prolonged.

The invention relates to the technical field of composite films, in particular to a polyester composite film and a preparation method and application thereof. The polyester composite membrane comprises a support membrane and a polyester separation layer, wherein the polyester separation layer comprises a polybasic hydroxyl monomer and a polybasic acyl chloride monomer. The polyester composite membrane provided by the invention can accurately regulate and control the effective cut-off molecular weight, can overcome the technical limitation that the existing polyester membrane is difficult to effectively separate small molecules especially in the aspect of separation of small molecular substances, and improves the separation effect.

The invention discloses a chickpea sprout peptide. The amino acid sequence of the chickpea sprout peptide is as follows: Glu-Glu-Cys-Pro-Cys-Ala-Asn-Cys-Cys, wherein the amino acid sequence of the chickpea sprout peptide is as follows: Glu-Glu-Cys-Pro-Cys-Ala-Asn-Cys-Cys; the preparation method of the chickpea sprouting peptide comprises the following steps: step 1, sprouting chickpeas until the sprouting length is 0.5-1.5 cm, wherein the sprouting time is 12-72 hours; step 2, mixing and pulping germinated chickpeas and water according to a weight ratio of 1: 1-1: 1.2, and adjusting the pH value of the pulp to 6.5-8.0; step 3, adding neutral protease and compound flavor protease, and performing enzymolysis at the enzymolysis temperature of 50-55 DEG C for 2-3 hours; step 4, treating the enzymatic hydrolysate through an ultrafiltration membrane with the molecular weight cut-off of 5000Da under the conditions that the working pressure is 0.15-0.25 MPa and the working temperature is 20-45 DEG C, and collecting filtrate; and step 5, carrying out corrosion prevention and drying on the filtrate to obtain the chickpea sprout peptide. The chickpea sprout peptide has the effects of resisting obesity, resisting oxidation and adjusting immunity, in addition, the preparation method can achieve efficient and high-quality preparation of the chickpea sprout peptide, the chickpea sprout peptide is accurately screened, and the ineffective experiment cost is reduced.

The invention discloses a desalting nanofiltration membrane as well as a preparation method and application thereof. The preparation method of the desalting nanofiltration membrane comprises the step of compounding a polyaminopiperazine selective separation layer on the surface of a base membrane to obtain the desalting nanofiltration membrane. The molecular weight cut-off of the desalting nanofiltration membrane provided by the invention can be as low as 150Da, the cut-off rate of the desalting nanofiltration membrane to small molecular organic matters such as xylose and glucose is greater than 90%, and the cut-off rate of sodium chloride is less than 30%, namely, the desalting nanofiltration membrane shows relatively high small molecular organic matter-salt selectivity.

The invention discloses a preparation method of a crocodile polypeptide extract and a beverage, and relates to the technical field of polypeptide extraction and beverage preparation, and the preparation method comprises the following steps: pretreatment of crocodile skin; denaturation treatment: adding a NaHCO3 buffer solution, and treating under a microwave condition; performing ultrasonic pretreatment; carrying out enzymolysis reaction, namely sequentially carrying out primary enzymolysis of alkaline protease and secondary enzymolysis of compounding trypsin and neutral protease; adding composite colloid after enzyme deactivation treatment, wherein the composite colloid comprises flaxseed gum and xanthan gum; centrifuging to take supernate, and carrying out fractional separation through ultrafiltration membranes with the molecular weight cut-off of 500Da and 1000Da; and concentrating and drying to obtain polypeptide powder. According to the method, the polypeptide yield, the beverage stability and the oral bioavailability are improved; finally, the obtained polypeptide is scientifically matched with hyaluronic acid and vitamin C to prepare the beautifying beverage with the effects of remarkably improving skin stains and fine wrinkles and brightening the skin color, and the breakthrough of high-value utilization of crocodile skin resources and product function integration is realized.

The application discloses a kind of multilayer dialysis device and use method for separating landfill leachate, belong to landfill leachate processing technical field, multilayer dialysis device includes magnetic stirring module and multilayer dialysis module;Magnetic stirring module includes magnetic stirring rotor and the magnetic field control device of driving magnetic stirring rotor rotation;Multilayer dialysis module includes the experimental cylinder being set on stirring table, and multiple different diameters and coaxially arranged dialysis cylinders are arranged in experimental cylinder, and magnetic stirring rotor is arranged at the bottom of the smallest diameter dialysis cylinder;By setting multiple dialysis cylinders with different molecular weight cut-off in multilayer dialysis module, and setting magnetic stirring rotor at the bottom of the smallest diameter dialysis cylinder, not only can simultaneously process the dialysis work of multiple molecular weight organic matter and ionic landfill leachate, but also significantly improve the separation efficiency of multiple molecular weight organic matter and ions with magnetic stirring rotor, compared with single membrane technology, more separation tasks can be completed in shorter time.

The invention discloses an egg yolk globulin crude extraction method, extraction process and extraction equipment, and relates to the technical field of egg yolk globulin extraction.The process comprises the following steps that S1, egg yolk liquid is poured into a mold to be subjected to liquid nitrogen quick freezing, demolding is conducted, and the egg yolk liquid is smashed into particles; s2, mixing and stirring precooled acetone and the frozen egg yolk particles, centrifuging, and removing lipid precipitates on the upper layer; s3, adding the pre-cooled PBS, mixing, stirring and centrifuging, taking supernate, and carrying out treatment at the temperature of 0-5 DEG C; s4, slowly adding ammonium sulfate until the saturation degree is 30-40%, standing for 2 hours in an environment of 0-5 DEG C, then performing centrifugal treatment, taking precipitate, and redissolving the precipitate with PBS to obtain a redissolved solution; s5, performing ultrafiltration concentration on the reconstitution fluid by using an ultrafiltration membrane with the molecular weight cutoff of 100-200kDa; s6, carrying out ion exchange layer and hydrophobic layer chromatography treatment in sequence; and S7, carrying out pre-freezing in an environment of-80 DEG C, and then carrying out vacuum freeze-drying treatment. The method has the effect of improving the comprehensive benefit of extracting high-purity and high-activity egg yolk globulin.

The invention belongs to the technical field of separation and purification, and particularly relates to a separation and purification method for active components of wasp venom. According to the invention, only an ultrafiltration membrane method is adopted, reverse operation is carried out according to a sequence from large to small, ultrafiltration membranes with molecular weight cutoff of 30kDa, 10kDa and 3kDa are respectively used for sequentially intercepting a vespa velutina venom solution, and freeze drying is carried out, so that three active components with antifungal (candida albicans) and antibacterial (escherichia coli and staphylococcus aureus) effects are obtained. The method is simple to operate and relatively high in efficiency, purification time is greatly saved, the whole process only relates to physical separation, inactivation of active components is greatly avoided, and the method is very beneficial to process amplification.

The invention discloses a sea-buckthorn small molecule peptide and a preparation method thereof, and relates to the field of biological medicine and food processing. According to the method, sea-buckthorn pulp residues and sea-buckthorn seed residues are used as composite raw materials and are mixed and stirred to form homogenate, and then cell wall structures are destroyed through ultrasonic wall breaking treatment to release protein components; then cutting off a peptide bond under the action of compound enzymes (plant protease, neutral protease and pepsase) by adopting an ultrasonic-enzyme synergistic hydrolysis process to generate a small molecule peptide fragment; after removing impurities through centrifugal separation, purifying through an ultrafiltration membrane (the molecular weight cut-off is 1-3kDa) to obtain a small molecule peptide solution; and performing debitterizing treatment by using macroporous adsorption resin, and preparing sea-buckthorn small molecule peptide powder by using a vacuum freeze-drying technology. According to the method, through ultrasonic-enzyme synergistic interaction, multi-stage purification combination and low-temperature keep-alive processes, the yield, molecular weight uniformity and antioxidant activity of small molecular peptides are remarkably improved, and high-valued utilization of sea-buckthorn processing by-products is achieved.

The invention discloses a full-value protein biological feed production method, and relates to the technical field of protein feed production, the production method comprises the following steps: double-strain co-fermentation: cooling fermentable syrup to 38-42 DEG C, adjusting the pH value to 6.5-7.0, inoculating a mixed strain of Thermoactinomyces vulgaris and Candida utilis, fermenting for 18-24 hours under the condition that the dissolved oxygen is maintained to be 30-60%, and carrying out double-strain co-fermentation; in the process, the pH, dissolved oxygen and temperature are monitored in real time by an on-line sensor controlled by a PLC (Programmable Logic Controller), and materials are automatically supplemented; and membrane separation and concentration: enabling the fermentation liquor to pass through a PVDF (Polyvinylidene Fluoride) ultrafiltration membrane with the molecular weight cutoff of 10kDa-30kDa, and intercepting thalli and protein aggregates by a membrane concentration multiple of 5-10 to obtain a membrane concentrated solution with the protein concentration of more than or equal to 50g / L. According to the method, agricultural waste is efficiently converted into complete protein through double-bacterium synergistic fermentation, the problems that traditional single-bacterium fermentation is low in yield and unbalanced in nutrition are solved, and the protein yield is increased.

This invention relates to the field of fertilizer technology, specifically to an organic liquid fertilizer based on straw enzymatic hydrolysate and its preparation method. The method includes: pretreating corn straw with potassium hydroxide, followed by enzymatic hydrolysis with cellulase and xylanase to obtain the enzymatic supernatant; sequentially treating the supernatant with an ultrafiltration membrane with a molecular weight cutoff of 3000 Da and a nanofiltration membrane with a molecular weight cutoff of 500 Da to collect oligosaccharides with a molecular weight window of 500-3000 Da; partially stabilizing the reducing end of the oligosaccharides with sodium borohydride; pre-complexing with boric acid at pH 8.4-8.8; then sequentially adding relatively low molecular weight sodium polyglutamate, calcium chloride dihydrate aqueous solution, and ultra-high molecular weight sodium polyglutamate to construct a sequential complexation system; subsequently adding potassium nitrate and citric acid aqueous solution; and finally, after filtration at 5 μm and heat treatment at 70℃, obtaining the organic liquid fertilizer. This fertilizer has a high proportion of 500-3000 Da oligosaccharides and a low reducing sugar equivalent, inhibiting storage precipitation and browning, and improving the retention rate of extractable oligosaccharides in the soil.

The invention discloses a preparation method of dendrobium polysaccharides and cosmetic application of the dendrobium polysaccharides, and relates to the technical field of daily necessities. The preparation method of the dendrobium polysaccharide comprises the following steps: mixing dendrobium officinale powder with water to obtain a to-be-extracted solution; performing ultrasonic extraction on the to-be-extracted solution, adding a compound enzyme into the to-be-extracted solution for enzymolysis after ultrasonic extraction, and filtering the enzymatic hydrolysate by adopting an ultrafiltration membrane with the molecular weight cut-off of 5000-10000 Da after enzymolysis is finished. According to the method disclosed by the invention, the extraction effect of the dendrobium polysaccharides can be remarkably improved and the content of the dendrobium polysaccharides can be increased in a manner of ultrasonic extraction, enzymolysis and ultrafiltration membrane filtration, and the prepared dendrobium polysaccharides are relatively high in content and relatively small in molecular weight. The ultra-low molecular dendrobium polysaccharide (the molecular weight is generally less than 10kDa) is selected as a component of the anti-oxidation and anti-wrinkle composition, so that the transdermal absorption efficiency and bioavailability of the anti-oxidation and anti-wrinkle composition can be remarkably improved. The antioxidant and anti-wrinkle composition can be widely applied to preparation of skin care products or cosmetics.

The invention discloses an improved loading method of a nano-drug carrier, which comprises the following steps: adding a carrier of recombinant human heavy-chain ferritin or a derivative thereof into a high-concentration urea solution, mixing and reacting to depolymerize a shell of the recombinant human heavy-chain ferritin; adding a medicine, mixing and incubating; and diluting a reaction solution obtained by incubation into a low-concentration urea solution by using a Tris buffer solution, reacting for 8-15 hours to re-polymerize the recombinant human heavy chain ferritin shell, and finally changing the solution by using a membrane bag with the molecular weight cutoff of 50 KD through the Tris buffer solution to obtain the loaded ferritin drug composite particles. According to the preparation method provided by the invention, the effect of obviously improving the protein recovery rate and the drug loading capacity is achieved by providing a preparation method of replacing liquid after dilution and then standing and optimizing the drug-mass ratio, the protein recovery rate can reach 100%, and the drug loading capacity can reach 186 mu g / mL.

The present invention relates to the field of biotechnology, and discloses a white mullet antioxidant peptide, a preparation method and application thereof. The white mullet antioxidant peptide of the present invention is extracted from white mullet, and the amino acid sequence is shown in SEQ ID NO: 1. The preparation method comprises the following steps: first, simulating human in vitro digestion to obtain an enzymatic hydrolyzate from the white mullet, using ultrafiltration to separate ultrafiltration components with a molecular weight cutoff of less than 3000Da, and after gel chromatography, using an RP-HPLC method to further separate and purify the chromatography components with antioxidant activity to obtain the white mullet antioxidant peptide. The white mullet antioxidant peptide prepared by the present invention has a strong antioxidant effect and can be used to prepare antioxidant products.

The invention relates to application of a high-selectivity nanofiltration membrane regulated and controlled by chitosan hydrogel to separation of salt ions and perfluorinated compounds in a mineral salt solution. The invention provides application of a high-selectivity nanofiltration membrane regulated and controlled by chitosan hydrogel to separation of salt ions and perfluorinated compounds in a mineral salt solution. The high-selectivity nanofiltration membrane comprises a base membrane, and a hydrogel layer and a polyamide layer which are respectively arranged on the surface of the base membrane. Experiments prove that when natural water is treated, the total salt rejection rate is reduced along with the increase of the concentration of the middle layer, the conductivity is reduced under the combined action of the size screening effect of the cut-off molecular weight and electronegative electrostatic repulsion, and the modified membrane can permeate more mineral elements.

The present invention relates to a method for preparing a composite nanofiltration membrane and a composite nanofiltration membrane prepared thereby. The method for preparing the composite nanofiltration membrane comprises the following steps: preparing a polymer solution as a casting liquid, solidifying the casting liquid on a reinforcing material to form a base membrane; then sequentially contacting with an aqueous solution containing an amine compound, a silane coupling agent and a biomass acid, and an oil phase solution containing a polyacid chloride to form a functional layer; and obtaining a composite nanofiltration membrane after post-treatment and drying. In the preparation method of the present invention, base membranes with different surface average pore sizes are obtained by adjusting the concentration of the polymer in the casting liquid; by adding a silane coupling agent and a biomass acid to the aqueous solution to eliminate other reaction variable factors, the interfacial polymerization reaction is only affected by the average pore size of the base membrane, and accordingly, composite nanofiltration membranes with functional layers with different surface average pore sizes are obtained, thereby having different maximum retention molecular weights.

The invention discloses a preparation method of fishbone collagen tripeptide, which comprises the following steps: soaking fishbone dust (30-60 meshes) in a choline-arginine eutectic solvent, stirring, centrifuging or filtering, and collecting supernate; adding pure water with the volume 3-6 times that of the supernatant into the supernatant, standing for more than 24 hours, centrifuging or filtering again, and collecting the supernatant; carrying out tangential filtration treatment by adopting a nanofiltration membrane with the molecular weight cutoff of 200Da, recovering the eutectic solvent in the filtrate through vacuum concentration, adding pure water into the trapped fluid, carrying out repeated nanofiltration treatment to remove solvent residues, and collecting the trapped fluid; and carrying out spray drying on the trapped fluid to obtain a powder product with the collagen tripeptide content of more than 50%. Compared with a traditional enzyme method for preparing fishbone collagen tripeptide, the method disclosed by the invention has the advantages that the extraction rate is high, a deliming step is not needed, the enzyme cost is saved, an extraction solvent is green and can be recycled, and the like.

The invention discloses a preparation method of shiitake mushroom foot umami peptide based on an enzyme membrane reactor. The preparation method comprises the following steps: extracting shiitake mushroom foot protein; the shiitake mushroom foot umami peptide is prepared based on enzymolysis of an enzyme membrane reactor, and the molecular weight cutoff of an ultrafiltration membrane configured in the enzyme membrane reactor is 5-30 kDa, preferably 30 kDa. The invention also discloses five shiitake mushroom foot umami peptide products screened from the prepared shiitake mushroom foot umami peptide. The mushroom foot umami peptide is prepared by using the enzyme membrane reactor, and the protein conversion rate is improved, so that the yield of the mushroom foot umami peptide is improved. Wherein the shiitake mushroom foot umami peptide prepared by the enzyme membrane reactor with the ultrafiltration membrane molecular weight cutoff of 30 kDa has higher umami strength and relatively small bitter taste. Five shiitake mushroom foot umami peptide products are screened from the prepared shiitake mushroom foot umami peptides, and the umami threshold value of the shiitake mushroom foot umami peptide products is low and ranges from 0.023 mM to 0.375 mM; the fresh taste score is high (electronic tongue score), and is 16.66-18.11.

The application provides a layer-by-layer self-assembly nanofiltration membrane, a preparation method and application thereof. The layer-by-layer self-assembly nanofiltration membrane comprises a base film and a self-assembly coating layer formed on the base film, wherein the self-assembly coating layer comprises at least a starting alternating coating layer and a separation alternating coating layer; the molecular weight cut-off of the base film is not less than 500 kDa; the starting alternating coating layer is alternately assembled by a high-molecular-weight cationic polyelectrolyte layer and an anionic polyelectrolyte layer; the separation alternating coating layer is alternately assembled by a low-molecular-weight cationic polyelectrolyte layer and an anionic polyelectrolyte layer; the starting alternating coating layer is formed on the base film, and the high-molecular-weight cationic polyelectrolyte layer in the starting alternating coating layer adopts a cationic polyelectrolyte with a number-average molecular weight of not less than 500 kDa; and the low-molecular-weight cationic polyelectrolyte layer in the separation alternating coating layer adopts a cationic polyelectrolyte with a number-average molecular weight of not more than 100 kDa. The layer-by-layer self-assembly nanofiltration membrane has more excellent permeability and micro-pollutant rejection rate.