7results about How to "Improves pH stability" patented technology

The invention discloses a chitosan-casein peptide nano-particle and a preparation method and application thereof, and belongs to the technical field of food manufacturing, chitosan and casein peptide are combined into a nano-composite with the particle size of 10-1000 nm through electrostatic interaction in a non-covalent binding mode, and the nano-composite is used for preparing the chitosan-casein peptide nano-particle. A more stable oil-in-water emulsion can be prepared by utilizing the nano composite; the invention also provides a preparation method and application of the chitosan-casein peptide nanocomposite, and a preparation method of the oil-in-water emulsion. The nano-composite prepared by the invention has relatively strong oxidation resistance, foamability and foaming stability when the ratio of chitosan to casein peptide is 1: 1, and an oil-in-water emulsion prepared from the nano-composite has good storage stability, pH stability and ion stability. The preparation method of the nanocomposite is simple and low in cost, and has a good application prospect.

This invention belongs to the technical field of bactericide residue analysis and determination in plant-derived foods, specifically relating to a method for detecting isobutylethoxyquinoline and its metabolites in plant-derived foods. The method includes extraction with acetonitrile under citrate conditions, followed by purification with C18 (25 mg), PAX (25 mg), and XFM64 (nitrogen-doped multi-walled carbon nanotubes, 10 mg) adsorbents. Chromatographic separation is performed using a C18 column with methanol-2 mmol / L ammonium acetate (containing 0.1% formic acid) as the mobile phase, isocratic elution at a flow rate of 0.40 mL / min, electrospray ionization (ESI+), and detection in multiple reaction monitoring (MRM) mode. This invention is simple to operate, has high pretreatment efficiency, and its precision and recovery rate meet the regulatory residue limit monitoring requirements. It is suitable for the simultaneous determination of isobutylethoxyquinoline and its metabolites in plant-derived foods.

This invention discloses a method for preparing recombinant dextranase from Chaetomium globosum and its uses. The amino acid sequence of the recombinant dextranase is shown in SEQ ID NO.2 or SEQ ID NO.4, and the nucleotide sequence of its encoding gene is shown in SEQ ID NO.1 or SEQ ID NO.3. The optimal pH of the recombinant dextranase is 4.5-7.0, and the optimal reaction temperature is 45-60℃. + K + and Ca 2+ It has an activating effect on enzyme activity, Mg 2+ NH4 + and Mn 2+ It had no significant effect on enzyme activity, Fe 3+ Zn 2+ Cu 2+ and Co 2+ It has an inhibitory effect on enzyme activity. Furthermore, this enzyme exhibits excellent pH stability, good thermal stability, and anti-interference ability, making it well-suited to the application requirements of the food, pharmaceutical, and chemical industries.

The invention discloses a nicotine oral product and a preparation method thereof and a preparation method of alkaline electrolyzed water. The alkaline electrolyzed water has alkaline characteristics and is colorless and tasteless, and has the condition of being able to adjust the pH value in oral cigarettes. Compared with the existing chemical reagents for adjusting the pH value, the alkaline electrolyzed water is more environmentally friendly, safer, and has no peculiar smell and no irritation. The prepared oral product has better mouth feel and good pH stability. In addition, the water content in the oral cigarette needs to be adjusted by adding water. Therefore, the pH value of the nicotine oral product can be adjusted by using alkaline electrolyzed water, and the water content can be adjusted at the same time. The production process is simple, time-consuming, cost-effective, and economical and environmentally friendly.

The invention discloses an RNase III mutant with high stability, a gene and a preparation method of the RNase III mutant. Wherein the RNase III mutant is obtained by mutating the 46th amino acid of a wild type RNase III amino acid sequence from serine to lysine, and the amino acid sequence of the RNase III mutant is as shown in SEQ ID NO: 1. The enzymatic property of the RNase III mutant is the same as that of wild type RNase III, and the pH stability and the temperature stability of the RNase III mutant are obviously higher than those of the wild type RNase III; according to the preparation method of the RNase III mutant, a gene engineering means is adopted, RNase III mutant genes are cloned to an expression vector, host cells are transformed for prokaryotic expression, a large number of high-stability RNase III mutants can be obtained, a basis is provided for preparation of siRNA and development of mRNA vaccines, and the production cost is reduced.

The invention relates to a method for preparing amphoteric radix pseudostellariae polysaccharide-curcumin nanoparticles through Pickering emulsion polymerization and the amphoteric radix pseudostellariae polysaccharide-curcumin nanoparticles. The method comprises the following steps: (1) preparing amphoteric radix pseudostellariae polysaccharide: dissolving purified radix pseudostellariae polysaccharide in water, and reacting with a glutaric anhydride ethanol solution to prepare the amphoteric radix pseudostellariae polysaccharide; (2) preparing amphoteric radix pseudostellariae polysaccharide-curcumin nanoparticles by an anti-solvent method: dissolving amphoteric radix pseudostellariae polysaccharide in ethanol to obtain an amphoteric radix pseudostellariae polysaccharide ethanol solution, adding a certain amount of curcumin into the amphoteric radix pseudostellariae polysaccharide ethanol solution, and stirring and mixing to obtain a mixed solution; slowly submitting the mixed solution into a container containing the dispersion liquid, centrifuging, removing supernate, and freeze-drying to obtain the amphoteric radix pseudostellariae polysaccharide-curcumin nano-particles. According to the invention, radix pseudostellariae polysaccharide is modified into amphoteric polysaccharide by grafting glutaric anhydride, so that efficient loading of curcumin is realized.

The application discloses a method for immobilizing transaminase by cross-linking-adsorption, and immobilized enzyme and application thereof. The application adopts the adsorption-cross-linking method, and through screening of an immobilization method and optimization of key process parameters of immobilization, the prepared immobilized cell enzyme activity reaches 25.31 U / mg, and the enzyme activity recovery rate reaches 95.88%, which is obviously superior to traditional embedding methods or single adsorption methods, and effectively reduces enzyme activity loss in the immobilization process. The method directly uses whole cells, and does not need an enzyme purification step. Diatomite is widely available and low in price, and the modification and immobilization conditions are mild, the operation is simple, and the method is easy to scale up, so the method has a good industrial application prospect.