6 results about "Isoamylase" patented technology

The method for catalytically preparing D-mannose provided in the application can effectively reduce the amount of by-products glucose and fructose, and greatly improve the conversion rate of D-mannose. Specifically, the engineering bacteria expressing isoamylase gene and the engineering bacteria expressing alpha-glucan phosphorylase gene, glucose phosphomutase gene, bifunctional enzyme glucose phosphate isomerase / mannose 6-phosphate isomerase gene and mannose 6-phosphate phosphatase gene are used, starch or starch derivatives are used as substrates, phosphate buffer solution and Mg 2+ A preliminary catalytic system is constructed, and after the reaction is completed, there are unreacted substrates and maltodextrin in the reaction system, the saccharifying enzyme can hydrolyze the unreacted substrates and maltodextrin into glucose, the polyphosphate glucose kinase can convert all the glucose into phosphorylated glucose with the assistance of sodium hexametaphosphate, and then D-mannose is generated, thereby improving the yield and removing the by-products in the system.

This invention discloses a multi-step sequential enzymatic hydrolysis combined with multi-stage membrane purification method for preparing kudzu oligosaccharides, relating to the field of functional food processing technology. The preparation method includes the following steps: adding kudzu powder to water to prepare a starch slurry, then liquefying it using α-amylase, followed by enzymatic hydrolysis using debranching enzymes and glycoside hydrolases to obtain an enzymatic hydrolysate; performing membrane separation on the enzymatic hydrolysate to obtain a fraction with a molecular weight higher than 1 kDa and lower than 5 kDa, followed by drying to obtain the kudzu oligosaccharides; the debranching enzymes are pullulanase and isoamylase; the glycoside hydrolases are β-glucosidase or α-transglucosidase. This preparation method can effectively increase the proportion of the DP3-15 fraction of kudzu oligosaccharides, achieving a product purity of over 91% and a total yield exceeding 22%.

The invention discloses a tagatose-6-phosphate phosphatase mutant and application of the tagatose-6-phosphate phosphatase mutant in production of D-tagatose, and belongs to the technical field of enzyme engineering. The tagatose-6-phosphate phosphatase mutant disclosed by the invention is obtained by mutating wild type tagatose-6-phosphate phosphatase of which the amino acid sequence is shown as SEQ ID NO.5, and the mutation site is selected from at least one of the 45th site, the 108th site, the 168th site and the 186th site. After the mutant is coupled with isoamylase, dextran phosphorylase, glucose phosphate mutase, glucose-6-phosphate isomerase, 4-alpha-glucosyltransferase and tagatose-6-phosphate isomerase, the yield of D-tagatose synthesized by substrate starch is increased, the accumulation amount of by-products glucose and fructose is low, and the yield of D-tagatose synthesized by substrate starch is increased. Therefore, the production efficiency is greatly improved, and the separation and purification cost is reduced. Therefore, the mutant disclosed by the invention is suitable for industrial production and has a good application prospect.

The invention provides low-GI steamed buns and a preparation method thereof. Saccharomyces cerevisiae, lactobacillus brevis, lactobacillus plantarum and lactobacillus pentosus which are separated and screened from traditional yeast are used for performing multi-strain fermentation on dough, a composite modifier composed of polydextrose, isoamylase and tannic acid is added after fermentation, and steaming is performed after fermentation to obtain the low-GI steamed buns. The prepared steamed bun has low GI value and excellent sensory quality, the bottleneck problem that low GI, texture characteristics and sensory quality are difficult to consider in the traditional process is solved, the unification of low GI health function and excellent eating quality is realized, the process is simple, the trend of cleaning labels is met, and industrial production is easy.

The invention provides a recombinant plasmid, a heat-resistant isoamylase gene engineering strain and application, the nucleotide sequence of a promoter in the recombinant plasmid is shown as SEQ ID NO.1 in a sequence table, and the nucleotide sequence of RBS is shown as SEQ ID NO.2 in the sequence table. The gene engineering strain is prepared by taking bacillus subtilis as a host. The strain is obtained by transferring plasmids with the fragment into bacillus subtilis and screening to obtain correct transformants, can be used for producing soluble isoamylase, can efficiently express isoamylase in cells, is short in fermentation period and low in production cost, does not form inclusion bodies, is easy to purify, and is beneficial to large-scale production of isoamylase.

The invention belongs to the field of biological enzyme preparations, and particularly relates to a compound enzyme preparation for improving combustibility of Nanping cigars and application of the compound enzyme preparation. According to the method, the Nanping cigar tobacco leaves with improved combustion performance are prepared by harvesting the Nanping cigars, airing the Nanping cigars, screening and compounding enzyme preparations, optimizing an enzymolysis mode and controlling enzymolysis parameters only by adopting a compound enzyme preparation without non-enzyme preparations. Pectate lyase and pectin esterase in pectinase, papain in protease, beta-amylase saccharifying enzyme and isoamylase in amylase and cellulase are screened out and combined, and further optimized that pectate lyase, pectate esterase and cellulase are subjected to mixed enzymolysis, enzymolysis is carried out, enzymolysis is carried out, and enzymolysis is carried out. The papain, beta-amylase and isoamylase solutions are mixed for enzymolysis, and the temperature and time of two times of enzymolysis are controlled, so that the combustibility of the Nanping cigar tobacco leaves is remarkably improved, and meanwhile, the smoking evaluation result of the Nanping cigar tobacco leaves is good.