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Application of α-amylase and Research
α-amylase to be widely distributed throughout microorganisms to higher plants. The International Enzyme classification number is EC. 3.2.1.1, acting on the starch from the starch molecules within the random cut α a 1,4 glycosidic bond to produce dextrin and reducing sugar, because the end product of carbon residues as Α configuration configuration, it is called α-amylase. Now refers to α-amylase were cut from the starch molecules within the α-1,4 glycosidic bond from the liquefaction of a class of enzymes.
α-amylase is an important enzyme, a large number of used food processing, food industry, brewing, fermentation, textile industry and pharmaceutical industries, which account for the enzyme about 25% market share. Currently, both industrial production to large-scale production by fermentation α-amylase. α-amylase in industrial applications
1.1 The bread baking industry, as a preservative enzymes used in baking industry, production of high quality products have been hundreds of years old. In recent decades, malt and microbial α-amylase, α-amylase is widely used in baking industry. The enzymes used for making bread, so that these products are much larger, better colors, more soft particles.
Even today, baking industry have been α-amylase from barley malt and bacterial, fungal leaf extract. Since 1955 and after 1963 in the UK GRAS level validation, fungal amylase, has served as a bread additive. Now, they are used in different areas. Modern continuous baking process, add in f lour α-amylase can not only increase the fermentation rate and reduce dough viscosity (improving product volume and texture) to increase the sugar content in the dough, improved bread texture, skin color and baking quality, but also to extend the preservation time for baked goods. In the storage process, the bread particles become dry, hard, not crisp skin, resulting in deterioration of the taste of bread. These changes collectively referred to as degenerate. Each year simply because the losses caused by deterioration of bread more than 100 million U.S. dollars. A variety of traditional food additives are used to prevent deterioration and improve the texture and taste of baked goods. Recently, people started to pay attention enzyme as a preservative, preservative agent in improving the role of the dough, as amylopectin, amylase enzyme and a match can be effectively used as a preservative. However, excessive amylase causes a sticky bread too. Therefore, the recent trend is the use of temperature stability (ITS) α a amylase activity are high in starch liquefaction, but the baking process is completed before the inactivation. Despite the large number of microbes have been found to produce α-amylase, but with the temperature stability of the nature of the α-amylase only been found in several microorganisms.
1.2 starch liquefaction and saccharification of the main α-amylase starch hydrolysis product market, such as glucose and fructose. Starch is converted into high fructose corn syrup (HFCS). Because of their high sweetness, are used in the soft drink beverage industry sweeteners. The liquefaction process is used in thermal stability at high temperature α-amylase. α-amylase in starch liquefaction of
the application process is already quite mature, and many relevant reports.
1.3 fiber desizing modern fiber manufacturing process in knitting yarn in the process will produce large amounts of bacteria, to prevent these yarn faults, often increase in the surface layer of the yarn can remove the protective layer. The surface layer of the material there are many, starch is a very good choice because it is cheap and easy to obtain, and can be easily removed. Starch desizing α-amylase can be used, it can selectively remove the starch without harming the yarn fibers, but also random degradation of starch dextrin soluble in water, and are easily washed off. 1.4 Paper Industry amylase used in the paper industry mainly to improve the paper coating starch. Paste on the paper is primarily to protect the paper in the process from mechanical damage, it also improved the quality of finished paper. Paste to improve the hardness and strength of paper, enhanced erasable paper, and is a good paper coating. When the paper through two rolls, the starch slurry is added the paper. The process temperature was controlled at 45 ~ 6O ℃, need a stable viscosity of starch. Grinding can also be controlled according to different grades of paper starch viscosity. Nature of the starch concentration is too high for the sizing of paper, you can use part of α-amylase degradation of starch to adjust.
1.5 Application of detergents in the enzyme is a component of modern high-efficiency detergents. Enzymes in detergents in the most important function is to make detergents more modest sound. Automatic dishwasher detergents early is very rough, easy to eat when the body hurts, and on ceramics, wood tableware can also cause damage. α-amylase was used from 1975 to washing powder. Now, 90% of the liquid detergents contain an amylase, and automatic dishwasher detergents α-amylase on demand is also growing. α 1 amylase ca2 + is too sensitive to low ca2 + in the stability of poor environment, which limits an amylase in the remover in. And, most of the wild-type strains produced an amylase on raw materials as one of the oxidants detergents are too sensitive. Keep household detergents, this limitation by increasing the number of process steps can be improved. Recently, two major manufacturers of detergents NovozymesandGcncncoreInternational enzyme protein technology has been used to improve the stability of amylase bleaching. They leucine substitution of Bacillus licheniformis α-amylase protein in the first 197 on the methionine, resulting in enzymes of the oxidant component of resistance increased greatly enhanced the oxidation stability of the enzyme stability during storage better. The two companies have been pushing in the market these new products.
1.6 Pharmaceutical and clinical chemical analysis with the continuous development of biological engineering, the application of amylase involved in many other areas, such as clinical, pharmaceutical and analytical chemistry. Have been reported, based on the liquid α-amylase stability of reagents have been applied to automatic biochemical analyzer (CibaComingExpress) clinical chemistry system. Amylase has been established by means of a method of detecting a higher content of oligosaccharides, is said this method is more than the effective detection method of silver nitrate.
2.1 Research amylase α-amylase enzymes in domestic production and application in 1965, China began to apply for a 7658 BF Bacillus amyloliquefaciens amylase production of one, when only exclusive manufacturing plant in Wuxi Enzyme. 1967 Hangzhou Yi sugar to achieve the application of α-amylase production of caramel new technology can save 7% ~ 10% malt, sugar, increase the rate of 10%.1964, China began a process of enzymatic hydrolysis of starch production of glucose. In September l979 injection of glucose by the enzyme and identification of new technology and worked in North China Pharmaceutical Factory, Hebei Dongfeng Pharmaceutical Factory, Zhengzhou Songshan applied pharmaceutical units and achieved good economic benefits. Compared with the traditional acid to improve the yield of 10% Oh, cost more than 15%. In addition to enzyme for citric acid production in China, glutamic acid fermentation system for beer saccharification, fermentation, rice wine, soy sauce manufacture, vinegar production also has been studied and put into production successfully.
2.2 Overseas Researc h α-amylase, present, and in addition a large number of T for conventional mutation breeding, the overseas production has been initially figure out the regulation of α-amylase gene, the transduction of the transformation and gene cloning techniques such as breeding. The Bacillus subtilis recombinant gene into the production strain to increase α-amylase yield of 7 to 10 times and has been used in food and the wine industry, for breeding high-yield strains of α-amylase to create a new way.
2.3 domestic and foreign research institutions and major research direction as α-amylase is an important value of industrial enzymes, weekly discussion group and outside it was a lot of research. Representative of the domestic units: Sichuan University, major research produc tion of α-amylase strains and culture conditions; Jiangnan University, the main research structure of α-amylase and application performance, such as heat resistance, acid resistance; Northwest universities, major research denatured α-amylase and the environment on the mechanism of α-amylase; South China University of Technology, the main α-amylase of immobilization and dynamic nature; there Huazhong Agricultural University, Chinese Academy of Sciences Institute of Applied Ecology in Shenyang, Tianjin University, Nankai University, College of Life Sciences, Chinese Academy of Agricultural Sciences, Chinese Academy of Sciences Institute of Microbiology and a number of research institutions on a variety of bacterial α-amylase production of a amylase gene cloning and expression. Representative of foreign research units are: Canada UniversityofBritishColumbia, they were a pancreatic amylase structure and mechanism of in-depth research; Denmark's Carlsberg Research Laboratory of the main structure of barley α-amylase domain and binding sites; U.S. WesternRegionalResearchCenter major study α-amylase in barley and the role of antibiotics and the barley α-amylase active site.
3, α-amylase conclusion has become the industrial application of one of the most important enzymes, and a large number of micro-organisms can be used for efficient production of amylase, but large-scale commercial production of the enzyme is still limited to some specific fungi and bacteria. For the effective demand
for α-amylase more and more, this enzyme by chemical modification of existing or improved technology through the white matter are. Benefit from the development of modern biotechnology, α an amylase in the pharmaceutical aspects of growing importance. Of course, the food and starch indust ries is still the main market, α amylase in these areas, a demand is still the largest.
Journal of Southeast University(English Edition)2008 24（4）。