Starch sugars are formed by utilizing starch as the raw material, they are worked out through chemical methods or enzymatic biotechnology through liquefaction, saccharification, transglycoside, decolorization and ion exchange and other refining processes to produce different kinds of sugars.
Due to the vigorous support and popularization implemented by China, China's starch sugar industry has made significant development, technology achieves continuous improvement, the cost has dropped significantly, the market has expanded year by year. Because of the above reason, China's starch sugar enterprises are moving towards the trend of a variety of varieties, personalized, specialized, large-scale development,which leads to the result that production quantity is increased substantially and variety structure is increasingly perfect.
The starch sugar industry has developed rapidly in recent years because of its unique biotechnological characteristics, and the newly developed amylase has technical advantages that must be matched with existing production methods, and can bring huge economic advantages, while the enzyme can provide sufficient quantities to support large-scale industrial production.
It mainly depends on the development of the used amylase and the large-scale production of amylase. The enzymes which are commonly used to produce starch sugar mainly include liquifying enzyme, saccharifying enzyme, debranching enzyme and so on.
The liquifying enzyme commonly which is used in industrial production is α-amylase, which is mainly divided into high temperature resistant α-amylase, medium temperature α-amylase and fungal α-amylase. α-amylase mainly comes from fungi, bacteria and molds, and different sources of α-amylase have different thermal stability and optimal reaction temperature. The reaction efficiencies of the two kinds of liquifying enzymes are the highest under the condition of pH 6.0-6.5, but the optimal reaction temperatures of the two kinds of liquifying enzymes are different. As the the implication which is mentioned in the above content, the medium temperature α-amylase is the most suitable temperature under the condition of 60-70 ℃. However, the additional Ca2+ is needed to added so as to improve the heat stability of the enzyme, because the enzyme molecule can be tightly bound to calcium ions, thus maintaining its optimal spatial conformation, so as to realize the highest activity and maximum stability.
Compared with the medium temperature enzyme, the optimal reaction temperature of high temperature resistant α-amylase is 90-100℃, and only a small amount or no anhydrous CaCl2 is needed to be added. Calcium ions which are above 0.001mol/L are added to the substrate during the liquefaction reaction to stabilize and promote the enzyme-catalyzed reaction.
Liquifying enzymes are enzymatically hydrolyze starch molecules from the inside of molecules, which can quickly hydrolyze large starch molecules to form small molecules, and the viscosity of the slurry will also be sharply reduced. This process is called starch liquefaction reaction.
Dextrin is the main product of starch liquefaction. After the initial rapid enzymolysis stage is completed, the hydrolysis effect of liquefaction enzyme on small molecule products is significantly reduced, and then it will enter the slow enzymolysis process.
Saccharifying enzymes are widely used in the field of food and medicine, they are the most widely used enzymes in the modern starch sugar industry, and they have the largest annual production quantity in the world.
There are many types of saccharifying enzymes, among which fungal α-amylase, β-amylase and glucose amylase are the most widely used. The enzymatic hydrolysis principle of saccharifying enzyme is to further interact with maltodextrin molecules in starch liquefaction liquid to produce oligosaccharides, monosaccharides and other small molecular sugars. The enzymolysis site of glucose amylase is from the α-1,4 bond at the non-reducing end, so that glucose units are separated one by one, and its product is glucose in β-configuration, and no other sugar is generated, which can be used to produce glucose in the industry.
Glucosidase, as an exonuclease enzyme, breaks the carbon-oxygen bond between glucose units in the process of hydrolyzing starch or short-chain dextrin. The mechanism of enzymolysis is the same as that of liquefaction enzyme. Because the longer the carbon chain is, the greater the affinity is, the longer the carbon chain is, the greater the activity of enzymolysis of long chain is than that of short chain.The maximum reaction rate of saccharifying enzyme increases linearly with the extension of carbon chain.
pH and temperature are the two main factors which affect the action of glucose amylase. Glucose amylases from different sources have large differences in enzymatic hydrolysis efficiency at different temperatures and pH. For example, some glucose amylase products have fewer colored substances, light colors and easy decolorization under the condition of low pH.
β-amylase, which is known as one kind of excision enzyme and it is also called maltose producing enzyme, is the key enzyme in the industrial production of maltose.
Fungal alpha-amylase is an endonuclease extracted from fungi.
Fungal α-amylase is widely used because it can be used not only as the liquefaction enzyme but also as the saccharifying enzyme. It is especially suitable for the production of high quality maltose in industry. However, only a few foreign biotechnology companies have internationally advanced production technology and products.
Therefore, fungal α-amylase has broad development and application prospects in the process of starch sugar production in China.
In the starch sugar industry, the composition of the fungal α-starch malt syrup to maltose accounts for 40%-60%, maltose triose accounts for about 10%-20%, the other composition is glucose, oligosaccharides , dextrins, etc., many excellent characteristics have gradually replaced β-amylase and become the key enzyme in the production of high-quality malt syrup.
In the process of industrial production, it is often used in combination with dedendrases such as β-amylase and pullulanase to produce ultra-high malt syrup with the maltose content is more than 70%.
Debranching enzymes are the generic terms for enzymes that hydrolyze the alpha-1, 6-glucoside bond in glycogen and amylopectin.
There are two kinds of isoamylase and pullulanase (also known as ZPU). Pullulanase is widely used in the saccharification reaction as one kind of debranching enzymes. It can concerted reaction with the saccharifying enzyme to improve the yield and quality of starch sugar products such as maltose,etc. It can not only hydrolyze the side chain of amylopectin containing α-1, 6-glucoside bond into short straight chain dextrin, but also hydrolyze α-limiting dextrin andβ-limiting dextrin which are composed of small molecules of α-1, and 4-glucoside bond.
Moreover, in the production of high-purity glucose, it is combinedly used with saccharifying enzymes, rather than using alone, which can improve the yield and purity of glucose. Most of the branched chain amylase used in the industry is obtained by fungi, bacteria, other microorganisms and so on. For example, the debranching enzyme produced by the acid keprulan bacillus has good stability such as acid resistance, heat resistance,etc.
Therefore, as an auxiliary enzyme, pullulanase has a wide range of application prospects in the sugar industry. Because pullulanase can also be used as an effective additive of detergent and detergent under alkaline conditions, it can enzymatic hydrolysis of biological proteins, etc., it is also used in the washing industry.