α-Amylase, system name is 1,4-α-D-glucan glucan hydrolase, also known as liquefying amylase, liquefying enzymeα-1,4-dextrinase.Yellow brown solid powder or yellow brown to dark brown liquid, with water content of 5%~8%.Soluble in water, insoluble in ethanol or ether.According to FAO/WHO, ADI has no special restrictions[1]。
English name:α-Amylase(Bacilus subtilis) ；1,4-α-D-Glucan-glucanohydrolase
Other names: medium temperatureamylase；Liquefying amylase;Liquefying enzyme;α-1,4-dextrinase;Bacterial amylase;α-Starch enzyme;Dextrinase[2]CAS No.: 9000-90-2
Level: BioChemika
Vitality: ≥ 50U/mg
Definition of vitality: 1 U responses to the amount of energy which liberates 1μmole maltose per minute at pH 6.9 at 25 °C (starch acc. to Zulkowsky, Catalog No. 85642, as substrate).
Character: yellowish brown or almost white powder.Extracted from Bacillus subtilis
Use: biochemical research.It can quickly liquefy starch to form low molecular weight.[3]Storage: 2~8 ℃
nature
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Under the protection of high concentration starchα-The thermostability of amylase is very strong. In the presence of proper calcium salt and table salt, when the pH value is 5.3~7.0, the activity of amylase is still high enough when the temperature is raised to 93~95 ℃.In order to facilitate storage, an appropriate amount of calcium carbonate is often added as an anti caking agent to prevent caking.
α-Amylase can hydrolyze theα-1,4-glycosidic bond, the hydrolysate is dextrin, oligosaccharide and monosaccharide, which can rapidly reduce the viscosity of gelatinized starch after enzymatic action and become liquefied starch, so it is also called liquefied amylase, liquefied enzymeα-1,4-dextrinase.
α-When amylase takes amylose as substrate, the reaction is generally carried out in two stages.First of all, amylose degrades rapidly to produce oligosaccharides. At this stage, the viscosity of amylose and its ability to color react with iodine rapidly decline.The reaction in the second stage is much slower than that in the first stage, including the slow hydrolysis of oligosaccharides to produce the final products glucose and maltose.α-Amylase acts on amylopectin to produce glucose, maltose and a series of restricted dextrins (oligosaccharides composed of 4 or more glucose groups), which all containα-1,6-glycosidic bond.
α-Amylase molecule contains a calcium ion that is firmly bound. This calcium ion is not directly involved in the formation of enzyme substrate complex. Its function is to maintain the structure of the enzyme, so that the enzyme has the maximum stability and activity.
α-The optimum pH value of amylase is between 4.5 and 7.0 according to the source. The amylase is obtained from human saliva and pig pancreasα-The optimal pH range of amylase is narrow, between 6.0 and 7.0;Bacillus subtilisα-The optimum pH value of amylase is wide, ranging from 5.0 to 7.0;The optimum pH value of Bacillus stearothermophilus amylase was about 3.0;Sorghum budα-The optimum pH value of amylase is 4.8~5.4;Wheatα-The optimal pH value of amylase is about 4.5. When the pH value is lower than 4, the activity of amylase decreases significantly, while when it exceeds 5, the activity decreases slowly.
according toα-The thermal stability of amylase can be divided into high temperature resistanceα-Amylase and medium temperature amylase.In high temperature resistanceα-Among amylases, enzymes produced by Bacillus amyloliquefaciens and Bacillus licheniformis have been widely used in food processing.Temperature has different effects on the activity of the two enzymes. The optimum temperature of Bacillus licheniformis amylase is 92 ℃, while the optimum temperature of Bacillus amyloliquefaciens amylase is only 70 ℃. In addition to the difference in thermal stability, the end products of the two enzymes acting on starch are also different[1]。
Function
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Onlyα-1,4-glucoside bond, which cuts the starch chain into short chain dextrin, oligosaccharide and a small amount of maltose and glucose, so that the starch viscosity drops rapidly to achieve the purpose of "liquefaction"[4]。
Toxicological basis
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(1) LD50 mice took 7375mg/kg orally.
(2) ADI: acceptable [from Aspergillus oryzae (JECFA, 1987)];There is no need to specify [from Bacillus subtilis, Bacillus stearothermophilus (JECFA, 1990) and Bacillus licheniformis (JECFA, 2003)].
(3) Mutagenicity.This product has no obvious accumulation effect and mutagenic effect in vivo[4]。
application
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α-Amylase is mainly used to hydrolyze starch to produce maltose, glucose and syrup, and to produce dextrin, beer, rice wine, alcohol, soy sauce, vinegar, fruit juice and monosodium glutamate.It is also used in bread production to improve dough, such as reducing dough viscosity, accelerating fermentation process, increasing sugar content and easing bread aging.It is used for pretreatment of cereal raw materials in infant food.In addition, it is also used in vegetable processing.Dosage: Bacillus subtilisα-Amylase (6000IU/g) meter, the added amount is about 0.1%[3]。
