Alpha amylase enzyme, also known as liquefaction amylase, liquefying enzyme, α-1,4-glucanase, is mainly used for the hydrolysis of starch to produce maltose, glucose and syrup maltodextrin. It is used in the production of bread to improve dough by reducing viscosity, accelerating fermentation process, increasing sugar content, and slowing down bread aging. Based on the heat stability of alpha amylase enzyme, it is divided into high-temperature alpha amylase enzyme and medium-temperature alpha amylase enzyme (usually referred to as medium-temperature starch enzyme and high-temperature starch enzyme). What is the difference between the two in the industrial production process?
Medium-temperature alpha amylase enzyme is refined from Bacillus licheniformis by deep fermentation, extraction and other processes.
pH value: it is more stable at pH 6.0-6.5, with the optimal pH being 6.0. It becomes inactive below pH 5.0.
Action temperature: It is relatively stable below 60℃, and optimal activity temperature is 60-70℃.
High-temperature alpha amylase enzyme is refined from Bacillus subtilis by deep fermentation, extraction and other processes.
pH influence: The pH range of this enzyme is 5.0-10.0, and the effective pH range is 5.0-8.0. The optimal pH range is 5.8-6.8.
Temperature influence: When used for saccharification, the optimal temperature for this enzyme is above 90℃. It liquefies rapidly at 95-97℃ and remains active at 100℃. When used for continuous injection liquefaction, the enzyme is very stable at high temperatures, liquefying rapidly, thoroughly, and instantaneously at temperatures up to 105-110℃ for 5-7 minutes.
Both medium-temperature alpha amylase enzyme and high-temperature alpha amylase enzyme possess the characteristics of enzyme catalysts produced by living cells. Compared with other catalytic agents, they exhibit high specificity, efficiency, and mild reaction conditions. As enzymes are proteins, they also share the general properties of proteins. UV radiation, heat, surfactants, heavy metal salts, and acid-base denaturants can all cause enzyme inactivation. Therefore, special attention is needed during storage and use.
Both medium-temperature alpha amylase enzyme and high-temperature alpha amylase enzyme act on starch as their substrate. Under suitable conditions, they can cut α-1,4 bonds inside starch molecules, thus rapidly degrading starch, reducing viscosity, and producing maltose, glucose, and dextrin. This process is commonly referred to as starch liquefaction, so alpha amylase enzyme is also known as liquefaction enzyme.
High-temperature alpha amylase enzyme is not affected by a wide range of pH values, even if the substrate pH drops to 5, liquefaction can still proceed normally, which does not affect fermentation. More importantly, high-temperature α-amylase has a wider temperature adaptation range. The enzyme activity can reach 50% at 50℃, 80% at 80℃, and even higher at temperatures above 90℃. The enzyme can rapidly liquefy at 95-97℃ and remain active at 100℃, which is unmatched by medium-temperature α-amylase. Therefore, the use of high-temperature α-amylase according to the conventional operations in the citric acid industry can ensure complete liquefaction and successful fermentation.
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