What enzyme converts starch to glucose ?|FAQ

What enzyme converts starch to glucose ?

2018-08-20 /

Glucose syrup is a concentrated aqueous solution of glucose maltose and other nutritive saccharides from edible starch. The technology of glucose syrup production has developed from acid technology , acid-enzyme technology and enzyme technology. At present ,the enzyme technology for converts starch to glucose is very popular for many glucose syrup production plant. Then what enzyme converts starch to glucose?

It's the α-enzyme and glucomylase, used in the liquefaction and saccharification process for glucose production. The enzyme technology converts starch to glucose can be subdivided into the following process areas of liquefaction, saccharification, purification and evaporation.

Glucose syrup production equipment

α-enzyme used for liquefaction process:
Native starch consists of microscopic granules having a complex internal structure. At room temperature, these granules are insoluble in water. However, if a starch slurry is heated above 60 ℃ , the granules will swell and eventually rupture. This results in a dramatic increase in viscosity. At this point, the starch has been “gelatinized”. The gelatinized starch is now susceptible to attack by amylase enzymes. In practice, native starch in gelatinized and partially hydrolyzed very rapidly in one step by heat-stable amylase. This step is called liquefaction.

A starch slurry is made with 30% dry solids and its pH is adjusted to 6.0-6.4. Calcium is added using calcium hydroxide or calcium chloride. Calcium ions stabilize the enzyme. A heat-stable amylase is mixed into the slurry, then the slurry is instantaneously heated to 100 ℃ and held at this temperature for 10 min before it is cooled to 90 ℃. This temperature is maintained for 1-3 h to further hydrolyze the starch.

At the end of this step, the starch has been converted to dextrins with a dextrose equivalent (DE) between 8 and 15 which suitable for saccharification to produce syrups with DE values of from 45 to 98 or more.

Starch glucose syrup processing

Glucomylase used for saccharification process:
After liquefaction, the pH is reduced to between 4.2 and 4.5 and the solution is cooled to 60 ℃. A glucomylase is added immediately. The reaction time for saccharification is usually between 4-48 hours depending on enzyme dose and final glucose syrup DE requirement. Glucoamylase releases single glucose units from the ends of dextrin molecule. Glucose syrups of 95% glucose or higher are manufactured .

The saccharified glucose syrup is filtered to remove fat and denatured protein released from the starch granules and may then be purified by passage through activated charcoal and ion-exchange resins . Then the purified glucose syrup will be evaporated at vacuum to remove the extra water to get the required density glucose syrup.

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