What Are the Factors That Affect the Activity of Fungal Alpha Amylase?

Fungal alpha amylase is a food grade alpha amylase produced by fermentation of Aspergillus oryzae, which can be used for starch dextrinization and saccharification. Fungal α-amylase enzyme is an endo-amylase, which can rapidly hydrolyze the (a-1,4 glycoside) chains in the aqueous solution of gelatinized starch, amylose and amylopectin. Dextrin after liquefaction of starch combines with fungal alpha amylase L-40000 to produce syrup with high maltose and low glucose content. These high maltose syrups are relatively non-hygroscopic and exhibit a downward trend towards the crystalline state and high levels of fermentability. What are the factors that affect the activity of fungal alpha amylase?

1. The pH value affects fungal α-amylase activity: the best pH value range: pH5.0-6.0

The optimum pH range of fungal alpha amylase at 40°C is 4.8-5.4, and it can effectively hydrolyze starch in a pH range of 4.0-6.6 at 40°C. It is most stable in the range of pH 6.0-8.0. If it is necessary to hydrolyze starch under conditions unfavorable to the stability of the enzyme, the pH value should be above 5.5. If a high reaction rate is the primary goal, the pH needs to be below 5.5.

2. Temperature affects fungal α-amylase activity: optimal temperature range: 50-60 °C

The optimum temperature for this enzyme is 55°C and can effectively hydrolyze starch in the temperature range of 45-55°C. If the starch content is high, the ability of this enzyme to hydrolyze starch can be exerted at a temperature not exceeding 65°C. Depending on the pH, the optimum temperature is 45-65°C.

3. Inhibitors affect fungal α-amylase activity

Several heavy metal ions can inhibit this enzyme. Copper and lead are strong inhibitors. When the content is higher, zinc, nickel and iron ions can also play an inhibitory role.

4. Substrates affect fungal α-amylase activity

Fungal alpha amylase can be used to dextrinize and gelatinize corn, potato, tapioca, wheat, soybean and various other starches. Starch content up to 50% on a dry matter basis (DSB) can be effectively hydrolyzed. High starch content (30%-50% DSB) can deactivate the enzyme preparation without adjusting to inappropriate temperature and pH.

The method for inactivating the fungal alpha amylase: the fungal alpha amylase can be inactivated by keeping it at 90-100°C for 5-10 minutes. When the starch content is high, it can be inactivated in about 30 minutes at 80 °C, and can be inactivated in about 60 minutes at 70 °C. If high temperature is not desired to stop fungal alpha amylase activity, the pH can be lowered outside the usable pH range to inactivate the enzyme. Inactivating enzymes sometimes requires both pH and temperature adjustments.

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