Amylase is a hydrolytic enzyme that helps with fermentation, volume and color in bread.

Amylase

Also known as amylolytic or starch-degrading enzymes


What is Amylase?

Amylase is a hydrolytic enzyme that breaks down starch into dextrins and sugars. It’s made up of a family of starch-degrading enzymes that include:1

  • Alpha-amylase
  • Beta-amylase
  • Amyloglucosidase or glucoamylase
  • Pullulanase
  • Maltogenic amylase

Amylases can work at the same time in perfect synergy. They are key ingredients that extend the textural shelf-life of bread, functioning as fermentation improvers.1

Origin

Amylase is widely distributed in nature. It is present in both plants and animals. Cereal and grains and their flours naturally contain different types of amylase. In cereals, it is found in the endosperm, bran and germ.

Commercial production

Amylase is generally produced by commercial fermentation with bacterial sources such as Bacillus subtilis or B. stearothermophilus, or fungal sources, such as Aspergillus oryzae or A. niger.

Function

Amylases perform the following functions in bakery products:

  • Provide fermentable and reducing sugars.
  • Accelerate yeast fermentation and boost gassing for optimum dough expansion during proofing and baking
  • Intensify flavors and crust color by enhancing Maillard browning and caramelization reactions.
  • Reduce dough/batter viscosity during starch gelatinization in the oven.
  • Extend oven rise/spring and improve product volume.
  • Act as crumb softeners by inhibiting staling.
  • Modify dough handling properties by reducing stickiness.

Application

Features of amylases used in baking include:2,3,4

Type EC number Chemical bond cleaved/Reaction catalyzed Product Application
α-amylase (liquefying enzyme) 3.2.1.1. Random endo-hydrolysis of α(1→4)-D-glucosidic bonds between glucose units in amylose and amylopectin.

Cannot cross a branch point (α-1,6 bond)

Dextrins of 10–20 glucose units

Maltose

Production of starch syrups

Sprouting of cereals

Anti-staling agents

Alpha-amylase has the largest effect on dough properties and bread quality

β-amylase 3.2.1.2 Exo-hydrolysis of α(1→4)-D-glucosidic bonds

Successively removes maltose from the non-reducing ends of starch.

Cannot cross a branch point (α-1,6 bond)

Maltose Sprouting of cereals

Provides food for yeast for optimum product volume and color

Amyloglucosidase or glucoamylase (saccharifying enzyme) 3.2.1.3 Exo-hydrolysis of α(1→4)- and α(1→6)-D-glucosidic Glucose Decreases proofing time in low‐sugar and frozen dough

Production of high DE starch syrups

Provides substrate for glucose oxidase to properly function as dough strengthener

Maltogenic amylase 3.2.1.33 Hydrolysis of α(1→4)-D-glucosidic bonds Small dextrins from amylopectin exterior Anti-staling agent
Pullulanase (debranching enzyme) 3.2.1.41 Hydrolysis of α-1,6-glucosidic linkages Branches of starch Production of starch syrups

Activity of alpha-amylase

α-amylase acts only on damaged and gelatinized starch. Conversion of starch to dextrins and maltose via α-amylase catalysis takes place as follows:5

Starch + H2O → Dextrins + Maltose

Optimal conditions for α-amylase activity are:

  • pH: 5.5–6.0
  • Temperature range: 104–140°F (40–60°C)
  • Contact time between enzyme and substrate: at least 60 minutes of dough processing
  • Water availability: preferably aw of 0.9 or higher
  • Amount of damaged and gelatinized starch substrate
  • Enzyme dosage relative to substrate: Alpha-amylase is usually added to bread formulations at 0.002–0.006% (20 to 60 ppm) based on flour weight.

The enzymatic activity of α-amylase can be quantified analytically. One unit (1U) is defined as the amount of enzyme needed to release 1 μmol reducing groups, i.e. maltose/min from soluble starch at 25°C at pH 7.0.

α-Amylase can also be quantified indirectly using the Falling Number, RVA or amylograph tests.5

Comparative functionalities of amylases from various sources:

Source Purity Heat resistance / thermal stability Side activities Notes
Cereal Low Medium High Can be used in Falling Number (FN) test
Fungal Medium Low Medium Cannot be used in FN test
Bacterial High High Low Extremely heat stable

Over-dose problems

FDA regulation

This ingredient is considered GRAS (Generally Recognized as Safe) in the US by the FDA. It can be used in food with no limitation other than current good manufacturing practices.6

References

  1. Mathewson, P.R. Enzymes, 2nd edition, Eagan Press Handbook Series, AACC International, Inc., 1998, pp. 1–105.
  2. Van Oort, M. “Enzymes in Bread Making.” Enzymes in Food Technology, 2nd edition, Blackwell Publishing Ltd, 2010, pp. 103–143.
  3. Rosell, C.M., and Dura, A. “Enzymes in Bakeries.” Enzymes in Food and Beverage Processing, CRC Press, Taylor & Francis Group, LLC, 2016, pp. 171–195.
  4. Prasada Rao, U.J.S., and Hemalatha, M.S. “Enzymes.” Bakery Products Science and Technology, 2nd Edition, John Wiley & Sons, Ltd, 2014, pp. 276–291.
  5. Bisswanger, H. “Enzyme Assays.” Practical Enzymology, 2nd edition, Wiley-VCH Verlag & Co. KGaA, 2011, pp. 170–174.
  6. Smith, J. “Enzymes.” Food Additives Data Book, 2nd edition, Blackwell Publishing Ltd., 2011, pp. 366–454.