sliced white bread

Xylanase is an enzyme used in bread making as a dough conditioner.

Xylanase


What is Xylanase?

Xylanase is an enzyme that catalyzes the endohydrolysis of 1,4-β-D-xylosidic linkages in xylan. Xylan is a major structural polysaccharide in plant cells. It constitutes the major component of hemicellulose, which is a component of plant cell walls. naturally present in all biological systems. They can be selectively isolated from plant, animals and microorganisms.

Origin

Xylanase is naturally present in all biological systems. It can be selectively isolated from plants, animals and microorganisms.

Function

Xylanase breaks down the linear polysaccharide β-1,4-xylan into xylose. This releases water and makes it available for gluten hydration. Like other enzymes, it is sensitive to pH, temperature, moisture, ions and ionic strength, shearing and pressure. Xylanase functions best in the range of 30oC to 40oC (86oF to 104oF), and is usually denatured at temperatures above 45oC (113oF).

In breadmaking, xylanase is used in dough conditioners. Wheat flour contains 1% to 3% pentosans. The water-soluble pentosan is an important functional component because it can retain nearly 10 times its weight in water, accounting for almost 30% of the water-binding capacity of wheat flour.1

Water-insoluble pentosans interfere with the gluten network. Xylanase can randomly hydrolyze the pentosan backbone and decrease its degree of polymerization. The use of xylanase leads to improved dough flexibility, machinability and stability, as well as a larger volume and an improved crumb structure.1 Too much xylanase results in a sticky dough that is more difficult to handle.2 The exact mechanism by which xylanase does this is unknown.

Commercial production

Commercial production of xylanase is achieved from microorganisms, especially fungi.

Application

Xylanase is usually blended with other dough conditioners. Information on how to dose xylanase should be obtained from the technical sheet produced by the xylanase manufacturer, especially because different types and strengths of xylanase are available.

Glucose oxidase can be used together with xylanase to avoid the sticky dough caused by over-dosing xylanase.2

FDA regulation

Two forms of xylanase are listed as GRAS on the FDA GRAS Inventory: GRN No. 675 and GRN No. 472.3 Both are produced by Novozymes.

References

  1. Zheng, H., et al. “Improvement of the Quality of Wheat Bread by Addition of Glycoside Hydrolase Family 10 Xylanases.” Applied Microbiology and Biotechnology, vol. 90, no. 2, 2011, pp. 509–515, doi:10.1007/s00253-011-3088-7.
  2. Hilhorst, R., et al. “Baking Performance, Rheology, and Chemical Composition of Wheat Dough and Gluten Affected by Xylanase and Oxidative Enzymes.” Journal of Food Science, vol. 64, no. 5, 1999, pp. 808–813, doi:10.1111/j.1365-2621.1999.tb15917.x.
  3. U.S. Food & Drug Administration. “GRAS Notices.” Accessdata.fda.gov, 18 Aug. 2017, www.accessdata.fda.gov/scripts/fdcc/index.cfm?set=GRASNotices&sort=GRN_No&order=DESC&startrow=1&type=column&search=Intended Use%C2%A4VARCHAR%C2%A4enzyme. Accessed 7 Sept 2017.