Novel hemicellulases impact baked quality.

As you may know, hemicellulases are enzymes that act on hemicellulose, a polymer of pentose sugars. They are mainly used as an ingredient when baking to improve the quality of dough, improve crumb and crust properties, and increase overall volume. It is possible to develop innovative, high-quality bakery products by making modifications to established baking procedures.

Hemicellulases hydrolyze a range of heteroglycans found mainly in cell walls. They are believed to impact the quality of baked goods. Research at Ireland's National Food Centre involved investigating some noncommercial enzyme preparations developed by the Molecular Glycobiotechnology Group at the National University of Ireland, Galway, to determine their effects on various bread products, i.e., soft rolls and pan breads. Enzyme preparations were included in standard recipes at several levels, and breads were baked using conventional processing techniques.

The products were analyzed on the first and second days after they were baked. Scientists studied primary quality parameters, including volume, crumb firmness, crust color and crumb color. The enzyme preparations affected these properties differently. All preparations increased the product volume as the amount of added enzymes was increased. Maximum volume increases ranged from 4% to approximately 16%.

With regard to crumb firmness, the enzymes varied considerably in their ability to soften crumb at 24 hours, 48 hours and 72 hours after the product was baked. Reductions in firmness of up to 20% of the control bread were observed. No enzyme preparation had any significant effect on crust or crumb color. The heteroglycan breakdown products (oligosaccharide fragments produced by the action of each enzyme preparation) correlated with the quality differences produced by each of the enzymes.

The results obtained indicate that these enzymes clearly have potential use in the production of breads with improved staling properties, shelf life and organoleptic properties. Tests have been underway, in collaboration with the National Food Centre, to evaluate the performance of these and other enzyme preparations from the university in the production of breads made with flours derived from cereals other than wheat, flours that contain higher hemicellulose content, and hemicelluloses with a more complex structure or composition.

Further information. Dr. Maria Tuohy, Department of Biochemistry, National University of Ireland, Galway, University Road, Galway, Ireland; phone: +353 (0)91 524411 / 492439; email: maria.tuohy@nuigalway.ie.