The raw material in the baking industry is flour: a mixture of starch, protein (gluten), lipids, glucan and some wheat (naturally-occuring) enzymes. The most important enzymes contained in flour for the baking process are the amylases and proteases.
a-amylases produce dextrins, which are further broken down to sugars by naturally occuring b-amylases, thus improving yeast fermentation, bread volume and crust colour.
Dextrins formed by the action of a-amylases also reduce staling rate, thereby prolonging the freshness of baked products.
The a-amylase content of the flour is greatly dependant on the conditions of growth and harvesting as it increases during germination. This content must be supplemented or diluted to a suitable value in order to achieve a good quality bread without damaging the operational qualities of the process.
The proteases act on the protein material, weakening the gluten.
Proteases from various sources are commonly used to optimize the rheological properties of bread doughs made from strong wheat or, in biscuit and wafer production, to reduce gluten elasticity.
Hemicellulases (or cellulases and pentosanases) are used to improve the baking properties of stiff rye flours. Hemicellulases can also be used to improve dough properties and bread quality in the production of wheat breads.
Another known enzyme application in the baking industry is the use of lipoxygenases which are added to the dough by addition of soya flour or in improvers to whiten the bread.
Combined addition of oxidative and hemicellulolytic enzymes improves dough and bread properties and is a good alternative to the chemical additives, such as potassium bromate, whose use is being increasingly restricted by legislation (J. Tramper, 1994 7).
The addition of extra enzymes to the dough enables the baker improved control of the baking process, the advantages being: