Alpha amylases: The effect of storage conditions on cereal alpha amylases, a rapid method for measuring fungal alpha amylases, and their effects on dough rheological properties and francala (a hearth bread) production

In the first section, a laboratory-scale Francala (hearth bread) production procedure and a scoring system were developed to study the effect of alpha amylases. The effects of processing parameters on bread quality were also investigated. Fermentation time showed the most pronounced effect on bread quality. Increasing absorption more than 2% and ascorbic acid more than 40 ppm from the optimum produced undesirable bread.;Cereal alpha amylase is the most commonly used enzyme in baking. Activity losses may occur depending on the storage conditions. The second section investigates the effects of storage temperature (;Fungal alpha amylase is another alternative to cereal alpha amylase. The third section describes a new method for the assay of fungal alpha amylase using a Rapid Visco-Analyser (RVA) procedure modified with the addition of a substrate. Properly treated flour should give end viscosities between 85-95 RVU, corresponding to a 40-50 RVU reduction from the initial viscosity.;The last section examines the effect of alpha amylases from cereal, fungal, and bacterial sources on dough rheological properties and Francala bread attributes. Increasing the enzyme level to 160 SKB units decreased dough stabilities and increased mixing tolerance indexes. Gas production rates with cereal alpha amylase were higher than that with fungal alpha amylases, indicating more activity during fermentation. A higher adsorption rate occurred with cereal alpha amylase. Dough stability is very important for Francala production, as it is for other hearth breads. Spread ratio tests on fermented doughs and dynamic rheological properties of flour-and-water doughs showed significant changes in dough rheological properties as a function of alpha amylases. As a guide, the dough spread ratio should not be higher than 2 for desirable bread. An increase in bread volume and optimum bread attributes were obtained with the addition of 40 SKB cereal or 80 SKB fungal alpha amylases. Bacterial alpha amylase at 20 SKB gave a gummy and open crumb grain; the responses from the two sources of bacterial alpha amylases were also different.