12.Enzymes

__Understanding Enzyme Function in Bakery Foods__ 1.Where are the amylases used in the bakery food come from?

Amylases used in bakery foods come from three primary sources.
 * 1) Malt ingredients. As previously mentioned, flour contains naturally occurring amylases. The same is true for cereals other than wheat. When a cereal kernel becomes moist and germinates, it experiences a dramatic increase in alpha-amylase. Consequently, malting grains such as barley and wheat can serve as the basis for many alpha-amylase-containing ingredients. (For a discussion of the malting process, see "Grains: The Bottom of the Pyramid at the Center of Attention," in the September 1994 issue of **Food Product Design**.)
 * 2) Fungal amylase. During growth, certain fungi synthesize alpha-amylase. Cultures of Aspergillus oryzae are extracted, concentrated and dried to yield fungal amylases. These are available both in ready-to-use tablet form and blended to a predetermined activity with flour or starch to yield a powdered form. Fungal amylases can be used to standardize wheat flour, but are most often added at the production facility to aid with dough conditioning.
 * 3) Bacterial amylase. Certain bacteria, such as Bacillus subtillis, also synthesize alpha-amylase. This can be extracted and dried much like fungal amylases. Bacterial amylases, however, tend to be more thermally stable and are, therefore, useful for maintaining softness in finished baked products.

2.What are the methods that used to determine the enzyme activities?

On top of the tremendous number of standardized tests, individual enzyme suppliers often have a custom method of determining enzyme activity. This presents a challenge to product designers trying to compare activities in order to predict usage levels and cost impact. The goal of most methods of measuring enzyme activity is to determine how quickly the enzymes convert substrate molecules to product molecules. Because of this, the activity measurements often have little to do with the enzyme's activity in actual use, particularly in baked products. Designers will probably wish to create their own assay by testing enzymes at different levels in actual doughs. The observed effects can then be related to the amount of enzyme added. By using the level of activity per gram of enzyme as the measuring unit, product designers will have a common basis for comparing enzymes. In addition, the activity measurement will include a weight that can be directly related to the price of the ingredient in order to determine the cost of a given degree of effectiveness.