7.Protein Ingredients

Picking Out Proteins
1.What is the benefit that provided by wheat protein?

Wheat proteins are essential to our daily bread. Gliadins and glutenins are the two proteins in the wheat endosperm that are most responsible for the formation of an elastic dough. As the flour is hydrated and kneaded, the proteins partially unfold to allow hydrophobic groups to interact with each other and allow disulfide bonds across cysteine amine groups. A correct balance of glutenin and gliadin proteins gives bread dough the elasticity and extensibility required.Wheat proteins can provide other functionality. ADM, Decatur, IL, has developed functional wheat protein isolates that enhance the taste, texture and appearance of cereal clusters, baked products and snacks. In addition, they increase protein content without altering flavor, and reduce bitterness in whole-grain applications. They can be dissolved in water at relatively high concentrations for use as a sugar-free adhesive, and act as an economical replacement for dairy or egg proteins.

2.Describe the foaming ability of egg white.

Egg white, or albumen, consists nearly exclusively of water and protein. Glenn W. Froning, Ph.D., food science and technology advisor, American Egg Board, Park Ridge, IL, says the two top applications of egg white are foaming and gelation, or binding, in surimi and meat products. He adds that the desired functionality, high-foaming or highgelling, can be achieved by proprietary methods, and that hotroom pasteurization improves both. Whipping air into egg white causes the proteins migrate to the interface of the air and water, with the hydrophobic groups toward the air and hydrophilic groups toward the water. The molecules at the interface unfold, or denature, to form a film that traps the air. The foaming ability is diminished by contamination by the yolk and enhanced by whipping aids, such as sodium lauryl sulfate, according to Froning. Fresh, frozen and dried egg white can all form a foam, he adds. Meringues are based on an egg-white foam. When heated, the protein denatures and aggregates to form a gel that binds the ingredients together. Egg whites can also clarify broth by trapping particulates as they set. Lysozyme, an enzyme in egg white, lyses certain bacteria.