Blog Directory - Blogged foodliterate: What's My Function?

Monday, November 12, 2007

What's My Function?

Welcome back! So, we've covered what proteins are & how to score them. Now it's time to talk functionality. Why are they added to the foods you purchase and how do food scientists decide which ones to use where?

What do proteins do in food systems? They serve to provide structure & stability to food. Just a few of the functions they serve include: water binding, viscosity, emulsification, foaming, gelation, dough formation and texturizing. Proteins have primary, secondary & tertiary structures. This link is for chemistry junkies or those who want to understand the specifics. These structures and the protein's size, shape, charge, amino acid profile, hydrophobicity/hydrophilicity (water fearing/loving) and flexibility or rigidity determine how the protein will behave and interact with other food components.

Denaturation, the breaking of the protein chains and rearrangement of their structure, is how to accomplish changes in function. The behavior of proteins can be altered with denaturation by chemical (acid, salt), physical (heat, agitation), and/or biological (enzyme) means. How about some examples?

We add salt to meat proteins to draw out the soluble proteins, which are very sticky, to allow us to make formed products like boneless hams and luncheon meats. We add rennet (an enzyme) or acid to milk to separate the casein proteins from the whey proteins and then innoculate with specific cultures, press, salt, and age to turn the casein proteins into cheese. Whey proteins, which are highly soluble, are added to beverages to give them a protein claim (like Accelerade®). Gliadin & glutenin (wheat proteins) are worked to produce gluten which gives bread its structure and elasticity. And egg proteins (albumen) can be whipped to make a foam for cakes and souffles. Most of the time, multiple proteins are used - like milk, cereal and egg - to obtain the desired finished product and for nutritional and economic reasons.

Proteins also play an important role in flavor-producing interactions. The wonderful smell of baking bread comes from the interaction of the amino acids in the cereal protein reacting with reducing sugars (aka the Maillard reaction.). Water binding is another important protein function since it is needed for viscosity & gelling which impacts the texture of foods (think juiciness or tenderness). For those who want more information on where we use certain proteins and why, this is a great article.
Ahh, time for a summary of our protein discussion. You've learned that proteins are chains of amino acids and that they differ from carbohydrates & fats because proteins contain nitrogen in addition to carbon, hydrogen & oxygen. You know proteins are required by our bodies to make glycogen, blood plasma, muscle & connective tissues, hormones & enzymes, and quite a few other processes. You've learned that there are 20 amino acids, 9 of which are essential because our bodies cannot produce them and must be obtained through the foods we eat. And that the proteins with the most complete sets of essential amino acids have the highest protein quality scores. And now you've learned why proteins are so important to the manufacturing of food products and why certain proteins are chosen for certain applications.

My next post will be about a very specific protein in honor of Thanksgiving - yes the Turkey. So, if you have specific questions about protein, its structure, function or uses, send me an email or comment on my post and I will be happy to provide you with the information you seek!

1 comment:

Unknown said...

i am vegiterian i want to go for body building could you tell me suitable diet specially in matter of proteins. thank you.