1. FCS-FS-8. Students will discuss why proteins are important in food preparation and preservation.
a. Describe ways in which protein is used in food preparation. b. Identify the essential and nonessential amino acids. c. Compare and contrast complete and incomplete proteins. d. Explain what happens during the denaturation of protein and how the process occurs. e. Explain coagulation and apply basic principles of the chemistry of protein to cooking eggs, milk, and meat products and in creating egg foams and meringues.

2. Proteins
Proteins have a role in both living organisms and in food products
Primary food sources
Eggs, dairy products, meats, poultry, and fish
Grain sources

3. Proteins in our Body Structural Protein is needed by every body cell.
Helps to replace and repair cells
Most of the bodies hormones and enzymes are largely proteins.
Some proteins pick up, deliver, and store nutrients in the cells.
Antibodies (proteins) help ward off disease.
Help to stabilize pH levels
Proteins can supply energy but only when the body is starved of carbohydrates (this is not good for the body)

4. * Nitrogen is not a component in other nutrients ONLY PROTEIN
Protein Molecules
These are large and complex & often called MACROMOLECULES (large molecules containing many atoms).
Protein molecules are made of the following
Hydrogen
Carbon
Oxygen
Nitrogen
Sometimes other elements
* Nitrogen is not a component in other nutrients ONLY PROTEIN

5. Protein structure
Protein molecules are made up of a chain of acids that contain carbon molecules called amino acids
There are 20 amino acids in the human body, and about 150 others found in plants and animals

6. Amino Acids
Amino acids can be classified into two groups: essential and non-essential
There are 20 AA’s found in the body
12 Non-essential AA’s can be made by the body
This leaves 8 essential AA’s that MUST BE SUPPLIED BY THE DIET
The body must have these to grow new tissue and maintain its health

7. The essential AA’s are as follows:
Isoleucine (eye-suh-LOO-seen)
Leucine (LOO-seen)
Lysine (LYE-Seen)
Methionine (muh-THIGH-Uh-neen)
Phenylalanine (fen-ul-AL-uh-neen)
Threonin (THREE-uh-neen)
Tryptophan (TRIP-tuh-fan)
Valine (VAY-leen)
Histidine (HISS-tuh-deen)
*Because histidine is essential only for children, some scientist don’t consider it an essential amino acid.

8. COMPLETE and Incomplete Proteins
Foods that contain all eight essential AA’s are called complete proteins
Most of these sources come from animal products, with the soybean plant also added to the list
Foods that are short of one or more of the essential AA’s are called incomplete proteins
Most of these are found in grains and vegetables
Combining these will create an essential AA (examples):
Whole wheat bread and peanut butter
Rice and red beans
Refried beans and corn tortillas

9. Proteins in Foods
High sources of protein in the diet would be considered…
Eggs
Meat
Fish
Poultry
Legumes provide some protein as well

10. Eggs Eggs contain almost every vitamin and mineral you need.
Eggs lack Vitamin C and Calcium. (calcium is found in the shell)
Protein is the foundation of an egg.
Draw Figure 17-7 on page 262 of the “Food Science” Book.

11. Meat/Poultry We are considering “Meat” the edible portion of mammals
Muscle tissue (the lean part of meat) is
15-20% protein.
Muscle is composed of fibrous proteins called Actin (AK-tin) and Myosin (MY-uh-sin).

12. Fish Fish cooks quicker than meat due to less connective tissue.
When cooking fish is usually considered done when it will “flake with a fork”

13. Nuts & Legumes Carry a rich store of nutrients Cholesterol-free
Fat content range from 0-very high depending on what you are eating.
Nuts are usually too high in fat to be a main source of protein.
Soybeans are composed of 40% protein = to animal protein.
High in fiber
High in polyunsaturated fatty acids
May reduce coronary heart disease
Used to create meat substitutes

14. Denaturation and coagulation of proteins
Denaturation is when the actual nature of the protein is changed.
This usually occurs during food preparation when a protein is heated, agitated, or when chemicals are added to it
The molecules unravel themselves and lose their coiled structure. Creating a looser, less compact structure.
This process is usually not irreversible

15. coagulation of proteins
Coagulation occurs when a protein is heated.
Coagulation is when proteins form clots
Examples include curdling milk to form cheese or cooking an egg.
When a protein is agitated, disrupts the protein structures and causes them to form new positions with other molecules.
When chemicals, such as acids, are added to a proteins, it causes curdling

16. Denaturation and coagulation of proteins
Both of these processes are used to make new foods (ex; milk to cheese) or to prepare foods (ex; cooking an egg)
It is important to remember that denaturation can be over done (over coagulation), which can cause a change in taste and texture of food. It also can ruin a recipe (ex; over agitation of a meringue will cause clots to form)
*Draw FIGURE 17-6
“Food Science” Book
Page 260

17. Functions of proteins
Proteins are used in the preparation of foods in many ways:
Texturize
Proteins can be texturized through denaturation
This process is used to make soybeans into meat substitutes, or to create processed cheeses

18. Functions of proteins, cont.
Gelatin - Gelling agents
Gelatin protein can be heated in water and then cooled; or eggs, milk and sugar can be heated to make a custard
Geltain provides several benefits:
Structure and support
Stabilizer
Thickening agent
Controls ice crystal growth in frozen foods
Gelatin can bind 100 times its weight

19. Functions of proteins, cont.
Emulsifiers
An emulsion is a stable mixture of a fat and a water based liquid
An emulsifier is a molecule that has a polar end and a non polar end and require heat or mechanical action to denature and form the emulsion
Egg yolks are an excellent emulsifier, as is milk and cheese
Food products such as ice cream and mayonnaise require emulsifiers to stay together

20. Functions of proteins, cont.
Foams – air bubbles incorporated and trapped in a protein film by whipping.
Foam is gas suspended in a liquid or semi solid
Foams can be made using proteins such as eggs or dairy by incorporating air, mechanical agitation or by a sudden release in pressure (aerosol can)
Examples of foams are: Meringues, marshmallows, whipped cream, and bread

21. Functions of proteins, cont.
Gluten- an elastic substance formed by mixing water with the proteins found in wheat.
It coagulates when baked and forms an airy texture, such as bread.
Gluten is developed as dough is kneaded which mechanically denatures the protein molecules.