1. Chapter 17-Part 2
Protein in Foods

2. WHERE DO THEY COME FROM?
Variety of sources
Eggs
Meat
Fish
Poultry 2

3. Other Sources of Proteins
Fruits
Vegetables
Grains
Nuts
(They just do not have as many amino acids)

4. Eggs Contain almost every vitamin and mineral you need
Yolks are rich in: -iron -phosphorus -vitamin A -several B vitamins Lacking: -vitamin C -calcium only present in the shells

5. Proteins in Eggs Protein is the foundation of an egg.
Shell contains protein molecules interwoven with calcium carbonate crystals.

6. Structure of an egg Egg Membrane Thin albumen Yolk Thick albumen
Air Pocket
Egg
Membrane Thin albumen
Yolk Thick albumen
Chalaza
Shell membrane

7. Cracking open an egg you first encounter albumen (egg white) – makes up 54% of the inner contents of an egg, known for ovalbumin, a major protein in egg white.

8. Thickest part of the albumen is the Chalaza – a twisted ropelike structure that keeps the egg yolk centered. Last part of the egg to coagulate and may remain slightly watery.

9. Yolk – main components include
Globular protein livetin
High and low-density lipoproteins
Contains all of the fat, along with most of the
other nutrients

10. Effects of Storage
Where should eggs NOT be stored in a refrigerator? Why? It exposes eggs to light and temperature every time you open the door. It hastens chemical changes that ultimately deteriorates the egg.

11. How can you tell if an egg is fresh?

12. Meat Refers to any edible portion of mammals,
Including muscle and fatty tissue

13. Muscle tissue - Lean part of meat
About 15-20% protein
Other components include
Water, fat and minerals
Muscle is composed of
Fibrous proteins called actin and myosin
They form bundles of fibers , held together by
connective tissues made of collagen and elastin
Two proteins with long, strong molecules.

14. Fish
Shorter, segmented muscle fibers are layered between thin sheets of connective tissue

15. Nuts and Legumes
From plants nuts and legumes (dry deans, peas, lentils, soybeans Nuts – peanuts, walnuts cashews Carry a rich source of nutrients

16. Nuts too high in fat to be considered a main source of protein
Cholesterol-free
Range in fat from
Zero to very high
Nuts too high in fat to be considered a main source of protein
Soybeans are composed of 40% protein, their protein is equal to that of foods from animals.

17. Protein in Cooking

18. Emulsifiers – egg yolk, the most common emulsifier
Protein can stabilize oil- and-water mixture
Certain proteins contain amino acids that are polar.
One end of these amino acids is attracted to water while the other end avoids water and bonds to oil.

19. Foams
Air bubbles incorporated and trapped in a protein film by whipping.
Add volume and lightness
Begins when a protein- containing liquid is whipped.
Whipping introduces air and denatures the protein molecules

20. Air bubbles incorporated and
trapped in a protein film by whipping.
Add volume and lightness
Begins when a protein-containing liquid is whipped.
Whipping introduces air and denatures the protein molecules