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PROTEINS
What are proteins?
Proteins are complex molecules that make up as much as 50% of the dry weight of living cells.
These molecules are composed of carbon, hydrogen and oxygen.
In addition, proteins contain nitrogen and usually sulfur.
Some proteins also contain iron, copper, phosphorus or zinc.
Why do we need protein?
Support Growth and RepairFight DiseaseMaintain Fluid and Mineral BalanceMaintain pH BalanceControl Bodily FunctionsProvide Energy
Primary sources of protein Eggs
Diary Products
Meat
Poultry
Fish
Structure of Protein
Protein molecules are made up of subunits called amino acids.
There are 20 amino acids in the human body.
Proteins are chains of many amino acids bonded together.
Structure of Protein
When two amino acids combine, a water molecule is released.
The bond between them is called a peptide bond.
A dipeptide is a protein molecule made up of two amino acids.
A polypeptide is made up of many protein molecules.
Structure of Protein
http://www.youtube.com/watch?v=Q7dxi4ob2O4
Structure of Protein
20 amino acids used in the body are necessary for growth and body functions.
8 of them are essential amino acids meaning they cannot be produced by the body.
The essential amino acids must be supplied by foods in the diet.
There is a ninth amino acid called histamine that is essential for infants.
Structure of Protein
Foods that contain all 8 essential amino acids are called complete proteins.
Most complete proteins come from animal sources.
Foods that do not contain all 8 essential amino acids are called incomplete proteins.
Incomplete proteins also known as limiting amino acids come from plants.
Plant sources
Many people around the world get their source of protein from cooked dry beans, nuts and seeds.
Combining legumes with grains, nuts or seeds will generally create a complete source of protein.
Eating less animal-based protein reduces the amount of saturated oils and cholesterol you ingest.
Plant Source Combinations
Whole wheat bread and peanut butterRice and red beansRefried beans and corn tortillasHummus – a dip made with chickpeas
and sesame seeds
How much Protein do we need?
A 154lb man needs to consume 56g of protein daily.
A 120lb woman should consume 44g of protein daily.
How many grams of protein should you consume in a day?
AMERICAN DIET
On average, men consume 90g/day and the women consume 70g.
Our intake his high because we eat meat with every meal.
A single serving of meat is considered to be 3 oz. Few of us have this portion.
The daily requirement is 5-7 oz.
In one meal we can get all of the protein needed in one setting.
1 ounce = 28 grams
DENATURATION OF PROTEIN
The loosening or unfolding of the protein molecule.
Is usually not reversible.Methods of denaturation include:
Temperature ChangeMechanical ActionChemical Action
FUNCTIONS IN FOOD
Form GelsTexturizeEmulsifyForm FoamsDevelop Gluten
EGGstra Information Eggs lose CO2 through the eggshell and the
pH changes from neutral to basic. The change in pH causes the proteins to break
apart. Over time the water in an egg moves into the
yolk. This action stretches and weakens the yolk
membrane. So, fresh is better for separating and for frying.
EGGstra Information
High Heat + Long Time = Firm Egg White
Low Heat + Short Time = Soft Egg White
EGGstra Information
Hens lay fewer eggs during the winter months.
When eggs are plentiful they are dipped in mineral oil and put in cold storage.
Eggs are more expensive between Christmas and Easter.
MOO NEWS
Two common problems can occur when cooking milk.Curdling – when protein molecules in milk
unfold and stick together.Scorching – when protein clumps formed by
heat sink and then burn on the bottom of the pan.
COOKING MEAT
MOST MEATS CONTAIN 3 CATAGORIES OF PROTEINS:Muscle FibersConnective TissueMyoglobin
One of goals in cooking meat is to soften the connective tissue
COOKING MEAT
The most important goal in cooking meat is to reach the recommended internal temperature for the meat you are cooking.
Checking meat with a food thermometer will ensure that meat and poultry are cooked to the desired degree of doneness.
Improper cooking can result in bacterial contamination
HEATLH NEWS
IT IS VERY IMPORTANT THAT POULTRY AND PORK ARE COOKED TO RECOMMENDED TEMPERATURE.
HOW WOULD YOU KNOW IF YOU DID NOT COOK IT? IF IT IS NOT SMOKED, IT SHOULD NOT BE
PINK. IF THE MEAT JUICE IS PINK, IT IS NOT DONE. HOWEVER DARK RED STAINS NEAR BONES IN
POULTRY DO NOT RELATE TO DONENESS.
MYOGLOBIN
An iron-containing protein that holds oxygen in muscle tissue.
Gives meat its bright red color. Not to be confused with hemoglobin that is
found in the blood. The red juice from raw meat products is not
blood, it is water with dissolved myoglobin.
MORE ON MYOGLOBIN
PORK IS LIGHTER THAN BEEF BECAUSE IT CONTAINS LESS MYOGLOBIN.
POULTRY BREASTS AND WINGS ARE LIGHTER THAN LEGS AND THIGHS BECAUSE OF MYOGLOBIN.
BREAST AND WINGS ARE DESIGNED FOR SUDDEN USE AND BURN GLYCOGEN, WHICH DOESN’T REQUIRE OXYGEN, FOR ENERGY.
EAT LESS MYOGLOBIN
