Protein Chapter 5 Learning Objectives Define protein and

Protein Chapter 5

Learning Objectives � Define protein and explain the difference between essential and nonessential amino acids. � Compare and contrast the nutrients in animal and plant sources of protein � Distinguish between complete and incomplete protein and give two examples of how to complement proteins. � List five functions of protein in the body. � Explain how protein is digested, absorbed, and metabolized. � State the dietary recommendations for protein and explain the potential consequences of eating too much or too little protein.

Learning Objectives (cont’d) � Explain the concept of denaturation, or what happens to protein when it is cooked. � Identify six examples of meat, poultry, and fish that are moderate in fat and saturated fat, and describe three preparation techniques for balanced meat, poultry, and fish menu items. � Give two examples of how to menu and/or present balanced meat, poultry, and fish items. � List three benefits of vegetarian diets, use a vegetarian food guide to plan a balanced meal, and list nutrients (and their sources) that may be low in some vegetarian diets.

The Basics of Protein � Protein: Nutrients in all living cells in animals and plants that have important roles. � Whereas carbohydrates and lipids are used mostly to give you sources of energy, protein functions to build and maintain your body. � Protein ◦ ◦ ◦ is in your: Hair Skin Muscles Blood Nails And all your cells!

Amino Acids: Building Blocks of Protein Essential amino acids Amino acids that either can’t be made in the body or can’t be made in the quantities needed – so you have to get them from food. Nonessential amino acids These are made in the body.

Amino Acids � Like carbohydrates are made of sugars and lipids are made of triglycerides, proteins are made of long chains of amino acids � Amino acids are literally the building blocks of protein � Each consist of a backbone and a side group. � The backbone is the same for all amino acids, but the side group differs and makes each amino acid unique � There are 20 essential and nonessential amino acids

Amino Acids � Essential ◦ ◦ ◦ ◦ ◦ Histidine Isoleucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine � Nonessential ◦ ◦ ◦ Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Proline Serine Tyrosine

Genes are tiny sections of DNA (genetic material) that have codes to make proteins.

Enzymes �Enzymes are catalysts. They speed up reactions. �Various substances pass thru the enzyme, undergo a reaction and exit in a new form. �They help do the following ◦ Break down substances (catabolism)- digestion ◦ Build up substances (anabolism)- building bones ◦ Change one substance into another- fructose and galactose into glucose

Hormones � Chemical messengers secreted into the blood stream. Target specific organs and influence what they do. Pancreas secretes insulin when blood sugar goes up after you eat. Insulin stimulates the transport of sugar from the blood into your cells, resulting in a lower blood sugar level. � Homeostasis a constant internal environment in the body. All hormones strive to maintain homeostasis in the body

Antibodies � Bind with foreign bodies or invaders, called antigens, in the body (virus, bacteria, toxins). � Each antibody fights a specific invader, they are unique. When you are exposed to a certain antigen, you build up antibodies. The body remembers these the next time you encounter the antigen, your body can fight off the invasion more effectively � Immune system The body’s response to a foreign substance

Protein in Food and Protein Quality �One ◦ ◦ ◦ ◦ ounce of meat, poultry, or fish = 1 egg 2 tablespoon peanut butter ½ ounce nuts (12 almonds, 7 walnut halves) ½ ounce of seeds ¼ cup of cooked beans or peas ¼ cup tofu Animal proteins 1 ounce tempeh, cooked usually have more protein, fat, saturated 2 tablespoons hummus fat, and cholesterol than plant proteins.

Complete vs. Incomplete Proteins � Complete proteins ◦ Animal proteins ◦ Contain all the essential amino acids in the proportions needed by the body. � Incomplete proteins ◦ Plant proteins (except soybeans and quinoa) ◦ Dried beans and peas, grains, vegetables, nuts, seeds ◦ Low in one or more essential amino acids —called the limiting amino acid.

Complementary Protein The ability of two protein foods to make up for the lack of certain amino acids in each other when eaten over the course of a day.

Protein Pairings

Functions of Protein 1. 2. 3. 4. 5. 6. 7. 8. Act as a structural component of the body Builds and maintains the body (collagen) Found in many enzymes and hormones Found in all antibodies Transports iron, minerals, fats, and oxygen around the body Maintains fluid and acid-base balance Provides energy as last resort Helps blood clot

Digestion, Absorption, and Metabolism � Protein digestion begins in the stomach � Stomach: stomach acid (hydrochloric acid) helps uncoil proteins so enzymes can start separating amino acids. � Small intestine: enzymes break down proteins into single amino acids and some small proteins which are absorbed. � Amino acids travel in blood to the liver. � Amino acid pool provides cells the amino acids they need. If one is not available to build a protein, the protein is not made, and the amino acids are recycled

Dietary Recommendations for Protein �RDA: 0. 8 grams of protein/kilogram OR 0. 36 grams of protein/pound (your weight). ◦ 140 lbs x. 36 = 50 grams of protein daily �You should eat protein from both animal and plant sources. �The amount of protein you need is proportionally higher during periods of growth such as infancy, childhood, and pregnancy.

Dietary Recommendations �It is best to eat your protein evenly across your meals because it: ◦ Makes you feel fuller ◦ Helps the body maintain muscle tissue — especially as you get older �Endurance and power (strength or speed) athletes can benefit from more protein

Health Effects of Protein � Eating excessive protein does NOT: ◦ Result in bigger muscles ◦ Give you stronger bones ◦ Pump up your immune system � Eating too much protein can: ◦ Result in too many kcalories taken in and weight gain (fat, not protein) ◦ Result in high cholesterol if too much animal protein Plant sources of protein contain less fat (except for nuts/seeds) and more fiber.

Health Effects of Protein �Diets high in processed meats and/or red meats have been linked with a higher risk of colon cancer. �Eating too little protein can: ◦ Slow down repair of the body. ◦ Weaken the immune system.

Culinary Focus: Meat, Poultry, and Fish � Denaturation: The process in which proteins become firm, shrink in size, and lose moisture as they are cooked or whipped. � Causes: Heat- frying an egg, protein is denatured and turns white. In bread, gluten denatures and gives bread structure, gives meats a firm texture Acids and bases- marinades, acids Agitation and whipping- tenderizing a steak, whipping egg whites High salt concentration- curing meats, beef jerky Ultraviolet radiation- skin cancers

Culinary Focus: Product �Most fish is lower in fat, saturated fat, and cholesterol than are meat and skin on chicken and turkey. �Compared to red meat, skinless white meat chicken, and turkey are similar in cholesterol but lower in total fat and saturated fat. �Poultry skin can be left on during cooking, then removed for service.

Culinary Focus: Product �Lean ◦ ◦ ◦ ◦ cuts of beef: Bottom round steak or roast Flank steak Eye round roast Top sirloin steak Tenderloin filet Top round roast or steak 90/10 or 95/5 ground beef

Culinary Focus: Product Other lean animal proteins: �Lamb: Loin or rib chop, top round �Veal: cutlets �Pork: pork tenderloin, top loin chops �Poultry: breast (skinless or skin removed after cooking) �Seafood: all fish and shellfish Fish and shellfish are relatively low in kcalories and low to moderate in cholesterol.

Culinary Focus: Preparation �Use flavorful rubs—dry or wet. The larger the protein is, the longer the rub can stay on. The rub flavors the exterior. �Marinades build flavor profiles naturally so you don’t need as much fat, cream, or sauces. �To give marinated foods flavor, try minced fruits and veggies, low-sodium soy sauce, mustard, fresh herbs, and spices.