Meat and Egg Cooking Science

Meat and Meat Products, Eggs and Legumes, Nuts and Oilseeds

• Meat contains protein, fat, minerals, and vitamins
• It is one of the most important protein sources due to its high-quality protein content and high protein ratio
• The proportion of protein and fat in meat varies depending on whether the meat is lean or fatty
• Fatty meats have a higher saturated fatty acid and cholesterol content
• Fish, especially, are a significant source of omega-3 fatty acids
• Meat should be included in the diet during periods of increased protein requirements, such as infancy and childhood
• Meats are lean in vitamin C, vitamin E, and calcium. However, they are rich in vitamin B12, iron, and zinc
• The iron found in meat is highly bioavailable, making it significant in preventing iron deficiency anemia
• Individuals with certain conditions, such as coronary artery disease, diabetes, or hypertension should prefer lean red meat, skinless white meat (chicken, turkey), fish under the supervision of a dietitian.
• Fish meat contains proteins equivalent to red meat and poultry, such as chicken and turkey
• Marine fish are a good source of iodine
• Fatty fish, especially, are rich in n-3 (omega-3) fatty acids, and it is recommended to consume fish at least twice a week for a healthy diet
• Adequate dietary intake of n-3 fatty acids is crucial for the prevention of cardiovascular diseases and for brain development in children
• Various meat products are made through different processes
• Chemicals like nitrites and nitrates are used in the production of salami and sausages to prevent color changes and inhibit microbial growth
• Harmful substances produced by these chemicals can be neutralized or eliminated with antioxidants such as vitamins C and E
• When consuming such products, include fruits and vegetables rich in vitamins C and E in the diet
• Consumption of processed products should be limited due to their high saturated fat content

Meat Consumption (Red Meat, Poultry, Fish, and Seafood)

• United States: 82 kg/year
• In our country, it's 19 kg (52 g/day)
• Denmark: 60 kg/year
• % of individuals who do not consume red meat: 20%
• % of individuals who consume chicken once or twice a week: 42.9%
• % of individuals who do not consume fish: 39%
• In the 2010 TBSA study, 6.4% of adults consumed red meat every day or more than once a day in the past month
• 56.9% of adults consumed red meat only 1-2 times per month or never.

Structure of Meat

• As connective tissue increases, meat toughness increases
• The connective tissue is higher in parts of the animal that are highly active
• Muscle tissue, connective tissue—Collagen, Elastin
• Collagen hydrolyzes into gelatin at 60-80°C
• Elastin does not hydrolyze

Meat - Protein

• Actin, Myosin
• Actomyosin is important for muscle movement
• During Muscle Movement: Actomyosin + ATP
• During Muscle Relaxation: Kreatin-P → ATP + Kreatin
• Myogen (play a role in muscle contraction and structure)
• Albumin (maintaining osmotic pressure)
• Myoglobin: Gives red meat its characteristic red color

Rigor Mortis

• After slaughter, muscle movements continue, but oxygen intake is cut off
• This leads to the formation of lactic acid, causing the muscle to harden
• As the meat rests, the acids formed through metabolism increase the meat's ability to retain water
• With the action of enzymes, the hardness disappears
• Depending on the type of animal and the temperature at which the meat is stored
• In poultry, rigor mortis disappears within 1 hour
• In large animals (cattle, sheep), rigor mortis resolves in 10 days at 0°C and in 3 days at 15°C
• Animals with less fat lose rigidity faster

Meat- Composition

• Saturated fats (palmitic, stearic fatty acids)
• Minerals and some organic components
• Small molecules containing creatine and amino acid nitrogen
• Freshly slaughtered animal meat → Glycogen → Ç

Factors Affecting the Flavor of Meat

• Meat tenderness depends on species, age, fat content, diet, connective tissue, and nutritional condition
• Meat from poorly fed and/or highly active animals tends to be tough
• As fat content increases, tenderness increases
• Milk-fed lamb has a higher water content and is not as flavorful as meat from animals slaughtered at the optimal age
• Cooking method is applied depending on the type of meat and its connective tissue content
• Raw meat proteins → Proteins denature → Meat solidifies → Water loss
• If water loss is excessive, the meat becomes dry, negatively affecting its flavor
• Increased connective tissue makes meat tough when cooked with dry heat
• Collagen is hydrolyzed, making the meat tender when cooked as ground meat with moist heat

Changes in Meat During Cooking

• Proteins coagulate, and water is lost
• In moist heat, the connective tissue protein collagen is hydrolyzed, which helps tenderize the meat
• Myoglobin → Metmyoglobin (denaturation), resulting in a brown color
• Nitrogenous molecules (amines, hydrogen sulfate, and organic acids) are formed, enhancing flavor
• Melted fats + gelatin = forms a fatty gel when cooled
• Some vitamin loss occurs in meat cooked at high temperatures
• Heat and water loss result in a reduction of folic acid, B1, and B12 vitamins
• In baking, grilling, and frying, the loss of B vitamins depends on temperature and duration, ranging from 0% to 40% (average: 20%)
• In moist cooking, if the cooking water is not used, the loss can reach 70% (Thiamine is lost the most)
• Cooking with minimal water and retaining the cooking liquid prevents any loss
• Nitrosamines are formed in partially charred meat cooked at very high temperatures (deep frying in hot oil) or in close contact with fire (grilling), exhibiting carcinogenic activity

Meat Cooking Methods

• Dry Heat Cooking: Grilling, oven roasting, cooking in oil-free or lightly oiled heavy-bottomed pans
• Moist Heat Cooking: Kebabs, steaks, and chops cooked over low heat; water can be added. Examples include tray-baked chops, oven kebabs, and meatball dishes
• Frying in Oil: Meatballs. If the oil is too hot, the outer surface solidifies, making it difficult for heat to penetrate the interior.

Foods Made from Meat

• Sausage and Sucuk (Dry Fermented Sausage): Meat → Minced → Salt + Spices added → Stuffed into animal intestines, gelatin, or cellulose casings
• Salami and Pastrami: After partial drying, the meat is seasoned with spices
• Cold Cuts: Meat is boiled and cooked, then pressed together with gelatin under pressure to form cold cuts
• Kavurma (Braised Meat): Meat is braised as ground meat or in small pieces. It is preserved by sealing it with a layer of fat on top.

Health Standards for Meat

• Meat must come from healthy animals
• Diseases transmitted from animals to humans: intestinal parasites (such as tapeworms), bacterial diseases (anthrax, glanders, tuberculosis, salmonella), cattle plague, foot-and-mouth disease, smallpox, mad cow disease (Bovine spongiform encephalopathy)

Meat Storage

• Minced meat should not be kept in the refrigerator for more than 1 day
• Whole cuts of meat can be stored for 2-3 days in the refrigerator
• Meats should be divided into portions suitable for cooking and wrapped in parchment paper before freezing
• Frozen meat should be thawed in the refrigerator
• Thawed meat should not be refrozen

Meat Inspection Marks

• Edible Meats - Circle Shape
• Edible Low-Quality Meats - Circle shape
• Edible Meats After Proper Cooking - Square shape
• Meats to Be Discarded - Triangle shape

Poultry Meats

• Domestic Fowl (Poultry)- Fat↓, Energy↓, Saturated Fat and Cholesterol↓, Protein ↑, Iron ↑, Riboflavin, Niacin, B6, B12
• Red Meats- Fat ↑, Energy ↑, Saturated Fat and Cholesterol ↑, Protein ↓, Iron ↑

Seafood

• Consumption: Annual per capita consumption is 3 kg, comprising 65% fresh and 35% dried, salted, or canned products.
• Nutritional Value: High-quality protein, rich in vitamins A, K, and B; contains iodine, phosphorus, and zinc
• Energy: Fatty fish have higher energy content
• Unsaturated Fatty Acids: Contains high levels of omega-3 (n-3) fatty acids
• Calcium Intake: Consuming fish with bones increases calcium intake
• Health Benefits: Increased fish consumption reduces the risk of coronary heart disease

Fish

• Eyes: Bright and clear, free of blemishes
• Gills: Reddish-pink in color
• Scales and Fins: Firm, intact, and in good condition
• Odor: No unpleasant or fishy smell
• Press Test: When pressed, the indentation from a finger quickly bounces back

Fish Storage

• Short-Term Storage: Store in ice or at temperatures below 0°C (32°F)
• Long-Term Storage Methods: Freezing (fresh fish frozen at -32°C (-25.6°F) and stored at -18°C (0°F) for 3-6 months), Salting (Preserves fish by curing it with salt), Canning (Processed and sealed in airtight containers for extended shelf life), and Drying (Fish is dried to remove moisture for preservation)
• Shelf Life of Salted and Dried Fish: Varies between 6-12 months depending on storage temperature and humidity conditions

Fish Meal

• Fish meal is flour made from fish, processed into meal form in factories, used to enrich low-quality protein sources, and commonly utilized as animal feed

Fish Cooking Techniques

• Low connective tissue in fish: Causes it to break apart easily during cooking
• Fatty Fish: Best suited for grilling or steaming in its own juices (e.g., poaching or en papillote)
• Lean Fish: Ideal for frying. To prevent the fish from falling apart, coat it in flour before placing it in hot oil

Egg

• 11% Shell
• 58% Egg White
• 31% Egg Yolk
• Egg White Proteins: 63% Albumin, Remainder consists of mucin, mucoid, and avidin
• Egg Yolk Proteins: Mainly vitellin and phosvitin

Egg - Composition

• In Our Country: Average per capita egg consumption is 4 kg per year. The percentage of people who consume eggs daily is 30%.

Turkish Food Codex Egg Regulation

• Class A Eggs: Obtained from Gallus gallus var. domesticus, intended for direct human consumption or food industry use.
• Eggshell: Clean, intact, with normal shape, slightly rough texture
• Air Cell: For “extra fresh” eggs, ≤4mm; for others, ≤6mm
• Egg White: Should be clear, transparent, jelly-like
• Egg Yolk: Round shadow in the center, not visibly separate from the center, and should not contain foreign matter
• Embryo: No visible embryo
• Odor: No foreign or unpleasant smells
• Weight tolerance for Class A Eggs: For 180+ eggs: ≤5% eggs below specified; for <180 eggs: double the above tolerances.

Egg Composition and Nutritional Value

• Energy (kcal): 140, (kJ): 584
• Water (g): 76.11
• Ash (g): 0.93
• Protein (g): 13.13
• Nitrogen (g): 2.10
• Fat, Total (g): 9.69
• Carbohydrates (g): 0.00

Egg - Protein

• Eggs contain high-quality protein
• Studies on lab animals show 100% of egg proteins convert into body proteins
• For this reason, egg proteins are referred to as reference proteins

Importance of Egg Consumption

• Egg fat is composed of 33% saturated fats, 16% polyunsaturated fats, and the remainder are monounsaturated fats • The fat is concentrated in the egg yolk, which has a high cholesterol content. However, it also contains a significant amount of unsaturated fatty acids and lecithin, which reduces its cholesterol-raising effect compared to fatty meats and dairy products • Egg yolk is rich in iron, Vitamin A, and B-group vitamins • Consuming one egg daily is beneficial for infants and children • In cases where dietary protein intake is restricted (such as kidney and liver failure), eggs are a crucial source of nutrition as they contain exemplary protein

Importance of Egg Consumption (raw eggs)

• From a food safety perspective, consuming raw eggs is not recommended as they are difficult to digest and the beneficial effects of biotin (a B-group vitamin) cannot be fully utilized by the body

Importance of Egg Consumption(General)

• One egg is equivalent to half a portion of meat and meat products
• Consuming eggs together with vegetables and grains minimizes their negative impact on blood cholesterol levels
• The lecithin in eggs helps regulate brain functions and supports the protection of the liver • When purchasing eggs, choose those that are clean, with no cracks or breaks, and store them unwashed in the refrigerator • If the egg is old or cooked for too long, a green sulfur (iron-sulfur) ring may form around the yolk

Egg Yolk Color ~ Chicken's Diet

• The color of the egg yolk is influenced by the diet of the chicken

Changes in Stored Eggs

• Viscosity of the egg white decreases
• Water moves from the egg white to the yolk
• The air cell enlarges
• Overall, the egg becomes lighter due to water loss

Protein Quality

• Amino acid profile in foods
• Digestibility refers to the ability of food proteins to be converted into body proteins
• Processing methods and storage conditions applied to foods can lead to the breakdown of amino acids in their composition, affecting their digestibility
• Reference protein: Human Milk and Eggs
• High-quality Proteins- Meat, Fish, Milk, and Dairy Products
• Low-Quality Proteins- Plant-Based Foods

Food Digestibility

• Eggs, meat, milk, and animal-based foods 91-100%
• Cereal proteins 79-90%
• Legumes 69-90%

Ways to Improve Protein Quality

• Bulgur Pilaf + Kidney Beans → Balances the amino acid profile
• Cereals + Legumes → High-quality protein
• Rice + Milk → Rice Pudding: Balances the amino acid profile

Denaturation of Proteins

• Enzymes lose their activity
• Proteins' solubility decreases
• Proteins' functions diminish
• Digestibility increases
• The solidification and whitening of an egg due to heat is irreversible
• Many other denaturation processes are reversible

Which Eggs Are Healthy?

Different levels of cooking times (1 minute, 3 minutes, 5 minutes, 7 minutes, 9 minutes, 11 minutes, 13 minutes, 15 minutes) correlate with different degrees of egg firmness, resulting in varying nutrient bioavailability and potential health outcomes

How Long Should Eggs Be Cooked?

• The iron (Fe) in the egg yolk reacts with hydrogen sulfide (H2S) present in the egg white, forming iron sulfide (FeS)

Determining the Freshness of an Egg

• Size of the Air Cell: Fresh eggs have a small air cell, while older eggs have a larger one.
• Floating in Salt Water: Eggs that float in saltwater are considered stale
• Appearance When Cracked: When carefully cracked, the yolk should remain intact and centered, surrounded by thick egg white that holds its shape

Changes in Cooked Eggs

• Egg Proteins Coagulate: Egg white solidifies at 60°C, and the yolk solidifies at 70°C
• Digestibility: Normally cooked eggs are easy to digest
• Green Color Formation: Eggs cooked at high temperatures for extended periods or stale eggs may develop a green color
• High Heat + pH → Hydrogen Sulfide + Iron
• Effect on Avidin in Egg White: Avidin + Heat → Avidin loses its properties

Cooking Methods for Eggs

• Boiling in the Shell: depends on water temperature, cooking time, and amount of water used
• Frying in an Oiled Pan: Eggs are cracked directly into the pan and cooked
• Mixing with Other Foods: Eggs as a coagulating, leavening, or emulsifying agent, enhancing flavor, color, and aroma, ensuring proper firmness
• Tempering: Beaten egg + lemon juice/yogurt is slowly added while the dish is removed from the heat to prevent curdling

Leavening Property of Eggs

• Denaturation During Whipping: When eggs are whipped, the proteins in the egg denature
• Incorporation of Air: Air bubbles are introduced into the whipped eggs
• Leavening Effect in Baking: When well-whipped eggs are mixed with flour and baked (e.g., in cakes), the trapped air expands, causing the dough to rise
• Egg Yolk as an Emulsifier: Egg yolk → Lecithin (phospholipid) → Acts as an emulsifier
• Emulsion Formation: Lecithin reduces the surface tension between water and oil, allowing oil to disperse into water, forming an emulsion. This property is crucial in making rich pastries and mayonnaise

Other Topics

• Is Excess Protein Consumption Harmful?
• Should We Consume High Protein for Muscle Growth?
• For Individuals Who Exercise
• Foods Rich in Complex Carbohydrates for Those Who Exercise
• Endurance Sports
• Strength/Power Sports
• Team Sports
• Recommended Protein Intake

Data

• Additional information about specific foods, regions, figures, and percentages are included for each respective topic.

Test your knowledge on the science of cooking meat and eggs. Explore factors that influence meat tenderness, cooking methods, vitamin retention, and protein quality. This quiz will challenge your understanding of how cooking techniques affect food characteristics.