Meat Science Exam 3

L12: What is palatability?

The characteristics of meat that are agreeable to the eyes, nose, and palate; it drives whether consumers purchase and enjoy meat.

L12: What characteristics impact palatability?

Appearance, tenderness, juiciness, flavor, and aroma.

L12: How does appearance of the raw product impact palatability?

Raw appearance strongly drives purchasing; consumers prefer bright pink/red lean and white or creamy fat, while dark meat and yellow fat are less appealing.

L12: How can cooked product appearance impact palatability?

Brown/golden-brown surfaces are attractive and associated with crispness and flavor; preferred internal doneness matters, while excess fat, stringiness, and dryness are negatives.

L12: How does tenderness impact palatability?

Tenderness is one of the most studied palatability traits and strongly affects eating satisfaction.

L12: What methods do we have to evaluate tenderness?

Warner-Bratzler shear force, slice shear force, and trained sensory panels.

L12: What factors can influence the perception of tenderness?

Softness to tongue/cheek, resistance to tooth pressure, ease of fragmentation, mealiness, adhesion, and residue after chewing.

L12: How does connective tissue impact tenderness?

More connective tissue means more toughness; locomotion muscles are tougher than support muscles because they contain more connective tissue.

L12: How does connective tissue change over time in the animal?

Older animals have more total collagen, more heat-stable crosslinks, and less soluble collagen; young animals have more soluble collagen.

L12: What is background toughness?

Toughness caused by connective tissue that remains largely intact after cooking because of heat-stable collagen crosslinks.

L12: Which layers of connective tissue create background toughness?

Mainly perimysium and epimysium.

L12: How does rigor state impact tenderness?

Rigor and shortening increase toughness; later resolution/aging improves tenderness.

L12: What is actomyosin/rigor toughening?

Loss of tenderness in the first hours postmortem due to stable actin-myosin cross-bridge formation.

L12: When does actomyosin/rigor toughening start to occur in the rigor process?

During rigor onset, in the first few hours postmortem.

L12: When does the tension of meat peak during the rigor process?

At rigor completion.

L12: How does sarcomere length impact tenderness?

Shorter sarcomeres make meat tougher; longer sarcomeres make it more tender.

L12: Why are tenderness and water-holding capacity so closely correlated?

More shortening and structural damage both toughen meat and reduce water retention; less shortening helps both tenderness and juiciness.

L12: What changes are occurring during the resolution phase of rigor?

Proteolysis of myofibrillar/cytoskeletal proteins, Z-disk breakdown, sarcomere lengthening, and loss of tension.

L12: What enzymes are responsible for changes during the resolution phase of rigor?

Calpains and cathepsins.

L12: What is heat shortening?

High-temperature conditioning above about 16°C/61°F causes rapid ATP depletion, rapid rigor onset, and shortening.

L12: How does heat shortening impact tenderness?

It increases shortening and makes meat tougher.

L12: What is cold shortening?

Shortening that occurs when muscle is chilled too quickly pre-rigor, typically between about 0°C/32°F and 15°C/59°F while ATP is still available.

L12: How does cold shortening impact tenderness?

It causes toughening because muscle keeps contracting.

L12: When does cold shortening typically occur?

When prerigor carcasses are chilled too fast, especially lean beef and lamb with less fat cover.

L12: What is thaw rigor?

A severe rigor condition that occurs when prerigor muscle is frozen and then thawed, causing extreme contraction.

L12: Which rigor condition results in the most extreme shortening and toughest product?

Thaw rigor.

L12: How does adipose tissue impact palatability?

Its direct effect on tenderness is unclear, but marbling can influence perceived palatability through several theories and can help protect against overcooking.

L12: What is the relationship between marbling and palatability?

Acceptable palatability in beef is generally in the 3.0-7.3% fat range, roughly Select through Choice; palatability does not increase equally with every extra degree of marbling.

L12: What impacts the juiciness of meat products?

Water content and water-holding capacity contribute more to juiciness than fat content.

L12: How would you describe the bulk density effect?

Marbling lowers bulk density, like Swiss cheese, so the meat seems easier to bite through.

L12: How would you describe the lubrication effect?

Fat acts like a lubricant in the mouth, similar to oil in an engine.

L12: How would you describe the insurance theory?

Marbling helps protect against overcooking and drying out.

L12: How would you describe the strain theory?

Marbling disrupts perimysium and creates weak points that are easier to break.

L12: How does flavor impact palatability?

If tenderness is acceptable, flavor is usually the most important determinant of consumer satisfaction.

L12: What are the 5 basic tastes?

Sweet, sour, salty, bitter, and umami.

L12: How are the basic tastes perceived?

By gustatory nerve endings in taste buds on the tongue.

L12: What compounds create aromas and flavors?

Mainly volatile compounds plus other water-soluble muscle compounds.

L12: How are aromas and flavors perceived?

Taste is perceived by the gustatory system; aromas/flavors are perceived when volatile compounds stimulate the olfactory bulb.

L12: What are some compounds that have been found to influence flavor?

Inosine monophosphate (IMP), hypoxanthine, and sulfur-containing compounds.

L12: What compounds are thought to be responsible for species specific flavors?

Water-soluble compounds in adipose tissue.

L12: What muscles will have a stronger flavor?

Muscles with larger amounts of ATP.

L12: When can one palatability attribute impact the overall eating experience more than the others?

When one trait is notably better or worse than the others.

L12: How does cooking temperature impact overall satisfaction?

Higher cooking temperatures increase cooking loss, reduce juiciness/flavor, may harden proteins, and can reduce collagen solubilization.

L12: How does endpoint temperature (degree of doneness) impact overall satisfaction?

Higher endpoint temperatures usually reduce satisfaction by increasing cooking loss and toughness.

L12: How does quality grade impact palatability?

Higher quality grades generally give a better eating experience.

L12: How does postmortem aging impact palatability?

Longer aging improves tenderness and eating quality to a point; wet and dry aging differ mostly by flavor preference.

L12: How do tenderizers impact palatability?

They improve palatability mainly by increasing tenderness.

L12: How can processing methods impact palatability?

They can improve tenderness and create unique textures, forms, and flavors.

L12: How can microbes impact palatability?

Some microbes contribute desirable flavors in fermented or dry-aged products, while spoilage microbes create off-flavors such as bone sour or lactic acid overgrowth.

L12: How can chemical changes impact palatability?

Oxidative rancidity creates undesirable flavors when oxygen attacks unsaturated fatty acids.

L13: What is the main objective of cooking meat?

To achieve the desired internal/endpoint temperature.

L13: What other benefits do we gain from cooking meat?

Improved safety, surface browning/color, and cooked flavor development.

L13: What roles does water play in cooking meat?

Water conducts heat, helps develop tenderness and final texture, and supports collagen hydrolysis; moist surfaces can also slow heating by evaporative cooling.

L13: How do we measure endpoint temperature of meat?

Use a meat thermometer in the thickest part of the cut, avoiding bone and fat; for ground products, measure the geometric center.

L13: How can cooking systems be classified, and what is this based on?

They are classified as dry-heat or moist-heat systems based on conditions at the surface of the product.

L13: What are some examples of dry heat cookery methods?

Broiling, roasting, grilling, baking, frying, sautéing, and stir-frying.

L13: When are dry heat cookery methods used?

For tender cuts that do not need long cooking for connective tissue breakdown.

L13: What cuts are recommended for cooking using dry heat?

Seafood; young poultry; most pork except thin shoulder cuts and hocks; most lamb except breast and shank; veal roasts; youthful beef steaks/roasts from rib, loin, sirloin, and selected round areas; and comminuted meats.

L13: When is moist heat recommended?

For cuts with relatively large amounts of connective tissue.

L13: What protein does not break down during moist heat cooking?

Elastin.

L13: What are some examples of moist heat cookery methods?

Steaming, poaching, simmering, boiling, braising, and stewing.

L13: What cuts of meat are recommended to cook using moist heat cookery?

Pork shoulder and hocks; lamb breast and shank; veal chops/cutlets/steaks plus shoulder, round, shank, and breast cuts; and beef chuck, round, fore shank, brisket, short plate, flank, and tip cuts.

L13: What are the methods of heat transfer?

Conduction, convection, radiant heating, and microwave radiation.

L13: What is conduction heating, and what are examples?

Heat transfer by direct contact; examples include grilling, stewing, deep-fat frying, open-kettle cooking in water, and pressure cooking.

L13: What is convection heating, and what are examples?

Heat transfer by circulation of air, water, or oil; examples include convection ovens, smokehouses, deep-fat frying, and boiling.

L13: What is radiant/radiation heating, and what are examples?

Heat transfer from a hot radiant source to the surface; examples include gas/electric broilers and infrared heat lamps.

L13: What is microwave radiation heating, and when would this method be recommended?

Microwave energy is absorbed by the product and heats it quickly, often from deeper within; it is most useful for reheating precooked or processed meats rather than less tender cuts.

L13: When we cook, how are multiple heating methods generally used at the same time?

Most cookery uses combinations, such as radiation/convection heating the surface while conduction moves heat inward.

L13: What is the Maillard reaction?

Non-enzymatic browning involving amino acids and reducing sugars during dry heating.

L13: What does the Maillard reaction produce?

Surface browning/crust and many flavor notes such as roasted, toasted, nutty, bitter, burnt, caramel, sweet, and meaty.

L13: What do you need to have for the Maillard reaction to occur?

Amino acids, a reducing sugar such as glucose, and dry heat; it is optimal around 140-165°C.

L13: When would carving meat be appropriate?

For large cooked cuts such as rib roasts, loin roasts, hams, lamb legs, and whole turkeys, usually after a short rest.

L14: How are microorganisms introduced to meat products?

Healthy muscle is essentially sterile; contamination begins during slaughter and can spread during fabrication, processing, storage, distribution, and preparation.

L14: When does contamination of products begin?

At slaughter.

L14: What are viruses?

Very small organisms that usually do not spoil meat but can use meat as a carrier from infected workers or animals.

L14: What are some examples of viruses?

Avian flu and swine flu viruses.

L14: How are viruses impactful to meat products?

They are usually not spoilage organisms; they matter mainly as carriers between infected people/animals.

L14: What are molds, and how do they contaminate meat products?

Multicellular filamentous organisms that make airborne spores; they contaminate meat when spores land and grow under favorable conditions.

L14: What are yeasts, and how do they contaminate meat products?

Generally unicellular organisms that spread through the air and contaminate meat/equipment surfaces where they settle.

L14: What are parasites, and how do they contaminate meat products?

Organisms that spend part of their life cycle outside the primary host and can infect new hosts through feces or consumption of infected tissue.

L14: What are bacteria?

Unicellular microorganisms of varied shapes; some form spores and survive harsh conditions.

L14: What are the stages of bacterial growth, and what occurs in each?

Lag: enzyme synthesis with little growth. Log/exponential: rapid multiplication and spoilage signs. Stationary: growth equals death. Death: death exceeds replication.

L14: What factors impact microbial activity in meat?

Temperature, moisture/water activity, oxygen, acidity/pH, oxidation-reduction potential, nutrients, inhibitors, physical form, and interactions among factors.

L14: What types of bacteria can create problems in meat products?

Spoilage bacteria and pathogenic bacteria.

L14: What are the main spoilage bacteria on aerobic surfaces of refrigerated meat products?

Pseudomonas, Moraxella, Psychrobacter, and Acinetobacter.

L14: What changes the predominant species present in meat products?

Packaging conditions, salt addition, freezing, and other environmental/product factors.

L14: What are the dominant spoilage bacteria in vacuum packaged products?

Lactic acid bacteria.

L14: What is a food borne infection, and when does it generally occur?

Illness after ingesting viable pathogens that grow in the host; it usually occurs with raw/undercooked foods or cross-contamination of ready-to-eat foods.

L14: What is a food borne intoxication?

Illness caused by ingesting microbial toxins already present in the food.

L14: What are mycotoxins?

Toxins produced by fungi.

L14: What causes botulism, what products carry the greatest risk, and what does botulism impact?

Botulism is caused by toxin from Clostridium botulinum; greatest risk is home-canned low- to medium-acid foods, though seafood and honey spores are also noted; it attacks the central nervous system and can cause respiratory failure.

L14: How does Staphylococcus aureus cause food borne illness, what is the most common source, and what are the symptoms?

It grows in foods left at room temperature and produces a heat-stable enterotoxin; the most common source is humans (skin/nasal passages); symptoms include sudden nausea, cramps, vomiting, diarrhea, and low-grade fever.

L14: How do Clostridium perfringens outbreaks typically occur, what are symptoms, and what is its nickname?

Outbreaks occur when large amounts of food are held warm or cooled improperly; symptoms are diarrhea and gas pains; it is called the 'cafeteria germ.'

L14: What causes salmonellosis, what are common sources of Salmonella, and what are the symptoms?

Salmonellosis is caused by Salmonella; common sources are raw/undercooked poultry, eggs, meats, unpasteurized milk/dairy, and cross-contaminated foods; symptoms include headache, abdominal pain, diarrhea, fever, and nausea.

L14: What is the most reported cause of foodborne illness?

Salmonella.

L14: What causes campylobacteriosis, what are potential sources of Campylobacter, and what are symptoms?

Campylobacter jejuni causes it; sources include poultry, shellfish, livestock, pets, raw milk, untreated water, and undercooked meats; symptoms include muscle pain, headache, fever, diarrhea, abdominal pain, and nausea.

L14: What causes listeriosis, what are common sources of Listeria monocytogenes, what are symptoms, and who is at highest risk?

Listeria monocytogenes causes listeriosis; sources include unpasteurized dairy, pâtés, processed meats, milk, soil, vegetables, and processing environments; symptoms include fever, chills, headache, backache, and diarrhea; highest-risk groups include pregnant women/newborns, the elderly, and immunocompromised people.

L14: What are the virulent strains of E. coli called, what symptoms are caused, what are common sources, and what are possible complications?

Virulent strains are STECs such as E. coli O157:H7 plus O26, O45, O103, O111, O113, O121, and O145; sources include ground beef, unpasteurized milk, produce, contaminated water, and poor hygiene; symptoms include severe cramps and watery or bloody diarrhea; complications include hemorrhagic colitis, HUS, TTP, strokes, and seizures.

L14: What is bovine spongiform encephalopathy, what caused concern about it, and what steps are taken to eliminate risk?

BSE is a fatal prion disease affecting the CNS; concern rose after the Great Britain outbreak linked to feeding infected ruminant by-products; risk reduction includes removing specified risk materials and excluding non-ambulatory cattle from the food supply.

L14: What causes toxoplasmosis, which meats are most susceptible, and how can it be prevented?

Toxoplasma gondii causes toxoplasmosis; pork, lamb, and venison are common sources; proper cooking inactivates tissue cysts.