Meat Science Quiz

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Questions and Answers

What is the role of homeostasis during the muscle-to-meat conversion?

It disrupts the biochemical reactions involved.

It maintains the physiological balance in the muscles. (correct)

It accelerates the conversion process.

It sustains aerobic metabolic activity.

What initiates the sequence of postmortem changes in muscle?

Muscle contraction.

Blood pressure elevation.

Exsanguination. (correct)

Nutrient absorption.

Why is thorough bleeding important in the slaughter process?

To enhance meat color.

To reduce the growth of spoilage organisms. (correct)

To ensure better muscle contraction.

To maintain flavor profiles.

Which factor is most crucial in determining meat quality after slaughter?

Structural and biochemical attributes of muscle. Signup and view all the answers

What happens to aerobic metabolism after exsanguination?

It stops functioning as stored oxygen is depleted. Signup and view all the answers

What aspect of muscle contributes to its conversion to meat?

The biochemical and biophysical changes starting at death. Signup and view all the answers

How do sheep and goats differ from cattle during exsanguination?

They bleed more effectively when in a vertical position. Signup and view all the answers

What physiological change occurs in the muscle during exsanguination?

Contraction of peripheral blood vessels. Signup and view all the answers

What is the primary effect of lactic acid accumulation in muscle post-slaughter?

Lowers muscle pH Signup and view all the answers

Which enzyme is NOT involved in glycogen degradation?

Phosphofructokinase Signup and view all the answers

What condition is characterized by a rapid decline in pH and low water-holding capacity in meat?

Pale soft and exudative (PSE) Signup and view all the answers

What physiological mechanism can accelerate glycogenolysis in muscle?

Hormonal mechanisms triggered by stress Signup and view all the answers

What determines the ultimate pH of meat after exsanguination?

The glycogen level in the muscle Signup and view all the answers

Which of the following reflects a correct sequence of events during post-mortem muscle metabolism?

Glycogen converts to lactic acid when oxygen is absent Signup and view all the answers

How does a rapid pH decline impact muscle proteins?

Induces denaturation Signup and view all the answers

What is the main result of high levels of stress in animals before slaughter?

Depletion of glycogen and rise in pH Signup and view all the answers

What is the primary source of ATP in muscle cells prior to rigor mortis?

Glycogen stored in muscles Signup and view all the answers

What is a characteristic of DFD meat?

Lower muscle glycogen at slaughter Signup and view all the answers

What event triggers the release of cathepsins in muscle cells?

Drop in muscle pH Signup and view all the answers

How does rapid chilling affect meat toughness?

Causes irreversible muscle contraction Signup and view all the answers

What does cold shortening commonly affect?

The toughness of lean beef and lamb Signup and view all the answers

What changes occur to muscle tissues post exsanguination?

Acute degradative changes in membrane properties Signup and view all the answers

What effect does rapid pH decline have on muscle energy stores?

Speeds up ATP use and lactic acid buildup Signup and view all the answers

What is the first line of defense against bacterial invasion in living animals?

Epidermal tissues Signup and view all the answers

What percentage of the non-protein nitrogen (NPN) in the extracts is accounted for by histidine?

26% Signup and view all the answers

What is the process that occurs when collagen is converted into gelatin during cooking?

Hydrolysis Signup and view all the answers

Which of the following compounds is NOT involved in the transformation of color during cooking meat?

Sodium bicarbonate Signup and view all the answers

How does heat affect the properties of denatured proteins during cooking?

Alters solubility and density Signup and view all the answers

What primarily contributes to weight change in meat during cooking?

Drip formation Signup and view all the answers

Which of the following statements about fat cells during cooking is correct?

Fat cells rupture and disperse fat through the meat. Signup and view all the answers

What primarily influences the tenderness of meat?

The grain of the meat Signup and view all the answers

What taste can be characterized in cooked meat?

Slightly salty and slightly sweet Signup and view all the answers

How does connective tissue affect meat tenderness?

Collagen breaks down into gelatin during cooking Signup and view all the answers

What impact does cooking at higher temperatures have on collagen?

Increases collagen loss Signup and view all the answers

What effect does aging have on meat after rigor mortis?

Meat becomes more tender and flavorful Signup and view all the answers

Which factor contributes to the toughness of meat from older animals?

Increased collagen rigidity Signup and view all the answers

What role does fat play in meat tenderness during cooking?

Fat melts and lubricates the meat Signup and view all the answers

What is the effect of temperature on the aging process of meat?

Aging can happen more rapidly at room temperature Signup and view all the answers

Which amino acids are bound in form after beef has aged for two weeks?

Histidine and lysine Signup and view all the answers

What effect does fat marbling have on meat?

Contributes to meat tenderness Signup and view all the answers

Study Notes

Muscle to Meat Conversion

Muscle is the main component of meat and meat products.
After an animal dies, its systems shut down causing changes in muscle.
The conversion of muscle to meat is a gradual process.
Homeostasis is the maintenance of a balanced internal state.
The nervous system and endocrine glands control homeostasis.

Exsanguination

Exsanguination is the first step in conventional animal slaughter.
It involves removing as much blood as possible.
Thorough bleeding is important to prevent spoilage and improve consumer appeal.

Circulatory Failure and Lactic Acid Accumulation

Exsanguination stops oxygen delivery to muscle tissue.
Aerobic metabolism stops, causing a shift to anaerobic glycolysis.
Anaerobic glycolysis produces lactic acid, which accumulates in the muscle.
Lactic acid accumulation lowers muscle pH.

Glycogenolysis

After slaughter, muscle converts glycogen to lactic acid.
Glycogen breakdown affects meat quality by changing pH.
The enzymes glycogen phosphorylase and debranching enzyme break down glycogen.
Stress before slaughter can deplete glycogen and influence pH.

pH Decline and Meat Quality

The ultimate pH of meat depends on the glycogen level at slaughter.
Lowering pH is crucial for meat conversion as it affects protein denaturation.
High temperature and low pH denature proteins.
Denaturation affects water-holding capacity, pigment intensity, and texture.
Rapid pH decline leads to pale, soft, and exudative (PSE) meat.
Slow pH decline leads to dark, firm, and dry (DFD) meat.

Rigor Mortis

Rigor mortis is the stiffening of muscle after death.
It occurs due to the depletion of ATP and the binding of actin and myosin.
Muscle glycogen levels at slaughter influence rigor mortis onset.
Rapid pH decline (PSE) accelerates rigor onset.
High muscle temperature during rigor exacerbates protein denaturation.

Postmortem Changes in Muscle

Muscle loses its protective barriers against microorganisms.
Structural integrity of muscle is disrupted, affecting texture and tenderness.
Proteolytic enzymes, called cathepsins, are released and degrade muscle proteins.

Cold Shortening

Cold shortening occurs when carcasses are chilled rapidly before glycogen is depleted.
Rapid cooling induces irreversible muscle contraction.
Cold shortening makes meat tougher, particularly in lean beef and lamb.

Tenderness of Meat

Meat tenderness is influenced by grain, connective tissue, and fat.
Finer-grained meat is more tender.
Collagen in connective tissue affects toughness.
Fat content adds lubrication during cooking, improving tenderness.

Meat Ripening or Aging

Meat becomes more tender, juicy, and flavorful over time.
Ripening occurs faster at room temperature than in a refrigerator.
Aging increases free amino acid nitrogen.

Changes in Cooking

Cooking involves protein denaturation, collagen hydrolysis, color change, drip formation, flavor development, and nutrient loss.
Cooking denatures proteins, altering their properties.
Collagen breaks down into gelatin, increasing tenderness.
Meat color changes due to oxidation of iron in heme molecules.
Drip is the loss of water and other compounds during cooking.
Cooking enhances flavor and aroma through the formation of volatile compounds.

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Description

Test your knowledge on the conversion of muscle to meat and the processes involved in meat production. This quiz covers various topics including exsanguination, circulatory failure, and glycogenolysis. Learn how these processes affect meat quality and characteristics.