Rigor Mortis in Meat Science
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Questions and Answers

What metabolic shift occurs in muscle after an animal is slaughtered?

  • From aerobic to anaerobic metabolism (correct)
  • From glycolytic to oxidative metabolism
  • From anaerobic to aerobic metabolism
  • From aerobic to oxidative metabolism

    • Which of the following changes occur during rigor mortis?

  • Myosin heads form tight bonds with actin (correct)
  • Creatine Phosphate (CP) levels rise
  • ATP levels increase significantly
  • Muscle extensibility remains unaffected

    • What is the primary cause of muscle rigidity in rigor mortis?

  • Accumulation of oxygen
  • Excess production of carbon dioxide
  • Depletion of muscle glycogen
  • Full depletion of ATP and creatine phosphate (correct)

    • During which phase of rigor mortis do myosin heads begin to form bonds with actin?

    <p>Onset phase</p> Signup and view all the answers

    How long does it typically take for poultry to reach rigor mortis after exsanguination?

    <p>1-2 hours</p> Signup and view all the answers

    What happens to muscle extensibility as rigor mortis progresses?

    <p>It decreases gradually</p> Signup and view all the answers

    What metabolic byproduct contributes to the conditions of rigor mortis?

    <p>Lactic acid</p> Signup and view all the answers

    What is the result of the exhaustive muscular contraction during rigor mortis?

    <p>Reduced pH levels</p> Signup and view all the answers

    What is the primary characteristic of red muscles?

    <p>Carries out slow, prolonged activity</p> Signup and view all the answers

    How does stress impact post-mortem glycolysis?

    <p>It increases the rate of glycolysis</p> Signup and view all the answers

    Which of the following drugs is known to accelerate the rate of glycolysis?

    <p>Adrenaline</p> Signup and view all the answers

    What effect does temperature have on post-mortem glycolysis?

    <p>High temperature increases the rate</p> Signup and view all the answers

    Which pig breed is notably prone to PSE due to glycolysis rates?

    <p>Large White</p> Signup and view all the answers

    Rigor mortis is significant for which of the following reasons?

    <p>It retards putrefaction due to acid reaction</p> Signup and view all the answers

    What role does the method of slaughter play in glycolysis?

    <p>Pithing accelerates glycolysis</p> Signup and view all the answers

    What can result in the absence of post-mortem glycolysis?

    <p>Diseased or fatigued animals</p> Signup and view all the answers

    What is the primary role of calpastatins in the muscle aging process?

    <p>To inhibit the action of calpains</p> Signup and view all the answers

    What is the main consequence of excessive ante mortem stress in muscle?

    <p>Pale color and soft texture of meat</p> Signup and view all the answers

    Which factor is a significant contributor to the development of DFD muscle?

    <p>Insufficient glycogen at slaughter</p> Signup and view all the answers

    Which of the following best explains the difference between PSE and DFD muscle?

    <p>DFD muscle is firm and dry while PSE is pale and soft</p> Signup and view all the answers

    What does a higher level of calpastatin in an animal imply about its meat tenderness?

    <p>The meat will likely be tougher</p> Signup and view all the answers

    Which of the following factors is categorized as intrinsic in rigor mortis development?

    <p>Animal species</p> Signup and view all the answers

    How does the age of the animal affect the ultimate pH of its meat?

    <p>Younger animals have lower ultimate pH</p> Signup and view all the answers

    What physiological change occurs due to high levels of ante mortem stress?

    <p>Rapid decrease in muscle pH</p> Signup and view all the answers

    Study Notes

    Rigor Mortis

    • The process after slaughter where muscle tissue transitions to meat.
    • Involves a shift from aerobic to anaerobic metabolism, leading to the depletion of oxygen.
    • Glycogen is converted to lactic acid, lowering muscle pH.
    • Myosin heads form a tight bond with actin, resulting in muscle stiffness (rigor mortis).
    • Proteolysis (protein breakdown) begins, tenderizing meat.

    Phases of Rigor Mortis

    • Delay phase: Muscle remains relaxed due to sufficient ATP.
    • Onset phase: ATP and Creatine Phosphate (CP) are depleted, leading to the formation of rigor bonds.
    • Completion phase: CP is exhausted, resulting in full rigor mortis.

    Factors Influencing Rigor Mortis onset

    • Time: Poultry reaches rigor within 1-2 hours, pork within 4-6 hours, beef/lamb within 7-15 hours.
    • Species: Pig muscles reach rigor faster than cattle or sheep.
    • Muscle type: White muscles (fast twitch) have faster glycolysis than red muscles (slow twitch).

    Factors Affecting Rigor Mortis (Intrinsic)

    • Animal species: Different species have varying rates of glycolysis.
    • Age & Sex: Older animals and entire males have lower ultimate pH values.
    • Type of muscle: White muscle has a higher rate of glycolysis due to higher levels of ATP-ase, creatine phosphate, and glycogen.
    • Pathology: Diseased or fatigued animals may not experience post-mortem glycolysis.
    • Genotype: Breed and genotype can influence glycolysis, with certain breeds (e.g., Large White pigs) being prone to PSE.

    Factors Affecting Rigor Mortis (Extrinsic)

    • Stress: Pre-slaughter stress, fasting, high/low temperatures, and mishandling can accelerate glycolysis.
    • Pre-slaughter drug administration: Drugs can alter glycolysis. Calcium salts increase the rate, while magnesium salts decrease it.
    • Temperature: High temperatures increase glycolysis, while low temperatures decrease it.
    • Method of slaughter: Techniques like pithing can accelerate glycolysis.

    Significance of Rigor Mortis

    • Meat quality: Acidification due to rigor mortis retards putrefaction, extending meat's shelf life.
    • Meat quality assessment: The degree of rigor mortis can be used to assess meat's keeping quality.

    Abnormal Meat Conditions

    • PSE (Pale, Soft, Exudative) muscle: Occurs due to ante-mortem stress, causing rapid pH drop and muscle degradation.
    • DFD (Dark, Firm, Dry) muscle: Occurs due to lack of glycogen at slaughter, resulting in higher pH and muscle firmness.

    PSE Muscle Characteristics

    • Pale color
    • Soft texture
    • Increased water exudation
    • Negative impact on sales appeal and shelf life

    DFD Muscle Characteristics

    • Dark color
    • Firm texture
    • Dry surface
    • Sweeter flavor
    • Less common in poultry, more common in beef
    • Solution: Feed and rest animals for 24-48 hours before slaughter.

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    Description

    Explore the biochemical process of rigor mortis, the transition of muscle tissue to meat after slaughter. This quiz covers phases, influencing factors, and the metabolic changes that occur, providing insight into meat quality. Learn how time, species, and muscle type impact the onset of rigor mortis.

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