This set of Meat Processing Multiple Choice Questions & Answers (MCQs) focuses on “Post Mortem Changes in Muscle”.
1. Which of the following product is formed after the conversion of muscle to meat?
a) Pyruvic acid
b) Lactic acid
c) Acetic acid
d) Citric acid
View Answer
Explanation: After the death of animal, the circulatory system stops to work resulting in lack of oxygen. Due to glycolysis in postmortem muscle the pyruvate is generated as an end product, and it is converted into lactic acid. These metabolic waste ¬products cannot be removed without a blood stream, so the lactic acid accumulates in the muscle.
2. Which of the following statements are true about proteins and proteolytic enzymes in meat?
Statement 1: The myofibrillar proteins such as desmin, troponin T, titin, nebulin, and vinculin are partially or completely degraded during the first week of postmortem.
Statement 2: Calpains, cathepsin, proteasome, and caspases are the major proteolytic enzymes in muscle tissues.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: The myofibrillar proteins desmin, troponin T, titin, nebulin, and vinculin become partially or completely degraded during the first week of postmortem. The major proteolytic enzymes in muscle tissues include calpains, cathepsin, proteasome, caspases, etc. The calpains are responsible for making cleavages in the myofilaments. Followed by other enzymes, peptidases and the proteasome complex would further degrade the proteins into amino acids.
3. Which of the following statement is true regarding the activity of calpains in meat?
a) µ-Calpins require micromolar concentration of calcium and m-calpains require millimolar concentration of calcium for their activity
b) µ-Calpins require millimolar concentration of calcium and m-calpains require micromolar concentration of calcium for their activity
c) µ-Calpins and m-calpains require same concentration of calcium for their activity
d) µ-Calpins require millimolar concentration of calcium and m-calpains require millimolar concentration of calcium for their activity
View Answer
Explanation: Calpains are the calcium-activated proteases responsible for postmortem protein degradation. There are three different isoforms of the calpain identified in muscle. They are μ-calpain, m-calpain, and P94-calpain. µ -Calpains requires micromolar concentration of Calcium and m-calpains require millimolar levels of calcium for their activity.
4. Which of the following term is used to refer stiffness of death in muscle?
a) Scalding
b) Rigor mortis
c) Slaughter
d) Stunning
View Answer
Explanation: Rigor mortis or stiffness of death is the major physicochemical change that occurs in postmortem muscle which causes an increased toughness in meat. The onset of rigor mortis is associated with the depletion of the adenosine triphosphate (ATP) from the muscle so that in the absence of ATP, actin and myosin combine to form actomyosin.
5. Which of the following statement is correct about calpastatin activity in meat?
a) Rapid postmortem pH reduction causes the reduced calpastatin activity
b) Rapid postmortem pH reduction causes the increased calpastatin activity
c) Rapid postmortem pH increase causes the increased calpastatin activity
d) Rapid postmortem pH increase causes the decreased calpastatin activity
View Answer
Explanation: Calpastatin is the protein responsible for the inhibition of calpain. It also requires calcium to bind the calpain and their activity decline after the death of an animal. The rapid postmortem pH decrease in the meat causes the reduced calpastatin activity and enhances the activity of calpains.
6. Which the following statement is true about the post rigor muscle?
Statement 1: In post rigor muscle, the supply of adenosine triphosphate (ATP) is depleted leading to strong actin–myosin bonding.
Statement 2: Inextensibility in post rigor muscle is due to the strong attachment of the myosin heads to actin.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: In the normal muscle contraction, adenosine triphosphate (ATP) is necessary to dissociate actin and myosin and allow these filaments to slide over one another. After the rigor, the supply of ATP is depleted which causes strong actin–myosin bonding thereby preventing muscle contraction or extension. The inextensibility of post rigor muscle is due to the strong attachment of the myosin heads to actin.
7. Which of the following is the pH condition for Dark Firm and Dry (DFD) meat?
a) 5
b) 5.2
c) 5.4
d) 6
View Answer
Explanation: Dark Firm and Dry (DFD) condition occur after 12-48 hours of postmortem and at high pH in the range of 5.9-6.4. The characteristics of DFD meat are dark color, firm texture, and dry sticky surface. It mainly occurs as a result of long term stress on animals prior to slaughter. The pH of normal meat is in the range of 5.4- 5.7.
8. Which of the following change is not found during thaw rigor of meat muscles?
a) Shortening
b) Loss of liquid
c) Liquid gain
d) Ice crystal formation
View Answer
Explanation: The term, “thaw rigor” refers to the shortening that occurs when a muscle is rapidly frozen before rigor and then thawed. Muscle treated in this way shows shortening and loss of liquid as drip. The Ice crystal formation in the muscle cell leads to the disruption of sarcoplasmic reticulum. There is no liquid gain observed during thaw rigor.
9. Which of the following process can prevent cold shortening?
a) Electrical stimulation
b) Quick freezing
c) Homogenization
d) Thawing
View Answer
Explanation: Electrical stimulation is a method used for the tenderization of meat. It helps to accelerate adenosine triphosphate (ATP) depletion and hence the development of early rigor mortis. Therefore, the process reduces the occurrence of cold shortening, and also helps to improve meat color and sensory characteristics.
10. Which of the following is not a method used to minimize the incidence of PSE in meat?
a) Improper chilling
b) Fasting
c) Reduce stress
d) Proper chilling
View Answer
Explanation: PSE or Pale, soft, and exudative is the term used to describe meat with abnormally light color, soft texture, and less ability to hold water. The incidence of PSE can be minimized by reducing stress during handling and transport, fasting and providing proper chilling conditions. Improper chilling leads to the development of PSE so, it is not a method to reduce PSE condition in meat.
11. Which of the following are the characteristics of DFD meat?
a) Dark color, firm texture, dry sticky surface
b) Fast glycolysis, poor water holding capacity
c) Dark color, fast glycolysis, dry sticky surface
d) Dark color, poor water holding capacity
View Answer
Explanation: DFD or Dark, firm, and dry meat is characterized by the abnormal dark color, firm texture, and dry sticky surface. This condition is due to muscle glycogen deficiency resulted from long-term exposure to pre-slaughter stresses. Hence, the postmortem glycolysis is slow and has good water holding capacity.
12. Which of the following represents the order of rate of postmortem pH decline among different meat species?
a) Lamb > beef > poultry > pork
b) Poultry > beef > lamb > pork
c) Poultry > pork > beef > lamb
d) Pork > poultry > beef > lamb
View Answer
Explanation: The rate of postmortem pH reduction is associated with many factors including species, type of muscle fiber, and antemortem and postmortem handling conditions. In general, the rate of postmortem pH reduction differs among meat species in the following order: poultry > pork > beef > lamb.
13. Which of the following ions are liberated when an electric current is passed through the carcass during early postmortem?
a) Cl–
b) CO32-
c) Ca2+
d) Mn2+
View Answer
Explanation: When an electric current is passed through the carcass during early postmortem, it causes the enormous liberation of Ca2+ from the sarcoplasmic reticulum. They are also responsible for increasing the postmortem metabolism. This method is also known as electrical stimulation of meat.
14. A meat sample has a pH less than 5.4, which of the following characteristics are not observed in the sample?
a) Pale color
b) High water holding capacity
c) Reduced protein extractability
d) Poor processing yield
View Answer
Explanation: The normal ultimate pH values of meat in major meat species is in the range of 5.5 and 5.7, and within this range meat has the most desirable quality characteristics. Meat of pH less than 5.4 has the characteristics such as pale color, lower water-holding capacity, reduced protein extractability, and poor processing yield. High water holding capacity is not observed.
15. Which enzyme converts phosphenol pyruvate to pyruvate in the glycolytic pathway?
a) Pyruvate Kinase
b) Enolase
c) Phosphoglycerate mutase
d) Phosphofructokinase
View Answer
Explanation: Pyruvate kinase catalyzes the conversion of phospenol pyruvate to pyruvate which is the end product of glycolysis. It is a rate-limiting step of glycolysis since the reaction is irreversible. This reaction is coupled to adenosine triphosphate (ATP) production and produces two ATP molecules for each molecule of glucose metabolized.
Sanfoundry Global Education & Learning Series – Meat Processing.
To practice all areas of Meat Processing, here is complete set of Multiple Choice Questions and Answers.
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