Conversion of Muscle to Meat Flashcards
What is skeletal muscle made up of?
Skeletal muscle is made up of individual muscle cells (fibers), connective tissue, myofibrils (which contain sarcomeres), and various proteins like myosin, actin, and collagen.
What are the main proteins found in meat?
The main proteins in meat include:
Contractile proteins: Myosin, Actin, Troponin, Tropomyosin
Structural proteins: Collagen, Elastin
Sarcoplasmic proteins: Myoglobin, Enzymes
What happens to muscle tissue post-mortem?
After slaughter, muscle metabolism shifts from aerobic to anaerobic, leading to a build-up of lactate, a drop in pH, and the onset of rigor mortis (formation of permanent actomyosin bridges).
What is rigor mortis?
Rigor mortis is a post-mortem condition where muscle fibers become stiff due to the permanent formation of actomyosin cross-bridges, caused by ATP depletion. This leads to a tough, inextensible muscle.
What factors influence the rate of rigor mortis?
Factors include:
Glycogen levels
Stress levels
Handling and transport of the animal
Muscle type
Temperature (muscle and environment)
What is the ultimate pH of meat, and how does it affect meat quality?
The ultimate pH of meat is typically between 5.3 and 5.7. A lower pH (below 5.4) can reduce water-holding capacity (WHC), while a higher pH can increase WHC but may also lead to problems like dark, firm, dry (DFD) meat.
What is the isoelectric point (IEP) of meat proteins, and why is it important?
The IEP of meat proteins is around pH 5.4. At this pH, meat proteins have the lowest water-holding capacity (WHC), leading to a drier, less tender texture.
What are the key components of the connective tissue in meat?
The main components of connective tissue are:
Collagen: Provides strength and structure
Elastin: Provides elasticity
Ground substance: Contains glycoproteins
What factors affect the water-holding capacity (WHC) of meat?
Factors affecting WHC include:
pH: Lowest at the isoelectric point
Sarcomere length
Connective tissue content
Rigor mortis
Post-slaughter chilling rate
What is the difference between PSE (Pale, Soft, Exudative) and DFD (Dark, Firm, Dry) meat?
PSE: Caused by rapid pH drop and high temperature; results in soft, watery, pale meat with low WHC.
DFD: Caused by low glycogen stores; results in dark, dry, firm meat with high WHC and higher pH.
What is the role of calpains and cathepsins in meat aging?
Calpains (calcium-activated enzymes) and cathepsins (found in fish) break down proteins like collagen and cytoskeletal proteins, enhancing tenderness and flavor during meat conditioning/aging.
Collagen affects meat tenderness. As collagen denatures with heat (in cooking or during aging), it transforms into gelatin, making the meat more tender.
What are some methods used to minimize hazards in raw meat?
Methods include:
Proper slaughtering techniques
Chilling or freezing
Hygiene in handling
Use of preservatives like salt and nitrites
Temperature control during processing
What is the role of myoglobin in meat color?
Myoglobin is responsible for the red color of meat. The concentration and form of myoglobin (deoxymyoglobin, oxymyoglobin, metmyoglobin) determine the color, which can change during processing due to oxidation.
What is cold shortening, and how can it be avoided?
Cold shortening occurs when muscle temperature drops too quickly after slaughter, causing rapid rigor mortis and tough meat. It can be avoided by controlling post-mortem temperature decline to 15-20°C.
