Week 5 Flashcards
Why do pieces of meat look different?
- Collagen fibers, fibroblasts and elastin make up connective tissue
- Muscle fibers
- Adipose tissue
These three make up muscle
Muscle structure
Made of individual muscle fibers
- Packed full of protein and moisture
- Fibers arranged in longitudinal bundles
- Connective tissue helps to provide framework and
structural support to the muscle
- Silverside steak has a lot of striation because it has a lot of connective tissue
- Bundles are arranged into primary, secondary and tertiary groups and encased in connective tissue
- Size of the bundles related to:
- Muscle function
- Meat texture
- Thick myosin and thin actin filaments make up sarcomere
- During contraction actin-myosin cross bridges form through ATP and Ca+ and troponin triggering a slide reaction
white meat muscle
fish and chicken
- pale colour
- fast twitch muscles
- designed to conduct brief, powerful movements (flapping)
- soft texture
- lean
-lower protein, iron and flavour
Red meat msucle
- red
- slow twitch muscles
- endurance muscles
- coarser texture (due to function)
- contains more fat to sustain function
- higher protein, iron, fat and flavour
Impact of stress on energy reserves
Any stressor activated the metabolic energy pathway
- Best practice approaches minimize the risk of depleted energy reserves prior to processing to help reduce incidence of undesirable meat pH level
- If you enter the flight-zone it will mobilize glycogen reserves and go down glycolysis
- So less glycogen available for processing
pH 5.71-6.9 meat
Meat classified as ‘dark cutting’; shelf life decreased; not suitable for vacuum packaging; generally darker and tougher
pH 5.30 - 5.70 Meat
meat with good visual appeal and potentially good eating quality
pH on meat quality
- Dark cutters
- Inconsistent EQ (eating quality) - Reduced shelf life
- Decrease in water capacity
- Coarser texture
- Darker color
- Combined leads to reduced grading score at processing
- Price penalty for product
- Low pH meat (PSE)
- Inconsistent EQ
- Linked to acute stress
- Rapid acidification and drop in pH - Poor water holding capacity
- Unappealing to consumers
Effect of carcase chilling on muscle shortening
- Shorter of muscle pre rigor results in: - Increased moisture loss
- Tougher product
- Reduced EQ juiciness values
- 3 main formed
1. Heat shortening
2. Cold shortening
3. Thaw shortening
Heat shortening
- Carcase temp cooled to slowly pre rigorous (>20C) - Prolonged maintenance of energy
- Leads to PSE
- Issues in pork
- Relaxing sarcomere too much
Cold shortening
- Carcase temp cooled to quickly pre rigor (<10C)
- Causes a mass release of Ca triggering attached of actin and myosin shortening of
sarcomere - Lean carcass at risk
Thaw shortening
- Muscle frozen pre rigor
- Hot boned product at higher risk
- Cause shortening of 80%
- Can reduce impact of meat quality by thawing
slowly
Processing techniques used to reduce shortening
Stimulation of carcases
- Using a electrical current to cause micro
contractions - Used to speed up the onset rigor
- Effective in reducing cold and thaw shortening
- Micro contractions speed up glycolysis
Processing techniques used to reduce shortening Tender Stretching carcases
- Carcase suspicion technique
- Used to physically prevent muscle contracting pre regiour - Micro contractions speed up glycolysis
