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
Aging meat to improve quality traits
Aging = the process by which enzymes degrade and breakdown the protein and structure of the meat, in a controlled environment allowing it to become more tender overtime
- Times to reach 80% maximum tenderness - Pork 4-10 days
- Labm 7-14 days - Beef 10-21 days
Different methods Dry age
- Cheaper to do
- Stronger flavor
- Moisture loss
- Requires controlled temperature and humidity - Increased trimming
- Absorbs smell
- Outside of meat is very tough so reduction in yield
Wet aging
Using vacuum shield
- Retains more moisture
- Requires specialist equipment and bags - Consumers turned off by the purge
Changes in meat color
- Related to myoglobin
- Red coloured oxygen supplying muscles
- Differs across muscles
- Higher levels of myoglobin = darker and redder meat color
- Related to muscle function and animal age
Marbling
- External fat (located on the outside of the carcase_
- Internal fat (located in the internal cavity around the kidneys) 3. Seam fat (fat between the muscles)
- Intramuscular fat or marbling (located within the muscle)
Poultry industry
- Increase fat leads to white stirpping caused by adipose tissue deposition
- Linked to fast growth rates, animal diet and animal health ailments (wooden breasts) - Investigating impact on consumers
The importance of fat
- Solid at RT
- When heated fats reach their melting point - Solid state → liquid state
- Release oils and aromas
- IMF melts
- Aids in flavor enhancement
- Improve mouthfeel
- At risk of oxidation
Millard reaction
- The chemical reaction that occurs when food is heated and results in enhanced flavors and aromatic compounds
- This is why food goes brown
- Dependent upon the types of proteins and sugars
- The reaction begins at 140 and ends at 180C
- > 180C pyrolysis (burning)
Reaction of cooking temperatures
Up to 140 C
start of cooking
- temperature generates energy
140
- Food starts to turn brown
- protein and sugars react generating new flavours and aromas
- as temperature increases the rate of reaction increases
160+
- molecules changes continue and increased flavours and aromas
- cascade of malty, nutty caramel like flavours
180+
- pyrolysis (burning occurs)
- develop butter flavours
- proteins and fats break down
