Muscle to meat Flashcards
What are the 4 phases of rigor mortis?
-Delay phase (6-8hrs):
formation of crossbrigdes delayed due to creatine phosphate phosphorylating ADP to ATP allowing for relaxation
-Onset phase:
Muscle becomes inextensible as max tension is reach and all possible crossbridges are formed.
-Resolution phase:
muscle tension decrases caused by proteolytic degredation not breakdown of crossbridges
How is pH related to rigor mortis?
pH declines related to rigor mortis because glycogen metabolism causes the drop in pH that is responsible for conversion to muscle to meat.
What qualities are used to assess meat quality?
- Water holding capacity
- Colour/ paleness
- Succulence// juiciness
What influences the water holding capacity of meat?
pH of the meat- influences charge of the muscle proteins. This charge attracts/ holds dissociated form of water. Most proteins in meat lose charge between pH 5.1= close to ultimate pH of meat (releasing water)
What influences the colour of the meat?
Myoglobin: more oxygen makes meat more red
What is the MFI?
Myofibrillar fragmentation index -used to measure tenderness of meat
What can affect the tenderness of meat?
- Age (more collagen in older animals)
- Kind of muscle (white muscle less tender than red)
- Amount of sarcomere shortening
- Meat maturation
What problems can occur during ageing of meat?
- Excessive microbial growth
- Excessive dehydration of carcass
- Rancid aromas
How long is optimum for most meats to age for?
21 days
What are the benefits of vacumn packing meat?
- Lack of oxygen inhibits microorganisms improving shelf life
- Minimise gas/ moisture permeability: improves flavour and moisture loss
What is dark cutting beef?
-Condition associated with incomplete acidification. Red meat should have 5.1-5.5 pH but DCB have pH higher than 6.
What is pale soft exudative meat?
- Mainly a problem in pork
- Caused by accelerated glycolysis after slaughter resulting in build up of lactic acid
- if pH less than 6 within 45 minutes post slaughter the carcass will probably develop PSE
- Possible connection to mutated RYR1 receptor.
What is cold shortening?
- Occurs when muscle is cooled below 10 degrees before rigor mortis occurs.
- Casued by build up of Ca ions
- Prevention: pork not chilled below 10 in first 3 hours. Beef/ lamb not below 10 in first 10 hours.
What causes boar taint?
Depositions of sex steroids in the intramuscular fat.
What are the 3 different specifications for carcass dressing?
- Standard spec
- EC reference spec
- UK spec
