Animals as food part 2 Flashcards
When was carcase classification initiated?
1967
What information is recorded in carcase classification?
- weight
- Conformation class
- Fat class
- Sex/ Category
What are the confirmation classes?
- Excellent
- Very Good
- Good
- Fair
- Poor
How many thoracic vertebrae and sternum do cattle and horses have respectively?
Bovine- 13 thoracic vertebrae
7 sternum bones and more straight
Equine- 18 thoracic vertebrae
6 sternum bones
What is the definition of meat traceability?
ability to trace and follow a food, food producing animal through all stages of production
What are the legal requirements for traceability?
- Food Business operator must identify suppliers and customers
- Must keep record of name, adress, product description, date of receipt/delivery
What does meat chain traceability include requrements for?
- Animal ID information
- Movement documents
- Food chain information
- supplier documents
- veterinary certificates
- health and the ID marking of a product
What two things effect carcase quality?
- Age
- Marbling
What meat makes up the muscular system?
Skeletal muscle, connective tissue, intermuscular fat
What percentage of an animals live weight is meat?
25-45%
What 5 things make up the structure of the muscle?
» Muscle cells or fibres: spindle-shaped multinucleated
» Membrane: sarcolemma
» Endomysium: join groups of muscle cells
» Perimysium form bundles sheathed in connective tissue
» Epimysium: connective tissue covering the complete muscle
How does muscle contraction occur?
Sliding of actin and myosin filaments
Ca2+ triggers contraction
Constant stream of ATP
* Energy source for contraction through the action of CA- ATPase
* Hydrolysis is then also required for calcium transport back into the sarcoplasmic reticulum
How does muscle relaxation work?
- After muscle contraction is no longer required, the sarcoplasmic reticulum sequesters all the Ca2+ ions
- There is then a change in configuration of troponin and tropomyosin
- myosin heads cannot reach the thin filaments and contraction stops
- sustained muscle contraction or tetanus is the result of fusion of individual muscle twitches
What happens post-mortem when there is no breathing or blood circulation?
No blood supply, no oxidation/ reduction process
* Not ATP is produced this causes anaerobiosis and production of lactic acid
* no ATP then leads to rigor mortis which influences the temperature
* pH reduction leads to protein degredation, activation of autolytic enzymes and an increased water-holding capacity
What does protein-degredation lead to?
Tendering, and therefore myoglobin degredation, which goes on to effect meat colour
How does rigor mortis set in?
When respiration stops after death, there is a build up of lactic acid due to anaerobic respiration -> decrease in pH
ATP generation halts and without ATP the myosin then stays locked onto actin (rigor mortis develops)
it gradually disappears after 24 hours
What does muscle look like after rigor-mortis?
lower pH
* light surface
* exudation of fluid
* not sticky when minced
* low electrical resistance
* penetration of salts and sugars is high
What factors can effect rigor-mortis?
- Physical stress,/ fatigue and rest before slaughter
- animal health
- exercise training/ genetics
post-mortem (external temperature, carcase suspension, previous electrical stimulation, hot boning)
What causes DFD meat (dark, firm,dry)
- any animal that is stressed or exhausted
- any animal with low glycogen reserves
- very limited glycolysis
- advanced spoilage
- it is fit for food but only low quality
*
What animal typically gets DFD meat?
cattle
What species are mainly effected by PSE meat?
pigs
What factors contribute to PSE meat?
- rapid fall in muscle pH after death
- change in muscle protein- causes it to become flesh watery with excessive drip
How may you prevent DFD or PSE?
avoid stress-
* handle animals gently
* adequate loading ramps
* avoid mixing animals
* lairage pen design and races to allow for easy and efficient movement
* water should be provided at all times
What are carcasses broken down to produce?
- Primal joints, retail cuts or boneless meats
What determines the microbial flora of the carcasse?
The microbial flora is determined by the previous history of the carcasse and the hygeinic conditions of the processing
What does handling of the meat do to microbes?
It increases microbial load
What does vacuum packing do?
It extends the shelf-life of food by decreasing the oxygen
* inhibits growth of aerobic gram negative bacteria
What are the risks of vacuum packaged meat?
- not enough vacuum tight
- bone splinters or other foreign bodies
- seal is not applied properly
- inappropriate plastic bags
What are the control measures of vacuum packaged meat?
- initial bacterial levels must be low
- must be hygeinic storage
- packs must be transported in rigid plastics
*
What is the function of modified atmosphere packaging?
- Extends the food shelf life
- replaces the air with a gas mixture- gives bright red colour (oxyhaemoglobin)
- typically high O2 and high CO2
What is the definition of ‘mince’ meat
Boned meat minced into fragments
What is mince made from?
Made from trimmings and meat left on bones after butchery
contains additivies
* fat
* dried milk
* salt/ spices
* cereal products
chilled or frozen after production
What are the effects of processing on microorganisms?
- there is a large bacterial load
- usually distributed throughout the mince
- grinding increases meat temperature
- shorter shelf-life
What parts are you not allowed to use for mince meat?
- scraps
- diaphragm
- linea alba
- bone scrapings
What is MSM?
Mechanically separated meat- product obtained bt removing meat from flesh-bearing bones after boning or from polutry carcasses using mechanical means resulting in the loss or modification of the muscle fibre structures
What is high pressure MSM?
The carcasse or meat parts are pressed through a machine-like sieve
What is low pressure MSM
The meat is mechanically scraped from the carcasse
What meats are allowed to be MSM?
poultry and pork
cant use, head, neck, feet, tail, legs
How can you determine MSM?
- Calcium content cannot exceed 0.1%
- Can use histological parameters e.g microscopic detection of muscle, connective and adipose tissue
What temperature is MSM stored at if not to be used immediately?
2 or 18C
What is the definition of poultry meat?
Poultry meat is the muscle tissue, attached skin, connective tissue, and edible organs of avian species that are commonly used for food
What is the water and fat content in broiler chickens?
71% water in broiler chickens
3% fat
What does the AMI of poultry include?
Accurate AMI should include listening to the birds and observation of a random sample checking
posture, wattle colour and cleanliness, and
* Consider the information available on the documentation: Food Chain Information (FCI)
What must you do when unloading poultry
relates to welfare
Crates containing birds must be unloaded from vehicles with care in a calm unhurried manner.
» The crates should be maintained in the upright position so that the birds are not in an unsettled
or excitable state when they are subsequently handled before slaughter.
» Crates are stacked far enough apart to permit adequate airflow between stacks
What effects poultry welfare?
- Cleanliness
- Heat/ Cold stress
- ventilation, layout of the crates, over-crowding
- trapped birds or injuries
- light and noise levels
What actions can you do to reduce heat stress in poultry?
- Reduce the stocking density of birds in the crates
- install extraction fans which extract humid air and excessive heat
- reduce moisture sources in the lairage
What are the key points for shackling?
- Must have enough time to become settled in the shackling position
- They should be individually shackled and hung on by both legs
- Breast comforters are good shackle design
- Birds must not be shackled for any longer than 3 minutes in turkeys or 2 minutes in the case of any other bird
- must be low lighting levels
How does the poultry automatic neck cutter work?
Blade must be at correct height to severe the carotid arteries
What are some of the faults of the automatic neck cutter?
- Mechanical failure
- at least one of the carotid arteries is not severed
- uneven flock size
- insufficient bleeding time
How does the scalding and plucking work?
- Use a spray or water tank
- water temperature at 51-53 degrees C for 3 minutes
- may potentially have contaminated water
What can be a major source of contamination for the de-feathering machine?
Worn or cracked fingers
What happens during the poultry evisceration?
- Removal of the heart, liver, gizzard, GI tract…
- can be manual or automatic
- possible contamination with gut spill
What following checks do the polutry undergo along with the post-mortem inspection?
done by an OV
- Daily inspection of the viscera and body cavities of a representative sample of birds, the
minimum number to check is 300 birds or 20% of the flock whichever is the lowest. - A detailed inspection of a random sample, from each batch of birds having the same origin,
of parts of birds or entire birds declared unfit for human consumption following post-mortem
inspection
What are the four potential outcomes for a post-mortem inspection?
- Pass meat as fit for human consumption:
* Identification mark applied.
» 2. Partially unfit for human consumption:
* Part of carcase / offal disposed off,
* Rest ID marked.
» 3. Totally unfit for human consumption:
* ID mark must not be applied,
* All body parts must be disposed of.
» 4. Detain meat for further examination:
* Under control of OV,
* Keep correlation essential,
* Off-line detention facilities
what does activation of autolytic enzymes do?
Increases the water holding capacity
