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VPH > Slaughter 4 > Flashcards

Slaughter 4 Flashcards

1
Q

Describe the conformation classification of lamb carcasses

A
  • Visual appraisal of shape, taking into account carcass blockiness and fullness of legs
  • No adjustment made for influence of fatness on overall shape
  • 5 classes: EUROP
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2
Q

Describe the fat cover classification of lamb carcasses

A
  • Fat class determined by visual appraisal of external fat development
  • 5 main classes from 1-5 as in beef, but classes 3 and 4 subdivided into L (leaner) and H (fatter)
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3
Q

What are the requirements for pig carcass classification?

A
  • Slaughterhouse slaughtering more than 200 clean pigs per week averaged over 12 month rolling period, must be registered with Pig Carcass Grading Scheme
  • Regulations on carcass weighing, dressing and grading for lean meat content
  • Grade marked on the carcass or documented
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4
Q

What are the pig dressing requirements?

A

Dressed according to either EU or UK dressing specifications only

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5
Q

Which parts must be removed from pig carcasses before weighing under EU specification?

A
  • Tongue
  • Bristles
  • Hooves
  • Genital organs
  • Flare fat
  • Kidney
  • Diaphragm
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6
Q

Which parts can be left in the pig carcass before weighing according to UK specification?

A
  • Kidneys
  • Flare fat
  • Diaphragm
  • Tongue may be left in or taken out
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7
Q

What are the requirements regarding carcass weighing in pigs?

A
  • Must be recorded as appear on actual scale display
  • Dressed carcass weighed for its warm weight
  • Ideal up to 45 mins after pig has been stuck
  • Coefficients applied by FBO to account for different conditions of carcass (organs left in, time after sticking)
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8
Q

Describe the grading of pig carcasses

A
  • Assessment is estimate by measuring fat thickness over Longissimus dorsi, 6.5cm from dorsal midline at the last rib
  • Measurement performed using optical probe
  • Probe must be approved by legislation
  • Result of probe assigned to grade on scale (SEUROP)
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9
Q

Outline the recording of pig carcass grades

A
  • Grade either marked directly on carcass or recorded at time of grading
  • Carcasses destined for export uncut to EU member state marked with either appropriate letter from grading scale, or %age lean meat content
  • For other cases, also need to keep record of letter or %age lean meat content
  • Marking: use indelible, non-toxic, heat resistant ink
  • Letters and numbers min 2cm high
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10
Q

Outline the process of rigor in the conversion of muscle to meat

A
  • Muscle contraction requires Ach, broken down by Achases to stop contraction
  • Onset of rigor is variable
  • May be less than 1 hour after death to several hours
  • Marks the start of conversion from muscle to meat
  • Depends on length of time ATP production can be sustained, ATP consumption rate
  • Rigor occurs when ATP supply is exhausted and myosin heads remain irreversibly locked onto actin
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11
Q

What leads to dark cutting beef?

A
  • Condition associated with incomplete acidification
  • Normally red meat has pH 5.5-5.6, DCB has pH >6.0 at 24 hours post slaughter
  • Caused by depleted muscle glycogen in stressed animal, early onset of rigor mortis
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12
Q

Describe the meat quality of dark cutting beef

A
  • Darker than normal
  • Able to retain structural water
  • Prone to rapid spoilage
  • Meat is tougher (actin-myosin complexes still present)
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13
Q

What is Pale Soft Exudative meat?

A
  • Primarily condition of pork
  • Accelerated glycolysis after slaughter, rapid lactic acid build up
  • pH lower than 6.0 less than 45 mins after slaughter
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14
Q

Describe some characteristics of Pale Soft Exudative meat

A
  • Rapid onset of rigor mortis
  • Excessive drip loss from cut surface and cooking
  • Paleness due to high reflectance from wet surface
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15
Q

What condition is associated with Pale Soft Exudative meat?

A
  • Mutation in ryanodine receptor (RYR1)
  • Causes uncontrolled calcium release
  • Leads to rapid glycolysis
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16
Q

What is cold shortening of meat and how does it occur?

A
  • Carcass shortening (can be as much as 1/3 of original length)
  • Muscle cooled to below 10degreesC before rigor mortis
  • Rapid chilling leads to accumulation of cytosolic Ca2+ causing muscle contraction and shortening
17
Q

How can cold shortening be prevented?

A
  • Beef and lamb not chilled below 10degreesC in first 10 hours
  • Pork not chilled below 10degreesC in first 3 hours
18
Q

What is boar taint?

A

Unpleasant urine like odour of entire boards and a minority of pigs

19
Q

What is boar taint caused by?

A
  • Sex steroids e.g. androstenon deposited in intramuscular fat
  • Microbial breakdown of tryptophan in gut to skatole and indole
  • Absorbed and if not broken down effectively is deposited in adipose tissues
20
Q

How can boar taint be prevented?

A
  • Castration in male piglets
  • Avoid overcrowding
  • Use slatted floors to reduce faecal contamination
  • Earlier slaughter of boars
21
Q

What properties of meat can be used to assess meat quality?

A
  • Water holding capacity
  • Colour and paleness
  • Succulence/juiciness (subjective trait)
  • Tenderness
22
Q

How can meat tenderness be improved?

A
  • Conditioning/ageing
  • Electrical stimulation
  • Hip suspension
  • Mincing
  • Use of proteases
  • Marination
23
Q

Explain the principle water holding capacity of meat

A
  • pH of meat influences extent of muscle proteins that are charged
  • Is necessary to attract and hold dissociated forms of water
  • Most proteins in meat lose their charge between pH 5.1-5.5, close to ultimate pH of meat
  • In this range, muscle releases water
24
Q

Explain the role of colour and paleness in the assessment of meat quality

A
  • Colour influenced by presence of myoglobin
  • Bright red colour in presence of oxygen (blooming) is synonymous with freshness
  • Different muscles have different colour (higher proportion of myoglobin in slow vs fast muscle)
25
Q

Explain the role of succulence/juiciness in the assessment of meat quality

A
  • Succulence is an eating quality, often related to level of fat and moisture in cooked meat
  • Excessively lean carcass confers less juicy meat
  • tenderness and succulence can be improved by increasing the amount of fat present
26
Q

How can tenderness of meat be assessed?

A
  • Objective (laboratory based) methods e.g. measuring shear force and myofibrillar fragmentation index (MFI)
  • Subjective methods e.g. taste or eating quality assessment
27
Q

What is meat tenderness dependent on?

A
  • Afe of animal (increased collagenous tissue with age, increased intermolecular collagen bonds)
  • Type of muscle (white less vs red more tender)
  • Amount of sarcomeric shortening during rigor mortis
  • Meat maturation (longer = more tender)
28
Q

Outline the process of meat conditioning/ageing

A
  • Allows proteolysis to occur leading to more tender meat, more complex flavours and aromas
  • Widely used
  • Storage must be under right conditions
29
Q

What are some problems that may occur during meat conditioning/ageing?

A
  • Excessive dehydration of carcass
  • Mould overgrowth
  • Development of rancid aromas
  • Potential overgrowth of pathogenic microorganisms
30
Q

Outline the process of electrical stimulation

A
  • Electric current transmitted through carcass of animal that has been freshly slaughtered and eviscerated (up to 1 hour after exsanguination)
  • Can be low (up to 100volts) or high current (100-500volts)
  • Fast-tracks post-mortem glycolysis, and so hastens onset and resolution of rigor mortis
31
Q

What is the purpose of electrical stimulation in meat processing?

A
  • Hastens onset and resolution of rigor mortis
  • Shortens processing time and labour
  • Improves meat tenderness and other meat quality traits
32
Q

What are some potential disadvantages of electrical stimulation in meat processing?

A
  • Rapid chilling required to minimise weight loss and microbial growth
  • May have negative impact on some meat quality traits e.g. colour stability and water holding capacity in some animals
33
Q

Outline the role of hip suspension in improving meat quality

A
  • Traditionally hung by gastrocnemius
  • But suspension from obturator foramen means gluteal muscles stretched-
  • Reduces likelihood of problems such as cold shortening
  • Back quarter of carcass has most expensive meat cuts
34
Q

Give examples of proteases that can be used to improve meat quality

A
  • Papain in papaya
  • Bromelin in pineapple skins
  • Ficin in fig trees
35
Q

Give examples of marination ingredients that improve meat quality

A
  • NaCl
  • Polyphsophate
  • CaCl2
  • Bicarbonate

VPH (14 decks)

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