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Flashcards in Slaughter 4 Deck (35)
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1

Describe the conformation classification of lamb carcasses

- 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

2

Describe the fat cover classification of lamb carcasses

- 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)

3

What are the requirements for pig carcass classification?

- 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

4

What are the pig dressing requirements?

Dressed according to either EU or UK dressing specifications only

5

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

- Tongue
- Bristles
- Hooves
- Genital organs
- Flare fat
- Kidney
- Diaphragm

6

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

- Kidneys
- Flare fat
- Diaphragm
- Tongue may be left in or taken out

7

What are the requirements regarding carcass weighing in pigs?

- 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)

8

Describe the grading of pig carcasses

- 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)

9

Outline the recording of pig carcass grades

- 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

10

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

- 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

11

What leads to dark cutting beef?

- 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

12

Describe the meat quality of dark cutting beef

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

13

What is Pale Soft Exudative meat?

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

14

Describe some characteristics of Pale Soft Exudative meat

- Rapid onset of rigor mortis
- Excessive drip loss from cut surface and cooking
- Paleness due to high reflectance from wet surface

15

What condition is associated with Pale Soft Exudative meat?

- Mutation in ryanodine receptor (RYR1)
- Causes uncontrolled calcium release
- Leads to rapid glycolysis

16

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

- 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

How can cold shortening be prevented?

- Beef and lamb not chilled below 10degreesC in first 10 hours
- Pork not chilled below 10degreesC in first 3 hours

18

What is boar taint?

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

19

What is boar taint caused by?

- 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

How can boar taint be prevented?

- Castration in male piglets
- Avoid overcrowding
- Use slatted floors to reduce faecal contamination
- Earlier slaughter of boars

21

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

- Water holding capacity
- Colour and paleness
- Succulence/juiciness (subjective trait)
- Tenderness

22

How can meat tenderness be improved?

- Conditioning/ageing
- Electrical stimulation
- Hip suspension
- Mincing
- Use of proteases
- Marination

23

Explain the principle water holding capacity of meat

- 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

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

- 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

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

- 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

How can tenderness of meat be assessed?

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

27

What is meat tenderness dependent on?

- 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

Outline the process of meat conditioning/ageing

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

29

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

- Excessive dehydration of carcass
- Mould overgrowth
- Development of rancid aromas
- Potential overgrowth of pathogenic microorganisms

30

Outline the process of electrical stimulation

- 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