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ANSC 2340 > PSE and DFD > Flashcards

PSE and DFD Flashcards

1
Q

what can cause different pH muscle pH?

A
  • genetics
  • muscle glycogen at slaughter
  • management from farm to packing (stress)
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2
Q

what is normal pH in living muscle?

A

7.4

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3
Q

why does pH decline post mortem?

A

continues production of lactic acid from the anaerobic system

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4
Q

DFD pork pH

A

stays relatively high, around 6.7 ish

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5
Q

normal meat pH 1 and 24h post mortem

A

1 h - >6.0

24h - range of 5.3-5.7

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6
Q

rapid PSE pork pH 1h and 24h PM

A

1h- rapid decrease, <6.0, but can be 5.4ish too

24h - range of 5.3-5.6, similar to normal pork.

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7
Q

gradual PSE pork pH 1h and 24h PM

A

1h - >6.0

24h- very low pH, 5.0-5.4

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8
Q

what is stress

A

physiological adjustments made when exposed to adverse conditions.
occurs when envorionment has become uncomfortable or hazardous

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9
Q

what changes in an animal when stressed?

A

heart rate, respiration, body temp, blood pressure, etc

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10
Q

stockman ship in relation to factors affecting stress in meat animals

A

previous exposure to humans - may not see ppl day to day.

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11
Q

how animals are marketed in relation to factors affecting stress in meat animals

A

direct to packer vs auction - more stress when going to auction before slaughter

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12
Q

truck loading technique in relation to factors affecting stress in meat animals

A

experienced truckers = lower stress, reduced use of electric prod.

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13
Q

transportation in relation to factors affecting stress in meat animals

A

diff stage of life can be scarier for others, may be on trailer for a long time. they will be handled diff at end of a trip depending on age and destination

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14
Q

co-mingling in relation to factors affecting stress in meat animals

A

often leads to stress and fighting when unfamiliar animals are put together

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15
Q

temperature in relation to factors affecting stress in meat animals

A

hot out- heat stress

age impacts too

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16
Q

lairage in relation to factors affecting stress in meat animals

A

hours vs overnight- recommended for long haul, but not for mixed pens bc more time and room to fight

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17
Q

type of stunning in relation to factors affecting stress in meat animals

A

captive bolt makes them struggle more

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18
Q

things that impact glycogen from farm to slaughter/preslaughter stress

A
  • fatigue
  • fasting
  • excitement
  • exercise
  • fighting
  • restraint
  • electrical shock
  • leaving home pen
  • truck ride
  • meeting new pigs
  • experiences at packing plant
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19
Q

stress impact on muscle contraction

A

increased

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20
Q

stress impact on circulatory system

A

increase nutrient and oxygen demands to meet requirements.

temp regulation - more activity, more glycogen (hot?)

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21
Q

what happens to oxygen supply, temp if muscle demands are not met

A

lower oxygen supply, greater demand

greater heat production

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22
Q

what happens if lactic acid production overwhelms ability of the body to use it?

A

systemic acidosis

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23
Q

what does exposure to stressors cause

A

shock and circulatory collapse (effects muscle temp, lactic acid production, ATP)

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24
Q

post mortem effect on the conversation of muscle to meat when animal is stressed at slaughter

A

temp increase, glycolysis increase, sped up rigor mortis, increased pH decline

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25
Q

stress resistant animals- how do they handle stress?

A

lowering muscle glycogen stores - good if it can rest and replete glycogen pre slaughter

26
Q

porcine stress syndrome (PSS)

A

hereditary susceptibility to stress, genetic defect, alongside preslaughter stress.

27
Q

what can happen when a PSS pig is stressed?

A

death during transport - can not cope due to acidosis or hypothermia
poor quality meat - PSE and DFD pork

28
Q

halothane impact

A

high body temp, high lactate production

muscles get rigid, affects red and white muscles.

29
Q

halothane sensitivity

A

rapid- will see effect w/in 5 min w muscle spasms

reliable and cheap

30
Q

PSS pig rxn to stress

A 
trembling muscles
rigid muscles w lethargy
excessive lactic acid production - acidosis which can be deadly
circulatory failure- deadly
hyperthermia - deadly
31
Q

PSS breed effects

A

seen in some pigs more than others, usually lean breeds (pietrain, Poland, China, landrace)

32
Q

how does PSS work

A

AA replaced in Ca release channel of SR, can’t stop excess release of Ca when they get stressed.

33
Q

what does PSE stand for

A

pale, soft, exudative (wet, meat is losing fluid)

34
Q

what happens if muscle pH drops before heat is dissipated?

A

protien is denatured, resulting in PSE pork
blast chilling can control
pse a bit.

35
Q

when can PSE meat be detected by colour?

A

abt 90min PM

36
Q

is 24h pH a good indicator for PSE?

A

no

37
Q

where can you usually find PSE pork in the animal?

A

loin and ham muscles

38
Q

RN gene

A

also called Hampshire effect bc common in that breed

  • high glycogen at slaughter
  • produces lots of lactic acid
  • slowed rate of glycolysis
39
Q

what happens when PSE meat protein gets denatured

A

loss of pigment (more pale)
loss of water and protien binding capacity - meat looks wet
fluid may drip from surface

40
Q

what are the effects of protein denaturation

A

loss of protien solubility

affects the appearance and processing characteristics - can’t hold brine to process.

41
Q

DFD pork - how do they get it?

A

animal survives stress, lots of lactate produced, makes muscles dark, firm to the touch, and dry bc increased water binding to protiens

42
Q

is DF`D desirable?

A

trends to DFD for Japanese markets

43
Q

what meat can you get from a PSS pig?

A

PSE, DFD, and normal. PSS is just a genetic condition, other genetics give PSE pork too

44
Q

water absorption

A

ability to bind water from external environment - marinate

45
Q

what is water holding capacity

A
  • ability to bind/hold its water
  • pH 10 - high WHC
  • Ph 5 - low WHC
    water associated with muscle fire escapes and leaves muscle
46
Q

how does water holding capacity decrease? where does the water come from?

A

escapes between the fasciculi

47
Q

what does WHC impact?

A

affects:

  • processing yields (water loss during chilling)
  • appearance of meat pre cooking
  • behavoiur during cooking
  • juiciness upon chewing
  • processing of meat
48
Q

what is water loss known as?

A

weep
drip/ drip loss
shrink

49
Q

how does water holding capacity change with the pH declines postmortem

A

thick and thin filaments move together, decreases water space between myofilaments
myofibril shrinks
sarcoplasm volume increased
ATP depleted, no energy to hold water or maintain protein integrity

50
Q

PSE pork drip loss

A

lower w greater water holding capacity

51
Q

paleness of PSE pork relation to pH

A

inversely proportional

  • lower pH, more paler meat
  • caused by scattering light
52
Q

effect of decrease in pH post mortem

A

protien denatured, myosin denatured, increased light scattering, increase paleness.

53
Q

what is DFD in beef called?

A

dark cutting

54
Q

what causes DFD in swine

A

PSS, stress, - transport exhaustion, hunger, fear, climatic stress, aggressive behaviour, any factor that depletes glycogen before killed.

55
Q

what causes DFD in beef

A

glycogen depletion before death, inadequate lactic acid produced to lower the pH

56
Q

how does glycogen get depleted?

A

more rapid in muscles w high ATPase, like fast twitch red

57
Q

characteristics of DFD beef

A

dark colour. - muscle absorbs light, not reflect
dependent on pH
firm consistency.
high water holding capacity, very juicy.
sticky surface
prone to bacterial spoilage

58
Q

DFD flavour in pork vs cows

A

good in pork, gross in cows

DFD carcasses discounted in beef. producers lose $200-250.

59
Q

factors affecting dark cutting beef

A
  • animal category
  • nutritional status
  • season of the year
  • genetics
  • temperament
  • mixing of unfamiliar cattle
  • large time
  • fiber type
60
Q

steer vs heifer vs bull DFD

A

lower incidence of DFD than heifers in steers bc of estrus cycles.
heifers in feedlots fed hormone regulators to stop cycling.
- bulls increased aggression

ANSC 2340 (13 decks)

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