Term
| What factors affect the range of pH decline in pork muscle? |
|
Definition
-genetics
-muscle glycogen levels at slaughter
-management from farm to packing plant
-stress |
|
|
Term
|
Definition
| the pH of meat after the acidification process is complete |
|
|
Term
| What is the typical pH of normal meat 1 hour post-mortem? 6-8 hours PM? 24h PM? |
|
Definition
1h PM: >6.0
6-8h PM: 5.6-5.7
24hPM: 5.3-5.7 |
|
|
Term
| What is typical pH pale PSE P1 meat, 1 hour post-mortem? 24h PM? |
|
Definition
1h PM: <6.0, as low as 5.4-5.5
24h PM: 5.3-5.6 |
|
|
Term
| What is typical pH pale PSE P2 meat, 1 hour post-mortem? 24h PM? |
|
Definition
1h PM: >6.0
6-8h PM: <5.5
24h PM: 5.2-5.4 |
|
|
Term
| What is stress? What are some of the physiological responses we observe? |
|
Definition
physiological adjustments that an animal makes when exposed to adverse conditions
-heart rate
-respiration
-body temperature
-blood pressure |
|
|
Term
| What is the role of epinephrine in stress response? |
|
Definition
-maintenance of circulation
-breakdown of glycogen & lipid stores |
|
|
Term
| What are some of the pre-slaughter management & handling factors that can affect stress in meat animals? |
|
Definition
-herd environment & human exposure
-marketing direct to packer vs auction
-truck loading technique
-experience of shippers
-use of electric prod
-transportation time
-crowding & co-mingling
-temperature
-lairage period
-post slaughter handling of meat |
|
|
Term
True or False
Cattle are usually shipped direct to packer rather than run through an auction |
|
Definition
False
Pigs & poultry are often marketed direct to packer |
|
|
Term
|
Definition
| holding of animals at plant before slaughter |
|
|
Term
| What is the trade-off to be considered concerning the lairage period? |
|
Definition
| longer rest period allows for more time to recuperate, but also more room & opportunity for fights between animals |
|
|
Term
| What is the term for DFD in beef? |
|
Definition
|
|
Term
| What are some causes of DFD in swine? |
|
Definition
Porcine Stress Syndrome (PSS)
General stress due to transport, hunger, fear, aggression etc. |
|
|
Term
| What type of muscle fibers are associated with DFD? |
|
Definition
|
|
Term
|
Definition
| -depletion of glycogen stores before death means inadequate amounts of lactic acid are produced to lower pH |
|
|
Term
| What are some characteristics of DFD beef? |
|
Definition
-dark colour
-firm consistency
-high water holding capacity
-sticky surface
-prone to bacterial spoilage |
|
|
Term
| What colour characteristics would be observed in meat at pH 5.8-6.0? 6.5? |
|
Definition
5.8-6.0 abnormal colour
6.5 extremely dark colour |
|
|
Term
| Why does DFD meat appear dry? |
|
Definition
| because the water is tightly bound within muscle fibers |
|
|
Term
| Why is DFD beef prone to bacterial spoilage? |
|
Definition
| because the high pH is a good environment for bacterial growth |
|
|
Term
True or False
DFD carcasses are discounted by 10 cents per pound |
|
Definition
False
25 cents per pound on average |
|
|
Term
True or False
DFD pork is tough and has a lesser quality flavour |
|
Definition
False
DFD pork is tender & has good flavour |
|
|
Term
True or False
DFD beef is juicy |
|
Definition
True
due to its increased water holding capacity |
|
|
Term
| What gender has a higher incidence of DFD beef, steers or heifers? |
|
Definition
|
|
Term
| Why is there a higher incidence of DFD in heifers? |
|
Definition
| -mounting behaviour & physical stress during estrus |
|
|
Term
|
Definition
-feed additive for heifers in feedlots
-prevents heifers from going into heat, decreases mounting behaviour, maximizes nutrient use for weight gain |
|
|
Term
True or False
MGA can also be beneficial for steers |
|
Definition
True
If heiffers are not in heat, the steers housed nearby will be less stressed as well |
|
|
Term
| How does nutritional status affect dark cutting meat? |
|
Definition
| different energy percentage in forage, less energy in forage than grain , affects glycogen stores |
|
|
Term
| What is a more important factor in regards to animal stress, cool seasonal temperatures or a sudden increase in temperature? |
|
Definition
| sudden increase is more likely to stress an animal than a constant cool temperature |
|
|
Term
| How does stress affect muscle contraction? |
|
Definition
| -increases muscle activity, which increases lactic acid production |
|
|
Term
| How does stress affect the circulatory system? |
|
Definition
| blood flow increases due to increased demands for nutrients & oxygen |
|
|
Term
| What happens when the demands of muscle are not met? |
|
Definition
-shift from aerobic to anaerobic metabolism
-production of lactic acid
-increase in temperature |
|
|
Term
| What are the postmortem effects of stress on the conversion of muscle to meat? |
|
Definition
-temperature
-glycolysis
-onset of rigor
-rate of pH decline |
|
|
Term
| What happens if lactic acid production overwhelms the ability of the body to use it? |
|
Definition
|
|
Term
| What are the effects of circulatory collapse? |
|
Definition
-increased muscle temperature
-inability to remove lactic acid
-ATP production inhibited |
|
|
Term
| What is the 'expense' of stress handling in stress resistant animal? |
|
Definition
| handle stress at the expense of muscle glycogen, which affects lactic acid production & the conversion of muscle to meat |
|
|
Term
|
Definition
Porcine Stress Syndrome
-PSS is a genetic defect in pigs
-autosomal recessive gene, replacement of a single nucleotide in a Ca release channel protein of the SR
-excessive release of Ca2+ |
|
|
Term
| What is the importance of ryanodine in PSS? |
|
Definition
| -plant alkaloid used to test for the genetic defect |
|
|
Term
| Does PSS cause PSE or DFD meat? |
|
Definition
|
|
Term
| What receptor releases Ca2+ into the sarcoplasm? |
|
Definition
|
|
Term
| Describe the steps of the contraction process which involve Ca2+ & ryanodine |
|
Definition
1. dihydropyridine receptor releases Ca2+ into sarcoplasm
2. ryanodine receptor detects the release & allows additional Ca2+ from SR to be released
4. Troponin C binds Ca2+, myosin binding sites are exposed on actin to allow for contraction |
|
|
Term
| What is halothane sensitivity? What muscles are primarily affected? |
|
Definition
halothane is an old anaesthetic
-rapid increase in body temperature
-large amounts of lactic acid production due to anaerobic glycolysis
-muscle rigidity due to overstimulation
-affects muscles of the ham/hindquarter & loin |
|
|
Term
| What are the 3 classes of genotypes in PSS? |
|
Definition
NN: halothane resistant
Nn: carrier
nn: halothane sensitive |
|
|
Term
| How can halothane be used to detect PSS? |
|
Definition
| halothane-sensitive individuals will show muscle spasms/rigidity within 5 minutes of exposure |
|
|
Term
True or False
Halothane can be used to detect individuals heterozygous for PSS |
|
Definition
False
Need to do DNA testing |
|
|
Term
| How do PSS pigs react to stress? |
|
Definition
-trembling muscles
-rigid/weak muscles, lethargy
-excessive lactic acid production
-vasoconstriction increases BP
-hypertension increases BP
-decreased cardiac output
-hyperthermia
-increased metabolic activity can kill the animal
-dyspnea
-hyperkalemia |
|
|
Term
|
Definition
| rapid shallow breathing (PSS pigs) |
|
|
Term
|
Definition
| elevated blood potassium, can stop the heart |
|
|
Term
| What breeds are primarily affected by PSS? |
|
Definition
Pietrain
Poland
China
Landrace |
|
|
Term
| Will PSE pork have a higher or lower carcass temperature than normal post mortem? |
|
Definition
|
|
Term
|
Definition
rapid & extensive decline in pH
-if pH drops before heat dissipates, proteins are likely to denature |
|
|
Term
| How do we prevent denaturation of proteins PM? |
|
Definition
chilling of meat so heat can dissipate before pH drops
-blast chilling can be used to control PSE in pork |
|
|
Term
| Is protein denaturation a guaranteed process with rapid pH decline? |
|
Definition
|
|
Term
| When does visual appraisal for PSE pork take place? |
|
Definition
| in the cooler, 75 minutes after slaughter |
|
|
Term
| When is the carcass put into the cooler? |
|
Definition
| 35-45 minutes after slaughter |
|
|
Term
True or False
24h pH is a good indicator for PSE |
|
Definition
False
Only if the meat is severely PSE |
|
|
Term
| Is low pH necessarily bad for pork? |
|
Definition
| no, because it can prevent microbial growth |
|
|
Term
| What pH levels are good indicators for PSE & DFD? |
|
Definition
|
|
Term
| What is the importance of the 45-60 minute measurement for predicting PSE? |
|
Definition
| gives an indication of how fast acid production is occurring |
|
|
Term
| If pH is below 6.0 at the 45-60 minute measurement PM, what does this indicate? |
|
Definition
|
|
Term
|
Definition
| -can carry a genetic defect which results in high levels of glycogen at slaughter |
|
|
Term
| What effect does RN have in regards to pH decline post mortem? |
|
Definition
-slows the rate of glycolysis, will have a normal measurement at the 45-60 minute mark
-ultimate pH will be low
-causes PSE pork |
|
|
Term
| What are the effects of protein denaturation on meat quality? |
|
Definition
-pale meat
-loss of water binding capacity (exudative)
-fluid may drip from surface of meat
-loss of protein solubility |
|
|
Term
True or False
Consumers are good at judging whether a cut of meat is PSE |
|
Definition
False
The low water holding capacity makes them think it's juicy |
|
|
Term
| Describe the steps in the development of PSE |
|
Definition
1. Acidification
2. Protein denaturation
3. Proteins reach isoelectric point
4. increased light scattering & exudation of moisture
5. Opaque, pale appearance & drip loss |
|
|
Term
| How do we get DFD pork from a PSS animal? |
|
Definition
-if the animal survives the stress of the transport/pre-slaughter process
-low/nonexistent glycogen stores at slaughter
-no lactate is produced, pH remains high (5.8-5.9) |
|
|
Term
| Describe the palatability of DFD pork from a PSS animal |
|
Definition
-good aroma
-good flavour
-tender product
-moist/juicy |
|
|
Term
| If all pigs with PSS were eliminated, would the problem of PSE meat be eliminated as well? |
|
Definition
no, the RN defect still exists
PSE can develop from any pigs genetics predisposed to rapid rates of glycolysis & pH decline, don't need to have the PSS defect |
|
|
Term
True or False
PSS animals can produce normal pork |
|
Definition
|
|
Term
| PSS refers to ______ while PSE refers to _____ |
|
Definition
PSS: animal & its genetic defect
PSE: the meat that is produced |
|
|
Term
| What is the difference between water holding capacity & absorption? |
|
Definition
Absorption: ability to bind water from the external environment
WHC: ability to bind or hold its own water |
|
|
Term
|
Definition
pH
higher pH = higher WHC
if isoelectric point is reached there is no electrical charge, minimal water solubility |
|
|
Term
|
Definition
-water loss during chilling
-appearance of meat before cooking
-behaviour during cooking
-juicyness when chewing
-processing of meat |
|
|
Term
| What are some other terms for drip loss? |
|
Definition
|
|
Term
| What causes a reduction in WHC as pH declines PM? |
|
Definition
-thick & thin filaments move closer together
-water space between myofilaments decreases
-ATP is depleted, no energy for membranes to hold water
-fluid escapes between fasiculi
-denaturation of myosin |
|
|
Term
| What causes PSE pork to be soft? |
|
Definition
-escaped water between fasiculi = easily separated muscle fiber bundles
-detachment of myosin heads
-tougher meat |
|
|
Term
True or False
Paleness of PSE pork is directly proportional to pH |
|
Definition
False
inversely proportional |
|
|
Term
| Why is pork more prone to paleness in PSE? |
|
Definition
| -little myoglobin to begin with -oxidation of myoglobin to metmyoglobin would turn it brown |
|
|
Term
| What is the major reason for DFD beef? |
|
Definition
-mixing of unfamiliar cattle (co mingling) causes stress
-fighting, mounting, lots of physical activity depleting glycogen stores |
|
|
Term
True or False
As lairage time increases, the incidence of DFD also increases |
|
Definition
true (in general)
-short rest period is good, too long (e.g. overnight) might give more rest but is also very likely to result in more fights & stress between animals |
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