Factors Affecting Meat Quality

color, tenderness, juiciness, flacor

What are the sensory quality (physical) attributes that we focus on in meat quality?

emulsifying capacity, binding properties, cooking loss, cooked color, cooked texture

What are the technological quality (chemical and physical) attributes that we focus on in meat quality?

unfamiliar environment, being along, air movement, sound, space, temperature, humidity, light fasting

Animals may become excited fatigued, overheated, or chilled; this can be due to:

Stress

general expression referring to physiological adjustments that occur during the exposure of the animal to adverse condition

heart rate, respiration rate, body temperature, blood pressure

What are the physiological adjustments of stres?

adverse condition

What are stressors?

increased demand for muscle contraction

What is the primary consequence of stress in muscle?

blood flow increases to supply oxygen and nutrients

What happens to blood flow in muscles during stress?

epinephrine and norepinephrine

What hormones are released during stress to support muscle activity?

glycolysis

What type of metabolism is stimulated by epinephrine and norepinephrine?

glycogen levels, lactic acid production, and ultimately meat quality

What does stress before slaughter effect?

short-term stress just minutes before slaughter

What causes rapid pH decline in meat?

Pigs

What species is most associate with rapid pH decline?

very fast

How fast is the conversion of muscle to meat in rapid pH decline?

it is usually normal (~5.5), but drops very quickly while carcass is still warm

What happens to ultimate pH in PSE meat?

protein denaturation → reduced solubility

How does rapid pH decline affect protein solubility?

it decreases

What happens to WHC in PSE meat?

both increase

What happens to drip loss and cooked loss in PSE meat?

pale

What is the color in PSE meat?

long-term stress, at expense of glycogen storage

What causes a slow pH decline in meat?

ruminants

What type of animals are usually associated with slow pH decline?

it remains high (>6.0)

What happens to the ultimate pH of DFD (Dark, Firm, Dry) meat?

it increases

What happens to the WHC of DFD meat?

very dark

What is the color intensity of DFD meat?

high WHC improves yield

better water retention enhances product texture

Why is DFD great for processed meat?

Color, WHC, Protein Functionality

What can stress impact (pH and meat quality)?

Water-holding capacity (WHC)

the ability of meat to retain naturally occurring or added water during application of external forces

cutting, heating, grinding, pressing

What external forces to we expect water to be held during?

color, texture, firmness, binding, pH

What physical properties depend on WHC?

technological quality, shrinkage, yield

what effects does WHC have on processing?

bound water (4-5%), immobilized water (variable), free water (surface water)

What are the water layers of WHC - the three types of water in protein functionality?

negative

Meat proteins have ______ net charge.

decreasing

As pH declines, there is a _________ number of reactive groups on proteins available for water binding.

greater; negative; greater

______ pH = more ________ net charge = ______ WHC

it decreases significantly

What happens to WHC is the pH is lower than the isoelectric point?

carbon dioxide, electric shock, captive bolt

What are the methods of immobilization (stunning)?

blood pressure

What is increased dramatically after stunning?

hind quarter

What is most affected by blood splash?

blood splash

Rapid bleeding after stunning is the goal to prevent:

protein denaturation, enzymatic activities, bacteria/microbial growth

We lower carcass temperature to prevent:

Thaw rigor

severe rigor caused by thawing muscle that was frozen pre-rigor

Calcium; Muscle Contraction; Shortens meat

If you thaw meat that was frozen pre-rigor, there is a sudden release of _____ into the Sarcoplasm. The calcium reacts which ATP which causes ______ _____ and _______ ______.

Cool meat in fridge before moving to freezer

How can you prevent thaw rigor?

Heat ring

happens to lean carcasses

less than 0.25 in of backfat in beef

less that 0.1 in of backfat in lamb

not chilled properly (outside chilled to fast)

low glycotic metabolism

15-16 degrees celsius

What is the carcass temperature during rigor onset

Electrical Stimulation

What can be used to improve tenderness and meat quality in beef, veal, lamb, and turkey (NOT PORK)?

accelerated pH decline
rapid depletion of ATP reserves

rapidly developing rigor mortis

What does electrical stimulation do in the meat?

Cold shortening

sudden shortening pre-rigor caused by nervous stimulation
induced by cold temperature

pre-rigor deboning (hot boning)

cutting, deboning, and grinding immediately after slaughter

glycolysis is less extensive

greater ultimate pH (6-6.7)

better WHC

maximum WHC for processed meats: juiciness and texture

salting within 2-3 hours postmortem to prevent rigor and protein degradation
rapid chilling to 2-3 degrees celsius

What can you do to maintain pre-rigor characteristics in meat that was deboned pre-rigor?