Meat Science Exam 3

What is homeostasis

in a living state, all organs and systems within the body interact to maintain an environment under which each can perform its functions efficiently

maintenance of the physiological state is termed what

homeostasis

what are the 8 alpha helix sections

A-H

how does oxymyoglobin become metmyoglobin

-lose some O2

-Fe (2+) becomes Fe(3+)

what is glycolytic/anaerobic ATP used for

metabolism

what is creatine phosphate ATP used for

muscle contractions

why is the lympathic system failing important for meat safety?

failing of the lymphatic system can lead to increased bacterial presence in the meat, which causes potential health risks

when is the calpain system activated

when Ca2+ released from mitochondria and SR during storage

what is u-calpain

micromolar (low) calcium concentration

what is m-calpain

millimolar (high) calcium concentration

postmortem, what happens to make meat tender

-natural enzymes break down muscle fibers

-lower pH makes meat more tender

-aging post mortem makes meat more tender

what main four things influence homeostasis

-oxygen concentration

-pH

-temperature

-energy

how does deoxymyoglobin become oxymyoglobin

add oxygen via "bloom"

Dr. Melvin hunt said all brown meat should be vacuum packaged, why?

if you use a higher oxygen type packaged, there will be premature browning when it is cooked

-vacuum sealed package does not have this effect

-if you start with deoxymyoglobin the cooking process stays normal

how does deoxymyoglobin become metmyoglobin

oxidation

-lose hydroxyl ion and hydrogen ion complex

-gain oxygen but not enough O2 to become oxymyoglobin

how does deoxymyoglobin become carboxymyoglobin

adding carbon monoxide

what are the methods of immobilization

-CO2

-electric shock

-captive bolt

what animal species usually get chronic stress

ruminants

what animal species usually get acute stress

pigs and chickens

does post or pre rigor meat have a higher WHC and pH and is ideal for hot boning and further processing

pre-rigor meat

which forms of myoglobin contain iron in the ferrous (Fe 2+) state?

-deoxymyoglobin

-carboxymyoglobin (sometimes)

-oxymyoglobin

what ingredient increases pH and improves WHC of meat proteins

phosphate

what are some specific ingredient requirements for hamburgers

-can have added beef fat

-can have sea salt

-30% fat

-can have seasoning

-can have cheek meat

what is a pineapple derived enzyme effective on collagen

bromelain

T/F MDM is most commonly produced from pork due to its ease of separation

false

what ingrediant is extracted from red seaweed and used as an extender in meat

carrageenan

T/F further processing typically involves ingredient addition or thermal treatment

true

what conditions make meat highly perishable

-exposure to oxygen

-high water activity

-neutral pH

what is usually least likely to be considered a method of further processing

vacuum packaging

what are some ground beef specific ingrediant requirements

-can have cheek meat

-30% fat

-can have seasoning

what can accelerate discoloring in retail meat display

flourescent lighting

ground beef samples with added Vitamin E stay red longer during storage.

What mechanisms explain this effect?

-vit E acts as an antioxidant reducing lipid oxidation

-lower lipid oxidation helps prevent heme iron oxidation

a packer observes that vacuum packaged beef loins appear purplish-red when first opened, but turn bright red after exposure to the air

why?

-oxygen binds to ferrous (Fe2+) iron in heme group

-deoxymyoglobin on the surface is converted to oxymyoglobin upon oxygen exposure

a pork processor reports that a group of pigs delivered late to the plant showed PSE meat after chilling. Which factors likely contributed to this issue?

-protein denatured reduced WHC

-short term stress immediately before slaughter accelerated glycolysis

-rapid pH decline while carcass temperature was still high

which myoglobin form is predominant in vaccum packaged meat

deoxymyoglobin

a type of immobilization causing blood splash

electrical stunning

where is immobilized water located

between myofibrils

T/F z disk degradation contributes to meat tenderness

true

which enzyme is calcium dependent and involved in postmortem proteolysis

calpain

what is the ultimate pH of meat 24 hour postmortem under normal condition

5.5

what is an example of heat ring

two toned ribeye due to uneven chilling

what temperature range is optimal for carcass chilling during rigor onset

15-16 C

what amino acid is directly binding to Fe of heme ring

proximal histidine

what is the stabilizing binding ligand

distal histidine

what are included in the narrow range of physiological conditions for homeostasis

-oxygen concentration

-pH

-temperature

-energy supply

what marks the beginning of postmortem changes

removal of blood

-exsanguination

what is exanguination

removal of blood

is there a drop in blood pressure for postmortem

yes

how much of blood is redirected to vital organs in homeostatic control of postmortem

50%

what are some homeostatic control mechanisms that kick in postmortem

-increase in heart rate to maintain circulation

-peripheral vessels constrict to prioritize blood flow

when is muscle converted to meat

once metabolism stops

when the oxygen supply is depleted, what begins to fail

TCA cycle and electron transport

T/F premature browning makes meat appear fully cooked before it is safe to eat

true

what can accelerate the oxidation of oxymyoglobin

-fluorescent light

-low MRA

-lipid oxidation

which form of myoglobin gives meat a bright red color

oxymyoglobin

T/F long term stress may lead to PSE meat in pigs

-PSE: pale soft exudative

false

what is the isoelectric point of meat proteins

5.0-5.2

what is deoxymyoglobin

reduced myoglobin

what is oxymyoglobin

oxygenated myoglobin

what is oxidized myoglobin

metmyoglobin

the amino acid that directly binds to Fe of heme ring is called

proximal histine

what is a distal histidine

stabilizing binding ligand

which meat quality defect is associated with lean carcasses and fast chilling

heat ring

what is the ultimate pH of meat 24 hours postmortem under normal conditions

5.5

what causes rigor mortis to occur

depletion of ATP

Which enzyme is calcium-dependent and involved in postmortem proteolysis?

calpain

T/F z-disk degradation contributes to meat tenderness

true

what animal is PSE usually for

pork

what animal is DFD usually for

beef

what does DFD stand for

dark, firm dry

water of food that is 4-5% in proportion is

bound water

what is located between myofibrils and affected by pH and protein structure

immobilized water

what is water that is on the surface of foods and can be dried through various means

free water

what is a type of immobilization causing blood splashes

electrical stunning

what is a technique to accelerate rigor mortis

electrical stimulation

what is caused by freezing muscles before rigor, leading to severe contractions

thaw rigor

what is a two-toned ribeye due to uneven chilling and pH distribution

heat ring

what speeds rigor onset and prevents cold shortening by accelerating glycolysis

electrical stimulation

what are some traits of pre rigor meat

-has higher WHC and pH

-ideal for hot boning and furthering processing

postmortem oxygen depletion leads to

-lactic acid production

-switch to anaerobic metabolism

which myoglobin form is predominant in vaccum-packaged meat

deoxymyoglobin

what is the optimal carcass temperature during rigor onset

15-16 C

what changes occur during cold shortening

-nervous stimulation

-muscle contraction

-cold-induced contraction before onset of rigor mortis

which forms of myoglobin contain iron in the ferrous (Fe2+) state?

-deoxymyoglobin

-oxymyoglobin

what are some specific ingredient requirements for ground beef

-30% fat

-can have herbs

-can have sea salt

-can have cheek meat

what is the least likely method to be considered for further processing

vaccum packaging

what is a common visual sign of spoilage due to pH change

discoloration

what conditions make meat highly perishable

-neutral pH

-high water activity

-exposure to oxygen

minimal processing includes what

-raw intact meat

-edible offal

-raw non-intact meat

T/F further processing typically involves ingredient addition or thermal treatment

true

which ingredient is extracted from red seaweed and used as an extender in meat

carrageenan

T/F MDM is most commonly produced from pork due to ease of separation

-MDM: mechanically deboned meat

false

-most common in poultry

what is pineapple derived enzyme effective on collagen

bromelain

what is wet aging

vacuum package meat stored under refrigeration

what is IQF

freezing method preserving individual product pieces

what is transglutaminase

enzyme forcing protein cross-links known as meat glue

what is accelerated aging

tenderization method that increases bacterial risk if mishandled

what is purge

liquid loss in vacuum-packaged wet aged meat

what is the rule for cheek meat

no more than 25% allowed in ground beef per USDA rules

how long does it take the pH to decline from 7 to 5.7 posmortem

6-8 hours