meat color Flashcards
how do you define meat colour
total impression seen by the eye - light reflected off/ absorbed by meat influences appearance.
how do viewing conditions influence the colour of meat
concentration and state of heme pigments
what is heme
chemical structure of 2 pigments in haemoglobin
- hemoglobin and myoglobin
how does meat illumination changes colour
grocery stores do taste panel testing and use specific lighting to influence buying
how does structure and texture of the muscle influences reflection and absorption of light
PSE reflects and DFD absorbs
hemoglobin
piglet of blood
- found in RBC, for O2 and CO2 for transport
myoglobin
pigment of muscles
- found in sarcoplasm (stores O2 in muscle fibres)
- composed of globular protien and non-protein component.
- similar structure to hemoglobin, 4x smaller tho
myoglobin oxidation effect on meat colour
major influence on colour, Fe2+ is red, fe3+ is darker
how much of meat pigment is made of myoglibin
80-90%, depending on how well the animal has been bled out
effect of myoglobin content as animal ages?
increases, loses affinity for oxygen w oxygen, so it needs more to keep up w demand.
locomotive vs support muscle myoglobin content
almost double in locomotive muscles
myoglobin gender impact
intact males often have more myoglobin, a more dark red meat.
diet effect on myoglobin/meat redness
low Fe content decreases meat redness
underwater mammal myoglobin
high myoglobin due to the adaptation to being under water for long periods of time
fresh cut meat colour
kinda purple, this form of myoglobin is called deoxymyoglobin, reduced to form Fe2+ in uncut meat. can only react w water
oxymyoglobin
red in colour, formed 15-60 minutes after meat is cut and allowed to “bloom”
grading beef after bloom period to distinguish DFD beef.
- stability is dependent on O2 supply
- cold storage will reduce browning of meat.
metmyoglobin
small amounts of O2 available, Fe oxidized to a brown colour called metmyoglobin (Fe2+ to Fe3+)
- not post mortem aging of meat, rather over oxidizing in store
formation of metmyoglobin
influenced vey use of Vit E in beef diets, producers may feed more in feed lots before processing. delays Fe oxidation
drip loss and water holding capacity relation
inversely related, low drip loss= meat retaining water
extreme DFD has a lower light value and 0% drip loss. PSE has lots of light and 15% driploss
