Meat Colour

Question 1

The 3 forms of myoglobin in raw meat: provide names, colours and oxygen levels

Answer 1

Deoxmyoglobin- Purple- Absence of Oxygen
Oxymyoglobin- Red- Abundent oxygen
Metmyoglobin- Brown- either

Question 2

What are the 2 possible oxidation states of iron in myoglobin?

Answer 2

• Oxymyoglobin Fe2+ ormetmoglobin Fe3+

Question 3

How does the 6th ligand of myoglobin change in the 3 colours of raw meat?

Answer 3

Purple- Red Dexoxy- Fe2-
Red- Fe2 - Oxymoglobin -O2
Brown- Fe3- H20

Question 3

What are the 3 pO2 levels responsible of the 3 colours in meat?

Answer 3

pO2 = 0 mm Hg
pO2 > 30 mm Hg
0 mm < pO2 < 30 mm Hg

Question 4

Which intrinsic factors affect the myoglobin content in meat?

Answer 4

1. Myoglobin content
   - Species, Fibre type, Age of animal,Sex of animal, muscle physical activity.
2. pH, PSE, DFD conditions
3. Oxidation reactions, reduction reactions, Metmyoglobin reductase activity (MRA),Oxygen partial pressure, Oxygen consuming reactions (OCR).
4. Lipid oxidation

Question 4

What is the effect of lipid oxidation on colour?

Answer 4

Red to Brown

Question 5

What is the role of metmyoglobin reductase in colour?

Question 6

Which extrinsic factors affect the colour of meat?

Answer 6

Packaging, Bacterial growth, Storage temperature, Electrical stimulation, Hot-boning, Reducing agents, Oxidising agents, Metals, Heating (cooking

Question 7

What is the gas composition in MAP compared to air?

Answer 7

Air= 80% nitrogen, 20% oxygen, <1% carbon dioxide
MAP= 80% oxygen: 20% carbon dioxide

Question 8

What is the relationship between vitamin E and colour?

Answer 8

Enhancing colour stability