Question

Stable pink colour of cured and cooked meat products is due to:

• A. Oxymyoglobin
• B. Myoglobin
• C. Nitrosohemochrome
• D. Metmyoglobin

Hint:

The curing pigment pathway is:
Myoglobin + Nitric Oxide \(\rightarrow\) Nitrosomyoglobin (unstable red).
Nitrosomyoglobin + Heat \(\rightarrow\) Nitrosohemochrome (stable pink pigment of cooked cured meat).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Meat curing involves adding salts, nitrites, or nitrates to raw meat to preserve it, improve safety, and develop a stable, characteristic pink color.
The color of both fresh and cured meat is primarily determined by the state of myoglobin, the main oxygen-binding hemoprotein in muscle tissue.

Step 2: Detailed Explanation:
Let us analyze the chemical transformations of meat pigments during curing and cooking:
- Fresh meat contains deoxymyoglobin (purplish-red) and oxymyoglobin (bright red, when bound to oxygen).
If the iron in myoglobin oxidizes from the ferrous (\(\text{Fe}^{2+}\)) state to the ferric (\(\text{Fe}^{3+}\)) state, it forms metmyoglobin, which gives meat an undesirable brown color.
- When nitrites (\(\text{NO}_2^-\)) are added during curing, they are reduced to nitric oxide (\(\text{NO}\)) in the meat.
- Nitric oxide binds to the free coordination site of ferrous myoglobin, forming nitrosomyoglobin, which has a bright red color.
- When this cured meat is subsequently cooked or subjected to thermal processing, the globin protein part of nitrosomyoglobin denatures.
- This denaturation changes the pigment into a highly stable, heat-coagulated complex called nitrosohemochrome (or nitrosyl-hemochromogen).
This complex gives cured and cooked products (such as ham, bacon, and frankfurters) their stable, characteristic pink-rose color, which does not fade easily when exposed to heat or light.
Therefore, nitrosohemochrome is the pigment responsible for this stable pink color.

Step 3: Final Answer:
The stable pink colour of cured and cooked meat products is due to nitrosohemochrome.