Topics:
Animal Refresher, Meat Science
Cause of Greening in Cured Meat
Greening / green ring formation in cured meat is due to:
- Excess nitrite — Correct Answer
- Lack of nitrite
- Excess salt
- Lack of salt
Explanation:
Correct Answer: Excess nitrite
Greening (also called green ring formation) in cured meat is caused by the use of excess nitrite — i.e., nitrite added beyond the permitted level of 200 ppm.
How Does Excess Nitrite Cause Greening?
- Nitrite (NO₂⁻) in excess reacts with myoglobin to form choleglobin or oxidised porphyrin derivatives — green-coloured pigments.
- Excess nitrite also generates hydrogen peroxide (H₂O₂) which oxidises the porphyrin ring of haem → green colour.
- The green ring typically appears at the periphery of the cured meat product (sausage cross-section), hence 'green ring'.
Normal vs Excess Nitrite — Pigment Summary
- Normal nitrite (≤200 ppm): Nitrite → NO → NO + Myoglobin → Nitroso-myoglobin (pink) → after cooking → Nitroso-haemochromogen (stable pink). ✔
- Excess nitrite (>200 ppm): → Choleglobin / oxidised porphyrin → Green colour. ✘
Permitted Levels in Cured Meat
- Nitrate: 500 ppm (maximum).
- Nitrite: 200 ppm (maximum) — exceeding this causes greening.
📚 About this Topic — Animal Refresher
This multiple choice question is from Animal Refresher, Meat Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Refresher to strengthen your preparation.
