Processed meats — Greening of sausage: A green ring, green core, or green surface often arises due to hydrogen peroxide formed by which microbial/physiological factors?
Correct Answer: Both (a) and (b)
Introduction / Context:Greening defects in sausages and cured meats puzzle operators because they occur even under refrigeration. Understanding the microbial chemistry behind pigment changes is essential for prevention.
Given Data / Assumptions:
- Observed defect: green ring/core/surface in sausage.
- Chemical agent implicated: hydrogen peroxide (H2O2).
- Potential contributors: heterofermentative lactic acid bacteria and catalase-negative bacteria.
Concept / Approach:Heterofermentative lactic acid bacteria can generate H2O2 during carbohydrate metabolism in low-oxygen niches. If the flora are catalase-negative, H2O2 persists, oxidizing meat pigments (e.g., myoglobin) or interacting with nitrosylated heme, producing green discoloration. Therefore, both heterofermentation and catalase deficiency favor greening.
Step-by-Step Solution: Identify microbial source of H2O2: heterofermentative LAB in packaged meats. Assess detox capacity: catalase-negative populations fail to decompose H2O2. Connect chemistry: H2O2 oxidizes meat pigments → green hues. Conclude the correct option is the combination.
Verification / Alternative check:Meat science literature reports greening linked to H2O2 from lactobacilli under vacuum or modified atmospheres, particularly when catalase activity is minimal.
Why Other Options Are Wrong:
- (a) alone or (b) alone: incomplete; both conditions increase risk.
- None: contradicts the established mechanism of H2O2-mediated pigment change.
Common Pitfalls:Attributing greening only to nitrite chemistry; ignoring the role of peroxide accumulation and catalase status.
Final Answer:Both (a) and (b)