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?

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)