Cheese discoloration defects — Clostridium species causing dark green to black colours in cheese Which Clostridium species is most associated with the formation of dark green to black discoloration in cheese during ripening or storage?

Introduction / Context:
Besides gas and flavor defects, certain clostridia can cause striking color faults in cheese. Correctly distinguishing the species helps cheese plants target spore control, hygiene, and milk handling practices to prevent expensive downgrades.

Given Data / Assumptions:

• Observed defect: dark green to black color patches or streaks in cheese.
• Candidate organisms are Clostridium spp. known in dairy contexts.
• The question seeks the species most linked to this discoloration.

Concept / Approach:
Clostridium sporogenes is a proteolytic, spore-forming anaerobe frequently implicated in pigment and discoloration faults in dairy products under low-redox niches in cheese. In contrast, Clostridium tyrobutyricum is the hallmark “late-blowing” agent (gas/eyes, rancid notes) but is less associated with dark-green/black pigmentation.

Step-by-Step Solution:
Evaluate species vs. defect association: pigment discoloration aligns with C. sporogenes.Differentiate from C. tyrobutyricum (gas defect) and rare or non-dairy species.Select C. sporogenes as the most appropriate answer.

Verification / Alternative check:
Dairy defect catalogs attribute blackish discoloration more often to proteolytic clostridia like C. sporogenes and related anaerobes in contaminated curd zones.

Why Other Options Are Wrong:
C. tyrobutyricum drives late blowing and rancid flavors, not typical dark-green/black color; C. herbarum is not a standard dairy culprit; “none” ignores clostridial links; C. perfringens is primarily a pathogen with different spoilage signatures.

Common Pitfalls:
Attributing all clostridial cheese faults to C. tyrobutyricum; failing to control spore loads in silage-fed milk streams.

Final Answer:
Clostridium sporogenes.