pH and can defects: Foods with pH above about 5.3 are especially subject to which spoilage pattern?

Introduction / Context:
Low-acid canned foods (pH > 4.6 and particularly > 5.3) are vulnerable to thermophilic sporeformers. Two classic defects are flat sour (acid production without gas) and, under anaerobic conditions, putrefaction by proteolytic clostridia. The question asks which is especially associated with higher pH categories in canning texts.

Given Data / Assumptions:

• pH > ~5.3 (low-acid range).
• Candidate defects: flat sour vs putrefaction.
• Process: shelf-stable hermetic cans subjected to heat.

Concept / Approach:
Flat sour spoilage is classically caused by thermophilic Bacillus (for example, B. stearothermophilus, B. coagulans) that survive and grow in higher pH, low-acid foods, producing lactic or other acids without gas, so ends remain flat despite sour odor/flavor. While putrefaction can occur, flat sour is a hallmark defect emphasized for higher pH canned vegetables and starch-rich items.

Step-by-Step Solution:
Identify food category as low-acid by pH.Recall signature defect linked to thermophilic Bacillus growth.Select “flat sour spoilage” as especially associated.

Verification / Alternative check:
Process deviation manuals list flat sour as a classic quality failure in low-acid canned foods stored warm, even when cans are not swollen.

Why Other Options Are Wrong:

• Putrefaction: Possible, but the question emphasizes the well-known, especially associated flat sour pattern.
• TA spoilage only / No risk: Incorrect; low-acid cans carry notable risks.
• Both: Overly broad; a single best-match is sought.

Common Pitfalls:
Mistaking the absence of swelling for safety; flat sour cans can smell/taste off without visual bulging.

Final Answer:
Flat sour spoilage.