Acid foods (pH 4.5–3.7): Which spoilers are most often responsible for defects in this pH band?

Introduction / Context:
The pH band between roughly 4.5 and 3.7 is acidic enough to exclude many proteolytic clostridia, yet still permissive for acid-tolerant spoilers. Recognizing the major organisms in this band helps target retort values and formulation controls for tomato products and some fruit items.

Given Data / Assumptions:

• Product pH: 3.7 to 4.5.
• Candidates: Bacillus coagulans (thermophilic, aciduric) and saccharolytic anaerobes (e.g., Clostridium pasteurianum).
• Outcome: spoilage (acid development, gas, off-odors).

Concept / Approach:
B. coagulans is a classic cause of flat sour spoilage in tomato products due to its heat resistance and ability to grow at low pH and elevated storage temperatures. C. pasteurianum, being saccharolytic and relatively acid-tolerant, can grow and produce gas/acid in inadequately processed acid foods near the upper end of this band. Together, they represent the primary risk organisms in this range.

Step-by-Step Solution:
Define the pH window and exclude proteolytic clostridia (growth limited).Identify acid-tolerant thermophiles and saccharolytic anaerobes as key spoilers.Select the option containing both groups.

Verification / Alternative check:
Thermal process calculations for acid foods often specifically target B. coagulans and C. pasteurianum as design organisms.

Why Other Options Are Wrong:

• None of these: Incorrect; these spoilers are well documented.
• Proteolytic C. botulinum: Inhibited below about pH 4.6.

Common Pitfalls:
Assuming “acid food” equals shelf-stable with no risk; heat-resistant, acid-tolerant spores can still cause defects.

Final Answer:
Both (a) and (b).