Food safety — If thermal canning is inadequate, which type of microorganism is most likely to proliferate in the sealed, oxygen-depleted can and pose a serious health risk?
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AObligate aerobe
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BAcidophile
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CMesophile
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DObligate anaerobe
Answer
Correct Answer: Obligate anaerobe
Explanation
Introduction / Context:Canned foods are processed to inactivate spores of dangerous anaerobes, particularly Clostridium botulinum. Failure to reach proper lethality permits spore survival and germination in the oxygen-poor interior of sealed cans, potentially producing botulinum neurotoxin, a life-threatening hazard.
Given Data / Assumptions:
- Post-processing environment inside cans is anaerobic.
- Concern centers on spore-formers that grow without oxygen.
- Acid content and processing schedule influence required lethality.
Concept / Approach:Obligate anaerobes, especially Clostridium species, thrive in oxygen-free settings. Proper canning (retort) schedules target spore inactivation (e.g., 12D reduction for C. botulinum in low-acid foods). Aerobes cannot grow in sealed anaerobic cans; mesophile merely describes temperature preference; acidophiles favor low pH but many canned goods are low-acid and need severe processing to suppress anaerobes.
Step-by-Step Solution:
Identify can interior as anaerobic → favors obligate anaerobes.Recall target organism in low-acid canning: C. botulinum.Eliminate obligate aerobes (require O2).Note mesophile is nonspecific; acidophile depends on pH, not oxygen.Verification / Alternative check:Food safety standards (e.g., for low-acid canned foods) emphasize spore control of C. botulinum through validated thermal processes and container integrity checks (no swelling, gas).
Why Other Options Are Wrong:
- Obligate aerobe: cannot grow in anaerobic cans.
- Acidophile: growth determined by pH, not the primary risk in most low-acid canned foods.
- Mesophile: broad category lacking oxygen requirements.
Common Pitfalls:Assuming refrigeration alone prevents botulism; psychrotrophic strains and improper storage still pose risks if processing was inadequate.
Final Answer:Obligate anaerobe