Vacuum-packed meat ecology — Which microorganisms are most commonly responsible for spoilage under vacuum packaging conditions?

Introduction / Context:
Vacuum packaging limits oxygen, reshaping the spoilage flora on meat. Identifying the key organisms under reduced oxygen helps predict sensory defects (souring, slime) and set realistic shelf-life targets.

Given Data / Assumptions:

• Oxygen is minimal; aerobes like Pseudomonas are suppressed.
• Facultative or microaerotolerant organisms prevail.
• Two well-known spoilers in vacuum packs are Brochothrix thermosphacta (often abbreviated B. thermosphacta) and lactic acid bacteria (LAB).

Concept / Approach:
B. thermosphacta causes off-odors reminiscent of sour milk/buttery notes and may generate surface slime. LAB (e.g., Lactobacillus, Leuconostoc) ferment residual sugars, causing acidification and souring. Both are expected under vacuum at chill temperatures.

Step-by-Step Solution:

Verification / Alternative check:
Packaged-meat shelf-life studies repeatedly isolate B. thermosphacta and LAB as primary spoilers in vacuum and MAP with low O2/high CO2.

Why Other Options Are Wrong:
Single-group answers ignore the well-documented co-dominance of both organisms in vacuum systems.

Common Pitfalls:
Assuming vacuum eliminates spoilage; it merely shifts the ecology.

Final Answer:
Both (a) and (b)