Beef spoilage under chill — Which microorganisms commonly grow on beef at about 15°C and above (choose the most inclusive correct option)?

Introduction / Context:
Temperature is a key extrinsic factor shaping meat spoilage flora. Around 15°C (mild abuse above standard refrigeration), the surface microbiota of beef shifts toward faster-growing aerobes that drive off-odors and discoloration.

Given Data / Assumptions:

• Beef is typically stored near 0–4°C; 15°C reflects temperature abuse.
• Surface is aerobic; psychrotrophic to mesophilic aerobes dominate.
• Micrococci and Pseudomonas are classic meat spoilers under such conditions.

Concept / Approach:
Pseudomonads rapidly proliferate under oxygen and mild temperatures, producing slime and off-odors. Micrococci likewise grow at these temperatures, contributing to discolorations and spoilage. Lactobacilli are more relevant under vacuum or modified atmospheres and at lower temperatures, where they outcompete aerobes.

Step-by-Step Solution:

Verification / Alternative check:
Spoilage charts for beef enumerate pseudomonads and micrococci as dominant surface aerobes in mild abuse temperatures.

Why Other Options Are Wrong:

• Micrococci only or Pseudomonas only: each is incomplete.
• Lactobacillus: prominent under anaerobic vacuum conditions rather than warm aerobic surfaces.

Common Pitfalls:
Assuming one genus dominates in all scenarios; packaging and temperature change the ecology.

Final Answer:
Both (a) and (b)