Bacteria Responsible for Spoilage of Chilled Meat

Bacterial spoilage in chilled meat is due to:

Correct Answer: Psychrophilic Bacteria

Bacterial spoilage in chilled meat (stored at 4°C or below) is caused by psychrophilic bacteria — organisms that thrive at low temperatures and are responsible for surface sliminess, off-odours, and colour changes seen in refrigerated meat.

Three Categories of Bacteria by Growth Temperature

• Psychrophilic bacteria — optimal growth below 20°C; responsible for spoilage of chilled/refrigerated meat. Examples: Pseudomonas spp., Acinetobacter, Moraxella, Lactic acid bacteria
• Mesophilic bacteria — optimal growth at 20–45°C; responsible for spoilage at room temperature and most foodborne pathogens. Examples: Salmonella, E. coli, Staphylococcus aureus
• Thermophilic bacteria — optimal growth above 45°C; cause spoilage in canned goods (flat sour). Examples: Bacillus stearothermophilus, Clostridium thermosaccharolyticum

Why Psychrophiles Dominate Chilled Meat

• Chilling at 4°C slows mesophiles and thermophiles completely but does not inhibit psychrophiles.
• Pseudomonas spp. are the dominant spoilage organisms on aerobically stored chilled beef — they produce greenish discolouration, slime, and putrid odours.