Psychrotrophic Food Spoilage
Psychrotrophic bacteria constitute the bacterial species capable of growing at 5 ◦C and below, but multiply quite rapidly at 10–25 ◦C and even at higher temperatures. Many foods are stored on ice (chilling) and in refrigerators, and some are expected to have a long shelf life (50 days or more). Some microorganisms capable of causing food spoilage at refrigeration temperatures include:
• Pseudomonas fluorescens
• Pseudomonas fragi
• Other Pseudomonas species
• Acinetobacter
• Moraxella
• Flavobacterium
• Some molds and yeasts are included in this group as well
Important Thermoduric Psychrotrophs
If the food is given low-heat treatment and not exposed to post heating contamination during storage at low temperature, psychrotrophic thermoduric bacteria can cause it to spoil. Some microorganisms that are capable of this include:
• Bacillus coagulans
• Bacillus Megaterium
• some strains of Lactobacillus viridescens
• Spores of Clostridium laramie
• Clostridium estertheticum
• Clostridium algidicarnis
• Clostridium putrefaciens
• unidentified Clostridium spp.
Their spores survive low-heat treatment. Following germination and outgrowth, the cells grow at low temperature.