Pseudomonas

gram + or -

negative

type of organism

Psychrotolerant microorganism 

Vegetative Cell (Non-Spore-Former)

survival

Pseudomonas is able to grow at quite a low temperature, but is sensitive to a reduced water activity. 

Has barrier degrading enzymes: 

Lipolytic enzymes that act on lipids (milk) releases fatty acids and causing rancidity 

transmission and sources

high water, nutrients, chilled 
Mainly Pseudomonas 
- off-odours around 107 cfu/cm2 : sugar depleted: switch to amino acids

prevention and sources

Heating kills it. 

 

Barrier by compartmentalization 
By making the water droplets very small (<10 µm) and dispersed in fat: 

• Microbes and enzymes are “trapped” in tiny droplets. 

• They can’t move around or access enough nutrients. 

• This physical separation reduces microbial activity and spoilage. 

D value 

1 log decrease in D with a 5°C increase in temperature)