Conditions needed for bacterial growth

It is important to store, prepare and cook foods safely in order to reduce the risk of bacteria multiplying and causing foodborne illness.

Bacteria need the following conditions to grow:

  • Warmth – Bacteria need warmth to grow. The temperature a food is stored, prepared and cooked at is crucial. If this is not followed correctly then the food will not be safe to eat. The optimum temperature range for bacterial growth is between 5-63℃. This is known as the danger zone as it is dangerous for some foods to be in this temperature range for prolonged periods of time.
Priority Health Issues – Danger Zone
  • Moisture – Bacteria need moisture in order to grow. This is why they grow on foods with high moisture content such as chicken. Foods that are dehydrated or freeze-dried can be stored for much longer as the moisture has been removed.
  • Food – Food provides energy and nutrients for bacteria to grow. High risk foods particularly protein foods such as chicken and dairy products are rich in nutrients and moisture and so promote bacterial growth.
  • Time – If provided with the optimum conditions for growth, bacteria can multiply to millions over a small period of time via binary fission. This is when a bacterium divides in two every 20 minutes.
  • Suitable pH – Most bacteria reproduce best at a neutral pH level of 7. Acidic foods with a pH below 7, or alkaline foods with a pH above 7, may stop or slow down the rate of bacterial growth.