Control of Bacterial Growth and Key Temperatures

Control of Bacterial Growth and Key Temperatures

We can minimize the risk of causing food poisoning with cleanliness, good hygienic practices and by using different temperatures to either slow down the growth or kill pathogens.

Key Temperatures

Frozen temperatures (-18°C and colder)

Frozen food must be stored and sold below this temperature as a legal requirement. At these very cold temperatures food poisoning bacteria will not be destroyed but will be dormant & unable to multiply, so bacterial levels in frozen food will not increase no matter how long it is stored.

Chilled Temperatures (Ideally colder than 5°C )

General law about perishable or chilled food is that it should be stored at temperatures of 8°C, or below. Meat products should ideally be stored colder than 5°C and fresh fish should be stored as close as possible to freezing point. That is why fresh fish is often held in a Fish fridge or on ice.

At chilled temperatures bacterial growth is slowed down dramatically, however they will still be multiplying, and so high protein food in a fridge can still become unsafe to eat if kept for too long. Listeria is one pathogen which can still multiple reasonably quickly even in chill conditions.

Ambient Temperatures (room temperature)

The ideal temperature for bacterial growth is 37°C, and bacterial growth is usually fastest in the range of 5°C to 63°C (danger zone) and should be avoided for any food that is moist and high in protein. The only types of food that should be stored in ambient temperatures are those that are low in protein, dried, or have been through a process to make them suitable for storing in these conditions, for example tinned products. We also keep packaging in ambient conditions.

Cooking Temperatures (70 °C and hotter)

Food is cooked in order to make it taste nice, but also to make sure it is safe to eat. Hot temperatures will destroy bacteria. If food reaches an internal, core temperature of 70°C for at least 2 minutes it is pasteurised. This process destroys the pathogenic bacteria and makes it safe to eat. The easiest way to check that food has been cooked properly is to check that the core temperature is at least 75°C using a temperature probe.

Some Food Spoilage bacteria can survive these temperatures, so food can still go off. This is why deep fat frying methods using temperatures well above this temperature will make food safe to eat.

Hot Holding Temperatures (minimum 63°C)

Any food that will support the growth of bacteria, that has been cooked and is waiting to be sold, should be kept at a minimum temperature of 63°C. At these temperatures bacteria will not multiply and spores will not germinate into bacteria. The law does allow hot food to be held at lower temperatures, as long as it is for not more than 2 hours, however good practice is to hold all hot food at a minimum of 63°C. We aim to keep our food above 65°C.