|Heating foods will kill all microbes depending on the temperature. Most microbial cells will die at a temperature of 100 ºC. However, some bacterial spores will survive this and need temperatures around 130ºC to kill them. Cooking may kill all microbes in food but won’t get rid of any toxins they have already produced. The heat treatments used in food production include pasteurisation, sterilisation and canning. |
Pasteurised liquids have been heated for a short time (to around 72ºC for about 15 seconds) and then cooled quickly. This kills most, but not all, of the harmful and spoilage microbes without affecting the flavour. The storage life is extended as a result. Fruit juices, beer, wine and milk are often pasteurised.
This should kill all the microbes and their spores.
Some foods (like milks, soups and sauces) are heated to around 132ºC for a short time. The sterilised food is then put into sterilised containers (such as bottles or jars). These are then hermetically sealed so that no air or opportunistic microbes can get in.
Canning gives foods like meat, fish, fruit and vegetables a shelf life of many years. The product is sealed in a metal container and heated to an appropriate temperature and rapidly cooled. This process kills off the bacteria.