Is it safe to eat canned soup cold? (main risks)
In this article, we will discuss whether it is safe to eat canned soup cold, why is it safe to eat canned soup cold, what are the risks of eating canned soup cold, when should you not eat canned soup cold and how to reduce the risks of eating canned soup cold.
Canned soup is safe to eat without any previous cooking or heating process, as the soup is sterilised at high temperatures before being aseptically packed into sterile cans or pouches. However, there are risks in eating canned soup cold.
Is it safe to eat canned soup cold?
Yes, it is safe to eat canned soup cold (1), unless the soup has signs of spoilage or the can is rusted, dented or swollen (6). Canned soup is safe to eat cold immediately after being opened.
However, canned soup leftovers are not safe to eat after being stored. When the can is opened, the microorganisms from the can opener, from the outer side of the can and the air enter the soup, once sterile (4).
During storage, these microorganisms develop and can achieve a number considered unsafe for consumption. In addition, they can produce toxins (3, 5).
Reheating soup before eating can improve its safety and its flavour. I have never tried cold soup, not even during summer and I recommend reheating first.
Why is canned soup safe to eat cold?
Canned soup is safe to eat cold because it has been sterilised. Sterilisation is a process capable of reducing by 12-log the number of spores from the bacteria Clostridium botulinum.
In thermal sterilisation, the soup is heated to a temperature between 115 and 130 °C for enough time, and aseptically packed into sterile pouches or cans, before following an additional thermal treatment after the sealing of the cans (1).
In this way, the soup does not contain viable microorganisms, unless contamination occurred during the process or the process was improperly done, resulting in an insufficient destruction of spores.
What are the risks of eating canned soup cold?
The risks of eating canned soup cold are possible in the following cases:
1. The canned soup has been contaminated during the production process or the soup has been incorrectly canned. The risks are related to the unopened canned soup (2, 3).
2. The canned soup has been opened and stored (4).
In both cases, the risks of eating canned soup cold are foodborne infections and foodborne poisoning, as summarised in the table below (3, 4, 5):
Foodborne infection or
Unopened canned soup
|In the production process of canning the soup, many errors can occur, leading to contamination or insufficient sterilisation, which can result in the survival of microorganisms that develop during storage. These microorganisms can produce toxins. Important bacteria related to the contamination of unopened canned foods include Clostridium botulinum, which can survive in the form of spores and produce a fatal toxin.||The ingestion of a great number of microorganisms can lead to food infection, where bacteria and viruses infect the gastrointestinal tract or other organs in the body, leading to symptoms such as diarrhoea, nausea, dehydration and weakness. In severe cases, it can lead to meningitis and septicemia.
The ingestion of microbial toxins can lead to food poisoning, where toxins produced by bacteria and fungi can affect the gastrointestinal tract, the nervous system and other parts of the body, leading to vomiting, diarrhoea, headache, damage to the kidney and liver, blurry vision and hallucinations, depending on the type of toxin ingested.
Foodborne infection or
Opened and stored canned soup
|When the canned soup is opened, foreign microorganisms enter the soup. During storage, microorganisms multiply and can achieve a number considered unsafe for consumption. They can also produce toxins. Important microorganisms related to food leftovers are Salmonella, Escherichia coli and Listeria monocytogenes, which can lead to foodborne illnesses.|
How to improve the safety of eating canned soup cold?
To improve the safety of eating canned soup cold, you should (6):
- Store the canned soup in a cool and dry place in the pantry, protected from sunlight
- Wash your hands thoroughly with running water and soap and dry your hands with a clean towel
- Wash the outer surface of the can with running water and soap, rinse and dry the can
- Wash the can opener with running water and soap before opening the can
- Carefully verify the conditions of the product and reject the canned soup if it is swollen, rusted or dented
- Open the can carefully and verify the conditions of the soup: the odour, colour and texture and reject the soup if any unusual sign is present, such as an unpleasant odour, discolouration, and the presence of slime or mould on the surface
- Signs of damage in the inside part of the can, such as spots indicating rusting of the inner part of the metal
Why is reheating canned soup safer?
The reasons that make reheating canned soup safer to eat are the positive effects caused by heat, which are summarised in the table below (3, 5, 7):
Elimination of viable microorganisms
|Heat can partially destroy the microbial load of the food. If the canned soup is infected by microorganisms, heating will effectively reduce its number, improving its safety. However, some microorganisms need higher temperatures and longer cooking times than others|
Elimination of toxins
|Many microbial toxins are destroyed by heat. Examples are two toxins from Escherichia coli. On the other hand, the toxin produced by Clostridium botulinum needs 10 minutes of cooking at 100 °C to be destroyed and the toxin from Staphylococcus aureus cannot be destroyed by heat.|
|The flavour of the food can be influenced by the serving temperature. While cold foods require cold serving temperatures (such as ice cream), food usually served hot requires high serving temperatures. That is the case of soup.|
In this article, we discussed whether it is safe to eat canned soup cold, what are the risks of eating canned soup cold, and how to improve the safety of eating canned soup cold.
In my experience as a Student, the canned soup was a practical and fast meal option I I´ve always eaten it hot, as the reheating soup is very easy and does not need any special culinary skills.
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