What makes tinned food keep for SO long? And is that why tinned stuff is bad for you?

Question

Some stuff like baked beans, etc can keep for 3 years or something. Surely something that can keep for so long has been tampered with and therefore unhealthy for you?

Just curious, I don't eat much tinned stuff myself.

Answer 1

Tinned food is hermetically sealed and sterilised at a high temperature, so there are no bacteria to destroy the food. Usually there is no need for any preservatives, though I think some are used to help tinned vegetables retain their colour.

It's only once it's opened that one has to store it out of the tin and in the fridge. Once bacteria get access to the food it will go off as quickly as fresh food and once it's opened, the acid in the food can begin to dissolve the metal of the can where the lining has been damaged.

Tins of food have been found which are still ok to eat after 50 years or more but early tinned food sometimes used lead to seal the cans which made the food unfit to eat before very long.

Wikipedia has this:
http://en.wikipedia.org/wiki/Cannery

Answer 2

Tinned food keeps because it is cooked at high temperatures in the tin after it has been sealed. This kills all of the bacteria, and because the tin is already sealed no new ones can get in from outside. Nor can oxygen get in from outside. Because bacterial decay and oxidation are the main things that spoil food, and neither can occur in the tin, it keeps for a long time. NO PRESERVATIVES ARE NECESSARY, and tinned foods should not contain any, whatever else people say here.

Its quite clear from this that tinned food is not necessarily bad for you at all. In fact, it can be a very healthy way to preserve food.

The health issues come from two main things:

1. heating food destroys some nutrients - so tinned foods will contain less of those nutrients than uncooked fresh foods of the same kind

2. the types of food that are tinned are generally processed ones, and processing adds undesirable things (like fat, salt and sugar) to the food; a good example is tinned baked beans, which would be very healthy if som much salt and sugar was not added to them as they are processed

Answer 3

Tinned food keeps indefinitely because it has been STERILISED.

Food will only decay if microbes can get into it. The microbes digest the food themselves, and that digestion is what we call decay.

Tinned food is heated to kill any microbes that may be in there and then sealed so no more microbes can get in. No microbes, no decay. It’s really that simple. No tampering is required. Decay requires the presence of microbes and if you can physically keep the microbes out food will never decay.

And tinned bean will keep far more than three years. Provided the can doesn’t rust through they will keep for centuries, though they probably start tasting a bit funny after the first few years.

No, there is absolutely nothing unhealthy about tinned foods. In fact tinned foods are often better for you than fresh cooked foods. Because tinned foods are preserved at the point of maximal freshness and nutritional value they contain higher levels of essential nutrients and vitamins than “fresh” vegetables that have been kept in a warehouse cold store for 6 months or more.

Unless you have a supplier of guaranteed fresh picked food tinned foods will usually be healthier than what you buy from a greengrocer and cook yourself. You probably should eat more tinned foods.

NB: canned vegetables are NEVER a substitute for raw fruit or vegetables, but they are a more than adequate substitute for cooked vegetables or meats.

Answer 4

A chemical is added (or preservative) to keep the tinned food stable.
The tin just keeps the tinned food sterilised to not rot, lasting for a long time.
The preservatives added stabilises the food to help it not run out of taste while in the tin. The tin may keep it lasting but the preservative keeps the goodness. Although the preservative isn't good. That's why organic food isn't in tins if it's truely organic.

Answer 5

A preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, etc. to retard spoilage, whether from microbial growth, or undesirable chemical changes.

Preservatives may be added to wood to prevent the growth of fungi as well as to repel insects and termites. Typically copper, borate, and petroleum based chemical compounds are used. For more information on wood preservatives see timber treatment, lumber and creosote.

Preservative food additives are often used alone, or in conjunction with other methods of food preservation. A distinction is sometimes made between anti-microbial preservatives which function by inhibiting the growth of insects, bacteria and fungi, and antioxidants such as Oxygen absorbers, which inhibit the oxidation of food constituents. Common anti-microbial preservatives include sodium nitrate, sodium nitrite, sulfites, (sulfur dioxide, sodium bisulfate, potassium hydrogen sulfate, etc.) and disodium EDTA. Antioxidants include BHA and BHT. Other preservatives include formaldehyde (usually in solution), glutaraldehyde, diatomaceous earth (kills insects), ethanol, dimethyl dicarbonate and methylchloroisothiazolinone. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics specializing in food science and toxicology.

Some methods of food preservation involve the use of salt, sugar or vinegar, which are sometimes considered to be foods rather than additives. Some people believe preservatives are harmful to human health.

Answer 6

Tinned foods are added with preservatives.These preservatives have anti oxidant property also.So whenever any molecule of oxygen reaches the tinned can,it is trapped by preservative & hence preserved.Excess use of these chemicals can cause cancer also.

Answer 7

Tinned food has a higher sodium content.

Answer 8

tinned food is not attacked by chemicals and other oraganisms..it is dangerous bcus it may contain the metal tin after a while and being a heavy metal..a poison

Answer 9

Preservatives are used. Its bad only if you are allergic to the preservatives used or if the stuff inside has gone bad.

Answer 10

Keeping materials. It is not good to eat,but s.t. you have to in this wild industrial world