Canning

Canning is a way to keep food safe to eat for a long time. It works by cooking the food and putting it into a container that is sealed tightly, like jars or cans. This helps stop bad things from spoiling the food. Canned food can stay good for one to five years, and in some special cases, even longer. For example, freeze-dried canned lentils might stay edible for up to 30 years.

A long time ago, in 1974, people tested food that had been canned in 1865 from a steamboat called the Bertrand that sank in the Missouri River. Even though the food looked and smelled different and had lost some vitamins, it was still safe to eat because nothing bad had grown inside the cans. This shows how well canning can keep food for many years.

food preservation Mason jars steel and tin cans shelf life lentils Bertrand National Food Processors Association

History and development

See also: Mason jar

The Dutch were the first to tin food, carrying cleaned and brine-cooked salmon in tin-plated iron boxes as early as 1772.

Shortly before the Napoleonic Wars, the French government offered a large cash prize to anyone who could find a cheap and effective way to preserve food for the Grande Armée. In 1809, Nicolas Appert, a French confectioner and brewer, discovered that food cooked inside a jar stayed fresh if the seals were tight. He won the prize in 1810. At the time, no one knew why the food didn’t spoil—it would be many years before Louis Pasteur explained the role of tiny living things in food spoilage and developed pasteurization.

The Grande Armée tried using canned foods, but the slow canning process and transport delays made it hard to supply enough food across the French Empire. After the Napoleonic Wars, other European countries and the United States began using canning methods.

In the United Kingdom, Philippe de Girard used British merchant Peter Durand to patent his idea in 1810. Bryan Donkin and John Hall bought the patent and began making sealed cans from tinned iron. Early cans were slow and expensive to make, so only the British Army and Royal Navy could afford them. By 1817, Donkin sold £3000 worth of canned meat in just six months.

During World War I, armies needed lots of food that wouldn’t spoil during long trips or in tough conditions. Canned food became very important. British soldiers often ate canned pork and beans, bully beef, and stews. By 1916, soldiers weren’t happy with the food quality, so armies looked for better options. Soon, complete meals like coq au vin, beef bourguignon, and even canned spaghetti began appearing. After the war, companies that made food for the military started improving their products for everyday people to buy.

Methods

Early cans were made of glass, but they were heavy and broke easily. Later, people started using metal cans, which are cheaper and stronger. Today, most cans are made from tin-coated steel.

At first, people didn’t have can openers, so they had to use knives or other tools to open cans. Now, we have special tools just for opening cans.

Glass jars are still used sometimes, especially for foods people make at home.

Microbial control

To keep food from spoiling, people use many methods. They heat the food to high temperatures, cool it quickly, or use natural ingredients that stop bad things from growing. Some foods are dried or put in strong saltwater.

One big danger is a tiny germ called Clostridium botulinum, which can make people very sick. To be safe, most foods like vegetables, meat, and seafood need to be canned using high heat in a special machine called a pressure canner. Fruits and pickles can be canned using just boiling water because they are naturally sour.

Sealing: double seams

Main article: Double seam

In 1888, a new way to seal cans was invented. This method creates a tight seal that keeps air and germs out. Cans made this way are called Sanitary Cans. The top and bottom of the can are folded and pressed together to make a strong, airtight seal. This way, the food stays fresh and safe to eat.

Nutritional value

Canning is a way to keep food safe to eat for a long time. A study from 1997 showed that canned fruits and vegetables have just as many good things, like dietary fiber and vitamins, as fresh or frozen foods. Sometimes, canned foods even have more of these good things than fresh ones. For example, canned tomatoes have more lycopene, which is important for staying healthy. Because of this, canned meat and vegetables are often kept ready for use during emergencies.

Potential hazards

See also: Packaging and labeling and Food safety

In the early 1800s, canning food was often done in small factories that didn’t always keep things clean. Without refrigerators and strict rules, some cans could have harmful stuff in them.

Salt is used in canning to keep food from spoiling, but it can also make people eat too much salt. Too much salt can lead to health problems like high blood pressure. Some canned foods now come with less salt or no salt at all. Rinsing canned vegetables well can help lower the salt amount since a lot of the salt is in the liquid, not the food.

Further information: Botulism § Prevention

Sometimes, canned food that wasn’t heated enough can become unsafe to eat. This can let a special kind of germ grow and make a poison. This poison is very dangerous and can make people very sick, causing muscles to stop working. Because it’s so serious, doctors treat any possible cases right away to keep others from getting sick too.

Canning and economic recession

Further information: Recession

When money is tight, like during tough economic times, people often buy canned foods. This is because they save money by staying home and not spending on things like eating out or going to shows. Some people also like to keep extra canned food at home, just in case.

In February 2009, when the economy was struggling, sales of items for canning went up by 11.5% in the United States. Some places in the US even have special centers where people can learn how to can food or rent a kitchen to do it themselves.