Science Facts

Why Does Canned Food Last Long? (By Making Process)

Canned Food

Nicolas Appert discovered the process of canning in 1809. In the early 19th century, Napoleon offered 12,000 francs to any inventor who could devise a cheap and effective method of preserving large amounts of food. As a result, he successfully preserved the army supplies and a new food life enhancement technique called canning.

Canning has revolutionized the preservation of food. It is one of the most popular techniques for extending the shelf life of edibles. From baked beans to pineapple slices, a wide variety of food can be preserved by canning. Moreover, they’re affordable, convenient, and easily accessible.

Why does canned food last long?

Louis Pasteur demonstrated the role of microbes in food spoilage. Canning works on a principle known as Heat sterilization.

  • Heat Sterilization is the application of high heat to kill any microorganism present in the food or the can.

The first step in canning is filling the food in the cans. The most common material for making cans is tinplate, owing to resistance to corrosion. However, steel cans and aluminum cans with an inner layer of tin are used on a wide scale. In the next step, either sugar syrup or brine is added to the food in cans. This is done to enhance the taste and ensure that food doesn’t get burned during high heat. Air is then removed from the cans, and the cans are sealed.

  • Removal of air helps in eliminating the risk of oxidation during storage.

While sealing makes sure no external microorganism, foreign material, moisture, or light can enter the can. The cans are then subjected to a high temperature generally above 100 degrees Celcius or 212 degrees Fahrenheit at high pressure. The primary causes of food spoilage are bacteria, molds, and fungi.

  • The application of such a high amount of heat kills all the spoilage causing micro-organisms in the can, and since the can is sealed, there is no way for them to enter inside it.

Therefore food remains microbe-free and hence is not spoiled for a long time. The cans are then cooled and labeled. Canned foods require no preservatives and can be kept at room temperature.

There was a time when it was impossible to preserve food for more than a day, but canning food can be kept safe for 1 to 5 years. In 1974, samples of canned food from the wreck of a steamboat that sank in 1865 were tested. And there was no trace of microbial growth, and the 109-year-old food was determined to be still safe to eat.

These days, many new techniques like freeze-drying and aseptic packaging are used to prolong the shelf life of foods. But canning remains the most popular choice owing to its low cost and high reliability.

Frequently asked questions

How long does canned food last?

Canned foods don’t have an expiration date. Rather the two main labels you’ll find on cans include the “Best Buy” or “Used by” date.

The best by date is optimal freshness. Something is gone beyond the best by the date. It typically can lose color, texture, flavor, and nutritional values. Best buy recommend time to use the product for the best physical and sensory quality. The food manufacturer recommends the date.

So there are a few downsides to keeping this for an extended period. According to the USDA, it does not change the safety factor. Typically they’ll say up to 6 years or so and sometimes in between that. One of the things that’s a little different is that acidic type foods like tomatoes go bad quicker than pH balanced foods like lima beans.

The ”use by” date refers to the final days that the product will peak freshness, flavor, and texture. After this date, the quality of the food deteriorates, but it’s still edible. Therefore, the food manufacturer recommends this data.

When you have a Best Buy or used by you should use the canned foods within a couple of years for the best quality of the product.

What are the disadvantages of canned food?

Canning helps preserve food for longer periods. However, there are some disadvantages of canned foods.

Firstly, canned foods can be high in sugar and salt. So, they can pose a risk for people with high blood pressure, diabetes, obesity, etc.

Secondly, most cans have a coating of Bisphenol A to prevent corrosion. However, studies suggest that Bisphenol A can leak into the food and negatively affect our hormones.

Thirdly, the acids present in food can react with the metal can. And acids produce hydrogen gas, creating bulges, thus making food unsafe to eat.

Lastly, an improper canning process can lead to the growth of dangerous bacteria called clostridium botulinum. It produces a lethal toxin which if consumed.


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