Why does canned food deteriorate?

Canned food is easy to use and durable for a long time. We can say that it is a reliable food product. This does not mean that canned food does not spoil. So, why does canned food deteriorate? The slightest negligence and carelessness in production causes negative quality changes before heat treatment, after heat treatment and during storage. And microbial, chemical, physical deterioration occurs. In this article, I will talk about the glitches that occur.

Canning is the process of filling the product purified from microorganisms by heat treatment into suitable tins, glass jars or similar containers and sealing the containers in an airtight manner.

Why Does Canned Food Deteriorate?

At the beginning of the article, I mentioned that the deterioration seen in canned foods can be microbial, physical and chemical. I would like to explain all these in detail under sub-headings.

Microbial Deterioration

Microbial spoilage may occur in canned foods due to insufficient heat treatment and leakage before heat treatment.

Microbial deterioration before heat treatment;

Generally caused by the microorganism content of the raw material. The raw material to be used is subjected to some pre-treatments such as sorting, washing and boiling before heat treatment. Such processes reduce the microbial load of the raw material. However, if the heat treatment to be applied is delayed, the microorganisms start to multiply again.

Microbial deterioration caused by insufficient heat treatment;

This type of distortion is very common. And this deterioration varies according to the microorganism content. In the type of deterioration called flat souring, the tin can is normal in appearance. However, the product in the box turned sour due to the lactic acid created by the microorganisms. Microorganisms causing spoilage are Bacillus species. It is often seen in canned peas, dried beans, and corn.

If the deterioration agent is a gas-forming microorganism (Clostridium species), the gas formed inside the box can be observed from the outside of the box. Depending on the amount of gas formed, the upper and lower lids of the box swell. This swelling is called a ‘bomb’. The product inside the bombed box was broken. Some types of microorganisms (Clostridium nigrificans) also cannot form gas from carbohydrates. Gases such as H₂S they create do not form bombardment because they can dissolve in water. The outer appearance of the box is normal. However, when the box is opened, a bad odor spreads and discoloration occurs.

Clostridium botulinum, another microorganism species, is also highly resistant to heat. It creates neurotoxin and causes poisoning in humans. It can result in death.

If we look at mold after bacteria, it is unlikely to grow in hermetically sealed boxes. Spoilage caused by molds is not common in canned foods. However, it is a major spoilage factor in poorly sealed and inadequately heat-treated home preserves.

Microbial spoilage caused by leakage;

It is the situation caused by the air and cooling water entering the box as a result of the error occurring during the closing of the box or the leakage that occurs after the box is closed properly. Commercially sterilized and sufficiently heat-treated cans deteriorate by this later event.

Physical and Chemical Deteriorations

In addition to microbial spoilage, chemical and physical deterioration can also occur. When we look at chemical degradation, it is due to the use of tin as a packaging material. The use of tin leads to corrosion (wear). As a result of corrosion, the quality of the food decreases and it becomes harmful to health. In addition, hydrogen gas formed as a result of corrosion also causes bombardment.

Deteriorations due to physical reasons are caused by swelling, collapse or similar deformations in the box. Such deformations break the clamps of the box, causing leakage.

As a result;

The deterioration factor in a deteriorated box can be only one of these factors, or it can be several factors at the same time. Any deterioration that occurs reduces the nutritional value of the box and poses a health hazard. That’s why we have to be careful with the products we buy. We have to look at the expiration date and be careful not to bomb it. Most of all, we need to pay attention to the canned food we make at home. We should apply sufficient heat treatment and take care not to get air. Jar lids should not be rusty either. I conclude my article by saying that health is more important than anything else and that attention and care should be taken.

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