Do Canned Tuna Really Taste Better After 3 Months?

I have a habit of buying ten cans of tuna whenever they’re on sale at the supermarket and stashing them in the back of my pantry. As a result, I constantly forget what I bought and when. While organizing recently, I found a can that was nearly six months past its production date. I was about to throw it away but decided to open it, and suddenly remembered something I had heard somewhere: canned tuna tastes better after about three months than when it’s freshly produced. A search revealed this was treated almost as a settled fact on Namuwiki. The sentence, “After complete sealing and manufacturing, waiting more than 3 months allows the oil to soak into the tuna, making it softer and more delicious,” was presented like common knowledge. But it made me wonder: is it even plausible for something to “age” inside a sealed can?

Where did the ‘3-month aging theory’ start?

I found the point where this story hit the airwaves and spread. It was a throwaway comment made by a factory worker with six years of experience at the end of a 2019 EBS episode titled ‘The Birth of Canned Tuna.’ They claimed that after three months from the production date, it ages and tastes truly delicious. The Kyunghyang Shinmun reported on the subsequent debate that erupted online, with arguments clashing between those who said aging is impossible in a can and those who shared personal anecdotes about older cans actually being softer.

There is only one sticking point here: the word ‘aging.’ Traditionally, aging refers to a process where enzymes remaining in food slowly break down components to create umami. This is the principle behind why miso, cheese, and dried seafood develop deeper flavors over time. However, canned food is designed specifically to kill those enzymes. Naturally, it feels contradictory to see these two concepts in the same sentence.

Can aging really occur inside a sterilized can?

After looking up retort sterilization standards, the answer became clearer. Under domestic regulations, sterilization generally requires heat treatment at a core temperature of 120 degrees Celsius or higher for at least 4 minutes. This temperature range is high enough to denature not only most microorganisms but also the enzyme proteins within the ingredients. Canned tuna undergoes high-temperature, high-pressure sterilization based on the same logic. In other words, by the time the can is sealed, the enzymes are already dead, leaving no conditions for biochemical reactions like fermentation or decomposition to occur.

Food information expert CEO Choi Nak-eon mentioned something similar during an interview. Strictly speaking, since autolytic enzymes vanish at the moment of sterilization, it is difficult to consider what happens inside a can as ‘aging.’ However, he added that the phenomenon of flavor improving over time is sometimes colloquially referred to as aging for convenience. So, while the word choice might be a bit of an exaggeration, the perception that something changes over time isn’t entirely wrong.

The real reason the taste changes — the time it takes for oil to penetrate

A hint came from an explanation provided by a representative from the Dongwon Group’s public relations team to the Kyunghyang Shinmun. While many foreign countries use water-based canning methods, domestic products are sealed with oils like cottonseed or canola oil to make the texture softer. As time passes in this state, the oil slowly penetrates the spaces between the meat fibers, deepening the flavor. They noted, however, that they do not officially promote a “3-month aging” period, as taste is subjective.

Reading this helped clear up my thoughts. This isn’t biochemical aging where enzymes break down materials, but rather a physical diffusion where the liquid oil slowly permeates solid tissue. It’s somewhat similar to how meat marinated for a longer time absorbs more flavor. It’s less of a reaction and more of an infiltration. Since this isn’t a process that finishes in a few days, the 3-month mark carries weight in terms of user experience.

Does this story exist overseas? — Oil-packed vs. Water-packed

I wanted to dig a little deeper. Since this is a topic of debate in Korea, I wondered how it was viewed in Western food cultures, where canned tuna has been consumed for much longer. To my surprise, the response from American culinary media was quite straightforward. Many outlets explained that tuna in olive oil is a pantry staple that improves in flavor as time goes by. Discussions on community forums also featured consensus that the flavor of oil-packed tuna improves over several months. In short, it’s not just a myth circulating in Korea, but an empirical rule commonly accepted wherever oil-packed tuna is handled.

At the same time, it was confirmed that this phenomenon is distinct to oil-packed products. Water-packed tuna has no oil to soak in, so one cannot expect the texture to soften over time. In fact, it’s more likely that the meat will become dry the moment you drain the water. Conversely, the viscosity of oil in oil-packed tuna prevents moisture loss, and as the oil permeates, the texture becomes smoother. There’s also a difference in nutrition; some data suggests oil-packed tuna has relatively higher levels of fat-soluble Vitamin D and selenium, while water-packed tuna retains more omega-3 fatty acids that aren’t washed away. It seems the subtle difference depends more on how it’s packaged than on what you eat.

Are there any safety issues with long-stored cans?

This naturally led to the next question: if it’s a food that can be stored for months or years, isn’t there some sort of preservative in it? But I found the opposite to be true. Canned foods contain no preservatives at all. Instead, the manufacturing process—removing all air from the contents, sealing them, and sterilizing them at high temperatures—serves as the preservative. Because it creates a state where bacteria cannot survive and completely blocks contact with outside air, it’s not rare to find products with shelf lives exceeding 10 years.

Can materials also play a part. Canned tuna often uses steel for the body and aluminum for the lid; steel is more impact-resistant and less permeable to air than aluminum, making it better for long-term storage. That said, there is criticism regarding trace amounts of bisphenol A potentially leaching from the epoxy resin coating used to prevent internal corrosion. Also, furan is produced during the high-temperature sterilization process as carbohydrates and proteins react; this is classified as a Group 2B carcinogen. However, since Group 2B is a low-risk category meaning “possibly carcinogenic,” it would be an overreaction to use this as a reason to avoid canned tuna entirely. Ultimately, whether it’s a can that’s sat for 3 months or a brand-new one, there isn’t a significant difference in terms of safety.

Come to think of it, when and why did canned tuna emerge?

This led me to wonder about the more fundamental origins. Who thought to put tuna in a can, and why? It turns out it started with sardines, not tuna. In 1903, Southern California experienced a bad year where sardine catches plummeted. Albert P. Halfhill, who ran a sardine cannery in San Pedro, needed a way to fill his empty cans and noticed albacore tuna, which was common but ignored by everyone. At the time, tuna was considered a fish that even anglers would catch and discard due to its “fishy” taste. Once Halfhill found a way to steam the tuna until it turned white, the flavor became much milder, and he began selling it under the name “Chicken of the Sea.” While first-year sales were only 700 cases, they exceeded 400,000 cases within a decade, which was a success for a product that started as a sardine substitute.

What’s interesting is what happened next. Halfhill’s early tuna cans were packed in California olive oil, but over time, this was replaced by cheaper cottonseed oil to reduce costs. Yet, this cottonseed oil is used exactly the same way on the other side of the world in Korea. In 1982, Dongwon Group founder Chairman Kim Jae-chul, having gained extensive experience in deep-sea fishing, toured the American Starkist factory and wondered, “Why doesn’t Korea have canned tuna?” At the time, Korea’s per capita income was only around $1,200–$1,300, leading many to believe that advanced food products like canned tuna were premature. However, he predicted that demand would arise when the era of $2,000 per capita income arrived. He developed a tuna can tailored to Korean tastes using oil, and the first Korean canned tuna was launched in December 1982. The oil chosen back then was cottonseed oil. The very same cottonseed oil mentioned in the explanation about “oil absorption” was actually a cost-cutting choice made to survive a sardine famine in the U.S. 80 years ago. Ultimately, what is happening inside a can of tuna today is a flow that has continued from the improvisation of a California fisherman a century ago.

So, do I have to wait 3 months?

To summarize: the word ‘aging’ was not an accurate expression. Fermentation or enzymatic decomposition does not occur inside a can. However, the physical process of oil penetration does actually happen, and it is a fact that this process, taking place over several months, changes the texture. Therefore, the number “3 months” is likely not an absolute threshold. The timing probably varies slightly depending on temperature, the amount of oil in the can, and the thickness of the tuna meat.

That six-month-old can from my pantry was indeed noticeably softer than usual. But honestly, I’m not sure if that’s truly the result of the oil soaking in, or just because of what I just read. Next time, I think I’ll have to put a fresh can side-by-side to compare.