Tuna, in the culinary sense, refers to the meat of a saltwater fish available year round either fresh or preserved in their canned form. With an extremely high protein to calorie ratio and high levels of certain minerals, tuna is quite popular throughout the world as a topping or a main ingredient.
Like all seafood, tuna tends to spoil quite quickly once it has been killed, and as such it is not uncommon for fishermen and home chefs to wonder – can tuna be frozen in order to preserve it?
In short, yes, tuna can and should be frozen in order to significantly extend its shelf-life. Like most other forms of high protein meat, tuna is highly susceptible to infestation from bacterial and fungal life, which will cause it to spoil rapidly if it is not immediately consumed or stored in the proper manner.
Why does Tuna Expire so Quickly?
Seafood- and by extension tuna- is notorious for expiring very quickly unless frozen or otherwise preserved in some way. This is due two a duality of reasons, the first of which was previously mentioned at the beginning of this article; the relatively high protein content of most fishes.
As bacteria and fungi often require the amino acids that make up proteins in order to reproduce and continue living, it is not surprising that the vast majority of these microbes will often choose to colonize protein-rich food over other types of food that may be available.
However, apart from the selective dietary choices of bacteria and fungi, there is also the fact that the microbial life present in seafood while it is still alive is accustomed to the cold temperatures of the ocean or other bodies of water their host may inhabit.
Because of this, when the bacteria and fungi present within the seafood are brought to the surface and subjected to room temperatures, it is likely that they will reproduce at an accelerated rate, therefore resulting in the seafood expiring far quicker than other forms of meat.
Can You Freeze Canned Tuna?
Yes, it is entirely possible to freeze canned tuna in much the same way fresh tuna may be frozen, though it is not advisable to freeze the tuna while still present in its can, as this may rupture it or cause other unforeseen effects.
In order to freeze canned tuna, simply follow the same steps as the next section of the article, but first drain the tuna meat before removing it from its can.
How to Freeze Tuna
In order to freeze your tuna, first have a butcher gut it and slice the edible parts into manageable-sized pieces, as the intestines of tuna often contain parasites and bacteria that will hasten the spoilage of the fish, even in the freezer.
First, dip the tuna pieces in a mixture of salt and water, ensuring that it is completely submerged before removing it from the salt water. This will help draw excess moisture out of the tuna’s flesh as well as kill some of the microbes present. This step is not necessary if you are freezing canned tuna, as it has likely already undergone this brining process.
Pat the surface of the tuna dry with a cloth towel, as water on the surface will turn into ice crystals and make the tuna even more difficult to thaw.
With plastic cling film, wrap the tuna repeatedly, using different directions with each sheet. Doing this will ensure that no part of the tuna is left exposed to the open air of the freezer, which will cause it to become freezer burnt.
After wrapping several times in plastic film, encase the tuna in a resealable plastic pouch or freezer bag. It is best to separate the tuna into individual multiple bags based on your desired serving size, as refreezing the left-over frozen tuna from thawing will severely impact its quality and shelf-life.
Push out any excess air that may still be present in the bags and ensure that they are fully sealed before storing in the deepest part of your freezer for up to three months.
Can Tuna be Refrigerated?
While tuna lasts a very short amount of time when no attempts are made at preserving it, choosing to refrigerate tuna will still only extend its shelf-life for up to two days.
This short shelf-life, even in the refrigerator, is often due to the fact that the tuna has already begun to develop microbiological colonies prior to refrigeration. This is largely unavoidable without making the tuna meat unpleasant or unsafe to eat.
In order to ensure that your tuna remains in a shelf-stable state for as long as possible, first wrap it in aluminum foil, ensuring that no areas are left exposed to the open air.
Once completely wrapped in aluminum foil, place the tuna meat in an air-tight container made of a material that will not absorb its smell or taste, such as porous plastic.
Store this container of tuna meat in the coldest section of your refrigerator, setting the thermostat as low as it can possibly go. Keep in mind that if the tuna is stored alongside other ingredients, they too will expire within two days owing to the transfer of bacteria and fungi between food in close proximity.
How Long Does Canned Tuna Last After Opening?
The large majority of canned tuna undergoes thorough sterilization in order to extend its shelf-life for as long as possible. Apart from these particular sterilization processes, canned tuna also frequently contains certain types of preservatives that help ward off infestation from microbes, such as high amounts of salt or certain kinds of oil.
However, none of these factors apply once the can has been opened and the tuna exposed to the open air, wherein they will immediately attract opportunistic bacteria and fungi.
According to an informational bulletin posted by the U.S. Department of Agriculture, temperatures between 40 °F and 140 °F are where bacteria and fungi grow best, allowing them to propagate and reproduce entirely unimpeded by the environment. This has been dubbed the “danger zone” by the same author.2
Left exposed in the temperature danger zone or otherwise at room temperature, canned tuna should be considered no longer safe to eat after approximately two hours, even if it does not display any sign of spoilage or rotting. As always, do not attempt to taste the tuna to see whether it has begun to spoil or not.
How Long Does Fresh Tuna Last at Room Temperature?
As previously mentioned in the last article, tuna should only be left exposed at room temperature for up to two hours, regardless of whether it is fresh or has been removed from a can.
However, in the event that you are still choosing to keep your fresh tuna at room temperature, several steps may be taken in order to extend its shelf-life somewhat. It is still best to discard the tuna within two hours, however, even if these steps have been employed.
Place the fresh tuna in a clean container filled with cold water. Use only air-tight containers with resealable lids, as this will help prevent the tuna from coming into contact with the open air, as well as partially insulate it from the temperatures of the environment.
Keep the container away from any sources of heat or light, of which will both accelerate the development of bacteria and fungi.
Ensure that the tuna is thoroughly cooked at high temperatures if you still choose to cook it, though we advise against it if the fresh tuna has been left out at room temperature for more than two hours.
References
1. Hickman, Martin (9 June 2009). “How Tuna Conquered the World”. www.independent.co.uk. The Independent.
2. Unknown Author. (June 2017) “”Danger Zone” (40 °F – 140 °F)” U.S. Department of Agriculture Food Safety and Inspection Service
