How Should You Store Opened Canned Food? Should It Stay in the Can?

It is better to move leftover canned food out of the can and into a glass or plastic container. When exposed to air, the cut edge of the can begins to oxidize; especially with acidic contents such as tomatoes and pickles, this can give the food a metallic taste and spoil its flavor and texture. Keep the transferred food in a covered container in the refrigerator. The time depends on the type of canned food: use canned meat, fish, and most vegetables within 3 to 4 days, and acidic foods such as tomatoes, pickles, and fruit within 5 to 7 days.

Why Is It a Problem to Leave Food in the Can?
The inside surface of a can is usually covered with a thin protective coating, but once the can is opened, the cut edge has no such protection and is in direct contact with air. Oxidation that develops over time can give the food inside the can a metallic taste and affect its texture. This risk is more pronounced with acidic contents such as tomatoes, pickles, and canned fruit; acid reacts more quickly with the metal surface. The risk is somewhat lower with low-acid canned foods such as corn and chickpeas, but transferring them to another container is still recommended. The sharpness of the cut edge is a separate risk; pouring the food into a container after opening the can without touching the edge reduces the risk of cuts and makes it easier to transfer the food without handling it.

How Soon Should Transferred Canned Food Be Eaten?
Use the contents of an opened can within 3–4 days when transferred to a container and kept in the refrigerator; this is close to the storage time for freshly cooked food in the refrigerator, because canned food begins to behave like fresh food once opened. If you will not use it before that time is up, freezing the remainder is safer. Canned fish, such as tuna and sardines, should be eaten at the lower end of this range, within 2–3 days; protein-rich contents spoil faster than other types of canned food. If possible, divide the portion to be frozen into single-use portions and freeze them separately; when a can’s contents are frozen in one large block, thawing it can result in more than you need being returned to the refrigerator and its storage period starting over once again.

Which Canned Foods Spoil Faster?
Canned foods stored in their own liquid or lightly salted water, such as corn and peas, spoil faster than foods stored in oil or concentrated brine because they have less salt; salt and oil naturally slow bacterial growth to some extent. This difference also affects how soon transferred canned food should be eaten. Canned fruit in syrup is the category that keeps the longest without spoiling, thanks to its high sugar content; still, after opening, store it in the refrigerator, not at room temperature.

Should You Save the Canning Liquid?
The liquid from canned chickpeas, beans, and similar foods, also known as aquafaba, can be saved in a separate container instead of discarded; it has a consistency that can be used in some recipes in place of egg whites. The liquid in canned tomatoes is generally used together with the contents, so it does not need to be stored separately. Even if canned foods drained of their liquid may seem to spoil less quickly than the remaining solids, they should still be considered within the same 3–4 day range; the absence of liquid does not stop spoilage, though it may slow it somewhat. Label the separated liquid in its own container too; otherwise, after a few days, you may forget which can it came from and throw it away without using it.