When I was growing up, my mom drilled a few kitchen tips into my brain: Never leave a milk carton sitting around—get that thing right back in the fridge. Don’t store food in open cans in the refrigerator—transfer it into a clean storage container.
OK, I get it with the milk, but why not keep food in the open can? Why get another thing dirty?
I polled teammates around America’s Test Kitchen, and the group was divided: Some people do it, others never would.
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I asked Sherrie Rosenblatt of the Can Manufacturers Institute. She referred me to the U.S. Department of Agriculture.
As it turns out, the USDA says Mom was wrong, up to a point: “Unused portions of canned food may be refrigerated in the can, but to preserve optimum quality and flavor, place the unused portion in a food-grade glass or plastic container. Use within 4 days.”
So why was Mom adamant about this? Because when she was growing up, cans were made differently.
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Early cans were made of tin-plated steel, with seams soldered together with lead. Until the U.S. banned lead-soldered food cans—in 1995!—there was a risk of lead poisoning in the food, especially once the can was opened. Ingesting tin is also mildly toxic, and exposure increased if food was stored in open cans, according to the Centers for Disease Control and Prevention.
In older cans, acidic food could react with metal after they were open and air got in. This lent food a metallic or “tinny” taste, especially when it was stored in the can.
Today, cans are made of aluminum or steel and typically heat-sealed with a special “double seam,” where the can and lid edges are interlocked and folded twice. Many cans are stamped from a single sheet so there are no seams except around the lid.
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Since the mid-20th century, most cans have been lined with a protective plastic coating to form a barrier between the metal and the food. (These days, some fruit cans are still left unlined because the metal contact inhibits oxidation on the shelf, but that’s largely an exception, not a rule.)
But that brings up another issue: The can lining contained BPA, which has been linked to significant health impacts. While manufacturers have begun using different linings, according to a 2020 article in Science, BPA lining is still used in 10 percent of steel cans in the U.S., and roughly half of all aluminum cans. The liner chemicals that are commonly used to replace BPA, such as BPAF and TMBPF (also known as V70), are still being evaluated for safety.
All that aside, the USDA ultimately noted that food quality and flavor will be better if you don’t store it in the can.
Bottom line: It’s technically safe—but I’m sticking with Mom.