The Problem With Storing Canned Tomatoes For More Than 18 Months

Tomatoes are one of those must-have canned foods to keep in your pantry at all times. They are a staple in many sauces and stews, and the perfect ingredient to use to make the easiest and tastiest soup of your life. Canned tomatoes are also conveniently available in many different forms, from diced to crushed. While we think it's best to buy canned tomatoes whole over any other option, no matter what variety you find kicking around in the cupboard, it's important to check the expiration date on the can. This is because tomatoes are highly acidic and have the potential to interact negatively with metal cans. To avoid a spoiled batch of this fruit, it's usually best to use these cans within 18 months of purchase.  This is a significantly shorter shelf life than other canned goods, such as meat and vegetables, which can maintain their quality for up to five years. 

While the whole point of buying canned goods is that they last for a long time, acidic foods can break down and cause metal to corrode. This means even the most well-preserved tomatoes and canned fruits, such as peaches and pears, can soften, become discolored, and lose flavor. 

Some canned acidic foods, including tomatoes, are lined with protective coatings that contain BPA to stop metal corrosion from happening. However, some people have raised concerns about this chemical, as it can leach from the can and into the food inside. BPA is a known endocrine disruptor and could have negative effects on health. Some companies have even stopped using these linings in canned goods because of the health risks, but not all. That's just another reason to use canned tomatoes within 18 months of purchase.

The best way to prevent tomatoes from interacting with the metal of a can, or having BPA leach into your tomatoes, is to use canned tomatoes soon after you've purchased them. It's also important to store all of your canned goods in a cool, dry storage space, as heat and air can speed up the deterioration process. Generally speaking, it's still safe to eat canned tomatoes after they have been stored for 18 months, but make sure to inspect the can for any leaks, rust, or swelling.  These could be signs of spoiled tomatoes or even botulism — a dangerous bacterial disease. Even if the can looks fine, but the color or smell of the tomatoes is off, discard the tomatoes.