While you don't need to automatically throw away an accidentally frozen canned good, the USDA recommends taking some precautions before eating the item in question. If the can appears swollen, try thawing it in the refrigerator before opening it. This applies only if you're absolutely sure the swelling is because of the cold. If the can swells for other reasons, toss it. If everything — color, texture, smell — appears normal, you're probably in the clear. If anything seems off, get rid of it. And if the seams on the can appear to have rusted or burst, don't risk it.