My mother always told me that when opening a can, I should listen to it go PFFT when you first break the seal, as that meant the seal was still good and the contents haven’t spoiled, and that I should discard a can if I don’t hear it.
True or an old wives tail? Is the canning industry good enough we don’t have to be paranoid? Was this true at one time, maybe when my mom’s parents were growing up in the 20s and 30s but not anymore? I’ve noticed especially with the new pull tab cans you often won’t hear an audible sound of a seal breaking.
Another question- usually we have ham and turkey for family dinners. After eating there’s no hurry to stick the stuff in the fridge while the “grownups” chew the rag for hours and hours on end. Bad idea or OK, I won’t eat the stuff but no-one else has ever gotten sick from it.
Well, for your second question, having worked in food service, I can tell you that food should be either kept below 40° F. or above 160° F. Any time spent in between those temperatures should be kept to a minimum in order to prevent bacteria growing and creating toxins. The time spent at room temperature should be limited to four hours cumulative. So the leftovers should be put back into the fridge as soon as possible in order to get them chilled more quickly.
What Oslo says. Press down on the can lid before you open it. If it doesn’t move, it should be okay. If you can move it, discard the can. Chances are it has botulism.
If you are talking about home-canned goods in a jar, the method for testing is the same. Press down on the lid. A concave lid is a sign that the tiny bit of air in the jar is still sealed in. If a jar has a questionable seal, the contents should be disposed of. Better safe than in the hospital.