Another Don't Look post.....
We take such precautions to can our food carefully and correctly. We make sure our processing times are correct, exact pressure is achieved, enough water maintained inside the canner.... Then when we open the lid on the jar, hearing that wonderful SWOOSH sound; the underside of the lid is black. What in the world?! I did it all correctly and now this....
THIS IS NOT MOLD. THIS IS NOT SPOILAGE. It is only discoloration of the lid from the product that is canned inside the jar. Eat the product anyway.
Sometimes, tomatoes will even "eat" a lid from the inside out. There have been several times that I've opened a lid and found a rust spot surrounded in red goo where the lining of the lid apparently had a defect that I missed. I used/ate the product anyway.
While I would like to switch to glass reusable lids entirely, that isn't available to me right now. This means that I'm still relying and will continue to rely on lids manufactured by someone else. I don't know what chemicals/coating they use on the underside of the flat lids. I just know that whatever it is; it reacts with some foods that we can. I'm not going to worry about it. It can't be any worse than the coatings they use inside the tin cans at the grocery store. The flat lids aren't touching the food inside the jar for the most part anyway.
My point is, STOP BEING AFRAID OF YOUR FOOD! I know it is so easy to question ourselves, especially when we weren't raised up during a time when home food preservation was used often. We're all learning. I promise you will get used to the process and get used to eating all the yummy things you create!