Question: what questions do you ask to know about methods of food preservation?
Answer: Why do you have to use a pressure canner for some foods and not for others?
How much lemon juice or citric acid has to be added to tomatoes to preserve them using a water bath canner?
Why didn't all my jars seal?
If a lid does not seal, can the food be processed?
How long is it safe to store canned food?