Just a few rules that will make your home food preservation safe and successful
Processing Temperatures. Foods suited for canning are divided into acidic (<4.6 PH) - basically all fruits, tomatoes, sauerkraut and all acid added products (pickles) and non-acidic (4.6PH or more) - vegetables, meats, fish and mixed sauces. Acidic canned products need to be boiled (212F degrees) and non-acidic canned products need to be pressure canned (240F degrees or more) to ensure the botulinum spore is destroyed.
Salt. Follow the recipe for brines very accurately, a lower salt content will produce inferior results and will encourage food spoilage.
Vacuum seal. Preventing air from getting into your canned foods will make it impossible for aerobic microbes and fungus to survive. Best way to maintain a great vacuum seal on jars is the use of Mason jars with two part lids. Always check for popping lids, that is a sure sign that the seal was broken and the food is probably altered.
Sugar content. Even with a good seal fruit preserves without enough sugar will sour and mold. Follow the recipe quantities.
Slow cooling. Allow the preserves to cool slowly over a 12 to 24 hour period.