This process seals the jars, protecting the jam from mold or bacteria. Here’s what you need to know (and what you need to have) to get started. The 15 Best Canning Tools, According to an Expert ...

Stir in the white balsamic vinegar and simmer over low heat, stirring a few times, until the jam is thick, about 5 minutes. Discard the herb bundle. Season the jam with salt and let cool to warm.

Jam is nothing more than a balance of pectin, sugar, and acid. No wonder Marie Curie loved making it so much. All preserved fruit—whether jam, jelly, or marmalade—depends on the same chemistry.

Jam, jelly, preserves, and marmalade all live life in the same, same, but different category. They start out almost identical, but take different paths to end up at their final form.

To sterilise the jars, preheat the oven to 110C/100C Fan/Gas ¼. Wash the jars in hot, soapy water, rinse thoroughly, then put them on a baking tray (rim side up) in the oven for 30 minutes.