Dip 30 to 60 seconds in boiling water until skins loosen. Dip in cold water. Cut in half, remove pits. Drop into water with ascorbic acid. Drain and drop into syrup, juice, or water and bring to a boil.
Fill jars with hot fruit and hot liquid to cover, leaving headspace.
Wipe jar rims, adjust lids, and process. Wash, cap, stem. Heat berries in boiling water for 30 seconds and drain. Pour hot berries and liquid into jars, leaving headspace. Wipe jar rims, adjust lids, and process.