Making Fruit Jam for Long-Term Storage
Turning seasonal fruit into jam is about managing water content and sugar concentration to create a stable environment. When done correctly, the result is a stable preserve that holds the character of the fruit for months on the shelf.
Cleanliness is the only non-negotiable step.
Your jars must be sterile and the lids must be free of nicks to ensure a proper seal. If a jar doesn't click or feel concave after cooling, it has not sealed.
- large non-reactive stainless steel pot
- water bath canner with rack
- jar lifter
- canning funnel
- half-pint glass jars with new lids
What goes in.
- 4 cupsprepared fruit, crushed or chopped
- 2 cupsgranulated sugar
- 2 tbspbottled lemon juice
Checking the Set
Place a small plate in the freezer before you start. When you think the jam is ready, drop a teaspoon onto the cold plate; if it wrinkles when you push it with your finger, it will set.
The method.
Prepare the fruit
Combine fruit and lemon juice in the pot over medium-high heat. Cook until the fruit releases its liquid and softens completely.
Incorporate sugar
Add the sugar all at once. Stir constantly with a wooden spoon to prevent scorching on the bottom until the sugar dissolves.
Boil to set
Increase heat to high. Boil rapidly until the mixture thickens and hits 220°F. Perform the plate test to confirm the set.
Fill jars
Ladle the hot jam into sterile jars, leaving a quarter-inch of headspace at the top. Wipe the rims clean with a damp cloth.
Process
Apply lids and rings until finger-tight. Lower into boiling water, cover, and boil for 10 minutes. Remove and let cool undisturbed for 24 hours.
Other turns to take.
Low-Sugar Jam
Requires specific low-methoxyl pectin to gel properly, as standard pectin relies on high sugar content.
When it doesn't go to plan.
Always use fresh, firm fruit; overripe fruit contains less natural pectin and may result in a runny consistency.
Do not double the recipe in one pot, as the increased boiling time will darken the color and ruin the fresh fruit taste.
If a jar fails to seal, place it in the refrigerator and consume it within three weeks.
The ones that keep coming up.
Why did my jam turn out runny?
The mixture likely did not reach the proper temperature or the fruit was low in natural pectin. You can re-boil it with a small amount of added pectin to fix it.
Can I reuse the lids?
No. The sealing compound on the underside of the lid is intended for one-time use only.
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