Quick Berry Jam

Use properly sterilised jars and seal while the jam is still hot - this creates a vacuum seal as it cools, which is what makes the jam shelf-stable. Jars that don't seal properly should be refrigerated and used within a few weeks.

01Ingredients

1000g berries (raspberries, strawberries, or a mix), hulled if needed
800g white sugar
2 tbsp lemon juice

02Method

Place berries, sugar, and lemon juice in a large, heavy-based pot. Let sit for 10 minutes to release some juice.
Bring to a boil over medium-high heat, stirring to dissolve the sugar.
Boil rapidly for 15-20 minutes, stirring occasionally, until it reaches setting point (a small amount dropped on a cold plate wrinkles when pushed).
Skim off any foam from the surface.
Pour hot jam into sterilised jars and seal immediately.

03Notes & substitutions

A mix of berries gives a rounder flavour than one type alone.
Reduce the sugar slightly if the berries are very sweet already, though this may extend the boil time needed to set.
Add a few whole berries near the end for texture, rather than boiling them all to a smooth consistency.
Vegetarian and vegan as written.

04Common mistakes

Not boiling long enough — jam needs a rapid boil to reach setting point; a gentle simmer will never set properly, however long you leave it.
Skipping the setting point test — jam that looks ready in the pot can still be runny once cooled; always test on a cold plate before jarring.
Using unsterilised jars — this affects both shelf life and safety; always sterilise jars properly first.

05Storage & leftovers

Sealed

Cool, dark place, up to 1 year.

Opened

Refrigerate, use within a few weeks.

Freezer

Freezes well for up to 1 year if not water-bath sealed.

More About This Recipe

06Ingredient notes

Berries. Slightly underripe berries contain more natural pectin than very ripe ones, helping the jam set a little more easily.

Lemon juice. Provides acidity and natural pectin that helps the jam set without needing commercial pectin added.

Sugar. Beyond sweetness, it's part of what preserves the jam and helps it set - reducing it significantly changes both the shelf life and the set.

07Troubleshooting

Jam won't set. Almost always needs more time at a rapid boil - return it to the heat and test again every few minutes on a cold plate.
Jam is too stiff or rubbery. Boiled slightly too long past setting point - still safe to eat, just firmer than intended.
Jam tastes overly sweet. Balance with a little extra lemon juice next time, added at the start.
Jars didn't seal properly. A sealed lid won't flex when pressed in the centre - if it does, refrigerate that jar and use it within a few weeks rather than storing at room temperature.

Frequently Asked Questions

Do I need to add pectin?

No - this method relies on the lemon juice's natural pectin plus a rapid, extended boil to reach setting point without needing added pectin.

How do I know when the jam has reached setting point?

Drop a small spoonful onto a cold plate and push it with your finger after a minute - if it wrinkles and holds a line, it's ready. If it's still runny, keep boiling and test again in a few minutes.

Can I use frozen berries?

Yes - frozen berries work well, though the mixture may take a little longer to come to the boil since it starts colder.

How long does homemade jam keep?

Properly sealed and stored in a cool, dark place, it keeps for up to a year. Once opened, refrigerate and use within a few weeks.