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How to get jam just right


If you use less sugar, you will get a softer set jam.

If you use less sugar, you will get a softer set jam.

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Jams actually set better with slightly underripe or just ripe fruit.

Jams actually set better with slightly underripe or just ripe fruit.


If you use less sugar, you will get a softer set jam.

I went to visit my friend Betty bearing a foodie gift of a jar of my freshly made mixed berry jam – only to be greeted at the door with a jar of her own beautifully presented raspberry jam made with raspberries from her own garden.

Admittedly, we both work in food, but it goes to show how homemade foodie gifts are making a comeback.

Jams and preserves aren't a way to use up overripe or excess fruit.

Jams actually set better with slightly underripe or just ripe fruit.

The reason for this is that this is when the pectin, the substance in fruit that makes it set, is at its highest.

The amount of pectin varies from fruit to fruit, with strawberries being very low in pectin.

So getting a strawberry jam right is an achievement.

If you're struggling, you can buy jam sugar, which has had pectin added to it, or add lemon juice, the old fashioned way.

Use the juice of one-to-two lemons per 1.8kg of fruit.

Another popular remedy is making jams with mixed fruit, where the fruits higher in pectin help the jam to set.

Sterilising jam jars

Sterilise jam jars by washing them thoroughly in warm soapy water.

Rinse well and dry with a clean tea towel.

Place upside down on the oven rack and bake for 10 minutes at 150°C.

Old glass jars are okay to recycle as long as the lids are in good nick.

If they are slightly dented or ill fitting, air can get in and cause the jam to spoil.

Cooking the fruit

Place the fruit in a large stainless steel pot or preserving pan with some water according to the recipe.

Berries may not need any water as they break up quickly and release their juices when heated and mashed.

Harder fruits need a little water and a longer cooking time to release their pectin and acid.

Simmer the fruits gently.

Blueberries and plums should be cooked until their skins are soft.

Once sugar is added, the skins may become tough if they haven't been cooked enough already.

Adding the sugar

Use white granulated sugar for jam making.

The amount of sugar needed varies, but the minimum amount recommended for 450g of fruit is 270g of sugar.

If you use less sugar, you will get a softer set jam.

To help the sugar dissolve, spread it out on a baking tray and get in a 150°C oven for 10 minutes before adding it to the fruit.

Take the jam off the heat, add the sugar and stir continuously until the sugar has dissolved.

Don't let the jam come to the boil before the sugar is dissolved as this may cause it to crystallise during storage.

Boiling the jam

When the sugar has dissolved, turn up the heat and bring the jam to the boil.

The time this takes will vary, and is something you'll learn with experience.

Jam needs a high temperature to reduce and thicken so that it will set when it cools.

Sometimes this will take a matter of minutes (for example raspberry jam) or up to half an hour (gooseberry jam), depending on the amount of water in the jam.

This stage is often referred to as a rolling boil.

Testing for set point

After five-10 minutes of rapid boiling, test the jam to see if it has reached setting point.

This can be done in several ways.

Remove the pan from the heat while testing, so that the jam doesn't overcook.

1. The wrinkle test: Place a small plate in the freezer to chill.

Drip a pool of jam on to the plate for a few seconds, push the jam with the spoon or your finger.

If setting point has been reached, the surface of the jam will 'wrinkle'.

When you lift your finger or spoon from the plate the jam should form a strand rather than dripping off.

2. Sugar/Jam thermometer: Dip the sugar thermometer into hot water, then push it into the jam, in the centre of the pan.

If the temperature reaches 105°C, setting point has been reached.

3. The flake test: Dip a spoon into the jam, then hold it above the pan.

Leave it to cool for a few seconds, then let the jam fall back into the pan.

If the jam has a sticky consistency and forms strands that hang on to the spoon, setting point has been reached.

If setting point hasn't been reached, place the pot back on the heat and boil rapidly for a further few minutes, testing at five-minute intervals.


During boiling, a scum forms on the surface due to bubbles rising to the surface as the fruit is agitated.

This is harmless but can spoil the appearance of the jam.

Stir in a small knob of butter to disperse the jam and scoop away with a spoon.

Filling and storing

Have your hot, sterilised jars ready. Pour the jam into the hot jars, leaving a 5mm gap between the top of the jam and the rim if using a screw top jar. Place a special wax jam disc on the surface of the jam or a circle of parchment paper.

Screw the jar tightly closed, and once cooled, label and store in a cool, dark place.

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