Raspberry jam needs only two ingredients: crushed berries and sugar, in a fixed ratio of about 560 g of sugar to every litre of crushed fruit. The tested recipe it follows uses no added pectin or lemon juice, so there's nothing else to buy. What takes care is the boil: bring it to setting point, then seal the jars in a boiling-water bath so they keep.

Makes
about 7 jars of about 250 ml
Keeps
about a year unopened in a cool, dark place after the water bath (step 13); once opened, in the fridge for a few weeks to a month or two
Ready to eat
once cool and set
In season
June to October, from summer and autumn varieties

Ingredients

  • 2 litres (measured after crushing) raspberries
  • 1.125 kg granulated sugar

Crush the berries first, then measure them in a jug; for a different amount, use about 560 g of sugar for every litre of crushed fruit (see the table below).

Method

  1. Sterilise the jars: a hot dishwasher cycle, 10 minutes in boiling water (add 1 minute for every 300 m of height above the first 300 m), or the oven at 160°C (gas mark 3) for 10 minutes. Check the jar maker's instructions; some (Kilner, for example) advise against the oven for their jars. Use new lids and sterilise them separately in hot water (see the sterilising guide).
  2. Chill two or three small plates in the freezer for the setting test.
  3. Wash the raspberries and pick out any leaves, stalks or mouldy fruit.
  4. Crush the berries and measure 2 litres into a large, wide pan.
  5. Add the sugar.
  6. Bring slowly to the boil, stirring now and then, until the sugar has dissolved.
  7. Once the sugar has dissolved, boil rapidly, stirring often as the jam thickens so it doesn't stick.
  8. Start testing early. Boil to setting point, about 104.5°C, for a firm jam, or stop just short of it for a softer one (see the setting point guide).
  9. Take the pan off the heat and skim off the foam quickly.
  10. Fill the jars while they are still hot from sterilising, with the jam straight from the pan, leaving about 6 mm (¼ inch) of space at the top.
  11. Wipe the rims with a clean, damp paper towel.
  12. Put the new lids on straight away.
  13. Stand the jars on a rack in a deep pan, cover them with hot water by about 2.5 cm, bring to the boil and boil for the time in the water-bath table below: 5 minutes for jars sterilised by boiling, if you live below about 300 m (1,000 ft).
  14. Lift the jars out and leave them to cool undisturbed.
  15. Once cold, press the centre of each lid. A sealed lid is pulled down slightly and doesn't move. Put any jar whose lid flexes or clicks in the fridge and treat it like an opened jar (see the preserve storage guide).
Raspberries and sugar coming to a rolling boil in a wide pan, foam gathering at the edges
Bring it slowly to the boil, stirring until the sugar has dissolved, before boiling hard for the set.

Batch sizes

The table keeps the same ratio at every size. Don't go bigger than 2 litres: small batches boiled hard reach setting point sooner and set more reliably than big ones.

Crushed raspberriesGranulated sugarMakes about
500 ml280 g2 jars of 250 ml
1 litre560 g3 or 4 jars of 250 ml
2 litres1.125 kg7 jars of 250 ml (the full recipe, the largest batch)

Why the sugar stays as it is

Sugar is the preservative in jam. It stops microorganisms growing, adds flavour and helps the gel form. Never cut the sugar in a jam recipe: with less, you get a runny, syrupy jam that spoils sooner. If you want a lower-sugar jam, use a tested recipe written for one.

Getting a set

Sources differ on whether raspberries are high or low in pectin, so test every batch rather than relying on the fruit. Pectin is at its best in fruit that is just ripe, so use berries at their peak rather than soft, overripe ones.

A thermometer is the most dependable test. Jam sets at about 104.5°C at sea level, and about 1°C lower for every 300 m of height, which matters if you live in the hills. The cold plate test makes a good cross-check: take the pan off the heat, put a little jam on a chilled plate for a minute or two and push it with a finger. If it wrinkles, it's ready. On a spoon, set jam runs off in a sheet rather than single drops. Jam thickens as it cools, so a set that looks slightly loose in the pan is often right. The setting point guide explains all three tests and what to do if a batch won't set.

Seedless raspberry jam

For a smooth jam, crush and measure the berries as in step 4, then heat them until soft and press them through a sieve (or a food mill, a hand-cranked sieve). Add the sugar for the amount you measured before sieving, then carry on from step 6.

The water bath and keeping the jars

Many UK recipes fill sterilised jars hot, lid them and go straight to the cupboard. This recipe was tested with the boiling-water bath in step 13, and its keeping time depends on it. How long the bath takes depends on how the jars were sterilised and how high you live.

Jars sterilised byHome below about 300 mHome above about 300 m
Boiling for 10 minutes5 minutes10 minutes
Dishwasher or oven10 minutes10 minutes, plus 1 minute for every 300 m (1,000 ft) of height

Waxed discs and cellophane covers don't give a seal, so they won't do for jars meant to keep. Jars that are only filled hot and lidded can't be relied on to keep as long: store them in the fridge and eat them soon.

Water-bathed jars keep for about a year in a cool, dark, dry place. Once a jar is open, keep it in the fridge and use it within a few weeks to a month or two. Throw out any jar with mould, or a fermented, yeasty or alcohol smell; don't scrape the mould off and eat the rest. The preserve storage guide has more detail, and the jars guide helps you choose jars and lids.

Two croppings, two jam sessions

Summer raspberries crop from June, depending on variety and the season, with later varieties still ripening into September. Autumn raspberries start in August and often carry on well into October, and new autumn canes fruit in their first year. Grow both and you can make jam twice in a season. The Glen raspberries, Glen Ample among them, come from the James Hutton Institute's breeding programme in Scotland and are named after Scottish glens.

Pick when the berries are richly coloured, plump and pull off easily. Pick on dry days, because damp fruit goes mouldy, and gather them into shallow containers only two or three layers deep so they don't crush. The raspberry growing guide covers varieties and care.

When the canes produce faster than you can make jam, freeze the extra. Spread the berries in a single layer on a tray, freeze them, then bag them. They are best used within about 3 months for quality, though they stay safe for longer. There's more in freezing soft fruit and dealing with a glut of raspberries and blackberries.

Common questions

Do I need pectin or lemon juice for raspberry jam?

Not for this recipe. Start testing for a set early, and let the test tell you when it's ready.

Why is my raspberry jam runny?

It may just need time, because jam firms up as it cools. The usual causes of a soft set are not boiling long enough, too large a batch, or overripe fruit, which holds less pectin. The setting point guide covers what to do next.

How do I make a firmer or softer jam?

Boil it all the way to setting point for a firm jam, or stop just short of it for a softer one. Don't change the amount of sugar to alter the texture.

Can I skip the water bath?

Only if you keep the jars in the fridge and eat them soon. The year's keeping time applies only to jars that have been through the bath.

Sources

Show the 21 sources