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Raspberry

Raspberries are fragile in the punnet and unusually good once preserved. They freeze whole better than almost any berry, they carry enough pectin and acid to set a jam with only sugar, and — unlike strawberries — they make a sensible juice and a very good uncooked preserve.

The season

Summer varieties in July, autumn-fruiting canes carrying on into September in a good year.

Acidity decides the method

Raspberries are acid at roughly pH 3.2–3.7, so every acid-dependent route is open.

This is a reference guide, not a recipe authority and not medical advice. The one organism the safety rules here are written against is Clostridium botulinum, and the one way to be protected against it is a tested recipe followed exactly — substitutions of the acid, the sugar or the salt are not cosmetic. Where the national food authority publishes advice for a specific food (Baltic fish, wild mushrooms), that advice outranks this page.

Method by method

The classic preparation: Uncooked raspberry preserve and raspberry juice

Raspberries have enough acid and enough natural pectin to set without much help, which makes them the best candidate for the cold preserve: crush the fruit, stir in sugar until it has fully dissolved, and freeze in small jars. It tastes of raspberries in a way no boiled jam does. For juice, which is the traditional northern winter remedy drink whether or not it does anything: simmer the berries gently with a little water, strain through a cloth without squeezing it if you want a clear juice, sweeten, bring back to the boil, bottle hot and process in a boiling-water canner. Raspberry is high-acid, so the jar needs nothing added.

Preparation that matters

Pick into a shallow container — a deep one crushes the bottom layer — and do not wash them if they came out of a clean garden, since raspberries absorb water and collapse. Freeze on the day you pick. For jam, a proportion of slightly under-ripe fruit improves the set. The seeds are a matter of taste: sieving the cooked pulp gives a smooth jelly and costs you roughly a third of the volume, which is why sieved raspberry preserves have always been the expensive kind.

What the preserve is worth

Raspberries are unusually high in fibre for a berry, most of it in and around the seeds, at around 52 kcal per 100 g. Freezing keeps the anthocyanins and most of the vitamin C. An uncooked sugar preserve keeps considerably more of both than a boiled jam does, which is the practical argument for making it. Sieving out the seeds removes most of the fibre along with them.

The ways this goes wrong

• Washing them. Raspberries take on water and turn to mush.
• Deep containers at picking time.
• Squeezing the straining cloth for juice, which gives a cloudy result.
• Storing an uncooked preserve in a cupboard. It is a freezer or fridge product.

Safety rules, temperatures, blanching times, headspace and the pH 4.6 line: USDA Complete Guide to Home Canning and the National Center for Home Food Preservation guidance (US Government / land-grant publications, public domain). Acidity classes: the FDA's published approximate-pH tables. Jam composition: Directive 2001/113/EC. Fish freezing before raw or lightly cured use: Regulation (EC) No 853/2004, Annex III. Checked 2026-09-06.

Sources for this food

• USDA Complete Guide to Home Canning (public domain)

Frequently asked questions

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