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Lingonberry
The lingonberry is the one fruit on this page that comes with its own preservative. It contains benzoic acid naturally, which is why the Nordic tradition includes preparations that are never cooked and never sealed — raw berries mashed with sugar, and berries simply covered with cold water — and why they keep for months where any other berry would ferment or mould.
The season
From late August to October, best after the first cold nights. They hold on the plant well into the autumn.
Acidity decides the method
Lingonberries are strongly acid, around pH 2.5–3.0, and they also carry their own natural benzoic acid.
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
| Method | Verdict | The note |
|---|---|---|
| Freezing | Best | They freeze loose and perfectly, with no sugar and no preparation beyond picking out the leaves. |
| Drying | OK | They dry into hard sour beads, useful in muesli and baking. |
| Fermenting | OK | Water-covered lingonberries are the traditional cold-store preparation and rely on the berry's own acidity. |
| Pickling in vinegar | OK | Spiced lingonberries in vinegar are a real northern condiment for game. |
| Jam and sugar preserves | Best | The famous uncooked preserve: raw berries stirred with sugar and kept cold. Traditionally around 300–400 g of sugar per kilo of berries. |
| Water-bath canning | Good | Cooked sauce, juice and compote process safely without any added acid. |
| Pressure canning | No | Unnecessary for a fruit this acid. |
| Curing and salting | No | No tradition. |
| Smoking | No | No tradition. |
| Root cellaring | Good | A tub of berries under cold water in the cellar is the old method and works. |
The classic preparation: Raw-stirred lingonberries, and berries in water
For the raw preserve — rårörda lingon in Swedish, and made across the whole region — clean the berries, crush them lightly or leave them whole, stir in sugar at roughly 300 to 400 grams per kilogram of berries, and keep stirring at intervals over an hour or two until the sugar has dissolved. Nothing is heated. Pack into clean jars and keep them cold. It keeps for months in a refrigerator or a cold cellar, because the berry's natural benzoic acid and its own high acidity do most of the preserving and the sugar and the cold do the rest. The even older method is simpler still: pick over the berries, put them in a jar or tub, cover them with cold water, and keep them cold. They stay usable for months with no sugar at all.
Preparation that matters
Pick over carefully — lingonberries come with leaves, twigs and the occasional unripe white berry, and the traditional trick is to roll them down a damp, tilted board, where the round berries run and the debris sticks. Do not wash them if you can avoid it, and if you must, dry them. For the raw preserve, use clean jars and clean hands: nothing is being sterilised here, and the cold store is part of the method rather than an afterthought.
What the preserve is worth
The raw preparations are the nutritional argument for this berry: nothing is boiled, so the vitamin C and the polyphenols survive in a way they never do in a cooked jam. Lingonberries are also very high in benzoic acid, which is what allows all of this, and which is the same compound used as the food additive E 210. The sugar in the traditional raw preserve is real and should be counted, but at 300–400 g per kilo it is well below what a cooked jam carries.
The ways this goes wrong
- Treating the raw preserve as shelf stable. It is a cold-store product and it belongs in the fridge or a genuinely cold cellar.
- Washing and then packing wet berries.
- Under-stirring, so the sugar sits at the bottom undissolved.
- Assuming every berry behaves this way. Lingonberry does because of its benzoic acid; a raspberry treated the same way ferments.
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
Frequently asked questions
Why do lingonberries keep without cooking?
Because they are naturally high in benzoic acid — the same compound used as the preservative E 210 — and very acid in their own right. Kept cold, with or without sugar, they resist the moulds and yeasts that would take any other berry.
How much sugar for raw-stirred lingonberries?
The traditional ratio is roughly 300 to 400 grams of sugar per kilogram of berries, stirred in cold until dissolved. Less sugar gives a sharper preserve that wants to be eaten sooner.
Do lingonberries in water really keep?
That is the old method across the region and it works, for months, in the cold. It relies entirely on the berry's own acidity and on a genuinely cold store — it is not a room-temperature preserve.
Related pages
From the garden to the log
TempoLife counts the berries you picked and the jam you ate from them, so the season's work shows up where it belongs.