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Curing and salting
Curing and salting — kept by salt. How the method works, the ratios and temperatures that make it safe, the steps in order, what it costs in nutrients, and the classic Nordic practice.
How it works
Salt preserves by osmosis: dissolved in the water phase of the food, it makes that water unavailable, and enough of it dehydrates and kills the microbes competing for it. How much is enough depends on what else is happening — refrigeration, drying, smoking and acidity all stack with it, which is why a 2 % cure works on a piece of fish that stays at 3 °C and would do nothing at all on the same fish in a warm room. Curing salts add sodium nitrite, which does something salt alone cannot: it specifically inhibits Clostridium botulinum in the anaerobic interior of a cured meat, and it fixes the pink colour and the cured flavour along the way.
How long it keeps
Depends entirely on how far the salt went. A light gravlax cure is a refrigerated fresh food good for days; a heavily salted, dried product keeps months in a cold larder.
The numbers
| Figure | Value |
|---|---|
| Curing salt #1 (pink salt) | 6.25 % sodium nitrite, the rest common salt, dyed pink so it is never mistaken for table salt |
| Rate for curing salt #1 | the rate printed on the packet — commonly 2.5 g per kg of meat. Never estimate it. |
| Curing salt #2 | also contains sodium nitrate, which converts slowly to nitrite over a long dry cure |
| Equilibrium salt cure | salt weighed as a percentage of the meat or fish, typically 2–3 % |
| Gravlax | salt and sugar cure, 12–48 hours refrigerated, weighted |
| Fish to be eaten raw or lightly cured | frozen at −20 °C for 24 hours, or −35 °C for 15 hours |
| Desalting a heavily salted product | soak cold with several changes of water |
How to do it
- Weigh the meat or fish, then weigh the cure as a percentage of it. Sprinkling by eye is how a cure goes wrong in both directions.
- Cure cold, at refrigerator temperature, on a rack over a tray so the drawn-out liquid runs away.
- Turn and re-distribute daily on anything thicker than a fillet.
- Rinse or wipe as the recipe says, then let a surface dry form before drying or smoking.
- If the finished product will be eaten without cooking, freeze it first to the published parasite figure.
- Label with the date. A cure is a clock, and an unlabelled bag in the fridge is an unknown.
What makes it safe
- Curing salts are toxic in excess and are dyed pink for that reason. Use the packet rate, keep them out of reach, never scale up "for safety".
- Salt does not kill parasites. Freezing does — the published EU figure for fish to be eaten raw or lightly cured is −20 °C for 24 hours throughout.
- Cold-smoked and lightly salted fish are ready-to-eat foods that can carry Listeria. Public-health advice in the Nordic countries is that people who are pregnant or immunocompromised avoid them.
- Cured meat is salty by definition. If you have been told to keep sodium down, that is a conversation with your own clinician, not a recipe adjustment.
Where it goes wrong
- A cure that is too short for the thickness, leaving an unsalted core.
- Curing at room temperature "for speed".
- Using curing salt where plain salt was meant, or the reverse.
- Assuming a salty surface means a salted interior. Salt moves through muscle slowly, roughly a centimetre a day in a wet cure.
What it costs in nutrients
| Nutrient | Survives the method |
|---|---|
| Vitamin C | Medium |
| B vitamins | Medium |
| Vitamin A and carotenoids | High |
| Minerals and fibre | High |
The nutrient question with curing is not what is lost but what is added. Sodium is the headline: cured products are among the saltiest food in a normal diet. Nitrite and nitrate are permitted additives with acceptable daily intakes set by EFSA, and the World Health Organization's cancer agency, IARC, classified processed meat as carcinogenic to humans in 2015 on the basis of colorectal cancer. That is a statement about processed meat as a category and about regular consumption, not a statement about one plate of home-cured fish.
The Nordic tradition
Salting is the deepest food tradition in this region. Salted Baltic herring, salted mushrooms in a wooden tub — soolaseened, suolasienet, solyonye griby — and salt-and-sugar cured salmon are all still made at home. Two regional details matter. Milk-cap mushrooms of the Lactarius family carry an acrid latex and are parboiled before they go under salt, which is standard practice in Finland and Estonia and not an optional refinement. And cold-water fish is the classic vector for Clostridium botulinum type E, which unlike most of its relatives grows at refrigerator temperatures — the reason lightly salted, vacuum-packed fish carries short and strict use-by dates.
Which foods suit it
| Food | Verdict | Why |
|---|---|---|
| Wild mushrooms | Best | The traditional Baltic and Finnish salted mushroom, layered under salt in a crock. Acrid milk-caps are parboiled first. |
| Baltic herring | Best | The oldest route. Light salting keeps refrigerated for days; a heavy salt cure keeps for months and is soaked before use. |
| Onion | Good | Curing here means drying the neck after lifting, and it is the whole basis of onion storage. |
| Garlic | Good | Curing after lifting is the whole basis of garlic storage. |
| Herbs | Good | Herb salt — chopped herbs packed with plenty of salt — is a genuine traditional preserve, and the salt is what keeps it. |
| Cabbage | OK | Salting is the first half of fermenting, not a separate route. |
| Cucumber | OK | Dry-salting is the first stage of some fermented recipes rather than a method of its own. |
| Pumpkin and winter squash | OK | Curing here means the warm drying period after cutting, which hardens the skin. |
| Green beans | OK | Salt-packed beans are an old method, superseded by the freezer. |
| Plum | OK | Salted and dried plums exist in other food cultures; not a Baltic tradition. |
| Tomato | Poor | Not a tradition worth reviving. |
| Beetroot | Poor | No tradition. |
| Carrot | Poor | Not a tradition. |
| Peas | No | No tradition. |
| Apple | No | No tradition. |
| Rhubarb | No | No tradition. |
| Strawberry | No | No tradition. |
| Raspberry | No | No tradition. |
| Blackcurrant | No | No tradition. |
| Lingonberry | No | No tradition. |
| Sea buckthorn | No | No tradition. |
| Bilberry and blueberry | No | No tradition. |
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 method
- EFSA re-evaluation of nitrites and nitrates as food additives
- IARC Monographs Volume 114 (2015) — red and processed meat
- Regulation (EC) No 853/2004, Annex III — parasite treatment of fishery products
Frequently asked questions
What is the difference between curing salt and table salt?
Curing salt #1 is ordinary salt with 6.25 % sodium nitrite mixed in and a pink dye added so nobody confuses the two. The nitrite is what inhibits botulinum in the airless interior of a cured meat, and it is why the packet rate is not a suggestion.
Do I need nitrite to make gravlax?
No. Gravlax is a short salt-and-sugar cure on fish that stays refrigerated throughout and is eaten within days, so it is not relying on nitrite. It is relying on the fridge — and on the fish having been frozen first if it will be eaten without cooking.
How salty is too salty?
For safety, a cure that is too weak is the risk, not one that is too strong. For health, cured food is a high-sodium food and the sensible framing is frequency and portion rather than a number on a page.
Can I make salted mushrooms from any species?
Only from species you have identified with certainty, and the acrid milk-caps used for this traditionally are parboiled first. Wild-mushroom identification is not something to take from a web page.
The other methods
All methods compared
The ten hurdles, and the foods each one suits.
Freezing
The default method in a northern kitchen: fast, forgiving, and the one that keeps the most of what was in the food. It pauses spoilage rather than ending it.
Drying
The oldest method, and the only one that needs no cold, no jars and no electricity once it is done. It works by taking the water away rather than by making the food hostile.
Fermenting
The method that makes its own preservative. Salt buys time for lactic acid bacteria, and the acid they produce is what keeps the jar.
A pantry you can see
TempoLife tracks the food you logged fresh and the jars you put down in autumn, so the batch numbers on the lids match the calendar.