Preserving a Catch Without a Freezer

Salt, brine, air drying, smoking and how bacalhau really works

6 minAdvancedUpdated 2026-10-23 Preserving a Catch Without a Freezer

You will learn

Salt and brine fish at correct ratios
Air dry fish safely in the right weather
Explain why cold smoking is not a beginner method

⚠️ Use weighed quantities of coarse non iodised salt. Under salting is the main cause of spoilage and botulism risk in home cured fish.

⚠️ Cold smoking does not cook fish and is not a beginner method. Use hot smoking to 63 degrees Celsius in the thickest part until you have proper temperature control and a tested recipe.

⚠️ Never home can low acid foods such as fish in a water bath. Only a pressure canner reaches the temperature required.

Salt is the method, everything else is detail

Preservation works by taking water out of the flesh until bacteria cannot grow. Dry salting, the strongest method, means burying split, gutted fish in coarse non iodised sea salt at roughly 25 to 30 percent of the fish weight, in layers, skin down, in a container that drains. The brine that forms must run away, not pool. Keep it cool, under about 10 degrees Celsius, for two to five days depending on thickness, then rinse and dry. Use real coarse sea salt, never table salt with anti caking agents, and never guess the quantity. Too little salt is how spoilage and botulism risk begin.

💡 Weigh the fish, weigh the salt. Preservation is arithmetic, not instinct.

Brining

A brine is salt dissolved in water, and it works faster and more evenly than dry salt on thin fillets. A strong preserving brine is about 200 to 250 grams of salt per litre of water, roughly a 20 to 25 percent solution, and it is the base for salt fish. A lighter brine at 70 to 80 grams per litre for one to two hours firms fillets and seasons them before smoking or drying. Keep brine cold, submerge the fish fully with a plate, and never reuse a brine that has held fish. If an egg floats showing a coin sized circle, you are near the strong end.

💡 200 to 250 grams of salt per litre for preserving, 70 to 80 for flavour.

Air drying

After salting, fish dries in moving air. You need cool temperatures, ideally between 2 and 15 degrees Celsius, low humidity and constant breeze, with the fish hung split and open, out of direct sun, and protected by fine mesh against flies. This is why Atlantic and Nordic winters produce great dried fish and a warm humid summer produces rotten fish. Dried salt fish should end up hard, board like, and lose roughly half its original weight or more. If the surface stays tacky, or you see pink or slimy patches, the drying conditions were wrong and the batch goes in the bin.

💡 Cool, dry, breezy and fly proof. Warm and humid ruins a batch.

Hot smoke and cold smoke

Hot smoking cooks as it flavours, holding the fish above 70 degrees Celsius until the thickest part reaches 63 degrees. It is safe, simple and the method a beginner should use, but the result is cooked food that keeps only a few days chilled. Cold smoking runs below 30 degrees Celsius for many hours and does not cook anything, so the fish is preserved only by the salt applied beforehand and the drying. Done wrong, it is a warm, moist, low oxygen environment holding raw fish, which is exactly where Clostridium botulinum thrives. Learn hot smoking first, and only attempt cold smoking with a tested recipe and proper temperature control.

💡 Hot smoking is cooking. Cold smoking is chemistry you must get exactly right.

How bacalhau actually works

Portuguese bacalhau is not cod that was simply dried. It is cod split, heavily dry salted for weeks with the brine drained off, then dried in cold air until it is rigid and keeps for a year at room temperature. The salt content is the preservative, which is why the fish is inedible as it comes. It is rehydrated at home by soaking in cold water in the fridge for 24 to 48 hours by thickness, with the water changed three or four times, and that soaking is what pulls the salt back out. The texture changes too: salting and drying give bacalhau its flaky character, which fresh cod does not have.

💡 Soak bacalhau in the fridge, not on the counter, changing the water three or four times.

Check yourself

Dry salting fish uses roughly

Preserving salt levels are far higher than seasoning levels, and the brine that forms must drain away rather than pool around the fish.

Cold smoking is risky for a beginner because

Below 30 degrees Celsius nothing is cooked, and a warm moist low oxygen environment with raw fish is where botulism risk lives.

Good air drying conditions for salted fish are

Cool, dry moving air removes water steadily. Warm humid air lets bacteria and mould win before the fish dries.

Bacalhau is made edible again by

Long cold soaking with changes of water draws the preserving salt back out. Soaking at room temperature risks spoilage.

Try it for real: Salt one fish properly

Weigh a gutted, split fish and weigh out 25 percent of that weight in coarse sea salt
Layer fish and salt in a draining container and keep it below 10 degrees Celsius
Pour off the brine daily for three days, then rinse and pat dry
Hang it in a cool breezy fly proof place and weigh it every day until it has lost half its weight
Soak a piece in cold fridge water for 24 hours with three water changes, then cook and taste