Home curing Olives from Ken Churches
Curing your own olives is one of the most satisfying things you can do with a bucket and some patience. It is also the kitchen project where casual instructions do the most damage. Here is how each method actually works, and where each one goes wrong.
There are more olive trees in gardens, parks and streets than most people realise, and almost all of that fruit is wasted. It should not be. Curing olives at home requires no special equipment, no expertise and no rare ingredients — just a container that is not metal, some salt, and a willingness to wait weeks rather than days. What it does require is understanding what you are doing, because the difference between the four methods is not preference. It is chemistry, timing and safety.
Choosing and preparing the fruit
Pick fruit that is intact, unbruised and free of the small brown holes that indicate olive fly damage. Sort ruthlessly : one soft, punctured olive will spoil the character of a whole jar. Wash the fruit and keep it out of the sun while you work.
Ripeness dictates everything that follows. Green, straw-coloured and just-turning cherry-red fruit is firm and takes any method well, giving a crisp result. Fully ripe black fruit is soft and will not survive an aggressive cure — it goes mushy — but is ideal for dry salt curing, which suits soft ripe flesh perfectly. Do not mix ripeness stages in one batch, because they will cure at different rates and you will end up with some olives still bitter and others collapsing.
Cracking or slitting the fruit speeds every method considerably by letting the bitter compounds diffuse out. Tap each olive with a wooden mallet or the flat of a knife until the flesh splits, taking care not to shatter the pit. Cracked olives cure in a fraction of the time but they will not keep as long.
| Method | How long | Result | Watch out for |
|---|---|---|---|
| Water cure | 1–3 weeks, changing water daily | Mild, clean, delicate ; the gentlest on texture | Skipping water changes : it turns sour and spoils |
| Brine ferment | 1–3 months in 6–10% salt | Complex, tangy, traditional ; the best flavour | Weak brine, warm room, fruit floating above the liquid |
| Lye cure | Hours, then days of rinsing | Fast, mild, Spanish-style ; firm and sweet | Any shortcut in the rinsing ; needs real care |
| Dry salt | 3–6 weeks buried in salt | Intense, wrinkled, concentrated ; for ripe black fruit | Damp salt caking ; the fruit must drain freely |
The four methods in practice
Water curing is the beginner’s method and the safest. Cover cracked olives with fresh cold water, keep them submerged with a plate, and change the water every day. After one to three weeks, taste one: when the bitterness has dropped to a level you like, move them to a finishing brine of about 6 to 8 per cent salt with a splash of vinegar. The daily change is not optional — stagnant water goes sour and the batch is lost.
Brine fermentation is the traditional route and gives by far the most interesting flavour. Submerge whole or cracked olives in brine of roughly 6 to 10 per cent salt — the classic test is a brine strong enough to float a raw egg. Keep everything under the surface, cover loosely so gases escape, and leave it somewhere cool for one to three months. A cloudy brine and a faint winey smell are the ferment working. A foul or putrid smell, slimy fruit or a fuzzy coloured mould means the batch has failed : discard it and start with stronger brine and cooler conditions.
Lye curing is what commercial Spanish-style green olives use, and it is fast — hours rather than weeks. It is also the only method with a genuine hazard. Food-grade sodium hydroxide is caustic and will burn skin and eyes badly. Use eye protection and gloves, always add lye to water and never water to lye, and use glass, stoneware or heavy food-grade plastic — never aluminium or galvanised metal, which react. A working solution is roughly two ounces of lye per gallon of water, or about 15 g per litre. Keep the olives submerged and check penetration by cutting one every hour or so: when the lye has darkened the flesh right through to the pit, usually after ten to twelve hours, stop. Then rinse — properly. Repeated changes of fresh water over one to two days until the water runs clear and the olives no longer taste soapy or slippery. This rinsing stage is the whole safety of the method ; do not shorten it.
Dry salt curing is for fully ripe black fruit. Layer olives with coarse salt in a basket or perforated container so the drawn-out liquid can escape, using roughly one part salt to three or four parts fruit by weight, and shake or turn every few days. After three to six weeks the olives are wrinkled, dark and intensely flavoured. Brush off the excess salt and toss them with a little olive oil and, if you like, orange peel or dried herbs.
Rules that keep a batch alive
- Never use aluminium, copper or galvanised containers — glass, stoneware and food-grade plastic only.
- Keep the fruit submerged, always. Olives above the liquid go mouldy and take the jar with them.
- Judge by taste, not by the calendar. Fruit size, variety and temperature change every timing on this page.
- Cool and dark beats warm and quick. A warm room pushes a ferment towards spoilage organisms.
- Trust your nose. Winey and cheesy are fine ; putrid, slimy or fuzzy mould means discard the batch.
- Store finished olives in fresh brine in the fridge, and top up as you eat them.
Home curing olives : common questions
Can I cure olives without lye?
Yes, and most home curers should. Water curing and brine fermentation both remove the bitterness perfectly well — they are slower but need no hazardous chemicals, and brine fermentation gives better flavour than lye ever will.
How do I know when they are ready?
By tasting. Bitterness should have dropped to a pleasant level with no soapy or caustic edge. Timings vary hugely with fruit size, variety, ripeness and temperature, so the clock is only a rough guide.
Is home lye curing dangerous?
The lye itself is genuinely caustic and demands gloves, eye protection and care — always add lye to water, never the reverse. The finished olives are safe provided the rinsing stage is done thoroughly, with repeated water changes until no slipperiness or soapy taste remains.
My brine went cloudy — is that bad?
No, cloudiness is normal in a live fermentation and usually a good sign. Worry about a putrid smell, slimy fruit or coloured fuzzy mould on the surface ; those mean the batch should be discarded.
Which olives should I use?
Firm green, straw or just-turning fruit for water, brine or lye curing ; fully ripe black fruit for dry salt. Discard anything soft or showing fly holes, and never mix ripeness stages in one batch.
The mistake almost everyone makes on their first batch is impatience with the rinse and the ferment — and the second mistake is treating the timings in any recipe as law. Fruit size, variety, ripeness and the temperature of your garage all change the schedule, sometimes by weeks. That is why every old family curing recipe reads like a secret: it is not hiding an ingredient, it is describing one person’s particular fruit in one particular shed. Learn the method, then taste your way to the end of it. That is the entire craft.
House guide, based on standard water, brine, lye and dry salt curing practice.