How to Store Olives (Zaitoon) After Opening: Green vs Black, Salt
You can’t eat an olive straight off the tree. It’s so bitter your whole mouth puckers, and every olive in a jar has been soaked in water, brine or salt to make it edible. So the useful questions are about salt and storage: how to store olives after opening so they don’t turn soft or mouldy, which colour to buy, and how many fit into a day if you watch your blood pressure. This guide is about table olives; for the oil, see our piece on roghan zaitoon for massage and cooking.
The short version
- Raw olives: inedibly bitter; soaking and brining remove the bitterness
- Green: picked unripe, firm, sharper taste
- Black: either ripened on the tree (wrinkly, purple-brown) or green olives darkened with air (smooth, jet-black, mild)
- Salt: high; ten olives can carry a quarter of a day’s sodium limit
- After opening: under their own brine, in a glass or plastic box, in the fridge
- Portion: about 5 to 10 olives, rinsed
Prefer to listen? This post as a 5 min video · Video page with transcript
Why raw olives are bitter, and how brining fixes it
A fresh olive is packed with a bitter compound called oleuropein. It’s the tree’s defence. Birds leave unripe olives alone because they taste awful.
Brining is just a slow way of pulling that bitterness out, and there are four common methods: soaking in fresh water changed daily, weeks or months in salty brine (the olive ferments a little, like achar, and turns winey), packing in dry salt until the olives shrivel (the saltiest of all), and the factory route, lye. Lye is food-grade caustic soda. It strips the bitterness in days and is how Spanish-style green olives and most tinned black olives begin. Don’t try it at home. It burns skin and eyes.
Whatever the method, the finished olive sits in brine. That’s where the salt comes from.
Green vs black olives: what the colour really means
Green and black olives come from the same tree. Colour is mostly ripeness, with one factory twist.
| Type | How to spot it | Taste |
|---|---|---|
| Green | Firm, olive-green, often stuffed or pitted | Sharp, crunchy, tangy |
| Naturally ripe black | Purple to brown-black, patchy, often wrinkly, sold with stones | Rich, fruity, strong |
| Oxidised black (tinned) | Jet-black, glossy, every olive the same shade | Mild, soft, a little bland |
The jet-black tinned kind are green olives treated with lye, then darkened by bubbling air through the liquid, the same way a cut apple browns. An iron salt called ferrous gluconate (sometimes listed as E579) fixes the colour. It’s permitted and harmless, but it tells you the olive wasn’t ripened on the tree.
Healthier? Neither by much. Tinned black olives are often a bit less salty; naturally ripe ones taste far better. Pick by taste, then compare the salt line on the label.
Salt in olives and blood pressure
This matters if anyone at home has high BP or kidney trouble.
The World Health Organization’s limit for adults is under 5 g of salt a day, about 2,000 mg of sodium, and green olives in brine commonly carry around 1,500 mg of sodium per 100 g, so ten medium green olives can hand you 500 mg or more, a quarter of the day’s allowance, before you’ve touched a roti. Black tinned olives are usually lower. Still salty.
Ten olives can use up a quarter of your day’s salt before dinner has started.
Read the label first. Look for sodium (or salt) per 100 g and compare brands; to turn sodium into salt, multiply by 2.5. Then rinse.
How to rinse olives to cut the salt
- Take out only what you’ll eat, say 8 to 10 olives. Leave the rest in their brine.
- Rinse them in a sieve under cold running water for about 30 seconds.
- For a bigger drop, soak them in about 250 ml of fresh water for 15 to 30 minutes, then drain.
- Use them straight away. Soaked olives have lost their protective brine, so they don’t go back in the jar.
Rinsing takes off the salty surface liquid and soaking draws a little salt out of the flesh. Neither makes olives a low-salt food. On a strict salt limit, count olives the way you’d count achar; our guide to sodium swaps in the desi kitchen shows where else salt hides.
How to choose olives at the shop
- Brine: fairly clear, with the olives sitting under it. Very cloudy, slimy or frothy liquid in a sealed jar is a bad sign.
- Tin or lid: never buy a bulging, leaking, rusty or badly dented tin, or a jar whose safety button has popped up.
- Stones or pitted: pitted is handy; olives with stones keep a firmer bite.
- Stuffed: the red strip is pimento (sweet red pepper), usually as a paste. Fine, just saltier.
Most table olives on Pakistani and Indian shelves are imported from Spain, Turkey, Greece and Egypt. Pakistan’s own olive planting has grown in the Pothohar region, Balochistan and Khyber Pakhtunkhwa, but most of that crop goes to oil.
How to store olives after opening
Brine is the olive’s bodyguard. Keep them in it and they last. Pour it away and they spoil fast.
- Unopened: a cool, dark cupboard, until the date on the label.
- Opened tin: tip the olives and all their liquid into a clean glass jar or food-grade plastic box, then refrigerate. Don’t store food in an open tin.
- Opened jar: lid tight, into the fridge, every olive under brine.
- How long: follow the “once opened, use within” line. Tinned olives are generally best within about two weeks; jarred olives in brine often keep a few weeks more.
- Clean, dry spoon every time. Fingers and wet spoons bring in mould.
Lost the brine? Dissolve 1 level teaspoon of salt in 250 ml of cooled boiled water, pour it over, refrigerate, and use those olives within a week or so.
Olives in oil need more care, because oil shuts out air, which is exactly what some dangerous bacteria like. If you add fresh garlic or herbs to olives in oil, keep the jar in the fridge and finish it within 4 days.
How to know if olives are bad
- Look at the surface. A thin, flat white film on the brine is usually a harmless yeast. Skim it off; if it keeps coming back or the olives under it are soft, bin the lot.
- Check for mould. Raised, fuzzy spots in green, blue, black or pink mean the whole jar goes. Don’t scoop around it.
- Feel them. Mushy or slimy olives are past it.
- Smell. Normal is salty, sour and a bit winey. Rotten, cheesy or nail-polish smells mean spoiled.
- Never taste to check. A tin or jar that bulged or spurted when opened gets thrown out without tasting a drop.
What olives do for you, honestly
Olives are a fatty fruit, and most of that fat is the kind that makes olive oil popular: monounsaturated, mainly oleic acid. Ten medium olives come to roughly 40 to 60 kcal, with a little fibre, some vitamin E and, in black tinned olives, some iron from that ferrous gluconate.
They also hold plant compounds called polyphenols, though the soaking washes a fair share out. So a jar of olives isn’t a shortcut to whatever people credit olive oil with. A few olives add flavour, good fat and a feeling of fullness to a salad. Salt is the price.
For diabetes, olives are easy: very little sugar or starch, so they barely move blood sugar. The catch is again salt, since many people with diabetes also have high BP.
Easy ways to eat them
Olive kachumber
Dice 1 cucumber, 1 tomato and half an onion. Add 8 rinsed, sliced olives and 2 tablespoons of chopped coriander, squeeze in half a lemon, and finish with black pepper and roasted zeera. No salt; the olives bring enough.
- Chana and olive salad: 1 cup boiled chickpeas, 6 chopped olives, half a chopped capsicum, 1 teaspoon olive oil, lemon juice and chilli flakes. A filling lunch box.
- Anda bhurji twist: fold 5 or 6 sliced olives into 2 scrambled eggs with onion and green chilli, and taste before you add any salt.
Olives go well with tomato, cucumber and lemon, which bring water and potassium to balance the salty bite. Olives, cheese, pickles and crisps on one plate? That’s a salt pile-up.
Myths and surprising facts
Myth: black olives grow on a different tree
Same tree. Green olives are picked early; black ones either ripen on the branch or get darkened in the factory. The myth sticks because the two look and taste so different.
Zaitoon holds a special place in Muslim homes because the olive is named in the Quran (Surah At-Tin opens “By the fig and the olive”). Many families keep olives or zaitoon oil in the house as much out of respect as taste, and Unani tradition talks far more about the oil than the fruit. Respect the tradition, and still count the salt.
Surprising fact: an olive is a stone fruit, built like a small mango, with flesh around a single hard stone. And olive trees can live for centuries; some Mediterranean trees are thought to be more than a thousand years old.
Anyone with high blood pressure, heart failure, kidney disease or a fluid limit should treat olives as a salty food and ask their doctor how they fit the day’s sodium. BP of 140/90 or more at the clinic, or about 135/85 at home, is where salt really matters, and 180/120 with chest pain, breathlessness or a severe headache is an emergency. Children under 5 get olives only pitted and cut small, since whole olives and stones can choke. Babies under 1 shouldn’t have them at all, because their kidneys can’t cope with added salt.
Olives (zaitoon): questions people ask
How do you store olives after opening a jar?
In the fridge, fully covered by their own brine, lid tight. Use a clean, dry spoon each time. Most last a few weeks this way, but the label’s “use within” line is the one to follow.
Are black olives better than green olives?
Not by much. Tinned black olives are often lower in salt, while green ones are firmer and tangier. Choose by taste and compare the sodium per 100 g.
How can I tell if olives have gone bad?
Bin them if you see fuzzy coloured mould, if they’ve gone mushy or slimy, or if the jar smells rotten or cheesy. A flat white film that skims off is usually harmless yeast.
Can diabetics eat olives every day?
Yes, in small amounts. Olives have very little sugar, which makes them a good savoury snack. Keep to around 5 to 10 rinsed olives because of the salt.
What are the side effects of eating too many olives?
Mostly salt: thirst, puffy fingers and ankles, and a rise in BP in people who are sensitive to it. A big bowl can also upset the stomach. Allergy is rare.
Can children eat olives?
Over 1, as an occasional food. For under-5s, take the stone out and cut them into small pieces, because whole olives are a choking risk, and rinse them first.
Can I eat olives in pregnancy?
Olives from a sealed jar or tin are fine in pregnancy. Keep portions modest because of salt, mention it to your doctor if your BP is creeping up, and skip deli olives left sitting out uncovered.
Are olive stones poisonous?
No. They’re hard enough to crack a tooth and can choke a small child, though, so spit them out.
Can I make fresh olives edible at home?
With plain water and then brine, if you’re patient; it takes weeks. Skip lye, which is caustic and dangerous in a home kitchen, and keep every olive under liquid.
More produce guides live in our Fruits and Vegetables section. If you make your own pickles, read homemade achar safety; the same mould rules apply to olives.