Olives have a long, rich culinary history that dates back thousands of years. They’re a staple ingredient in Mediterranean cuisine, adding a burst of unique flavour and saltiness to these dishes.
With their culinary origins in ancient Greek, Roman and Middle Eastern cuisine, olives have been adapted to different cultures and culinary traditions, becoming a globally used ingredient in a wide range of international cuisines.
Typically, olives are used as table olives, which are eaten as a snack or appetizer, or as a cooking ingredient in various dishes, such as stews, pasta sauces, and Mediterranean-inspired recipes. They can be used in various forms, such as whole olives, sliced olives, or in olive-based foods such as dips and pastes.
In recent decades, there has been a resurgence of interest in the Mediterranean diet, which promotes the consumption of olive oil and olives due to their health benefits, that has also helped popularise the use of olives in modern cooking.
Nutritionally, olives and olive oil are an excellent source of healthy fats, particularly monounsaturated fats. They also contain a range of protective antioxidant compounds, including vitamin E. Studies have shown that consuming olives and olive oil is associated with several health benefits, including improved heart health and reduced inflammation.
Green olives are typically more bitter and firm, while black olives are softer and milder in taste. Olives need to be processed to make them palatable, and curing is a traditional method that is used to preserve them, and also to remove the natural bitterness and improves the taste of raw, freshly harvested olives.
Why Do Olives Need to Be Cured Before They Can Be Eaten?
Fresh, uncured olives are intensely bitter, which makes them unpalatable and even mildly irritating to the digestive system. The bitterness is primarily due to the presence of the phenolic compounds oleuropein and ligstroside, which are more concentrated in unripe or green olives, and serve as a natural antifeedant defense mechanism to deter animals from consuming the fruit before they have a chance to ripen and the seeds inside to mature.
To make olives edible, the bitterness must be removed or significantly reduced using a curing process to leach out or break down these bitter compounds.
These same curing processes are also used to preserve the olives, and each method imparts a distinct flavour and texture to the olives.
The most common curing methods of olive preparation include:
- Brining – Olives are soaked in a saltwater solution for an extended period, which helps leach out the bitterness and preserves them. The duration of brining varies depending on the desired texture and flavour.
- Water Curing – This involves soaking olives in water, changing the water regularly over several days or weeks. It is a gentler method compared to brining and is often used for green olives.
- Dry Curing – Olives are typically coated with salt or a salt mixture and left to air-dry. Dry curing is used for black olives and produces a wrinkled appearance and concentrated flavour.
- Fermentation – Some olives are naturally fermented, often using their own lactic acid-producing bacteria. Fermentation can take several months and produces in a unique flavour.
When preserving green or green-red olives, it is desirable to retain a slight amount of the bitterness which provides the distinct flavour, though the degree of bitterness can be adjusted to taste during the curing process.
Some bitterness is retained for its health benefits too. According to studies, the bitter phenolic compound oleuropein in olives doesn’t just serve as protection against microbial and insect damage to the plant, and an antifeedant against animals eating the unripe fruit. It also has significant health promoting properties that include antioxidant activity, and protection against cardiovascular disease and metabolic disorders such as diabetes. The strong antioxidant activity may also contribute to the prevention of cancer through its ability to neutralise reactive oxygen species (ROS).
Incidentally, oleuropein is the same beneficial compound found in olive leaf extract and olive leaf tea. For more information, see article – What Are The Health Benefits Of Olive Leaf Tea And How To Dry Olive Leaves To Make Your Own
Curing olives is the traditional way to preserve them, to make them suitable for human consumption, and also enhance their flavour. In the instructions below, we will outline the steps to cure olives at home.
A Step-by Step Guide to Making Homemade Mediterranean Cracked Green Olives
Olives are a versatile fruit that adds a distinct flavour to many Mediterranean dishes. Even though jars of preserved olives are fairly commonly found in stores, preserving olives at home allows us to customize their taste and texture, ensuring a truly unique culinary experience.
The process detailed below is a traditional, time-tested method that my mum uses to make Mediterranean-style cracked green olives. It’s a water-curing process that uses brining in the final step, that was taught to her by her grandmother from Cyprus, so it dates back quite a while!
In this guide, we’ll go through the process of preserving green olives, from selection to storing the finished product.
- 2kg (4.5lbs) olives
- 2L (0.5 gal) glass jar with airtight lid
- 1 cup of coarse salt
- 7 cups of water
- Olive oil
- Clean food-grade plastic bucket or other large container
- Colander or large sieve
- Clean cutting board and kitchen mallet or rolling pin to split olives
- Bucket of water
Step 1 – Select Olives for Processing
- When choosing olives for preserving, select only freshly harvested, unbruised olives for processing, and discard any bruised or damaged fruit.
After harvesting olives, sort them based on their ripeness and quality.
It’s best to process fresh olives within a few days after harvesting to maintain freshness.
Green olives are ready to be gathered when they reach their full size, before they turn fully black. The colour should be mostly green with a slight blush. The flesh should be firm, and mature green-ripe olives will release a creamy white juice when squeezed.
The olives can still be used as they ripen further, changing from yellow-green to rose to red-brown, as the flesh is still firm at these stages of ripening and lacks dark pigment, or is partially pigmented close to the skin.
For more information, see article – Harvesting Olives, A Guide On When And How To Pick Them
Storing Harvested Olives
If olives can’t be processed soon after harvest, they can be stored for a while. Green olives generally store better than black ripe olives.
To maintain the best quality, store them in well-ventilated containers such as shallow, ventilated crates at temperatures between 5-10°C (41-50°F). Prolonged storage of 6 weeks or more at 10°C (50°F) can cause pitting and spotting on the surface of the olive.
Avoid airtight containers to prevent mould growth. Also, avoid storing fresh olives at colder temperatures from 0-2°C (32-36°F) for 2 weeks or more, as this can cause chill injury that will lead browning of the skin and flesh of the olives.
Step 2 – Rinse Olives with Water
Harvested olives will need to be washed first to clean then before processing.
- To wash the olives, place them in a colander or large sieve, rinse them under the tap, and allow the excess water to drain.
- Next, place them into a clean plastic container for the next step in processing.
Step 3 – Crack the Olives and Put Them in Water
- Place olives one or two at a time on a clean cutting board and strike with the smooth flat side of a kitchen mallet or with a rolling pin. Crush each olive just enough to crack the flesh, but don’t break the pits or remove them.
- After splitting each olive, place it into a food-grade plastic bucket or container filled with clean water so they don’t oxidise and darken.
Warning: Cracking olives is a messy process, as oil will squirt out when the olives are struck, so it’s best to lay down some newspaper or butcher’s paper in the working area beforehand.
As an interesting aside, since I documented and photographed my mum preparing the olives for this article, here’s the really old school way of cracking olives that she used, with two clean, washed, non-porous stones!
With the first few olives split, some oil spatter can be seen on the butchers paper…
Eventually, this is the degree of oil platter that results from splitting a lot of olives. The hessian sheet spread beneath the white butcher’s paper keeps the floor from getting messy.
Step 4 – Soak the Olives in Water
- Once all olives are split, leave them to soak in the bucket of water.
- Cover the bucket loosely it with a lid, or any other clean cover, such as a sheet of aluminium foil or baking paper, or even a baking tray, to prevent anything falling into the water.
Some instructions suggest placing a plate face-down on top of the olives to force them all below the surface of the water, but from the picture they are all appear fairly well submerged.
Step 5 – Change the Water Daily
- After 24 hours, pour out the water which now contains the bitter compounds that have leached out, and replace it with fresh water.
- Repeat the water change daily for the next 5 to 7 days depending on the desired level of de-bittering. For less-bitter olives, simply continue the daily water changes for more days.
Step 6 – Rinse Olives with Water
- After the de-bittered olives have finished soaking the required amount of days, place them into a colander and rinse them under tap with water.
- Next, allow the olives to drain for a few minutes as you prepare the brine.
Step 7 – Prepare the Brine Solution
- To prepare the brine, add 7 cups of water into a large pot and boil the water.
- Once the water is boiling, add one cup of coarse salt while stirring till it fully dissolves.
- Next, allow brine to cool until you can dip your little finger in comfortably, but don’t let it to get too cool.
Note: This is a much stronger brine solution than is used in modern cracked green olive recipes, and preserves them much better, so they can be kept in a cool place without refrigeration.
The modern recipes recommend a weak brine solution that is approximately half the strength, made using only 1.5 cups of coarse salt dissolved in 16 cups (4.5L or 1 gallon) of water, along with 2 cups of white wine vinegar, to process 4.5kg (10lbs) of olives, but the end product will require refrigeration.
Step 8 – Transfer the Olives into Jars
- Transfer the olives into large clean jars, filling the jars almost all the way, leaving a bit of space at the top.
Step 9 – Pour Brine into Jars
- Fill the jars with brine until it completely covers the olives.
Step 10 – Add Thin Layer of Olive Oil
- So that the olives aren’t floating above the brine solution, add a tablespoon or two of olive oil until the olives are covered and not exposed to the air.
Step 11 – Seal Jars and Allow to Sit
The jars need to be sealed properly at this stage to prevent leakage.
- If the jar lids do not have adequate seals, cover the jars first with cling wrap to make a good airtight seal.
- Next, screw on the lid and leave jars to sit for 40-50 days in a cool, dark place to allow the flavours to develop more fully.
With the stronger brine solution used in this recipe, my mum is able to store these jars in a cool, dark area that was once used to store wine by the previous owners of the property. She doesn’t use refrigeration.
Step 12 – Sample the Olives to Test Flavour
- After letting the jar sit for 40-50 days, open jar and place a few olives into a small plate and try for taste to determine if they’re ready.
- If they’re not ready, and are a bit too bitter, leave a little longer.
When the olives taste ready, if desired, fill smaller jars with olives along with their brine to bring into the kitchen to keep in the refrigerator.
Storage of Preserved Olives
These Mediterranean-style cracked olives in brine, prepared as described, can be stored in a cool, dark place or in the refrigerator for up to 1 year.
Don’t store preserved olives in a warm location, otherwise they’ll soon go mouldy and spoil, which would be a real waste, especially after this effort!
Before concluding, it’s worth mentioning that this olive curing/preserving process can be scaled up to preserve boxes of olives, or scaled down for much smaller quantities.
I’ve seen my mum harvest a few handfuls of olives from a small Manzanillo olive tree growing in a pot, and preserve a large jam jar of olives from it. It’s a simple matter of using proportionally more of less of the ingredients to match the quantity of olives available.
Preserving olives at home is a great way of utilising olive crops that are often left unharvested in backyards or public areas, and allows us to experiment with tailoring the flavours to our own personal tastes rather than buying a jar of olives from a store or supermarket. It’s woth giving iot a go, you might just like it!
- My mum’s recipe!
- Michael Zeece, Chapter six – Flavors, Editor(s): Michael Zeece, Introduction to the Chemistry of Food, Academic Press, 2020, Pages 213-250, ISBN 9780128094341, https://doi.org/10.1016/B978-0-12-809434-1.00006-2. (https://www.sciencedirect.com/science/article/pii/B9780128094341000062)