Making Lye Cured Olives



We harvested our olives this week, and followed the usual tradition of picking the best olives for preserving and the rest for pressing into olive oil. The majority of the olives we grow are Sevillano olives, which are perfect for preserving using a traditional lye cure, or for making Spanish style fermented olives. They can also be cured using a water extraction process, which I explained in another post several years ago.

Curing olives leaches out the bitter compounds that make the raw olives inedible. These bitter phenolic compounds are more concentrated in green olives and decrease as the olives mature. The phenols in olives give the “peppery bite” found in many high quality extra virgin olive oils and are the primary source of the many health benefits attributed to olive oil including reducing the risk of cancer, heart disease, inflammatory disease and Alzheimer’s.

We definitely like some bitterness in our olive oil, and thus prefer to harvest and press our olives green. A touch of bitterness in brined fermented olives is fine too, but all olives require leaching of the majority of bitter compounds prior to consumption, and in green olives treatment with lye is the most rapid and effective way to do this. The traditional black olives most Americans grew up eating are green lye cured olives that are then treated with iron and an oxidation process to create a black olive. Green lye cured olives have the familiar mild olive flavor that most of us grew up with. They are also like a blank slate that can then be jazzed up with a variety of flavorings depending upon your preferences.

The University of California guide to preserving olives is a dependable resource for making a variety of olives. Over the years we have tried many of their recipes, but the lye cured olives are always the most popular. The recipe in their guide along with these visuals will guide you on the steps in the process.

The first step is the olive harvest. For preserved olives, harvest carefully to prevent bruising of the fruit.


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The 2015 Olive Harvest

Olives for oil are stripped from the trees onto cloths placed on the orchard floor. For preserved olives picking by hand and gently placing into a collection vessel will lessen the risk of bruising. On occasion I have picked through the “oil olives” after harvest looking for the nicest fruit and preserved those but I examine them carefully to avoid bruised olives.

You also should inspect the olive carefully for any spots which might indicate the presence of the olive fly. Do not preserve the fruit with spots.olives-with-flyw


Olives with olive fly damage. Each of these has a spot from the fly and are unacceptable for making preserved olives but can be used for olive oil.

If you have any doubts about whether the spots you see on your olives are from olive fly, cut them open and examine them. Often the damage on the inside is much worse than what might appear on the exterior.

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Olive fly damage inside the olive

If you are harvesting olives from trees that have been neglected it may be difficult to find any olives that are acceptable. We prune yearly and spray our olives several times with an organic kaolin clay compound (brand name Surround) to discourage the moths. Even with all this care, most of our olives have damage on them.

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Basket of carefully selected Sevillano Olives ready to cure

Once you harvest the olives you should treat them soon, preferably within 24 hours. Don’t chill the olives, just store them at cool room temperature until you begin processing.

The lye that is used to cure olives might be sold as a product for making soap, or as a drain cleaner. It sounds scary, as in strong concentrations it is a caustic base which can burn you if splashed on your skin or swallowed. But lye is used in a variety of processed food products that you might routinely eat, including hominy, soft baked pretzels and peeled mandarin oranges. It is even on the list of substances allowed in organic food production. Lye (sodium hydroxide) is a compound that is only harmful when in a very high concentration. Just as the acid you might add to your pool can burn you when taken straight, but can be completely safe to swim in when diluted, so the caustic base of lye can burn you when concentrated but when diluted is not harmful. When your olives are made properly, the residual amount of lye in the final product should be negligible.

Find a source of lye that is 100 percent lye. I found this lye at a local hardware store.


100 percent lye sold as drain cleaner

Read the directions on using lye in the UC guide for making olives carefully prior to beginning the lye curing process. It is very important that you read these precautions as exposure to concentrated lye can cause burns to the skin or blindness if splashed in the eyes. Remember to always protect your hands with gloves and your eyes with goggles before beginning to work with the lye solution. Be gentle during the process so you don’t splash the liquid, and don’t worry. I am uncoordinated but have been doing this for years and have never splashed it on myself.

Fill a food safe plastic bucket or other lye resistant container with enough water to cover your olives completely. I had about 3 gallons of olives, and I used 3 gallons of water. Add 3 Tablespoons of the powdered lye to each gallon of water. For this 3 gallons I used 9 Tablespoons of lye. Do not add water to lye, you should only add lye to water. Stir gently to dissolve the lye.

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Adding lye gently to the water.  Notice the eye and hand protection. Long sleeved shirts, long pants and shoes are recommended, and goggles are preferred over glasses too so I was somewhat negligent here! mixing-lye-and-waterw

Stir to dissolve lye in the water

Once all the lye has been added the temperature of the liquid might warm up. Check the temperature with a thermometer, and don’t add the olives until it has cooled down to cool room temperature (below 70 degrees).

Now carefull add the olives to the lye bath, again gently to avoid splashing. I put them in a glass measuring cup, then gradually tipped the cup to pour them into the solution.adding-olives-to-the-lye-bucketw

 Gently add olives to the lye bath

The olives must be protected from contact with air as this will cause discoloration. Cover the top of the olives in the bucket with a wet dish cloth. Then place a plate, a bowl or something else (I used a strainer) on top of the cloth to hold them under the liquid.

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A wet towel is used to hold the olives under the lye solution while curing. Put a plate or bowl or strainer on the cloth to hold the olives under.

The UC guide says to stir the olives every few hours while curing, but I only stirred them once and they seemed to cure well.

The olives are finished curing when one of the larger olives is removed from the water, rinsed and cut and the cure has softened the olive and turned the flesh green all the way to the pit. testing-lye-penetrationwThis olive is not fully cured. Note the white ring close to the pit. Cure the batch longer if your test olive looks like this.

Usually after about 12 hours my Sevillano olives are ready. Sometimes theoretically the olives may require a separate new lye cure but that has never been my experience. You can read more about that in the UC Guide.

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When the olives have been cured, you will note the lye bath has become very dark from all the compounds leached from the olives.

Once the test olive has been adequately penetrated by the lye, your lye cure is finished. You must now remove the lye from the olives. First drain the liquid from the olives by pouring them into a large strainer or colander. It is safe to pour the lye solution down the drain at this time. Return the olives to the bucket, cover the olives well with cool water, then drain them and rinse them in the strainer several times to rinse off the surface lye. During this whole process you should still be careful about avoiding any contact of the lye with your skin or eyes. Once they are rinsed the residual lye is no longer concentrated enough to be caustic.

You now will begin the process of soaking and rinsing several times per day to gradually remove the lye from the olives. Put the olives back in the bucket, cover them with water, put a clean wet cloth over the top, and let them soak for a few hours. Rinse off the water in the strainer or colander and repeat this process several times per day for at least 3 days. This process leaches the lye from the olives. The water should be completely free of any color when the olives have been adequately cleaned of the lye. The olives will no longer feel soapy or slippery. At this point you can taste an olive and should not note any soapiness or lye residue. 

Congratulations, you have successfully lye cured your olives!  Your olives are now a blank slate for flavoring. There are so many ways to flavor these plain olives. To eat some in the next few days, flavor them with a simple marinade. A good starting marinade can be made with 1 quart of water, 2 teaspoons of salt, 2 Tablespoons of vinegar, several sliced cloves of garlic, and some hot pepper slices or flakes to taste. For some variety, rosemary, thyme or bay leaves can be added to the brine or 1/4 cup of lemon juice can replace the vinegar, and sliced lemon rind can be added. The olives are usually ready to eat after 24 hours of soaking in the marinade.


 Marinated olives with lemon, garlic and hot peppers

Olives you are not planning to eat in the next few days must be preserved for long-term storage. Preservation requires either salt or vinegar brine and refrigeration. I prefer salt as it is easier to remove with soaking and leaves me with a bland olive to flavor later.

Salt brining for storage is a multiple step process. First make a lighter brine using 3/4 cup salt per gallon of water. Soak the drained olives in this brine for about 1 week. Then drain the olives and soak them in a stronger brine of 1 1/2 cups of salt per gallon of water for 10-12 days, Now drain them again and store them in the final freshly made brine of 1 1/2 cups salt per gallon of water. Store the olives in the refrigerator int he brine and use them within 2 months. I consider the olives a seasonal treat to enjoy over the holiday season and usually finish them by New Years Day.

Home cured olives in strong salt brine ready for the holidays! 

Don’t forget to plan ahead when you want to eat these olives because they are salty! A day or two before you want to eat some olives, soak them in water in the refrigerator to remove the salt.  You can then eat them plain or flavor them by soaking in the marinade discussed previously.


© 2015. Dayna Green-Burgeson RD, CDE. All Rights Reserved.

Reproduction of any content in the article without the written persmission of the author is prohibited.

The Easiest Home-made Olives Ever

It has been “olive week” here at Burgeson Family Farm.  We made olive oil, which was a 2 day process, and we have been finishing up some batches of home cured olives.

I am going ahead with the post even though I am not crazy about the photos. Starting a blog before you know anything about photography can get you into trouble and that is where I am right about now. Nevertheless, we are getting to the end of olive season here in California and if I do not post this now it will be a full year before olives are around again. So here we go…please excuse the photos…

Olives grow everywhere in California. I am not sure what the history is on that, maybe in the past more people made home-made olives, or maybe they were planted because they are such beautiful trees. But In the fall, olives become somewhat of a nuisance as the olives fall off the tree and litter the ground all over California.  I have always loved olives, I remember putting the pitted California black olives on my fingertips when I was little and eating them off one by one. So when I would see olives on the ground in the fall, it always seemed like such a waste to me. But the methods required to turn those incredibly bitter fruits into something deliciously edible had always seemed foreign and unattainable to me.

We have been making our own olive oil with some friends now for about 10 years, and recently we planted our own little olive grove. I finally decided several years ago to give olive making a try using home-grown olives.  I first tried a lye cure, which is fast and produces very mild green olives, and I have done that for the past few years. I have also tried a slow salt water soak, which took about 6 months to produce tasty black olives, and I have been using last year’s batch in my salads for the past 6 months. I was planning to make some olives using both of these methods this year when I ran into a bit of a problem.

California has a pest called the olive fruit fly, which will bore a hole into the fruit, leaving brown tunnels in its wake. These tunnels make cured olives unacceptable. There are organic ways to control these, but as I have mentioned, we are lazy and don’t tend to spray much of anything, organic or not. This year, when I went to pick olives, the majority of them had the tell-tale spots on the outside that are the hallmark of the fruit fly.

I had been reading about a method of curing the olives with only water, and decided to try a modification of that method to deal with my problem olives. We have now finished one batch and have started on the second and I am happy to report that this also is the easiest and fastest method for making olives ever. If you have access to an olive tree I urge you to get outside in the next few weeks, pick at least a quart or two of olives and give this a try.

We picked these Sevillano olives when they were still green. Sevillano olives are very large, so they are one of the preferred olives for preserving. You can pick them with a bit of color on them as well. If you have smaller olives, such as the Kalamata variety, this water method is a traditional way of preserving them.

Now sort through the olives and get rid of any that have obvious spots on them from the fly. Next, put the olives on a board. Here is one of the Sevillanos.

Now get a mallet or something heavy similar to a mallet and give the olive a smack. Don’t hit it so hard that you crush the pit or smash it to pieces.

My olives were relatively crisp and cracked fairly cleanly. If the olives are black and mushy this method is not going to work!

At his point the normal method is to leave in the pit and cure the olives in this manner. However, I needed to inspect the olives for fly damage in case I missed any. So I went ahead and broke the olives in half and got rid of the pit.

This is an olive with fly damage.

Only one side was damaged (the left, see the brown marks?).  So I took out the pit, threw that side away, and saved the good half.

Once you have cracked all the olives (and removed the pits if you so choose), just put them in a jar and cover them with a lot of good fresh water. Make sure the jar is filled to the top, and put on a lid, so the olives are kept under the water as much as possible. You can even put a smaller plastic jar lid under your wider mouth jar lid if necessary to keep the olives under the water. When they are exposed to air they will turn a bit brown. I really did not care if mine turned a little bit brown so I just filled the jar all the way up and put on the lid.

Let them sit somewhere near a sink, because for the next 7 days or so you will be changing the water every day.  All you do is drain off the water (I put a strainer over the mouth of the jar) and refill with water.  After about 7 days, taste one of the olives. If they are no longer bitter, you are finished with this step. If they are still bitter, continue with this process until the bitterness is gone.

Now they are ready to be flavored. Olives are perishable, so at this point you need to either use them quickly or preserve them in a fairly strong brine.  The recommended brine is made by putting 3/4 cup vinegar in a jar or large container, adding water to equal 1 quart total liquid, then adding 5 Tablespoons of salt. Mix it well to dissolve the salt. You can add dried garlic and/or chili flakes for seasoning. Cover the olives with this brine, and make sure you put a plastic lid or some such under the outer lid to hold the olives down in the brine. Then refrigerate them. I would use them within a few months. If the brine makes them too strong for you, you can soak them in water in the refrigerator for a day or two right before you use them, but then you should use them up right away.

Here are my olives before they were tucked away in the refrigerator:

They are very crisp, so if that is not to your liking, you can bake them for 30 minutes or so, then let them cool before eating. I just put them in the microwave for a minute or two and that softened them up nicely as well.

You also might try baking the unseasoned olives with lemon, salt,  garlic, rosemary and olive oil in a covered dish when you take them out of the water bath, and then you can eat them right away.  MMM, that sounds so good I may need to scrounge up so more olives to preserve so I can give it a try.

I got the original recipe idea from Penna olives. They have directions for making other types of olives, including lye curing, and they sell both uncured and cured olives.

© 2011. Dayna Green-Burgeson RD, CDE. All Rights Reserved.