Recipes

Olives, Lye-Cured (Reference)

A reference card, not an encouragement. Lye curing is what industry does and what nearly every olive you buy has had done to it, and it is the only cure that produces a shelf-stable canned olive. It is also the only one that can burn you. **Written out in full because the safety detail is worth having whether or not you ever do it** -- and because of a genuinely awkward fact: the tested pressure-canning process for home olives applies to lye-cured fruit and to nothing else.

Informational · Pickled · Vegetable · Spanish · Canned

Olives, Lye-Cured (Reference)
Prep 1 hour
Cook 10-30 hours, plus the wash
Serves Reference
Level Hard

A reference card, not an encouragement. Lye curing is what industry does and what nearly every olive you buy has had done to it, and it is the only cure that produces a shelf-stable canned olive. It is also the only one that can burn you. Written out in full because the safety detail is worth having whether or not you ever do it — and because of a genuinely awkward fact: the tested pressure-canning process for home olives applies to lye-cured fruit and to nothing else.

Ingredients

THE OLIVES

  • Fresh green olives, graded rigorously by size and free of bruising

LYE SOLUTION (per gallon of water)

  • 2 oz sodium hydroxide = 4 level tablespoons flake, or 3 level tablespoons granular
  • 100% sodium hydroxide only — NOT a drain cleaner
  • 1 gallon of solution covers about 2 gallons of olives

SPANISH-STYLE FERMENT, ADDITIONALLY

  • 6 fl oz (3/4 cup) live unheated dill pickle or sauerkraut brine per gallon, as a starter

CANNING BRINE (lye-cured olives only)

  • 1 gallon water
  • 4 oz pickling salt (6 level tablespoons)

EQUIPMENT

  • Glass, stoneware or stainless steel only — NEVER aluminium, tin, lead or galvanised
  • Rubber gloves and eye protection
  • A pressure canner, if you intend to can them

Directions

Key ingredients

Salt

  1. 🔴 Read this paragraph before the recipe. Sodium hydroxide dissolves skin and blinds eyes, and this is the one recipe in the collection where a mistake in the process — not the eating — is what hurts you. Gloves, eye protection, and never aluminium, tin, lead or galvanised metal: UC’s warning about galvanised is specific and unpleasant, that dissolved zinc “may make olives poisonous.” Never taste an olive during the lye stage. UC gives a first-aid protocol worth reading before you start: rinse 15 minutes, call Poison Control, do not induce vomiting.
  2. Step 1 - Grade by size, ruthlessly. More important here than anywhere else. Lye penetrates on a clock, so mixed sizes give you small olives turned to mush and large ones still caustic in the middle — and the middle is exactly where you cannot taste-test.
  3. Step 2 - Mix the solution: 2 oz lye per gallon of water. That is 4 level tablespoons of flake or 3 level tablespoons of granular. Only 100% sodium hydroxide sold for food or soap use. Drain cleaners contain other things and are not a substitute. (⚠ Red Devil lye, which older recipes name, is no longer manufactured.)
  4. Step 3 - ALWAYS add the lye to the water, never water to the lye. The reaction is strongly exothermic and adding water to solid lye can spatter caustic solution. Mix in glass, stoneware or stainless, somewhere ventilated, and let it cool to 65-70 °F before use.
  5. Step 4 - Submerge the olives completely. One gallon of solution covers about two gallons of fruit. Any olive that floats will oxidise and darken where the air touched it — weight them under with a plate.
  6. 🔴 Step 5 - Now decide which olive you are making, because the two styles diverge here.
  7. Californian green or dark-ripe style — lye all the way to the pit. Stir every two hours and check by halving an olive: the flesh should have turned a deep yellowish-green right through. Expect 10 to 12 hours.
  8. Spanish style — lye about three-quarters of the way in, at least 5 hours, leaving the rest of the bitterness to a lactic fermentation. ⭐ Both of these are inside 8267, so penetration depth is not a California-versus-Europe disagreement; it is one publication describing two different products. Spanish-style strength is also variety-specific: Sevillano 2 oz/gal (stronger blisters and peels it), Manzanillo and Mission 2 1/2 oz/gal.
  9. Step 6 - If the lye stalls, escalate — and there are three steps, not two. Not through in about 12 hours → fresh solution at 1 oz/gal, which can take up to 30 hours on very green fruit. Still not through, because the fruit can neutralise the lye → fresh solution at 1 1/2 oz/gal.
  10. 🔴 Step 7 - The wash schedule contradicts itself between styles, deliberately.
  11. Non-fermented (Californian) styles: rinse, then cover with fresh cold water and change at least twice daily for up to 7-8 days, until there is no soapy taste and no slipperiness. Tasting is only safe in the last two days.
  12. Spanish style: only 3 or 4 changes over 24 to 30 hours — and UC gives the reason outright, that “washing more frequently would leach out the sugars needed for fermentation.” Wash a Spanish-style olive as thoroughly as a Californian one and you have starved the ferment before it starts.
  13. ⭐ Step 7a - The rinse water is a progress gauge. It runs olive green → yellow → pink → clear.
  14. Step 8 - Spanish style only: start the ferment. 6 fl oz (3/4 cup) of live, unheated dill pickle or sauerkraut brine per gallon of olives and brine. Canned brine is dead and will do nothing.
  15. Step 9 - Pressure canning, if you are doing it. Brine of 4 oz pickling salt (6 level tablespoons) per gallon, boiling. Whole olives only. Pack to the shoulder, cover completely, 1/2-inch headspace, debubble. Pints 60 minutes, quarts 70 minutes.
  16. Altitude matters and the sea-level number is not general:
  17. | Altitude | Weighted gauge | Dial gauge |
  18. |---|---|---|
  19. | Sea level - 1,000 ft | 10 psi | 11 psi |
  20. | 1,001 - 2,000 ft | 15 psi | 11 psi |
  21. | 2,001 - 4,000 ft | 15 psi | 12 psi |
  22. | 4,001 - 6,000 ft | 15 psi | 13 psi |

| Above 6,000 ft | 15 psi | 14 psi |

  1. Step 10 - Freezing, if that is your storage plan. ⚠ Lye-cured olives must be boiled in light brine (4 oz/gal) for 10 to 15 minutes before freezing to limit softening. Higher-oil varieties — Mission, Kalamata, Picholine — freeze best; Sevillano, Ascolano and Barouni soften. (Dry salt-cured olives need no such pre-treatment.)
  2. LONG STORAGE IN CONCENTRATED BRINE: start at 4 cups (2 1/2 lb) salt per gallon, add 1 cup after two days, and another 1 cup two days later — 6 cups (3 3/4 lb) per gallon total. Room temperature, 8 to 9 months. Desalt in four changes of water over two days.
  3. DRYING: sun-dry 5 to 6 days, or a dehydrator at 140 °F for 20 to 24 hours. Rehydrate in 1/2 cup salt per gallon, 8 to 12 hours.

Notes

Where the numbers come from. Olives: Safe Methods for Home Pickling, UC ANR Publication 8267 (Yada and Harris, UC Davis, 2007), read in full. An earlier version of this recipe was built from a county extension digest of that publication and has been corrected against the original.

🔴 THE FINDING THAT MADE ME WRITE THIS CARD. The olives page used to say, in effect, do not can olives at home without a tested process. There is a tested process, and it is above. But read UC’s Table 1 before reaching for the canner:

StyleBrineRefrigerateFreezeDryPressure can
Water-cured (Kalamata / Mediterranean cracked)✓✓
Brine-cured (Greek black / Sicilian green)✓✓
Dry salt cured✓✓✓
Lye-cured (green / dark ripe)✓✓✓✓✓
Lye-cured fermented (Spanish-style green)✓✓✓

Only the lye-cured olive may be canned, and note the last row carefully — the fermented Spanish style may be canned but is not cleared for freezing or drying. So the shelf-stable jar is available specifically to the method every home-curing guide, mine included, steers people away from. Everything I would actually recommend making is a refrigerator food. That is an honest limitation, not a failure of the other recipes — but it is the reverse of what I assumed.

🔴 And 8267 says the thing plainly, so I will too: “Olives canned improperly at home have caused botulism poisoning.”

⭐ Why lye works when water only leaches. Water dissolves oleuropein and carries it away, slowly. Alkali hydrolyses it — breaks the molecule — so the bitterness is destroyed rather than removed. That is the whole reason a twelve-hour cure can replace a month.

⭐ And a historical note that puts the method in its place. This is the newest of the cures by a wide margin. People were curing table olives in seawater and salt around 6,600 years before present; the first alkali was wood ash, undated but pre-modern; and sodium hydroxide is an industrial product of the Leblanc and Solvay eras. The lye cure as practised today is younger than the steam engine. The full account is on the “How They Became Edible” page.

⚠ Troubleshooting, from 8267’s own FAQ. Blisters — lye too strong; safe to eat. Fish eyes — bacteria raising gas blisters under the skin during the wash; safe, change the water more often. Foaming during the lye soak — overripe, over-oily fruit reacting with the lye; drain and use a fresh solution. Softening — five named causes, of which microbial is the big one, which is why the storage brine is 10%: 13 oz (1 1/4 cups) salt per gallon.

Cultivars: Manzanilla, Sevillano, Nocellara and Lucques are the classic lye fruit. Firm, uniform, low oil.

Related: Olives, Water-Cured (Green) is the beginner’s cure and the one I would actually start with.