Fresh olives taste awful because of a compound called oleuropein. This is why are fresh olives bitter enough to make you spit them out. Raw olives straight from the tree are so bitter that nobody would buy them at a store. Every olive you've eaten went through a curing process first.
I bit into a fresh olive from my tree once and regretted it for hours. The bitterness hit my tongue like nothing I'd tasted before. It made my mouth pucker and left a harsh taste that lasted through dinner. The olives at the grocery store taste nothing like that because they've been treated.
The oleuropein in olives serves as a defense against pests and disease. This phenolic compound makes up 14% of the dry weight of unripe olives. It has to come out before the fruit is safe to eat and tastes good. People have been removing oleuropein through curing for thousands of years.
Three main methods exist for curing olives at home and each takes a different amount of time. Water-curing is the oldest method and takes 6 to 8 weeks of soaking with daily water changes. Brine-curing uses salt water and needs 3 to 6 months to finish. Lye-curing works fastest at just 1 to 2 weeks but uses harsh chemicals.
Water-curing draws out bitterness through constant fresh water contact. You soak the olives and change the water every day for weeks. The water turns dark as it pulls out the oleuropein. This method is safe but takes a lot of daily work and attention to finish well.
Brine-curing creates the rich flavor you find in many store-bought olives. Salt water breaks down the bitter compound over several months. The olives ferment slightly and develop complex tastes during this time. Greek and Spanish olives use this method for their classic flavors.
Lye-curing moves fast but you must handle the chemicals with care. Food-grade lye strips out bitterness in days rather than months. Commercial producers use this method for the canned olives you see at stores. Home curers should use proper safety gear and rinse olives well after treatment.
Start with brine-curing if you want to cure olives at home for the first time. It takes longer but needs less daily work than water-curing. You don't have to handle dangerous chemicals like you do with lye. Just mix salt and water then wait a few months for tasty results.
Read the full article: Growing Olives: Step-by-Step Plan for Home Gardeners
