What are immature green olives soaked in to remove bitterness?

Immature green olives are traditionally soaked in lye, a strong alkaline solution, to effectively remove their natural bitterness. The lye acts by altering the bitter glycosides present in the olives, allowing for a more palatable flavor profile. This process is crucial, as raw olives are typically inedible due to their high bitterness. After the lye treatment, the olives must be rinsed thoroughly and often subjected to further soaking in water to ensure all lye residues are removed and to help balance the flavor.

In contrast, methods such as soaking in salt, water, or vinegar may reduce some bitterness but do not achieve the same level of efficacy in removing the compounds responsible for the intense bitterness found in fresh, unprocessed olives. Therefore, the soaking of olives in lye is a specific and essential step in their preparation for safe consumption.