Like wine, the flavor of an olive oil can tell you where it’s from. California olive oils come in a variety of styles, but in general, they tend to be richer and more buttery than the peppery, pleasantly bitter oils from Tuscany.
The first step is to wash the olives and remove any stems and debris. Zecca likes to include a few leaves in the mix, however, which he believes contribute to a better tasting oil.
Enormous, 3,600-pound granite stones crush the olives into a paste. Modern hammermills can pulverize the olives in just seconds, but they heat the olives, which alters the taste of the oil. Crushing the olives with stones is time-consuming, but because they create only negligible heat, the granite stones produce superior oil.
The olive paste is spread on nylon mats, which are stacked, layered with steel plates, and hydraulically pressed with 5,000 pounds of pressure per square inch to extract the oil. The paste releases a cloudy liquid full of small particles of suspended fruit.
The liquid is spun in a centrifuge, which separates the olive oil from the water and solids. After a resting period of a month or two, during which the oil mellows and loses some of its natural pepperiness, the oil is bottled.