Olives From The Grove To The Press To The Bottle To The Palate - Part 2
Freshness and handling of the freshly picked olives are the two most important factors in determining purity of flavor and extra virgin classification. Raw olives begin oxidizing immediately after being harvested. They contain an oleic acid that can degrade the quality of the oil if too much is present in the olives. The more you bruise an olive with rough handling, and the longer the olives wait after harvesting before being processed, the more oleic acid you release into the olives flesh. Oleic acid is the number one contributor to bitterness in the finished oil. The classification of olive oil grades is based on the oleic acid content.
Extra Virgin Olive Oil is the first cold pressing of the olives with up to 1% oleic acid present. It is considered the finest and fruitiest, and thus the most expensive. Generally deeper in color and more intense in flavor.
Virgin Olive Oil is also the first cold pressing of the olives, but the oleic acid content is up to 3%.
Fino Olive Oil is a blend of extra virgin and virgin olive oils
Light Olive Oil this version contains the same amount of beneficial monounsaturated fats as regular olive oils, but due to the refining process, it is lighter in color and has essentially no flavor. This makes a good choice for baking and other purposes where the heavier flavor might not be desirable. This process also gives it a higher smoke point, making it a prime candidate for high-heat cooking.
All olive oil production regardless of classification begins much the same way. This process has not seen much change in 5000 years. Even today’s most modern olive mill equipment can still be comprised of two heavy stone wheels for gentle crushing. Each olive contains millions of plant cells that each contain one drop of oil. By crushing the olives, you crush all of those individual drops together to form larger drops that keep combining until a rich fluid is formed. There are two basic methods for drawing the olive oil away from the olives.
The Olive Press – The technique behind pressing the olives is basically as old as the first cultivated tree. The first relics of olive presses found date back to the Greeks and are around 5000 years old.
~Harvest the olives all at once from each tree at the peak of perfect ripeness.
~Harvesting is accomplished by either a machine grabber for shaking the olive tree by the trunk and collecting the olives onto tarps as they fall off, or by the manual method of long poles used to grab each branch of the olive tree by hand and shake it until all of the ripe olives fall onto a tarp.
~Olive harvest can run from October to February.
~Wash the olives to remove foreign materials and dirt and dust.
~The olives are gently ground for 30 minutes under the granite millstones or pulverized in a hammer mill until a glistening paste forms.
~The olive paste is spread onto fiber disks and stacked on top of each other.
~These disks are placed under a hydraulic piston and compressed.
~The resulting liquid is a combination of olive oil and water.
~The olive oil and water need to be separated. Old school is to place the liquid in a vessel and let the oil and water separate naturally. Modern style is to place the liquid in a centrifuge and spin the water out.
~Good quality can be achieved with this method given extreme devotion to sanitation of the press disks between pressings.
~Quality can degrade if the sanitation is not kept up, and in order to clean the disks properly, there is a delay between pressings, allowing the paste to oxidize further increasing the bitter oleic acids.
The Olive Mill-This technique differs from the press in that the system is designed to process the olives without exposing them to oxygen. The efficiency of this continuous process and the ability to maximize the quality yield of the olives has contributed to an increase in quality. With no delays in processing for filter pad cleaning, and a hands-off precision to the separation phase, the achievable quality goes up.
~ Harvest the olives all at once from each tree at the peak of perfect ripeness.
~Olive harvest can run from October to February.
~ Wash the olives to remove foreign materials and dirt and dust.
~The olives can be transformed into paste with two methods. The paste is a combination of the mashed olives water and olive oil.
~The Hammer Mill – which pulverizes the olives and releases more of the peppery pungency of the olives.
~The Stone Mill – which crushes the olives under one ton stone wheels, considered a more gentle process for extracting the pure richness and luxury of the olives.
~The two processes can be utilized in the same mill to create complexity and mouthfeel to perfection.
~The olive paste is then massaged in a vat with an auger for thirty five minutes until it literally glistens with olive oil.
~The paste now needs to be separated from the olive oil so it is transferred into a horizontal centrifuge, where the oil and water are spun out of the paste.
~The remaining dry paste is composted and used as nutrient material for the olive groves.
~The olive oil and water now need to be separated. This time it is a vertical centrifuge that spins the water out of the olive oil.
~The pure olive oil can now be transferred into steel tanks with a nitrogen gas blanket on top of the liquid so as to eliminate any oxidation. This also allows for the oil to be drawn fresh for months after harvest, or until ready for bottling.
Written By: Khristopher Lund
Khristopher is a freelance writer and Sommelier living in the Napa Valley. Check out his Blog.