Making Traditional Olive Oil

  • 01 of 10

    Into the Hopper

    Olive Oil hopper
    Kyle Phillips

    In Tuscany, quality olive oil all starts the same way: The olive grower spreads a silken parachute around the base of the olive tree, rests a ladder against the branches, and then climbs up into the tree and picks the olives. What's next? Straight to the olive oil press, ideally as quickly as possible, because the olives start to deteriorate the moment they're picked.

    Regardless of the kind of press, the first step is to put the olives in a hopper that starts them on their journey through the system. The paths are quite different, however, for olives that go through modern industrial presses and those that go through traditional presses. 

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  • 02 of 10

    Into the Grinder

    Olives being put into grinder
    Kyle Phillips

    Traditional olive presses employ grindstones to grind the olives, reducing them to a paste from which the oil can be extracted. Unlike the grindstones of a mill, which are horizontally mounted, the grindstones of an olive press are vertically mounted and rotate in a tub, crushing the olives against the floor of the tub.

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  • 03 of 10

    Rotating Grindstones

    Olive oil grindstones spinning
    Kyle Phillips

    The grindstones of this press are made of granite, 4 feet in diameter, and more than a foot thick. They weigh about 1.5 metric tons each and are turned by an electric motor. The paste is ready for the next step when it becomes oily. It takes about a half hour of grinding to reach this stage.

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  • 04 of 10

    Onto Fiscoli Round Mats

    Gramolatrice tub and fiscoli round mats
    Kyle Phillips

    The paste goes into a second tub called a gramolatrice, where it is stirred by several rotating paddles. The stirring breaks up the water-oil emulsion derived from the grinding process, and thus forms droplets of oil that can be more easily extracted from the paste during the subsequent pressing. Again, the stirring phase—simple mechanical action with no heat or addition of water—takes about a half hour.

    When it's done, an assistant puts the paste onto round pads called fiscoli, which he stacks in the press. There are about 2 1/4 pounds of paste per pad, the pads are stacked in sets of five, separating each 5th pad stack with a steel plate.

    It's impossible to get all of the olive oil residue out of the fiscoli, and since the residues in them would become rancid from one year to the next, they're repurchased every year from an outfit in Perugia. In the past, the fiscoli would have been produced on the farm, probably from hemp.

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  • 05 of 10

    Stacking the Press

    Stacking the olive oil press
    Kyle Phillips

    The fiscoli, with their layers of olive paste, are stacked in the press, in five-pad stacks separated by steel plates.

    Loading the press takes 45 minutes to an hour, and by the time the press is half loaded, the weight of the stack is already pressing oil from the lowermost disks.

    And this brings up an important point: One of the things one often hears now from olive oil producers is how important it is to keep the oil from oxidizing. In fact, some modern presses are pressurized with nitrogen (an inert gas) to keep oxygen from reaching the olives as they are ground and the paste is stirred. No oxidation, they say, makes for a better oil.

    However, Sandro Bosticco, an expert olive oil taster, says that the situation isn't quite that simple. While it's true that exposure to oxygen leads to deterioration, exposure to oxygen during the grinding and gramolatura phases appears to promote the development of the compounds that give olive oil its distinctive (and captivating) aromas.

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  • 06 of 10

    The Loaded Press

    Fully loaded olive oil press
    Kyle Phillips

    Therefore, what one wants is to strike a balance of some exposure to oxygen during the pressing and as little exposure as possible subsequently.

    With the press loaded—this volume of olive paste will yield around 30 liters of oil—the operator turns on the hydraulics, and the floor of the press begins to rise, pressing the pads against the top of the press.

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  • 07 of 10

    Olive Oil Begins to Drip

    Olive oil dripping from press
    Kyle Phillips

    Olive oil begins to drip down the sides of the stack, collecting in a trough at the base of the press. From there, it drains into a holding tank.

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  • 08 of 10

    The Pressure Gauge

    Pressure gauge
    Kyle Phillips

    Olive presses squeeze hard. This isn't winemaking, where one hears about soft pressing and people wince at the idea of more than two atmospheres. Rather, the press cranks up to 400 atmospheres, close to 900 pounds, and maintains that pressure by continuing to lift the floor of the press as the oil seeps out. It takes about a half hour to press the stack, after which the assistant releases the pressure, removes the pressed paste (it goes back to the olive groves) and starts the cycle anew.

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  • 09 of 10

    Into the Centrifuge

    Olive oil centrifuge
    Kyle Phillips

    The oil that emerges from the press is anything but pure as there's still quite a bit of solid matter in it and also a fair amount of water. So the operator pumps it through two settling tanks, where some of the solid material settles out, and then into a centrifuge that separates the water from the oil.

    The centrifuge dates to the 1930s and as such was one of the first generations of centrifuges used to separate the oil from the water. Before then they used a longer succession of settling tanks to remove solid matter and then a special terracotta urn with a siphon rising up from its base — since water is heavier than oil it settles, and then the weight of the oil forced it up and out through the siphon.

    Using a centrifuge is, of course, both easier and much faster, and since we are by now at the stage when it is important to limit exposure to oxygen, the introduction of the centrifuge resulted in a dramatic increase in the quality of the oil.

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  • 10 of 10

    And Here We Have It!

    Freshly pressed extra virgin olive oil
    Kyle Phillips

    Here we have traditionally pressed extra-virgin olive oil!