Making Olive Oil
Taught by Kathryn Tomajan at Eat Retreat 2012
Early Saturday morning, Kathryn Tomajan started making olive oil. My assumption was that making olive oil was like making peanut butter. Just drop olives into a big machine, turn it on, and voila! Out comes olive oil.
I was wrong. It takes a few hours, some serious equipment, and after all that effort you end up with about one cup of olive oil for every ten pounds of raw olives. This work is not for the faint of heart.
To start, you'll need access to three pieces of industrial kitchen equipment -- a grinder, a mixer, and an olive press. Once the grinder is connected, slowly pour in the ten pounds of raw olives. There's no peeling or pitting, you just drop the whole fruit in and grind it up. The result is a grayish green sludge that sometimes is runny, but mostly looks and tastes like a bland paste. I asked Kathryn if I could do this at home with my KitchenAid grinder. She laughed and doubted the KitchenAid was strong enough to crush the pits.
Once the olives are ground, you need to mix the sludge with a paddle attachment in a mixer for 45 minutes. By mixing, you are encouraging the enzymes in the paste to react with each other, and in the process they chemically release the olive oil from the sludge. Once that process is complete, the third and final step is to extract the olive oil.
Commercial manufacturers extract the oil by putting it into a high speed centrifuge and spinning it. We didn't have one of these on the farm, so we instead used an olive press.
An olive press is a tall metal structure that contains several trays and between each tray is a coarse filter. One by one you put the paste in a tray, add the coarse filter, and stack. When all the paste is in place, you apply the heavy pressure and let gravity do the rest.
After a few hours, the bowl at the bottom of the olive press contains anywhere from 1.5 to 2 cups liquid. This liquid is a combination of olive oil and dirty water from the olive fruits. Thankfully, the oil and water automatically separate, so the final step is to remove the dirty water and bottle the oil.
There are several ways to do this, but Kathryn preferred to bottle all the liquid, then turn it upside-down to settle. Once settled, she opened the bottle slightly and poured out the dirty water from the bottom.