Lesson #4: Centrifuge

This week I’m spending some time off the grid. Currently writing to you from San Sebastian, Spain.

With that, I decided to repost a lesson from an old blog.

For those that are new here, I travelled through Europe in 2022 searching for great olive oil. The below excerpt is from Day 5 of my Europe Trip.

If you only want to learn about centrifuges, skip to “quick lesson on centrifuges.”

Hope you enjoy!

Day 5 in Quesada, Andalusia, Spain: October 29th, 2022

Any time I told people about why I'm in Quesada, aside from being stunned about me being from New York, I was always pointed towards the cooperative. At the Dia De Los Muertos party, I was told there's a 50/50 chance it's open given the day of the week - obviously operating hours are not online.

I sent a good morning text to Joana [who offered to bring me if open] at 8:30am. At 10:50 as I'm eating my Olive Oily eggs and bread and writing up a blog entry, I receive a text to be ready at 11am for pickup. I arrived at 11am at the top of the hill fully out of breath.

Here is my iPhone note from after the mill

My brain is so fried after 2 hours of Spanish. To give better context my Spanish translator didn't know a single word of English.

Time at the Mill

We head to the truck loading area and see where the Olives come in. This is a major operation. I've been to about a dozen mills in California and a couple of other small ones. Combine all of those and you are at about 1/10th the size of this one.

I received some numbers but things were moving too fast in Spanish for me to remember them. But this is the 5th biggest mill in Spain, and they had 200 BEHEMOTH storage tanks of oil. They're as low-margin high volume as one could get.

Each mill runs a similar process, there are only so many ways to get oil out of the olives. This is where the details come into play.

Olives go up an internal conveyer belt and get separated from the Olive Leaves (see leaves discarded)

Pictured is the Pieralisi (brand) malaxer machine where the olives are crushed into paste (similar image to Day 3).

At this point, olive flesh, olive water, and olive oil remain. The paste gets funneled through the pipe to the horizontal centrifuge.

Quick education on the centrifuge

This is the initial point of paste and water being removed from the oil.

I used to be too scared to go on these but if you've ever been on these rides, what happens?

You feel heavy against the wall because of centripetal force. The same force that causes you to not fall to the left when an airplane tilts left or right.

When salad dressing settles, is oil on the top or bottom? Top because it's less dense than water-based vinegar.

The horizontal centrifuge isolates the solids from the water/oil through that density property.

Then the slimy-looking oil flows out and onto the vertical centrifuge, where a similar process separates the water and oil. More on that process here.

I then got the luxury of tasting the oil out of the signature blue glass used to remove color bias. Greener does not equal higher quality.

It didn't seem like a big deal but this is the moment of truth. A good milling process and green olive should lead to a pungent oil, which I perhaps may purchase.

And quickly honorable mention to the filtering process they put the oil through. The unfiltered oil flows through about 8 sheets of this semi-permeable paperboard. The extra-fine dark sediment is now removed from the oil.

The Result

Unsurprisingly due to the quantities produced, the oil was OK. I think the oil may have oxidized a bit during the centrifuging process. My gut tells me the oil was touching wayyyy too much oxygen when transferred between centrifuges and into the tank. And even during the filtration process. More oxygen --> greater oxidation.

Shmoozed for another 20 minutes and got out of there.

Beautiful lookout point now my propic.

Joana showed me the best view in Quesada and then I headed home, had some almonds and worked the rest of the day on the computer.

Evening at the village:

So I got into a soccer game with 9-year-olds that only spoke Spanish.

At the beginning of the game, one kid came up to me after learning I'm American and immediately asked what the phrase "what the F***" meant - he didn’t know any other English words...I said it was bad but I couldn’t explain why! Then he kept screaming that during the game and after the game was over he apparently said it to a girl who got her dad (I saw from a distance) and the boy hid in a church when the dad was walking over. Crazy sights in the village.

I felt slightly guilty for not stopping it but I was also thrusted into breaking up a fight between a confident and shy 8-year-old while having to purposefully tank my team to keep the other one from complaining about an unfair match.

Then I met some friends (literally) at tapas and watched Barce beat Valencia 1-0. That was fun.

Call me crazy but low key kinda obsessed with sardines right now. I was eating them whole on bread until I realized these guys leave the bone, so I followed suit.

They gave me a gift :)

1 Olive Oil Takeaway:

Oxidation ~ (proportional to) reduction in oil quality, nutrition (polyphenols), and shelf life.

See this thread:

As always please comment any questions about this article or about olive oil in general.

If you think this article was useful for you, please share with a friend or on social media!

I’ll drop another lesson next week.

-Jack (@extravirginguy)