How are oils made/extracted?

[Cartooniverse]

If I take ten ears of corn and cut off the kernels after boiling them for a few minutes, there will be a soft watery mush in a bowl. If I mush them or puree them very finely using, say, a Cuisiniart, I will have pureed corn.

I won't have oil. How are oils extracted from everything from corn to peanuts? How hard was this to do thousands of years ago, as I suspect nowadays it is done with heavy machinery and electrically driven thingamabobs?

No wonder snake oil elixers were so expensive back in the day. What did they do to the snakes to get the oils outa them? ;)

Cartooniverse

[Mangetout]

I'm not sure about corn, but things like olives, sunflower and rapeseed are quite easy to extract the oil from - you just grind them coarsely, then press them and the oil drips out.

This only requires fairly basic technology - olives have been processed for oil for thousands of years (albeit perhaps not with such efficient extraction as we have nowadays.

[Sapo]

I understand that when you "squeeze" olives, you first do a cold press and get EVOO. Then you start adding heat and getting different qualities of oil until you get those super refined oils, very thin and clear and not too tasty.

[bump]

With seeds and the like, it's usually by pressing, although solvent extraction can be used for the last little bits.

Solvent extraction is the process whereby the mostly spent, ground seed particles are soaked in a solvent, then somehow, the solvent and dissolved oil is separated from the particles (centrifuge?). Then the solvent is recovered, leaving oil behind.

Another process which is used (for hops definitely) is supercritical carbon dioxide extraction. It's similar to solvent extraction, except that the solvent is liquid CO2 at room temperature under pressure. This has the obvious benefit of having a benign solvent, and some of the properties of the CO2 are advantageous as well. This is also the process by which coffee is decaffeinated. It's used in the brewing industry to extract hop oils and resins, because it doesn't mess up the volatile components as much.

[Cartooniverse]

I'm not sure about corn, but things like olives, sunflower and rapeseed are quite easy to extract the oil from - you just grind them coarsely, then press them and the oil drips out.

This only requires fairly basic technology - olives have been processed for oil for thousands of years (albeit perhaps not with such efficient extraction as we have nowadays.

Agreed- and the water drips out too. Do they just skim the oil off of the water? Nobody's addressing water-laden items such as corn.

[Little Nemo]

According to Wikipedia: The "modern" way of processing vegetable oil is by chemical extraction, using solvent extracts, which produces higher yields and is quicker and less expensive. The most common solvent is petroleum-derived hexane. This technique is used for most of the "newer" industrial oils such as soybean and corn oils.

[Fear Itself]

Nobody's addressing water-laden items such as corn.Corn harvested for oil is not the same as sweet corn for eating (corn-on-the-cob). The corn is dry when the harvest it, then oddly enough, they soak it in water until it has a moisture content of 45%. Here is the whole process (http://www.corn.org/web/processo.htm), including extracting the oil from the germ:The germs, containing about 85% of corn's oil, are pumped onto screens and washed repeatedly to remove any starch left in the mixture. A combination of mechanical and solvent processes extracts the oil from the germ. The oil is then refined and filtered into finished corn oil. The germ residue is saved as another useful component of animal feeds.

[mnemosyne]

Solvent extraction is the process whereby the mostly spent, ground seed particles are soaked in a solvent, then somehow, the solvent and dissolved oil is separated from the particles (centrifuge?). Then the solvent is recovered, leaving oil behind.

Educated WAG:

The separation of oil from solvent is likely done by some sort of distillation/evaporation technique, taking advantage of the different boiling points of the substances. Putting the mixture under heat and or vacuum can result in one substance (usually the solvent) boiling and evaporating away, while the extract (the oil) remains in liquid form. A quick google tells me hexane boils at 69deg Celsius and olive oil at about 300 deg Celsius, so it would be REALLY easy to remove that hexane.

For safety's sake, there is an analytical chemistry test commonly called "residual solvents" in which trace amounts of solvents are checked for to see if they are below the limits acceptable to ingest, so don't worry about that hexane in your olive oil!

[Cartooniverse]

So much for the marketing scheme I've been working on- Balsamic Vinegar and Hexane dressing.

[AskNott]

...
No wonder snake oil elixers were so expensive back in the day. What did they do to the snakes to get the oils outa them? ;)

Cartooniverse
It's the other way 'round, like baby oil. You put snake oil on the snake to keep it from squeaking when it moves. Without snake oil, they make a heck of a racket in the fields, and they can only catch the deaf mice (and the mice wearing I-Pods.)

You might be asking yourself, "How do you find the snakes that need re-oiling?" It's simple; you go out in the field, and you listen for the squeaking. ;)

[Cartooniverse]

:eek:




We are in the presence of greatness !!!!!!

[Cub Mistress]

In a book I have, it decribes

[Cub Mistress]

Let me try that again. *ahem*

the book (Pageant of the Rose by Jean Gordon) says this about extracting essential oils from rose petals:

Petals are placed in a wooden vessel with pure water and exposed to the heat of the sun for several days. Gradually oil particles rise to the surface. These are scooped up with absorbent cotton from which the oil is expressed into bottles that are then carefully sealed.


Sorry about that first bit, don't know exactly what happened.

[Bryan Ekers]

Sorry about that first bit, don't know exactly what happened.
Maybe your keyboard's too slippery.

[Fish]

This sounds like a job for the scientists at Monkeydyne! (http://boards.straightdope.com/sdmb/showthread.php?t=349748&highlight=monkeydyne) :)