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Is it safe to consume lemon oil in the quantities that would be found in fried food? Could I fry corn tortillas, for instance? Would it fry?

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    Essential oil as „the stuff that’s usually sold in 10-20 ml bottles” where a few drops in a diffuser are enough for a room?
    – Stephie
    Jan 13 at 16:10
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    Correct; specifically the lemon variety. Jan 13 at 16:13
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    Upvoting because, based on the answers, it's really good that you asked before trying this.
    – adam.baker
    Jan 14 at 5:33
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    Since the answers highlight why it's dangerous (even in mL quantities), I would recommend normal frying and then a healthy coating of lemon juice/citric acid if you're wanting a strong lemon flavor.
    – Drake P
    Jan 14 at 7:10
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    Essential oils are generally volatile meaning they evaporate at room temperature. Aside from fire and toxicity risks, it doesn't really make sense to fry with them. Typically a major point of frying with oil is that at it can reach temperatures much higher than the boiling point of water.
    – JimmyJames
    Jan 14 at 19:03
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It would be dangerous to attempt to fry in lemon oil

Lemon & other citrus oils are primarily (90+%) made up of Limonene, which has a "fire diamond" of 🟦2-🟥2-🟨0:

2-2-0 fire diamond

🟥 Flammable

The red 2 indicates flammability:

Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur (e.g. diesel fuel, paper, sulfur and multiple finely divided suspended solids that do not require heating before ignition can occur). Flash point between 37.8 and 93.3 °C (100 and 200 °F).

Limonene has a flash point of only 50°C (122°F). Canola oil & most "frying oils", by contrast has a flash point of closer to 315°C (600°F).

Note that the "flash point" is the temperature where flames & active combustion take place. This is generally a good bit above the usual "smoke point" which is used to rank cooking oils. The flash point is the more dangerous temperature, as it equates to fire.

This limits the feasibility of doing any cooking in citrus oils, due to their flammability. The high limonene content would render lemon oil to be a fire hazard well below "frying" temperatures. If you've ever seen a flamed citrus peel used as a cocktail garnish, you would have witnessed the flammability of citrus oils.

🟦 Health risk

The blue 2 indicates a health risk:

Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (e.g. diethyl ether, ammonium phosphate, carbon dioxide, iodine, chloroform, DEET).

As mentioned in another answer, even if flammability wasn't an issue, this could be dangerous. Contact with the skin can cause a rash ("contact dermatitis" if you're being technical about it) in certain cases.

Even if it didn't burn at such a low temperature, the quantity of limonene needed for cooking, and the direct contact with your mouth while eating would result in a potentially dangerous situation.

Small amounts are considered safe for consumption (and even used in supplements), but any significant quantity of lemon oil should not be consumed directly.

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    For others curious about the yellow 0, it's for instability-reactivity: "Normally stable, even under fire exposure conditions, and is not reactive with water (e.g. helium, N2)"
    – dbmag9
    Jan 13 at 18:52
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    Flammability is kinda the point. Essential oils are used for their smell, and they have an aroma because of their vapors, and they have vapors because they are highly volatile. Generally speaking, the more fragrant something is, the lower its boiling point. And while boiling point and flash point aren't the same, they tend to be correlated. Jan 14 at 22:47
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Lemon essential oil is composed primarily of limonene. Limonene is a skin irritant at high concentration, so you wouldn't want to put it in your mouth. Limonene is also volatile enough to limit its use as a frying medium, and the vapor would cause severe lung irritation.

It would perhaps make more sense to add a bit of lemon oil to your frying oil, but again, it's a fairly volatile oil, so it would be better to add it after frying.

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    In the scientific sense. I don't really know if it's likely to burn.... if you're frying with limonene that's honestly the least of your concerns.
    – Sneftel
    Jan 13 at 17:09
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    @GdD For oils, those properties are fairly proportional. A volatile oil usually ignites or even explodes at lower temperatures. Jan 14 at 8:08
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    Take note that the final sentence of Sneftel's answer says "lemon oil," not "lemon essential oil." They are not the same thing.
    – Brian
    Jan 14 at 14:12
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    @Brian I'm pretty sure they are the same thing, at least anything labelled "pure lemon oil" will be... well, pure lemon oil (or lemon essential oil - same thing). Where you have to be careful is with lemon oil "products" like wood conditioners or other products which blend pure lemon oil with other mineral spirits or petroleum products. Those will usually have other words in their name to that effect, eg: lemon oil conditioner, etc.
    – J...
    Jan 14 at 18:18
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    @Brian Sure, but in that case what you're looking for is food grade lemon oil - not that there's any particular difference between the lemon oil components in either, and that goes for anything you would cook with that may be commonly distributed in both food grade and non-food-grade varieties. Food grade is a guarantee about the impurities (or lack thereof), not the product itself.
    – J...
    Jan 14 at 20:11
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Essential oils are toxic in larger quantities. This is simply the first google hit. A few milliliters can seriously harm small children; there have been deaths from larger amounts given to little children by misguided parents.

An adult will not die as quickly but a few milliliters more may require a visit to a doctor or hospital.

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In addition to the idea being unhealthy and a fire hazard (both properly discussed in the other answers), there is one more consideration:

In order to fry something, the oil has to be way hotter than the boiling water temperature (e.g. 250-300 deg C) and still safely below the oil's own boiling point.

Lemon oil will boil below 170 deg C and you don't have a temperature interval usable for frying.


edit: I solved it!

The ordinary cooking practice is yet to employ the reflux condensers, but we can borrow them from an adjacent field - the organic chemistry lab practice:

the usual reflux condenser setup (credit: https://biocyclopedia.com/index/chem_lab_methods/reflux.php)

This solves the low boiling point problem, the volatility problem, the flammability problem, the oil loss problem and the vapor toxicity problem - all at once.

The oil bath in the picture is important - a direct heating will enable some parts of the container to reach the self-ignition temperature of the lemon oil.

The internal magnetic bar will rather not be needed.

Well, the result will be still not tasty nor even safe to eat, but this is out of the scope of the question.

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    Edit: this comment is incorrect, see Peter's reply below. [I admire the chemists who managed to find out lemon oil's boiling point. Since it will also usually burst in flames when heated to only 50 C (as noted in other answers), the boiling point is not the practical obstacle for frying - it will never be reached anyway.]
    – rumtscho
    Jan 14 at 9:50
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    @rumtscho The flash point is the point at which a liquid will burn provided you ignite it. For example, a liquor with 35% alcohol will only be usable for a flambee if you heat it in the spoon, while a 50% liquor will catch fire at room temperature. The point of spontaneously bursting in flames (as opposed to being lit) is aptly called the auto ignition temperature which appears to be 235° C for lemon oil (Canola: >400°C). Jan 14 at 12:10
  • @Peter-ReinstateMonica thank you for the correction!
    – rumtscho
    Jan 14 at 12:21
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    @rumtscho My pleasure. Since you are a mod you are probably familiar with the mandatory xkcd but perhaps not with the timeless quote from Beckett's Watt: "For it is a strange thing, but apparently true, that those who speak speak rather for the pleasure of speaking against than for the pleasure of speaking with, and the reason for that is perhaps this, that in agreement the voice can not be raised perhaps quite so high as it can in disagreement." ;-) Jan 14 at 13:07
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    Frying above the flash point is rather popular, this is how the good part of the kitchen fires start.
    – fraxinus
    Jan 14 at 15:52

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