Citral Is Two Molecules, and Litsea Cubeba Has Both

Say "citral" and most people picture one ingredient. It is actually a pair: geranial and neral, two molecules with the same formula and the same atoms, differing only in how one part of the chain is twisted. That small twist is why two oils with the same citral percentage can smell a little different, and it is the most useful thing to know about the molecule that gives litsea cubeba its lemon-drop sparkle.

Litsea Cubeba Essential Oil bottle

Litsea Cubeba Essential Oil

Our own Litsea Cubeba Essential Oil, in sizes from 0.5 oz to bulk.

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Twins with different personalities

Both isomers are C10H16O with a molecular weight of about 152. PubChem lists geranial as the (2E) form and neral as the (2Z) form, and quotes handbook descriptions of their scent: geranial as a strong lemon odor, neral as lemon too, but "not as intense but sweeter than geranial" (PubChem compound record for citral, CID 638011). Those are handbook shorthand, not a panel test, but they hint at something lovely: the balance between the two shapes how an oil smells, a bit sharper when geranial leads, a bit sweeter and rounder when neral has more say.

How much of the scent is citral?

Researchers in China distilled the fruit of three litsea cubeba chemotypes and measured 27 odorants by gas chromatography with olfactometry, ranking each by its odor activity value, a measure of how far a compound sits above the level where people can smell it. Geranial and neral came out on top, with geranial's value roughly seven times that of the next compound listed, 1,8-cineole; beta-pinene, citronellal, myrcene and terpinen-4-ol followed behind (Zhao et al., 2023; we read the abstract). Our reading is that the lemon-drop impression is mostly those two molecules, with the others adding shading. The authors also note that the three chemotypes had distinct aromas, so no single ranking describes every bottle.

The supporting cast is worth a look in its own right, and our post on the minor notes in litsea cubeba oil introduces it.

What a citral percentage really is

When a report says "citral 70%," someone has added two peaks together, and the total depends on the sample, the method and the lab. In one study of fruit from eight regions of China, neral plus geranial came to 78.7% to 87.4% (Si et al., 2012). An EFSA opinion on six commercial batches from China averaged geranial at 36.35% and neral at 29.77%, about 66% together by our arithmetic, and noted that GC-MS underestimated geranial in two of them (EFSA, 2021). Two good sources, a gap of about twelve points, and a method effect on top. A single number without its method is a headline, not a description.

The Certificate of Analysis for our current batch gives relative density, refractive index and optical rotation, and no citral figure. If you want one for a lot you are considering, ask us in writing through the contact page before ordering, and our guide to reading a GC-MS report will help you read the answer.

One more reason the two isomers matter

Dermatologists have found that people can react to geranial and neral separately. In a Swedish clinic study of 1,476 patients with suspected contact allergy, 3.4% reacted to geranial, 1.9% to neral and 2.9% to citral, and the authors concluded the two are separate haptens, closely related chemically but distinct to the immune system (Hagvall et al., 2020). That is a group selected for skin problems, so it is not a rate for the general public, but it explains why citral gets careful treatment on skin.

The fragrance industry's citral standard puts the ceiling at 0.15% citral in body lotions and creams, 0.60% in fine fragrance, 1.2% in soaps and washes, and nothing in candles (IFRA Standard for Citral, Amendment 49, 2020). Divide a cap by an oil's citral share and you get the most oil a product can carry: 0.15 divided by 0.874 is about 0.17%, and divided by 0.66 about 0.23%. Our guidance for skin is 0.5% to 2% in a carrier, and against this arithmetic we start lower for anything that stays on the skin, and we would not call 2% safe. Our skin basics post and IFRA post take it further, and our citral comparison shows how other oils line up.

A practical way to use all this

A higher citral number is not a better oil, just a more concentrated lemon, and because citral is what limits how much a leave-on product can hold, more of it means a smaller dose. So choose for the scent you like, then size the dilution to the citral. Handbook records describe citral as not stable to alkalies and strong acids, which is a good reason for soap makers to trial scent in their own base instead of assuming.

Lemon without a lemon tree, and with two molecules doing most of the work: that is litsea cubeba in a sentence.

Litsea Cubeba Essential Oil bottle

Litsea Cubeba Essential Oil

Litsea Cubeba Essential Oil from our own shop, in sizes from 0.5 oz to bulk.

From $12.99

Shop Now →

Sources & Further Reading