In the perfume industry, a scent described as creamy or milky will usually involve a material called a lactone.
Basic Information
A lactone is a cyclic compound containing an ester group, -COO-. Its name comes from the Latin lac, meaning sour milk.
These compounds also occur naturally among the aroma constituents of fruit, dairy products, and flowers. There are many different types, and choosing the right one for the purpose is important.
First, the Greek letter at the beginning of the name changes according to the number of atoms in the ring (including one oxygen atom).
Number of Ring Members (Including One Oxygen Atom) and Greek Letter
3-membered ring…α
4-membered ring…β
5-membered ring…γ
6-membered ring…δ
7-membered ring…ε
…etc
Next, the part of the name before “lactone” changes according to the total number of carbon atoms.
Total Number of Carbon Atoms and Name
C5…Valerolactone
C6…Hexalactone
C7…Heptalactone
C8…Octalactone
C9…Nonalactone
C10…Decalactone
C11…Undecalactone
C12…Dodecalactone
…etc
Although their scents differ according to the number of ring members and the total number of carbon atoms in the molecule, lactones share a creamy, milky quality and are used not only in perfumes but also in flavorings (in Japanese).
In flavorings, they are used to increase the fatty impression of dairy products and beef, add richness to dishes, or enhance the fruit-juice character of fruit drinks.
Well-Known Lactones in Perfumery
Gamma-Undecalactone
The best-known lactone in the perfume industry is γ-undecalactone. Undeca means eleven in Latin. Applying the explanation above, γ-undecalactone is “a lactone with a five-membered ring (four carbon atoms and one oxygen atom) and eleven carbon atoms in total.”
Why is γ-undecalactone so well known? Because it was used for its peach scent in celebrated perfumes such as Guerlain’s Mitsouko (1919, Jacques Guerlain) and Rochas’s Femme (1944, Edmond Roudnitska (in Japanese)). It is still frequently used to create peach notes and milky fruit scents.
γ-Undecalactone is also known as aldehyde C14. In fact, however, this has nothing to do with the number of carbon atoms in γ-undecalactone. The name arose because its structure was unfamiliar when it was discovered, and there was a fashion for using “aldehyde + a number” to describe new substances with larger numbers of carbon atoms.
A (true) aldehyde (in Japanese) with fourteen carbon atoms does not smell of peach. The misleading name given to γ-undecalactone often causes confusion, so care is needed.
γ-Undecalactone and γ-decalactone are also well known because research by Rohto Pharmaceutical identified them as components of “the distinctive sweet body odor of young women.”
Gamma-Nonalactone
The lactone with two fewer carbon atoms than γ-undecalactone is called γ-nonalactone. Also known as aldehyde C18 (another misleading name, since it actually has nine carbon atoms), it is famous for its coconut scent. Besides coconut, it is used to create tropical fruit notes and exotic, creamy scents such as tuberose (in Japanese) and fig (in Japanese).
An Additional Note
Similarly, aldehyde C16 (strawberry aldehyde) is formally named ethyl methylphenylglycidate, and aldehyde C20 (raspberry aldehyde) is formally named ethyl para-methyl-β-phenylglycidate. (Neither of these two is a lactone or an aldehyde.)
How Do They Smell in Perfume?
In perfumery, lactones are not a single fragrance material but a chemical family whose individual molecules have different scents. γ-Undecalactone is known for its peach-like fruitiness, while γ-nonalactone has a coconut-like scent. Natural massoia lactone, obtained by fractionating the essential oil, has fruity and coconut notes with aldehydic and buttery facets. These materials can give fruity fragrances a sense of fleshy pulp or add creamy roundness to floral and woody compositions. Even within the lactone family, scent profiles and strengths vary considerably.
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