Alexis St-Gelais, M. Sc., chimiste
Mandarin fruit (Citrus nobilis) essential oil is an aromatic delicacy. By experience, we observe that it regularly is either adulterated or confused with other citruses. Chemically, there are a few good keypoints to look for that will tell if a mandarin oil is genuine. We also provide an annotated typical chromatogram (figure 1). The information provided below was prepared from our experience and ISO 3528:2011.
α-Pinene (A) and β-Pinene (B)
These two common monoterpenes are more concentrated in mandarin oil (respectively above 2 and 1% in general) than in sweet orange or grapefruit, while the β-pinene is much more prominent in expressed lemon (>8%) or lime (>16%) oils.
Limonene (C)
The hallmark of most citruses oil is prominent too in mandarin. However, it is found in smaller concentration in this oil than in orange or grapefruit, for example, usually remaining below 75%. Most of it is the (+) form.
γ-Terpinene (D)
Second to limonene, this is the most important monoterpene in mandarin (>16%). This feature is not shared by many other citruses, so it is a characteristic for Citrus nobilis.
Methyl N-Methyl Anthranilate (or Dimethyl Anthranilate) (E)
This is another quite characteristic marker of C. nobilis, as this compound is not encountered in most citruses. It can be encountered at levels up to 0.6% in mandarin. The leaf oil can even contain more than 50%! It contributes to the aroma of the oil.
α-Sinensal (F)
This relatively rare sesquiterpene (in fact, it is almost only found in specific citruses) is comparatively abundant in mandarin oil. There should be at least 0.1% of that compound in the oil. It also is a key contributor of the oil’s scent.
Tangeretin (G)
Expressed oils from citruses are brightly colored. This is in part due to flavonoids, which are yellow or orange polyphenolic compounds. They are not so volatile, so the GC run has to be longer to catch them. Tangeretin is one of those found in mandarin.
Years ago I was taught that only Green Mandarine contains Methyl N-Methyl Anthranilate (or Dimethyl Anthranilate), and that this is what makes the Green Mandarine a superior sedative, compared to the red mandarine or any of the other citrus oils. On checking the profiles of our red and green mandarine oils I see that both have the anthranilate… but the green has a larger percentage. (both are traces… 0.3% compared to 0.41%)… I’m wondering if my original source for that had been working with tangerine oil that had been labeled red mandarine. For all these years I’ve believed and taught the superior sleep inducing powers of the green oil… and it works! (The power of placebo is a wonderful thing 😉