Wednesday, May 11, 2016

Nerolidol: white tea, green tea, and now oolong?

In a previous post entitled “Why is white tea so elusive?” (April 26, 2016), I mentioned that there is some disagreement in the literature concerning the presence of nerolidol in white tea—is it there, or isn’t it? At this point the best we can say is that it may be in there, depending on what tea leaves are used and how they are processed.

Whether it is in white tea or not, it certainly is present in oolongs, and is a marker for oolong quality.* In the graph below, you can see how sun withering of oolong leads to the development of this chemical in the tea:

To me nerolidol has a very sweet, slightly woody smell—it has been described as a “tea” smell, and I can kinda sense that. Nerolidol is a significant component of natural jasmine smell. Worth noting: oolongs have a large number of these jasmine-related compounds.

Nerolidol's aroma is on the cool, fresh side, so probably binds to TRPM8, the same receptor as for menthol, and also, because of its slight pungency, to TRPA1 as well. In addition to its presence in tea, it can also be found in other foods that primarily activate cool/cold receptors, such as ginger and lemon grass. Furthermore, according to perfumers, it goes well with other cool/cold binding compounds such as linalool. 

However, with benzyl alcohol, another compound in oolongs (see the graph above), but one with a “warm” aroma, the aroma of nerolidol disappears completely, or if not completely, then it simply modifies the benzyl alcohol aroma in a pleasant but indescribable way.

Donna Fellman and I will be talking about sun withering and its effects on the production of nerolidol and other compounds in our presentation at World Tea Expo, and I will have samples of nerolidol and other aromas for you to smell. 

* Ma C, Qu Y, Zhang Y, Qiu B, Wang Y, Chen X. Determination of nerolidol in teas using headspace solid phase microextraction-gas chromatography. Food Chem. 2014;152:285-90. doi: 10.1016/j.foodchem.2013.11.010. Epub 2013 Nov 28.

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