Pumpkin spice latte? More like pumpkin LIES latte!
As we say goodbye to our beautiful summer months and begin to order warm lattes and teas in preparation for the autumn season, one specific drink comes to mind: that being the mouth-watering, jaw-dropping, breath-taking pumpkin spice latte. How could one not love a pumpkin spice latte, when each spice intermingles and gives a heavenly performance atop your tastebuds? From the aroma of ginger tickling your senses as if a feather was gently brushed upon the surface of your skin; to the subtle notes of nuttiness in the nutmeg as your lips first encounter the warmth of the latte; followed by the everlasting battle of sweet and bitter from the cloves; to finally, the hint of cinnamon wrapping all the flavours together to give rise to that final crescendo in the confines of your tastebuds. In my opinion, that is the true epitome of what the fall season is about.
You may be asking now, “How is he going to turn this into an NMR-related blog?”. Well, I am sure you have already guessed from the title, but if you look back, you’ll notice that I never mentioned pumpkin anywhere aside from the name of the drink. This is because pumpkin is not actually a significant flavour profile used in the pumpkin spice latte, or really any pumpkin spice-related theme. Although there are variations of pumpkin spice, the most common spices that comprise it include, ginger, nutmeg, cloves, and cinnamon. In this blog, I would like to centre your attention on cinnamon, however, in case you missed it, I’ve previously posted a holiday blog on the other spices, which you can view here!
Cinnamon is the bark harvested from a specific evergreen tree and has been a highly sought-after spice for a countless number of generations. It has since been used in many different medicines and herbal teas but remains mostly used for baking. For me, however, as a chemist, I had to find out what molecules make up cinnamon. To do this, I used my trusty detective skills and searched up, “What is in cinnamon?”. I found that cinnamon is comprised of molecules such as, cinnamic acid, cinnamaldehyde, and various oils.1 I obtained the 1H spectra of cinnamic acid and cinnamaldehyde on our 60 MHz benchtop NMR spectrometer, which are represented in Figures 1a and 1b.
Figure 1. 1H (60.7 MHz) NMR spectra of (a) cinnamic acid and (b) cinnamaldehyde in chloroform-d.
Now, this blog would not be complete unless I also analyzed cinnamon; therefore, I decided to grab some cinnamon sticks from my house for analysis. In preparation for analysis, I crushed up a few cinnamon sticks into a fine powder (or at least as fine as I could make it). With that, I used chloroform to extract anything I could from that powder. I collected those washes and analyzed them with our benchtop NMR spectrometer. Depicted in Figure 2 is the 1H spectrum of extracted raw cinnamon.
Figure 2. 1H (60.7 MHz) NMR spectrum of the crushed cinnamon stick extracts in chloroform-d.
After superimposing each 1H spectrum (Figure 3), as we would expect, there are characteristic regions of cinnamic acid and cinnamaldehyde that also appear in raw cinnamon. The first peaks I would like to mention stem from the alkene group of both cinnamic acid and cinnamaldehyde. For cinnamic acid, we can see one of the doublets at 6.59 ppm and 6.32 ppm, which relate to the peaks at 6.62 ppm and 6.32 ppm in cinnamon. For cinnamaldehyde we observe both sets of doublets from 6.89 ppm to 6.49 ppm, which are also evident in the spectrum of the cinnamon extract. Additionally, as the name suggests, cinnamaldehyde has an aldehyde functionality, where that proton adjacent to the double bonded oxygen group has a distinct set of peaks, which appear at approximately 9.77 ppm and 9.65 ppm and at a similar region in cinnamon.
Figure 3. Stacked 1H (60 MHz) spectra of crushed cinnamon sticks (blue trace), cinnamic acid (green trace), and cinnamaldehyde (red trace) in chloroform-d.
Well, I hope you enjoyed that journey through the world of cinnamon in NMR as much as I did. If you have any questions about this application, or anything at all, please do not hesitate to contact us!
[1] Rao, P.V.; Gan, S.H. Evid. Based Complementary Altern. Med. 2014, 642942.