Coca-Cola and Pepsi are two of the world’s most popular soft drinks, and most people have developed a preference for one or the other. When asked about their choice, many would describe the difference in taste between the two drinks, but not many talk about their differences in smell.
This is surprising, as the aroma of a substance plays as big a part in determining its overall taste as its flavor! Hence we set about to conduct an analysis of aromas of Coke and Pepsi, to see if we could determine any differences in their aroma.
We conducted headspace gas chromatography-mass spectrometry (HS GC-MS) on five samples of different types of Coke and Pepsi: regular Coke, Coke Stevia, Coke Zero, Pepsi, and Pepsi Black. HS GC-MS is an analytical method used to detect compounds within gas-phase samples.
We used ChemoPower’s own SmartDalton™ software to identify the chemical compounds present in these soft drinks. SmartDalton™ possesses features that are well suited for analyzing GC-MS data, as it is able to detect highly trace compounds, and separate those overlapping with each other.
SmartDalton™ at work separating 2 overlapping peaks
After we had finished analysis of the soft drink aromas, we tallied their compositions, but the Coke and Pepsi sample compositions were too similar for us to determine any significant differences between them! It was thus necessary for us to conduct a deeper analysis of the different drinks, for which we turned to Principal Component Analysis (PCA).
PCA is an analytical procedure used to represent the similarities and differences between different data sets, making it ideal to use in this situation. We conducted PCA on the Coke and the Pepsi samples separately and compared their significant compounds.
The significant compounds detected in Coke and Pepsi, as well as their compound totals
As it turns out, Coke and Pepsi share a number of significant compounds. However, the properties of those significant compounds which are NOT shared are of more interest: the Coke samples have 3 unique significant compounds, while the Pepsi samples have 4.
We looked up the reported aroma descriptors of these unique compounds, and came to the following: Coke aroma can be described as more ‘minty’ and ‘terpenic’, while Pepsi aroma can be described as more ‘pine’, as determined by the keywords of these compounds.
In summary, we studied samples of Coke and Pepsi to determine if their aromas could be differentiated, and found that their unique compounds could be described using aroma keywords. So the next time you drink a soft drink, don’t just focus on its taste, but also start thinking about how it smells as well!
All GC/MS data have been analyzed by ChemoPower’s software, SmartDalton™ and MoleculeDB™, to give a list of chemical compounds found in each sample within hours.
Written by Edmund Ho
Intern, National University of Singapore