Tea has been widely recognized as a beverage around the world and is believed to be inbuilt with many health benefits. However it is known that tea leaves do not solely exist as a single type and could be categorized into six different types of tea leaves based on the extent they are oxidized to.
These tea leaves not only differ in their appearances, aroma and taste but vary in the aspect of the health benefits each leaf can provide. However what is the underlying reason behind this differing health properties of each leaf? A study was conducted on 8 different tea leaves to gain a deeper understanding in this aspect.
Gas chromatography-mass spectroscopy (GC-MS) analysis has allowed us to identify a total of 347 different compounds, along with 10 important health beneficial properties that can be found amongst these compounds. A detection limit of 0.0068% of the total chromatogram area was achieved in this analysis.
Through the results of our analysis, certain types of tea are found to have more absolute area for certain properties than the others, and the results are as follows:
Pu Erh tea and Sri Lankan tea have relatively less compounds with health beneficial properties as compared to other tea samples.
Although 8 tea leaves were used in this project, only 6 were used for comparison with both Earl grey and Keemun Rose Petal tea leaves being excluded from the comparison. The reason for doing so is that these two tea leaves are not natural tea leaves but are black tea leaves that has been further processed with addition of additives that altered their compound composition.
To gain a better understanding of this, we will now look into how Earl grey tea is being made.
Here’s a breakdown of the compounds found in BEO itself:
As we can see D-limonene and linalyl acetate constitutes to more than half of the proportion of compounds in BEO itself. Like some of the compounds that exhibits health beneficial properties, D-limonene and Linalyl acetate are found to exhibit some of the health properties that we were looking into such as antiasthmatics and antioxidant effect etc.
With a large proportion of D-limonene in Earl Grey due to the addition of BEO itself, it would not be a fair comparison to compare Earl grey with the other natural black tea leaves on their absolute area of each of the health benefits since the additives would play a part too. As such Earl Grey and Keemun, having rose petal added to its tea leaves have been excluded from this comparison.
In conclusion, with the above-mentioned of some individual tea types having a higher proportion of a certain health property, one can consider drinking the specific tea to counteract a current illness he is facing if the tea happens to consist of a large proportion of compounds which exhibit that specific health benefit to fight the illness.
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Picture created by Melvin Chong, Intern from NUS
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