Black, green and white tea are all made from the same Camellia sinensis plant but they are all different in terms of taste, nutrients, antioxidant levels and caffeine content. The reason why is due to several factors, including different growing methods and tea processing steps. To understand the differences between these teas we looked at several studies and here are our findings.
Tea oxidation process
Before we dive deep into how different green, black and white teas are, you should understand a little bit about the tea oxidation process. This process is the reason why green, white and black tea are so different in terms of colour, flavour, scent and even health benefits.
Tea leaves naturally start to oxidise as soon as they are plucked. This means that when plucked tea is exposed to the oxygen in the air, a chemical reaction occurs, causing the leaf to change, including a change of flavour and colour. This process is similar to the one when you leave a peeled apple in the open air for a while and it turns brown.
This oxidation can be either prevented or accelerated and then stopped, depending on the type of tea being made.
Oxidation levels of the tea leaf affect its colour, scent and chemical properties.
Oxidation levels in green, white and black teas
During tea processing, the ‘initiation’ is employed which is a process used to speed up tea oxidation. This process damages the cell walls by tearing, rolling or even shaking the leaf. This helps to speed up oxidation.
Enzymes present in a tea leaf also encourage tea oxidation but if these enzymes are damaged, then the process of oxidation slows down. This happens when making white or green tea which are less oxidised than black tea. The enzymes are purposely damaged at a temperature of around 60 degrees Celsius which stops the oxidation process. This is done in various ways, for example, by drying, steaming or pan roasting tea.
When further oxidation is prevented, more catechins in tea are preserved. This means that green and white teas are richer in these natural antioxidants.
Oxidation in white vs green tea
White tea is traditionally produced by drying in the sun for 3-4 days. This means it is slowly dried at a low temperature which doesn’t totally stop the oxidation but it does reduce it. This makes white tea slightly oxidised tea.
Green tea, on the other hand, gets exposed to the sun only for a short period and then it is heated at relatively high temperatures to stop the oxidation process. Chinese traditionally pan-fry their green tea while Japanese typically steam it. This style of heating the tea results in lower levels of oxidation.
Oxidation levels in black tea
What makes black tea so different from green and white tea is the level of oxidation it is exposed to.
Black tea is almost fully oxidised resulting in its dark colour, different aroma and strong flavour. It is not exactly fully oxidised as many sources state. The oxidation is controlled and managed until black tea reaches the desired ratio of theaflavins and thearubigins (antioxidants).
White tea vs green tea vs black tea: Antioxidants
All varieties of tea produced from the Camellia sinensis plant contain antioxidants called polyphenols. These vary in type and levels depending on the level of tea oxidation.
The main antioxidants in green tea are flavonoids and they include:
- Epicatechin
- Gallocatechin
- Epigallocatechin
- Gallate derivates
Out of these, epigallocatechin-3-gallate, widely known as EGCG is the most abundant in tea leaves (representing 50–80% of the total catechins) and the most beneficial.
White tea contains the same catechins as green tea but in different amounts.
Black tea, on the other hand, has formed a different type of antioxidants during the oxidation process. These are theaflavins, theaflavinic acids and thearubigins, just to mention a few.
While the oxidation process does affect antioxidants in tea, it’s important to know that antioxidant levels are also affected by other factors, such as growing conditions and geographical location. The temperature and time of steeping also affect the antioxidant properties of white, green, and black tea. However, in general, green tea shows the highest antioxidant activity.
White tea vs green tea vs black tea: Caffeine levels
A 2008 study showed that caffeine content in tea varies from 14 to 61 mg per serving (6 oz). All types of tea have a much lower content of caffeine than coffee. This study showed that the caffeine content increases with the steeping time. This is the case with all types of tea studied.
For example, Lipton Regular black tea had 17 mg of caffeine in 6 oz (177 ml) after 1 minute of steeping but this increased to 47 mg after 5 minutes.
Similarly, Stash Premium Green tea had 16 mg of caffeine after 1 minute but after 5 minutes this increased to 36 mg.
Exotica China White tea was left with 23 mg of caffeine (6 oz) after 1 minute and after 5 minutes this grew to 47 mg.
The highest caffeine content had Tazo Awake black tea, reaching 61 mg per serving after 5 minutes.
Caffeine content in brewed teas with different steep times:
| BRAND | TEA TYPE | Caffeine content after 1 min steep time (mg/6 oz) | Caffeine content after 5 min steep time (mg/6 oz) |
| Lipton Regular | Black | 17 | 47 |
| Stash Darjeeling Black | Black | 14 | 27 |
| Tazo Awake | Black | 59 | 61 |
| Stash Earl Grey Black | Black | 24 | 47 |
| Stash Premium Green | Green | 16 | 36 |
| Tazo China Green Tips | Green | 23 | 41 |
| Exotica China White | White | 23 | 47 |
This is, of course, just one of the studies analysing caffeine content in tea. There are many others as well.
There was one study published in 2016 which looked at several commercial tea samples. 1 g of tea was steeped for 3 min in 100 ml of water at a temperature of 80°C.
The results showed that the caffeine content differed greatly from brand to brand.
Most of the green tea samples had less than 20 mg of caffeine (between 10.23 and 19.72 mg) but some samples were over that amount – H Green Mint, for example, had 21.97 mg of caffeine.
White tea samples, on the other hand, showed more consistent results with caffeine content ranging from 15.38 – 18.22 mg.
Many black tea samples also had less than 20 mg of caffeine but three of them exceeded this amount, for example, Lord Nelson Earl Grey with 23.44 mg of caffeine. This is pretty close to the caffeine content in green tea but the averages are a little bit higher.
Which tea has the highest caffeine content?
Based on these studies, it’s difficult to conclude which type of tea has higher caffeine content. It really depends on the brand and steeping times. It also depends on where the tea has been grown. However, based on the tea samples we looked at, it’s clear that green tea normally has lower amounts of caffeine compared to black tea.
When it comes to the caffeine content in white tea, there are many studies but not all show the same results. This study, for example, shows that white tea has less caffeine than green and black tea. This study, on the other hand, shows that the caffeine content in white tea comes somewhere in the middle between green and black tea.
The bottom line is the caffeine content in white, green and black teas varies significantly and depends on many factors, including tea brand, growing conditions, geographical location, etc. As a result, sometimes green tea will have more caffeine than black tea and white tea will have more caffeine than green tea. For this reason, we cannot generalise the caffeine content in different varieties of tea although there is a general belief that caffeine content is more in black tea and less in green tea and that white tea has the least caffeine content.
References:
https://www.eliteabar.com/blogs/tea-education/7564628-tea-oxidation
https://core.ac.uk/download/pdf/144768045.pdf
https://onlinelibrary.wiley.com/doi/abs/10.1111/1750-3841.13149
https://academic.oup.com/jat/article/32/8/702/829967?login=true