steeping tea

Tea Bag Science – Should You Dunk or Steep Your Tea Bag?

Nothing better on a cold day: a warm cup of tea. Not just to warm the inside, but to warm my hands as well. Making the cup sounds simple, just bring some water to the boil. Pour the water in a cup and add a tea bag. Take the teabag out within a minute or so and I’m ready to go!

Pretty normal I though, until various (non-Dutch, I must say) people commented on my tea making skills. Why did I take out that tea bag so quickly? They clearly preferred to leave it in for a lot longer, letting it steep.

The same happens every time I travel to the UK. First thing I do when I get my pot (never just a cup) of tea: take out the tea bags as fast as I can. Whereas British tea is black and bitter, I prefer mine lighter and faster. Just dunk the bag in and out a few times and you’re done.

But while doing so again one day I started wondering: “Is dunking my tea bag actually going to give me my tea faster?” And if so, is it of a better or worse quality than the slowly steeped version?

Tea & Extraction

To answer my question about dunking vs steeping tea we have to start with some basic tea science. Tea is made from tea leaves which are dried and processed in various different ways to make the different tea types (e.g. black, green and white) and flavours.

When making tea, you submerge your tea leaves in hot (maybe boiling) water. It’s the start of a process that chemists call extraction. Components in the tea leaves will dissolve in water. This enables you to extract the flavours from the tea leaves into the water, without having to actually drink the leaves.

steeping tea
Three cups of tea, with the same amount of tea, that have been steeping for the same amount of time. The only thing that differs: the temperature of the water at the start of this experiment. Notice the pronounced difference!

What’s in tea?

While steeping or dunking your tea bag in water, only those molecules dissolve in your tea water that can actually dissolve in water.

The most common molecule groups in your liquid tea are: polyphenols, caffeine (and related molecules), proteins & amino acids, carbohydrates, organic acids, pigments and vitamins & minerals. These all dissolve in water pretty well. These also happen to be the molecules that give flavour and colour to your water.

Tea leaves also contains larger structural molecules such as starches and cellulose. These do not dissolve well in water, nor do they release well from the leaves. You wouldn’t need them to dissolve either, since they don’t provide flavour.

Rates of extraction

Some molecules can be extracted very fast whereas others take more time. As a result, the flavour of your tea could be slightly different if you steep it for a short versus a long period of time. Steeping it for a short period of time might have a larger concentration of those molecules that dissolve very rapidly. Whereas for the tea that is steeped longer the slower molecules have had a chance to catch up.

Unfortunately, it is impossible to do a complete analysis of the components for all teas steeped in different ways. There are a lot of different molecules present and the actual extraction depends on a lot of other factors. The temperature of the water, pH-value (acidity) of the water, the presence of other minerals, etc. So it’s hard to quantify the difference a 3 vs 30 minutes steep will give as well as the difference between a quick dunk vs a slow steep.

steeping tea
Steeping some black tea.

Steeping or dunking?

When comparing steeping & dunking there is another factor to keep in mind: movement. While dunking your tea bag a few times, you’re creating movement of water inside your cup. This flow makes it easier for molecules to move away from your bag. If you wouldn’t move the bag, all those molecules need to move using diffusion only which does take longer to spread throughout the cup.

If molecules spread throughout, it lowers their concentration close to the tea bag itself. This in itself can help release some more molecules, but probably only to a small extent.

Speaking from experience, dunking tea definitely speeds up darkening of the tea. Could it be that dissolving the colour molecules is sped up this way?

Unfortunately, not a lot of researchers have actually investigated the steeping vs dunking question. Whether there is a (relevant) difference so far seems to be more of a personal preference, than one with a clear scientific explanation.

Early Grey tea leaves

Loose leafs vs Tea bags

To illustrate just how much the steeping vs dunking phenomenon depends on your tea drinking habits, let’s look at loose leaf teas vs tea bags.

Loose leaf teas are made up of whole, or at least decently sized tea leaves. They have been rolled up in the production process. Generally speaking these are not sold in pre-packaged tea bags. One reason for not doing so is that these leaves will unroll and thus expand a lot when steeping in water. Also, these leaves are more expensive.

Most (not all) tea bags contain tea leaves that have been reduced in size significantly. This ensures that they don’t unroll and expand as much as loose leaf teas. It also means they have a lot larger available surface area available for your tea water. As such, the tea extraction process happens a lot faster.

Whereas tea bags can be dunked and steeped for limited periods of time, this doesn’t work for most loose leaf teas. These leaves need to uncurl and absorb water and this needs time. Dunking these won’t give you enough surface area to work with to extract enough of those flavours and colours. For most loose leafs steeping and some additional patience definitely works best.

What I’ll do next time I make tea?

I’ll continue to dunk my tea bag for sure (and dip it out of the tea when in the UK!). For loose leaf teas, I’ll be patient and steep them slowly for several minutes. The best of both worlds, in my opinion at least!

Sources

Another great article about in-depth tea chemistry is: Black tea: chemical analysis & stability. Or read more on this website fully dedicated to tea.

Harbowy, M., Balentine, D., Tea Chemistry, Critical reviews in plant science, 1997, link

Harbowy, M., Does bouncing your tea bag actually do anything substantial? Does it make it steep faster, or enough to make a noticeable difference?, link

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