Roasting Tea at Home

Did you ever buy a large amount of a very special tea, say an expensive Taiwanese high mountain oolong tea, and only drank it rarely in order to make the your stash last longer? Did you ever forget a prized tea on the back of your shelf for months at a time, or even a year or two? If so, I’m sure you are familiar with the sinking feeling you get when brewing a cup of a special tea only to find that it has gone stale, the taste only a pale shadow of what it once was.

Fortunately there are alternatives to throwing out the rest of that special tea. Not all stale tea is past saving. And the means to restore your tea to a drinkable state is within your grasp with tools you already have at home.

Re-Roasting

The trick is re-roasting your tea.  Many teas are of course roasting in their original processing. It’s obvious in some teas like a heavily roasted Wuyi oolong or Japanese houjicha, but many other teas have some degree of roasting in their manufacture.  The roasting process you can do at home is very similar, but on a much more humble scale.

First, let it be said that there are some types of tea where re-roasting just won’t work well. Matcha is a prime example as the powdered form doesn’t lend itself to roasting techniques. If you have stale matcha I encourage you to use it in a nice sweet matcha latte or to bake a batch of chocolate-chip matcha cookies. Teas flavored with oils or fruit pieces are also poor roasting candidates. They go stale mostly through evaporation of the flavored oils or those in the dried fruit pieces, and those flavors are gone. Roasting might help with the base tea leaf, but the added flavors cannot be retrieved.

Other teas are worth rescue through roasting.  The concept is generally simple:  teas go stale mostly through slow absorption of humidity in the air, much the same way that a bag of chips left open overnight becomes inedible.  Adding gentle heat for a prolonged period encourages that moisture to evaporate out of the stale tea leaf, brightening up the flavor to a drinkable state.  It may not ever taste freshly-processed again, but a drinkable tea is far better than a tea in the trash can or compost bin.  A re-roasted tea has much more flavor than a stale one, and with care it can taste very similar to the original tea.

If you wish you can also use the re-roasting process to transform your tea.  Some people like to go beyond simply refreshing their stale tea and go straight into deepening the roast, resulting in an entirely different tea.  By using slightly hotter temperatures a tea can easily be coaxed into a slightly more roasted version, or with patience converted into a deeply roasted tea.  The final result is a robust new tea on your shelf, which one might prefer over a refreshed tea that is close to, but not quite, the same as the original tea.

So how does one go about re-roasting tea at home?

Well, if you find that you may need to re-roast tea a lot at home, it pays to buy an actual tea re-roaster.  Tea producers and some high-volume tea shop have large cabinet-sized tea roasters for this purpose, but that’s certainly overkill for home use.  Instead special order a small countertop tea re-roaster.  They look very similar to a round stacking bamboo steamer tray, except that the bottom layer is a heating element with a few simple controls.  This size roaster can process about a quarter pound of tea at a time.

The top basket of a home re-roaster is a bamboo ring with a mesh grate for a bottom. Pour your stale tea across this layer, no more than an inch deep.  If it fills the basket bottom entirely make a small empty space in the middle about an inch wide so air can flow between the layers more freely.  You may wish to shake the basket gently to remove any tiny leaf fragments.

Place the roasting basket and lid on the roaster base.  Turn the temperature control know to the desired level.  I recommend starting at the halfway mark — they are all relatively low temperatures but for a refresh re-roast the halfway point is usually fine.  Three quarters is used for a light darkening roast, and only use the highest heat setting if you intend to fully deepen the roast.  

There should also be a timer, which typically is about 45 minutes on most models.  This is about enough time for a light refresh roast of stale tea, but deeply stale tea or tea you wish to darken will take two or three rounds of 45 minutes.  When doing longer roasts, shake the leaf gently between each session but try not to allow it to cool down between roasts.

After the roasting is complete, let it sit just long enough for the tea to cool to just over room temperature, then immediately seal it in airtight storage,  You don’t want your newly rescued tea to go immediately stale again by leaving it sit too long!  that has happened to me many times, and if it happens to you just repeat the roasting process again.

One very nice benefit of doing home re-roasting of tea is the strong aromas that this process produces.  I sometimes save my re-roasting for the wintertime near the holidays as the warm smells of roasting tea are more pleasing than any potpourri in my opinion.

Re-Roasting Without a Fancy Tea Re-Roaster

Now let’s say that you don’t plan on re-roasting tea very often, so it is unlike that you will be spending a hundred dollars on a tea re-roaster.  You still have options for re-roasting tea at home, but be warned that it can be surprisingly tricky.  There are a number of techniques used.

One common and obvious method is oven baking.  Place your leaf in a pan, stick it in the oven, and set it at the lowest temperature your oven allows.  The key is low temperatures over a long period.  If the leaf gets too hot it will develop a burnt taste from which there is no recovery.  Even temperatures just above 150°F can burn the leaf more quickly than you would think.  There might be parts of you oven that are hotter than others.  The leaf on the edges of the pan may burn while the middle may be fine, but the smell will contaminate even the unburnt leaf.  Check the leaf frequently to make sure the appearance and aroma have no suggestion of becoming burnt!  Baking times are the same as for an actual tea re-roaster.  One final note:  make sure there are no remnants of cooking in your oven or the aroma of last night’s dinner may permeate your tea.  On the other hand, perhaps pot-roast scented oolong is a culinary discovery waiting to happen.

Another method, even tricker but one that often gives better results:  a dry frying pan.  This method allows you to re-roast small amounts of tea, even a single serving.  Place your tea in a dry clean frying pan and place it over very low heat on your stove.  If all of your stove burners are too hot, find a means to elevate your pan, perhaps by stacking burner racks.  Place the pan on the heat, but do not leave it unattended!  Every ten seconds or so shake the leaf about in your pan and check to see if it appears done.  Even at low temperatures this method is hotter than the dedicated re-roaster or the oven so the leaf will roast more quickly.  Remove the pan away from the heat for a few seconds if it appears to be getting too hot.  

Use your best judgement to determine when the leaf is roasted to your desired level.  It can take as little as five minutes or as long as a half hour depending on your stove and the tea in question.  It should never look or smell burnt.  This method takes practice and skill.  I’ve known people try this method over and over and then decide to order a tea re-roaster to save themselves the trouble.

The Rice-Cooker Method

There is another method the some people swear by that I have personally never attempted.  These adventurous folk re-roast their tea using an electric rice cooker.  The idea is that a rice cooker knows when to stop cooking the rice by monitoring the temperature inside.  When there is water inside the temperature is kept fairly steady by the boiling process, but when the water is fully absorbed the temperature suddenly shoots up.  This tells the rice cooker to shut down and go to warming mode.  This warming mode is just about right for a slow roast of tea.

By putting the leaf in a dry rice cooker pot, the cooker immediately senses that it is ready to go to warming mode and begins roasting the tea at a near ideal temperature.  From that point on the timing and process is just like an actual tea re-roaster.

It does have some significant drawbacks.  Rice cookers are fully contained except for a steam outlet, so you will not be able to tell by scent alone how the roasting is coming.  You have to open the cooker and take a look.  You may find the tea completely burnt, or barely roasted at all.  If you attempt this method open the rice cooker frequently to check how the process is coming along.  The other major drawback is that the small amount of moisture in the tea that is being removed through roasting has nowhere to go.  It is unlikely to be enough moisture to force venting through the steam vent, at least not completely, meaning some moisture is retained in the leaf.  The end results may not be as effective as the other roasting methods.

Whatever method you use, hopefully you will end up with tea that is worthy of drinking and savoring.  Certainly it has saved many of my stale teas from feeding the vegetables in my garden.  

Sometimes the results are surprising.  Once I was gifted several pounds of Emeishan green tea from Sichuan, China.  This is a very fine tea, consisting of delicate, closed needles of intensely green tea buds.  Unfortunately the tea had sat in a warehouse shelf for ten years and was written off as hopelessly stale.  I took this tea and did a mid-level roast in my tea re-roaster for almost five hours.  When fresh Emeishan green is like drinking sweet morning dew.  When stale it was like sucking on wet notebook paper.  After five hours of re-roasting it was a like sipping a cup of warm hazelnuts by a fire in a log cabin.  Not all results are an impressive, but experiences like these are why my tea re-roaster gets frequent use all year long.