Roasted Tea: A Smoldering Labor of Love
With cozy aromas of toasted nuts, caramel and toffee, nothing satisfies like a good roasted tea. Roasting is a critical step in making several styles of green tea and oolong tea, such as Hojicha, Tieguanyin and Wuyi cliff teas like Tieluohan. So what happens when a tea is roasted, and why roast tea leaves in the first place? Let's explore the traditional art—and yes, it's very much an art!—of roasting tea.
The early history of oolong and roasted tea
It's difficult to point to a singular origin of tea roasting, but most historical sources suggest the early Qing Dynasty in imperial China, which lasted from 1644 to 1912. This is also when oolong tea production in the Wuyi and Phoenix regions of Fujian and Guangdong Provinces, respectively, was likely initiated. Roasting is essential to these famous oolongs, and to this day, their histories are tightly intertwined.
Oolong teas are oxidized partway between green and black teas. They're distinguished by complex aromas and flavors, owing to an intricate production process that includes cycles of withering, rolling, shaping, and firing the leaves in a pan or hot oven to reduce their moisture content.
In hot and humid southern China, even a small amount of residual moisture can spoil a batch of tea, inviting mold and off flavors. Early Qing texts include roasting in their descriptions of oolong production, both as a means of safeguarding against spoilage and imbuing the tea with deeper, darker flavors. Teas from the Wuyi cliffs such as Drunken Begonia are renowned for their rich mineral backbone, which is highlighted with extended roasting and resting periods.
As oolong production spread to other nearby regions—such as Anxi, the home of Tieguanyin—the art of roasting followed suit. Roasters lit charcoal fires and let them smolder until they were free of smoke, with a layer of white ash on top. Then they spread processed oolong leaves into bamboo baskets and placed them over the coals. Collectors of aged teas sometimes re-roasted their stash periodically, which would drive off any moisture sucked into the leaves from the humid environment and refresh the tea's flavor.
Good roasting requires patience. It can take dozens of hours, spread over multiple sessions spaced months or even years apart, to roast a tea to its full potential. Yet it also demands constant attention: stirring the leaves so they heat evenly and monitoring the heat source to maintain the right temperature. A small misstep can scorch and ruin an expensive batch of tea.
For all these reasons, tea roasting in Asia grew into an industry all its own. Professional roasters bought processed oolong teas from farmers or merchants, then roasted the tea to sell under their own labels. Wealthy tea collectors might buy tea from their preferred farm, then send it to their favorite roaster to bake the tea to their specifications. Some roasters developed personal brands based on a "house taste" common to their roasts—a practice that continues to this day.
Modern roasted oolong tea
For the most part, advances in airtight packaging have made spoiled or moldy tea a thing of the past. Oolong makers no longer need to subject their teas to a heavy roast in order to ensure longevity. As a result, lightly oxidized, unroasted oolong styles like Nantou Four Seasons have emerged across Taiwan and China—in some cases supplanting traditional dark roasted teas.
Yet roasting remains an essential part of contemporary oolong production, less for reasons of shelf life than for the incomparable depth it can add to a tea. For instance, tieguanyin drinkers may note a preference for qing xiang ("fresh fragrance") oolong or nong xiang ("strong fragrance") teas. The former is lightly oxidized and minimally roasted (if at all) to emphasize a verdant, buttery brew with a powerful floral aroma. By comparison, the more heavily roasted "strong fragrance" tea may not share such a bright aroma, but it gains a smoother, richer flavor that can withstand more steeps in a pot. Our Tieguanyin Deep Roast is a classic nong xiang tea. Three rounds of roasting over four months develop notes of grilled peach, sandalwood incense, and brown sugar—complex flavors you won't find in most unroasted oolongs.
This is not to say heavily roasted oolongs are superior to all unroasted ones. It all comes down to the quality of the leaves and the craftsmanship of production. You can cover up a lot of processing errors with a burnt-marshmallow level roast, and it's easy to overpower a good tea's subtle aromatics with too much time over the fire.
These days, many roasters have traded charcoal fires for electric ovens to bake their tea. Modern ovens are easier to manage and can accommodate more leaves with less risk of ruining a batch. In Hong Kong, one roaster we know bakes Wuyi oolongs for a whopping 70 hours in an electric oven, to build layers of smoldering flavor.
For some hardcore drinkers, however, charcoal roasting remains the gold standard, both for the individual attention it requires of a roaster and the ineffable qualities that cooking over live fire adds to food and drink. Traditional charcoal roasting is a dying art at this point, so whenever we find a good batch we consider it a special treat.
Roasted green tea in Japan
In 1920s Japan, a separate tradition of roasting emerged: not to improve shelf life, but to utilize all parts of the tea plant. Faced with a glut of low grade leaves and stems that were sorted out of their premium teas, Kyoto tea merchants began roasting these leftovers until they turned dark and nutty. The resulting tea was called hojicha.
Hojicha is a rich but mellow tea with a clean, refreshing finish. The roast is less intense than traditional Chinese oolongs; leaves and stems are roasted in ovens or spinning drums over gas flames for minutes rather than hours. You can even mimic this roast at home with a ceramic pot called a horoku, which is made for roasting small batches of hojicha on the stove.
The particular flavor of hojicha depends on the materials and roasting methods. In the city of Kaga, north of Kyoto, stems and twigs are heated in infrared electric ovens to make a light-bodied tea called kaga boucha. Older Kyoto roasters use material with more leaves, and may toss some super-heated chunks of ceramic in the roasting drum to scorch the leaves for extra intensity. In Taiwan, where Japanese tea culture has a strong influence, similar hojicha roasting methods may be used on stems sorted out from high mountain oolong tea production. We call this tea Wood Dragon for its woody, butterscotchy flavor and caramel finish.
The genius of these roasted teas is making the most of material that would otherwise go to waste. We can see a similar ethos at work in the making of Genmaicha, a blend of unroasted green tea with roasted rice or sorghum. Originating as a way for poor drinkers to stretch pricey green tea with inexpensive grains, genmaicha is now a popular tea among all over Japan and around the world. This is especially the case in restaurants; like hojicha, refreshing genmaicha goes well food.
The chemistry of roasted tea
Roasting kicks off a complex chain of chemical reactions within the tea leaf, including the process of Maillard browning (which you may be familiar with when searing a steak or toasting a slice of bread). As natural sugars and amino acids interact, volatile compounds from these combinations develop toasted, savory flavors we associate with caramel, caramelized onions, and barley malt.
One study of Wuyi oolong teas notes that roasting decomposes amino acids that contribute to a tea's fresh and astringent flavors, along with compounds like catechins and theanine. In their place it develops a whole host of new ones, including gallic acid, responsible for a tea's sweet finish, as well as aldehydes, furans, and ketones that contribute to nutty aromas and flavors.
What does all this mean to us drinkers? Firstly, that tea roasting is a complex art that takes decades to master. Secondly, some research indicates that roasting can reduce—but not eliminate—caffeine in tea. If you're sensitive to caffeine or looking to reduce your intake, see how your body reacts to roasted teas.
How to brew roasted oolongs and green teas
We brew most roasted teas with boiling water to draw out their full depth of flavor. Longer brewing time contributes rich body to the brew, and be sure to steep the leaves several times to enjoy all they have to offer.
There are exceptions that benefit from a more delicate touch, such as Phoenix oolongs and lighter roasted green teas. If your roasted tea tastes like a bitter smokehouse, try lowering your water temperature to 195°F/90°C and reducing your steeping time. Or, for a refreshing alternative, try them iced using this hot-infused method.