Leaf Peeping in Your Cup: How Oxidation Makes These 3 Oolongs Perfect for Autumn
Oxidation is in the air. Literally. In fall, chlorophyll in plants breaks down, and oxygen exposure speeds up the decomposition. Leaf peeping? It happens, in part, thanks to oxidation. Also, leaves fall to the ground and literally oxidize in fall—they can represent so much carbon getting released back into the atmosphere.
Those smells, even the season’s crisp air—so much about the season enjoys connections to oxidation.
Which is one reason we celebrate oolong today. While most teas undergo varying levels of oxidation, oolongs’ variety and complexities hinge on the chemical process. To make oolongs, artisans submit tea leaves to different levels of oxidation. Formulas for making some oolongs invite relatively small amounts of oxidation. Others depend more heavily on the process. Most dwell somewhere in between.
Oolong’s reverence for oxidation differs from how artisans treat oxidation for black, green, white and pu-erh teas. Blacks undergo the most oxidation—the duration of oxidation is responsible for the deep colors. Greens experience almost no oxidation; farmers use heat immediately after harvesting to stop the process. Whites see a little oxidation. Pu-erhs can undergo quite a bit—oxidation, in fact, is essential for pu-erh’s fermentation.
The Oxidation Connection: Why Fall and Oolong Are Perfect Partners
But the many shades of oolong revolve around oxidation. The style famously yields an abundance of flavors, aromas and even textures. Some present as malty and chocolaty, others broadcast honey, floral, herbal and other notes. While terroir contributes toward the teas’ differences, so does oxidation, in ways that are more profound than with other styles of teas.
As this season of oxidative decay ripens and stirs our spirits—among other things, in coming weeks leaves begin turning gold, copper, scarlet and orange—we trumpet the glories of one of our favorite tea styles. If not for oxidation savvy and nuance, after all, we wouldn’t enjoy the glories of well-made oolong tea!
Let’s take a deep dive into a trio of our favorite oolongs. If you try all three, you’ll recognize how oxidation can produce significant differences in the same styles of tea.
Autumn Oolongs: Oriental Beauty
Decay and decomposition describe part of what makes autumn so special. The processes produce the season’s bold botanical colors and hauntingly beautiful perfumes. With Bai Hao, a famous Formosa Oolong from Mount Ali in northern Taiwan, the leaf breakdown goes one step further—with insects! Yes, insects in this region of the island nibble on the tea leaves before farmers harvest them. You might think the insect activity would destroy the tea, but quite the contrary. Instead, their dining enhances the flavor.
Outside of the insect activity, the leaves, which get harvested in summer, give off fall foliage vibes through their warm colors. Once picked, artisans oxidize the leaves to between 50%-60%, which is more robust than with other Taiwan oolongs. The result? A tea with a proudly aroma of ripe peaches and honey, with a smooth, sweet flavor absent of nearly all astringency.
Autumn Oolongs: Bai Ji Guan
The Wuyi Mountains in China’s Fujian Province turn into a spectacle of color and atmosphere during autumn. Ginkgo and maple tree leaves, among others, turn the region gorgeous as days shorten and cooler temperatures arrive. In addition to serving as an autumnal adventure for many, the Wuyi Mountains also yield some of the finest teas in the world. The rocky soils and rich legacy of tea farming produce especially grand teas. For aficionados, oolongs from the Wuyi Mountains are as good as it gets.
Our Bai Ji Guan, or White Crest, is famous for its whitish fresh leaves reminiscent of a rooster’s crest. Most Wuyi Mountain oolongs undergo extensive oxidation, for oolongs—often between 60%-80%. The process is responsible for the roasted and mineral-rich “rock charm” for which Wuyi Mountain oolongs are famous. Bai Ji Guan also sees more oxidation than many other oolongs, but less than most Wuyi teas. The resulting tea stands apart from many other Wuyi teas, with more bright, fruity notes (such as peaches and pears) as well as floral attributes and a creamy mouthfeel.
Autumn Oolongs: Milk Oolong
Over the years—two decades of business in 2025 for Ku Cha House of Tea!—our milk oolong has emerged as a customer favorite. We adore the style, which comes from Taiwan. This medium-oxidized tea captures classic oolong notes of flowers, herbs and honey, but the flavors don’t end there. Just as milk tea is enormously popular in Taiwan—the style, with boba, was invented on the island—so is touching oolong with whispers of milkiness. In this case, however, the “milk” is plant-based rather than traditional dairy.
It’s not a milky tea. Don’t expect it to turn white! But the hint of non-dairy creamer used in the curing process makes for rich flavors and textures. If you desire a touch of honey with this oolong, go for it. This gem is made for pure enjoyment, no matter how you like preparing your tea.
