Pu-erh tea is one of the world's most unusual and distinctive types of tea. Also known as 'post-fermented' or 'fermented' tea, the production process for Pu-erh is very different from other teas.

Pu-erh is made from a different species of Camellia sinensis (the tea plant) than green, black, peppermint, and rooibos teas—it's a subspecies called Cunninghamia Kumaensis. It also undergoes a longer fermentation process, resulting in different aromatics and flavors.

Unlike most other teas, pu-erh isn't processed with heat to stop oxidation and prevent discoloration. It's fermented intentionally with moisture, humidity, and microorganisms to initiate an entire secondary process of enzymatic reactions, transforming the leaves into something entirely new.

What's the history of Pu-erh tea?

Pu-erh is one of the most ancient types of tea found anywhere in the world. It's believed that people in the southwestern Chinese province of Yunnan have been making Pu-erh for at least 1,000 years.

Cunninghamia Kumaensis, a subspecies of the Camellia sinensis found exclusively in Yunnan and its environs, are the source of pu-erh. The growing and fermentation of Pu-erh tea were primarily shaped by Yunnan's climate, geography, and ecology.

The thickly forested and mountainous region receives an average of 10 feet of rainfall yearly, with a long, hot, humid growing season. After harvesting, the leaves were initially allowed to oxidize as they were being processed, producing a darker tea mainly used locally.

In the late 1950s, the Chinese government launched a campaign to modernize tea production, stopping the natural oxidation process and artificially accelerating the fermentation process to produce a lighter-colored, higher-quality tea for export.

How is Pu-erh made?

Pu-erh is made in two stages: the first is a 'green' tea process: large, unrolled leaves are sun-dried, gently roasted, and then rolled into large, loose-leafed balls. Next, there's a secondary fermentation process where the tea is left to oxidize, with moisture, humidity, and microorganisms, for at least several months (or even years) to transform the leaves into something entirely new.

The tea leaves are piled into large, loose bamboo baskets or wooden chests where they're left to ferment. Fermentation is a natural process where microorganisms break down the leaves' proteins and polysaccharides (simple sugars) into amino acids, CO2, and other molecules.

In Pu-erh, this process is encouraged by using a humid environment, which induces the leaves to break down more thoroughly and produce CO2, giving the tea a distinctive flavor and aroma.

The fermentation process

Fermentation of Pu-erh tea is a complex process that can take up to several years to complete. During this time, the leaves undergo several stages of oxidation and enzymatic reactions that affect their appearance and flavor. The different stages of the fermentation process are:

• Initial stage: This stage lasts for the first few weeks of fermentation and is characterized by high levels of CO2 production. In this stage, the tea leaves are often covered with a foam that can reach up to an inch in height.
• Developed stage: Occurs when CO2 production levels have dropped, and the tea leaves have a "bready" aroma.
• Dry stage: The dry stage marks the transition between the wet and mature stages and lasts for several months. It is the period when the fermentation is slowing down.
• Mature stage: The mature stage is characterized by stable and consistent levels of fermentation.
• Over-fermented stage: The over-fermented stage can result from too much time in the mature stage or interruptions in the aging process. A strong, spicy aroma and a dark coloration characterize it.
• Storing Pu-erh

Pu-erh taste and smell

If you cut open a raw Pu-erh and sniff it, you'll get a woody, earthy whiff that's very different from the light, fresh aroma of fresh-cut green tea. And when you taste it, it's even more diverse:

Pu-erh is very rich, with a deep, musky flavor that lingers in your mouth. The main reason for this is the fermentation process: it oxidizes the tea leaves, triggering chemical reactions that break down the leaves' proteins and polysaccharides (simple sugars) into amino acids, CO2, and other molecules. The longer the leaves are fermented, the more they break down and become more affluent, complex, and dark.

Is Pu-erh healthy?

Much research has been done on whether Pu-erh is good for health, and the results are somewhat contradictory. One study found that the fermentation process in Pu-erh tea may increase the level of antioxidants in the leaves by as much as ten times compared to other teas.

Another study found that the fermentation process damages the antioxidants in Pu-erh. So there's yet to be a clear conclusion on whether fermented teas, including Pu-erh, are more or less healthy than unfermented teas. However, it's clear that Pu-erh tea is rich in phenolic compounds and amino acids and has a high antioxidant content, which is known to be beneficial to human health.

Where to buy good Pu-erh?

Pu-erh comes in an astonishing variety of shapes, tastes, and smells—probably more than any other tea type. If you're buying an unaged "young" Pu-erh tea (also called "raw" or "unfermented" Pu-erh), look out for leaves that are loose and unbroken and have a mild, earthy aroma.

If you're buying a more mature or aged Pu-erh, you'll want darker leaves with a rich, earthy scent. Aged Pu-erh teas have a darker color, are more oxidized, and are often sold as loose-leaf tea in a bag rather than in a cake.

Summing up

Pu-erh tea is one of the world's most unusual and distinctive types of tea. It's made from a completely different species of Camellia sinensis than green, black, peppermint, and rooibos teas—it's a subspecies called Cunninghamia Kumaensis.

Pu-erh is also fermented intentionally with moisture, humidity, and microorganisms to initiate an entire secondary process of enzymatic reactions, transforming the leaves into something entirely new. Compared to other types of tea, Pu-erh is very earthy and rich and has a complex, lingering flavor. It's also one of the healthiest teas, with a high antioxidant content that can help protect against heart disease, stroke, and certain cancers.