Fermented tea

Some tea is called dark tea.

It is made by letting tea leaves sit for a long time. Tiny living things help the tea change. This makes the tea look darker. It also makes the taste smooth and less bitter.

People in China make many kinds. Some tea is pressed into hard bricks or cakes. In some lands, people even eat tea as a vegetable. This tea can stay good for many years. It is a very special treat.

Some tea is called dark tea. This is also known as fermented tea. It is made by letting tea leaves sit for a long time. Tiny living things like molds help the tea change. This process can take many months or even many years.

As the tea changes, it turns a darker color. The taste also changes. It becomes smooth and less bitter. Some teas even grow bright yellow spots. People call these "golden flowers."

Many kinds of dark tea come from China. Some are pressed into hard shapes. You might see them as bricks, cakes, or even discs. In Korea, people made a tea called Tteokcha. They often pressed it into shapes like coins.

In some places, people do not just drink the tea. In Myanmar, people eat a fermented tea called lahpet. They eat it as a vegetable. In Thailand, people chew a pickled tea called miang. This tea can be aged for a very long time. Some raw teas can stay good for 50 years!

Fermented tea is a special group of teas. People also call it dark tea or post-fermented tea. It is different from black tea, which people in China call red tea. This tea changes because of tiny living things called microbes. These microbes include molds like Aspergillus luchuensis. The tea leaves sit in humidity and oxygen for a long time. This process can take many months or even many years.

As the tea changes, it becomes much darker. The smell and taste change in wonderful ways too. The tea becomes smoother and less bitter. It can also have a better feeling in your mouth. Some teas even grow bright yellow spots. People call these beautiful spots "golden flowers."

There are many ways to make these teas. Some are called piled teas, like the Toyama tea in Japan. These are made with fungus in dry conditions. Other kinds are called pickled teas. These use a wet process with lactic acid bacteria. Some teas, like Ishizuchi from Japan, use both ways. They ferment with fungi first and then with bacteria. In China, some teas are made very quickly. This is called a ripening process. It can take only a few months.

No one knows exactly how dark tea began. One legend tells a story about the Silk Road. It says tea caravans left tea in the rain. The tea got mildewed and was left behind. Later, people in nearby villages ate it to stay healthy. They say the tea cured them. Other stories say dark tea started in the Ming dynasty. This was during the 15th and 16th centuries. It might have been traded even earlier by merchants.

China makes many famous kinds of dark tea. Pu'er tea comes from the Yunnan province. In Anhui, they make Lu'an basket tea. People in Guangxi sell Liubao tea. Some teas are pressed into hard shapes for storage. You might see them as bricks, cakes, or discs. They can even look like bird nests or mushrooms. In Korea, people made Tteokcha. They often pressed it into shapes like coins.

People use tea in many different ways. In Myanmar, people eat lahpet as a vegetable. In Thailand, people chew a pickled tea called miang. This tea is kept in bamboo baskets. Some raw teas can age for 50 years. This makes them very valuable to collectors. In Tibet, people drink yak butter tea. They boil the tea with sugar, salt, and yak butter. It provides important energy and nutrients.

Fermented tea, often called dark tea or post-fermented tea, is a unique class of tea. It is distinct from black tea, which is known as "red tea" (hong cha) in China. This tea undergoes a microbial fermentation process that can last from several months to many years. During this time, tea leaves are exposed to humidity and oxygen. This exposure triggers two types of chemical changes. The first is endo-oxidation, which comes from enzymes inside the tea leaves. The second is exo-oxidation, which is catalyzed by microbes.

These chemical changes transform the tea's sensory qualities. As oxidation progresses, both the leaves and the brewed liquor become much darker. The fermentation process also alters the tea's chemistry to improve its organoleptic qualities. This means the smell changes and the taste becomes more mellow. It typically reduces bitterness and astringency while improving the aftertaste and mouthfeel. Some microbes may even produce metabolites that offer health benefits. However, substances like ethyl carbamate (urethane) may also be produced during the process.

Microbes play the most important role in this transformation. Molds are the primary drivers of fermentation. Scientists once believed Aspergillus niger was the main organism involved. However, newer PCR-DGGE analysis suggests that Aspergillus luchuensis is actually the primary agent. There are three main ways to produce these teas. Piled teas, such as Toyama in Japan, use naturally occurring fungus in relatively dry conditions. Pickled teas use a wet process involving lactic acid bacteria. A third type, like Ishizuchi in Japan, uses both methods in succession.

The history of dark tea is a mix of legend and historical record. One legend says dark tea was an accident on the Silk Road and Tea Road. It claims tea caravans left tea soaked in the rain. The transporters feared contamination and abandoned the wet tea. Later, local villagers ate the mildewed tea to survive a sickness. The legend says the tea cured their dysentery. Other accounts suggest dark tea production began during the Ming dynasty in the 15th and 16th centuries. It may have been traded even earlier across Han and Tibetan borders.

China is the primary producer of fermented teas, especially in warmer southern provinces. Yunnan province is famous for Pu'er tea, which can be "raw" or "ripened." In Anhui, people make Lu'an basket tea. Guangxi produces Liubao tea, which is often sold as loose dark tea. To help with aging and storage, tea is often pressed into specific shapes. These include bricks, cakes, discs, or even bird nests. Some varieties are shaped into squares or mushrooms. In Korea, Tteokcha was a common tea. It was often pressed into shapes resembling coins with holes.

Tea can also be consumed as food rather than just a drink. In Myanmar, a fermented tea called lahpet is eaten as a vegetable. It is a major part of Burmese ritual culture. In Northern Thailand, people chew a pickled tea called miang as a stimulant. The leaves are kept in sealed bamboo baskets for fermentation. For young leaves, this takes four to seven days. For mature leaves, the process takes about a year. The Blang people in Yunnan eat a similar tea called miam, which is fermented in buried bamboo tubes.

Because of the way it ages, fermented tea can be very valuable. Raw tea can be aged for up to 50 years without losing quality. Ripened tea is often aged for 10 to 15 years. Many varieties are purposely aged in humid environments. This promotes the growth of certain fungi. These fungi create bright yellow spots called "golden flowers" (jin hua). In Tibet and Central Asia, tea serves a vital nutritional purpose. People boil fermented tea with salt, sugar, and yak butter to create yak butter tea. This provides essential calories and micronutrients.