What are the types of Chinese tea? What is fermentation and enzymatic oxidation? What is "post-fermented" tea? We will try to answer these questions in our article.
Exist great amount various kinds Chinese tea, they are all made from the leaves and buds of the same plant - Camellia sinensis. But thanks to the different varieties of this plant, the geography of its growth and the processing technology of the collected, fresh tea leaves, ready tea may have absolutely different taste and aroma.
There are quite a few approaches to the classification of Chinese tea types, but today, the most common is the classification according to the degree of fermentation of the tea leaf, or rather, enzymatic oxidation (or simply oxidation) and fermentation. Although, for simplicity, many do not separate these different chemical processes that occur in the tea leaf during its processing, combining them and operating with one term - fermentation.
According to this classification, all Chinese tea can be divided into six main groups or types: green, white, yellow, oolong, red, and pu-erh. In order to understand the difference between green tea and white tea, or red tea and oolong tea, one should understand what processes take place in a fresh tea leaf and what happens to it as a result of processing.
We will deliberately not give complex and detailed definitions of the main chemical processes occurring in the tea leaf, this is not the purpose of this article. To understand the approach to the classification of Chinese tea, simple definitions will suffice, perhaps even with some small assumptions.
enzymatic oxidation.
Enzymatic oxidation by their own enzymes - This is a multi-stage process of interaction in the tea leaf of internal enzymes (enzymes) and oxidized substances. A similar process occurs with a cut apple or a peeled banana, when after a while their surface begins to darken. It is as a result of the oxidation green color fresh tea leaf changes to dark.
It is worth noting that as soon as a fresh tea leaf is plucked from a bush, spontaneous enzymatic oxidation begins, but this process is not controlled and proceeds rather slowly. In production, for controlled oxidation, special conditions are created under which a constant, high level oxygen. Tea leaves are laid out in a thin layer outdoors, or in a room that provides a constant supply of fresh air. The required level of enzymatic oxidation is carefully controlled by the tea master.
To speed up the oxidation process, at the next stage of production, tea leaves are softened, crushed, and twisted. The main goal is the destruction of the cell membrane, since in intact sheet, oxidizable substances and enzymes are separated by membranes.
When the required level of enzymatic oxidation (roughly speaking, fermentation) is reached, at the next stage, the process stops, or rather, it slows down as much as possible. To do this, the tea leaf is subjected to heat treatment, it is heated to a high temperature - roasted, the Chinese call this stage “killing greens”.
Fermentation.
Fermentation or enzymatic oxidation under the influence of external factors - this is the interaction of oxidizable substances with enzymes that are not formed and are not located in the tea leaf itself. These enzymes can be produced by various microorganisms and bacteria found on the surface of the leaf (microbial activity).
To speed up the fermentation process, special conditions are created in production - the absence of oxygen and high humidity and temperature. These conditions are completely different from the conditions for enzymatic oxidation (under the action of one's own enzymes), for which, on the contrary, air enriched with oxygen is very important.
Fermentation is an important step in the production of aged teas, especially pu-erh. In particular, in the production of shu pu-erh, the Vo Dui technology is used. Minimally processed tea leaves are collected in heaps, sprayed with water and covered with thick burlap, thereby creating ideal conditions for microbial activity - restriction of air flow and increased humidity and temperature. In this form, tea raw materials are left for enough long time, a month or more, stirring occasionally and maintaining the required level of humidity and temperature. Achieving the required fermentation is determined by the technologist who controls all production processes.
Classification of Chinese tea according to the degree of fermentation and its types.
And so, having figured out what chemical processes are possible in a tea leaf, we can proceed to the classification of Chinese tea into types according to the degree of fermentation. Under the fermentation this case we will understand either enzymatic oxidation (under the action of internal enzymes) or the process of fermentation (enzymatic oxidation under the action of external factors). In reality, these two processes can run in parallel, but depending on the type of tea, one of them actually dominates.
Green tea.
Green tea is practically not subjected to enzymatic oxidation, and even more so fermentation. As a result of its minimal processing, conditions for accelerated, controlled oxidation are not created, but on the contrary, tea leaves are almost immediately heat-treated - they are fried to stop spontaneous oxidation.
White tea.
For production white tea first of all, selected raw materials are collected - these are only the buds and the youngest leaves, which also undergo minimal processing and undergo a slight enzymatic oxidation.
Yellow tea.
Yellow tea is also practically not oxidized. The peculiarity and value of this tea lies in the special production technology, tea raw materials go through a very slow process. heat treatment- yearning. As a result yellow tea acquires a unique refined taste and aroma.
Oolong or oolong tea.
Oolong teas undergo partial (15-80%) enzymatic oxidation and are often referred to as semi-fermented teas. All oolongs can be divided into two groups: light - less oxidized and dark - more oxidized.
Red tea.
As a result of production, red tea undergoes almost complete enzymatic oxidation, under the action of its own enzymes. As a result, tea leaves have a dark color.
Puer.
Shu pu-erh during production undergoes both significant enzymatic oxidation under the influence of internal enzymes, and fermentation under the influence of external factors. And as we have already said, the fermentation process (aging of raw materials using the Vo Dui technology) is one of the main ones in the production of shu pu-erh.
Sheng Pu-erh undergoes a slight partial enzymatic oxidation during production, and therefore has a lighter leaf color. And only then, pressed, ready-made pancakes are placed in special rooms, with the required level of humidity and temperature, where it is stored for several years, undergoing slow fermentation.
Pu-erh tea is also often called “post-fermented” tea, meaning that it first undergoes the process of enzymatic oxidation by internal enzymes, and then undergoes fermentation under the influence of external factors using the “Wo Dui” technology, or stored in special storage facilities.
And so we summarize this article: only pu-erh undergoes pronounced processes of enzymatic oxidation, and especially fermentation, during production, while the rest of the types of Chinese tea, to one degree or another, undergo only enzymatic oxidation.
The history of pu-erh goes back several centuries. This is one of the most conservative teas in terms of manufacturing technology. It practically has not changed with the expiration of centuries.
Pu-erh production technology
This tea is made from leaves harvested from old tea trees. The older the tree, the more valuable the tea from its leaves. A large sheet is subjected to the procedure of "killing" greens, twisting, drying.
At this stage, the technology forks. In the first case, the tea leaf is pressed and allowed to grow old. naturally. This could take decades. From year to year taste qualities teas will improve and in 20-30 years you will get a wonderful, seasoned and very expensive pu-erh. Often, pressed pu-erh is placed for fermentation in the year of the daughter's birth. By the time of her wedding, pu-erh turns into a beautiful and expensive dowry.
Because natural fermentation is a fairly long process, manufacturers have learned to speed it up. Accelerated fermentation consists in the fact that the tea leaf is folded into heaps and wetted with water. There is a fermentation of juices in tea leaves with the participation of bacteria and microorganisms. By adjusting the temperature inside the "tea" heap (drying, watering), the fermentation process is controlled.
At present, when the demand for pu-erh has increased, it is produced more often in this accelerated way.
The last stage in the production of Shu Puer (this tea is presented on the tea market for the most part) is pressing. The tradition of pressing originates in those distant times, when tea was pressed for ease of storage and transportation. At present, for Shu-pu-erh it is more a tribute to tradition than a necessity.
And yet, it is pressed into different shapes: pancake, brick, rectangular tile, bird's nest, mushroom). Often, pressed forms of pu-erh are decorated with prints of various images, inscriptions, plots, etc. For making tea, it is most convenient to use small pressed balls for one tea leaves.
Types of pu-erh
There are four stages of fermentation and, accordingly, four types pu-erh tea:
Maocha - raw tea - is an unpressed sheet of pu-erh and is a raw material for the preparation of all types of pu-erh.
Shen Puer - this is tea, which is pressed maocha, not subjected to additional processing.
Shu Puer - pressed maocha, subjected to additional processing, accelerated fermentation. On receipt quality pu-erh This technology takes about 2-3 years. During this time, the bitterness, stiffness of the leaves, the smell and taste of mold leave the tea. The taste of tea is influenced by many factors, such as bacterial cultures, the organization of the process, the temperature maintained in heaps for fermentation, etc. The leaf of this pu-erh is shiny, red-brown, the color of the infusion is red, transparent, the aroma is bright and persistent .
Aged Sheng Pu-erh - This is a tea obtained by traditional technology with slow and gradual fermentation (post-fermentation). Its leaf is dense, dark green, the taste is strong, with a sweet aftertaste, the aroma is persistent and pleasant. This tea is considered the most expensive, noble in taste and environmentally friendly.
On sale, on the international tea market, there are two types of pu-erh - Shen and Shu.
According to the original leaf, tea is divided into varieties: jinya, gunting, licha, teji (highest), first, second, third, etc.
Pu-erh is a unique type of tea that does not lose its properties over time, but enriches them. Over the years, the taste and aroma of tea become only brighter and purer.
The impact of pu-erh
- Pu-erh is one of the most "energy" drinks, with a low content of caffeine - it increases efficiency, raises vitality.
- It has a beneficial effect on the digestive system.
- Promotes the digestion of fatty foods and the breakdown of body fat.
- Activates the liver and gallbladder.
- Activates metabolic processes.
- Reduces pressure, removes toxins.
- Improves skin color.
- Reduces cholesterol levels by 30-60% (when using pu-erh for a month three times a day).
- It is useful to drink Pu-erh in the morning, while driving for a long time, before a responsible business, but should not be consumed before going to bed.
- Strongly brewed pu-erh can create the effect of slight intoxication.
It is impossible to bypass the process of making pu-erh attention, because it is the secret of the uniqueness of this tea.
How to prepare pu-erh tea, we will tell in the next article, because this topic is worthy of a separate discussion.
Pu-erh is not only one of the most popular, but also one of the most expensive varieties tea in the world. What is pu-erh made of, why has it gained such popularity in the world and why is it so expensive?
Pu-erh is tea that has undergone a process of microbial fermentation from several months to many years, usually in a humid environment and with access to oxygen. Harvested green tea leaves undergo microbial fermentation - natural or artificial (accelerated) aging.
Pu-erh production steps:
- collection of tea leaves;
- withering;
- twisting (to extract as much juice from the leaves as possible);
- fermentation (necessary to accelerate the fermentation of tea leaves using high temperatures);
- drying (goal: to stop the fermentation process);
- pressing;
- ripening (for shen pu-erh).
Home hallmark pu-erh from other teas is a fermentation step that can take different times. Microorganisms participating in it noticeably change the chemical composition and taste of tea.
There are 2 main types of pu-erh:
- Sheng Puer. Traditionally, pu-erh is obtained by ripening the raw material. Depending on the technology, this process takes several days. The resulting product can then be marketed under the name "mao-cha" or undergo further ripening. In the second case, it is pressed into molds and stored under the necessary conditions.
Ripening time can vary from months to decades. Tea that has passed the ripening stage is called shen-puer.
- Shu Puer. In 1973, Kunming Tea Factory began to apply a new process of multiply accelerated fermentation. Soon Menghai Tea Factory introduced this technology and began to produce the new kind tea - shu-puer.
This technology is called "Wo Dui" wet stacking: tea leaves are collected in heaps, moistened with water, and then covered with a cloth. Under the influence of humidity and high temperature, the process of fermentation and fermentation begins with the participation of microorganisms, mold fungi. In order for the pu-erh to age evenly, the pile is stirred daily and covered again. The process of preparing high-quality shu pu-erh lasts at least a year.
You can often find sellers claiming that pu-erh only improves in taste over time. In reality, it depends on the technology of its production. Shen pu-erhs are distinguished by the fact that you can independently control the degree of fermentation, and, accordingly, the taste of tea. This process requires a considerable amount of time: after 2-3 years of storage, the bitterness and roughness of a fresh leaf begins to leave the tea. According to connoisseurs, tea becomes unique after 10-20 years (if stored properly).
Shu pu-erhs do not change much during long-term storage, since the technology of their production involves rapid fermentation with its subsequent stop without a ripening stage. It is believed that over time, the so-called “taste and smell of wet heaps” disappears from shu pu-erh, which improves their characteristics.
Shen pu-erhs over 40 years old are almost never found on free sale and are objects for collecting, and shu pu-erhs have been produced since 1973 after the invention of the necessary technology.
Dependence of tea color on age
How to brew pu-erh
There are several options for making pu-erh. For brewing, on average, take 4 g of tea per 150 ml of water (the standard ratio for tasting is 6 g per 100 ml of water).
You can find recommendations for pre-rinsing or frying pu-erh before brewing. Washing removes dust, and roasting provides disinfection, since long-term storage of pu-erh makes it possible for microorganisms to develop in it.
Very fast rinsing with boiling water is possible - in this case, both dust removal and disinfection are ensured. In any case, pu-erh in the form of a pressed "pancake" crumbles before brewing, and sometimes even rubbed more finely.
Brewing takes place quite traditionally - pu-erh is poured hot water at a temperature close to boiling.
By the time of infusion, options are also possible.
It is often recommended to infuse the first brew (the first two brews) of pu-erh for just a few seconds, then immediately drain the infusion, and with repeated brewing, increase the brewing time by 15-30 seconds each time. In this mode, pu-erh can withstand, depending on age and quality, from 5 to 10 brews.
There are lovers of brewing tea with a long exposure - up to several minutes. In this case, re-brewing is possible no more than 1-2 times, and the resulting infusion has a more pronounced taste.
Pu-erh can also be brewed according to the Lu Yu method: using a glass water container and soft water. Lu Yu recommends drinking tea after all the tea leaves have sunk to the bottom of the vessel.
It is customary to consume pu-erh in small portions in order to appreciate not only the taste, but also the aftertaste.
Pu-erh resin is a high quality product that is harvested from pu-erh trees. It belongs to the elite products and is very different from other tea varieties. Pu-erh resin invigorates and energizes. Its taste is very special and certainly not everyone will like it.
There is no such person in the world who would not drink tea. This soft drink drink in all countries. There are many different types tea, but the most famous and consumed are black and green. And today we will talk about one of the exotic types of this drink - pu-erh tea.
The birthplace of this drink is the Chinese province of Yunnan. The process of its preparation is unusual, it uses the so-called fermentation of the leaves, that is, enzymes are used to age them. Therefore, pu-erh can be attributed to centenarians. If ordinary tea becomes completely tasteless after ten years, then this variety can delight you with its qualities and bouquet of taste for up to thirty years. Interestingly, the tea that we call black, in fact, would be more correct to call it red, but pu-erh is real black tea.
Puer effect.
Some believe that pu-erh can have an effect similar to soft drugs or that you can feel intoxicated by using it - pu-erh effect. However, this can be argued, since it causes a different reaction. Someone does not feel anything at all, someone has a feeling of cheerfulness and some euphoria. In fact, the effect of the drink can be compared with a hookah, but unlike the latter, it does not bring harm to the body. Apparently, this is the secret of his popularity. When tasting pu-erh, no manifestations that are inherent in narcotic substances were noticed, but a positive effect on the body was noted. For example:
- 1. If you need to cheer up, then Puer tea is what you need. Its tonic effect, due to tannin, a substance contained in the tea leaf, is quite strong. Therefore, it is not recommended to drink the drink at night.
- 2. Another positive effect of this variety is that it helps to remove cholesterol plaques, helps cleanse blood vessels and thin the blood, which has a good effect on the cardiovascular system.
- 3. European scientists have proven that pu-erh removes toxic substances and toxins from the body, and also helps the gastrointestinal system to digest fatty foods. Moreover, it eliminates hangover syndrome and other types of poisoning.
- 4. Pu-erh contains substances that reduce the risk of various infections, as well as cancer.
- 5. Renders positive influence on the color and structure of the skin, that is, it rejuvenates it.
However, when using this drink, some nuances should be taken into account. It is not consumed hot, only warm. It is recommended to drink pu-erh only after eating, as it may have a negative effect on an empty stomach.
Pu-erh tea production technology.
The manufacturing technology of this variety consists of the following stages: collecting a tea leaf, withering it, twisting (leaves mechanically destroy and squeeze out juice), pressing.
This Chinese tea, in turn, can be divided into types, depending on the manufacturing technology. "Raw pu-erh" - is produced according to the usual technology, and fermented during transportation. "Forced Puer" - drink long-term storage. The advantage of the first type is that it is possible to control the degree of fermentation, and therefore the taste too. It happens in the following way. Tea is stored for about four years, by which time the bitterness and roughness inherent in fresh leaf, leaves, and the tea is ready to drink. And if you have patience and wait ten or fifteen years, then he will be able to surprise and please with a rich taste. And not only taste, but also useful properties.
Pu-erh tea is available in various forms:
Drink this drink should be in small portions, only then you can appreciate the taste and aftertaste.
How to choose the right pu-erh tea?
To begin with, in order to choose the right pu-erh tea, it is important to know which factories produce it in full accordance with the technology. These are Xiaguan, Shuangjiang Mengku, Menghai.
As a rule, buyers, having come to the store, rely on the advice of the seller, but it should be remembered that the main thing for him is to sell his goods. No need to buy the first tea that comes across, it is better to ask a specialist consultant about the properties and qualities in more detail. various options drink. And remember: the best tea is the most expensive.
Pay attention to how the pu-erh is packed and to the conditions of its storage. It is known that any tea, regardless of its variety, should be stored in a dry and cool place. As a rule, it goes on sale in paper packaging, which is difficult to confuse with something. Therefore, if you see pu-erh in some other packaging, you should not buy it, as it may become moldy.
The second thing you should pay attention to is the aroma of tea, as pu-erh has a special, characteristic smell. The aroma of the briquette may have a woody or smoky hue, it all depends on its age. But other extraneous odors should not be, especially the smell of mold. It is known that tea absorbs all odors well, and if it was stored incorrectly, you will immediately feel it. This tea is not worth buying.
The third selection criterion is the color of the tea. Briquettes of aged pu-erh have a reddish color, and if the tea is slightly aged, then greenish. It should be known and remembered that this variety is never uniformly black. If you see any white or yellow blotches on it, then most likely it has begun to mold. And yet, inspect the packaging carefully, it should not be damaged.
Before choosing a store or type of tea, search the Internet for reviews, you may find detailed information and it will help you in your choice. If you are just joining the ranks of this tea lovers, then it is best for you to start with fermented pu-erh, as it tastes simpler, and the exotic taste of raw pu-erh can forever discourage you from drinking it again, ever.
How to brew pu-erh?
One of the conditions useful properties Pu-erh tea is its proper preparation. The rules that we will introduce you to today came to us from China, and those who know a lot about tea adhere to them.
1. Sweet additives spoil the taste and properties of tea. If you lead a healthy lifestyle, then you probably strictly dose your sugar intake, in addition, the sweetness will prevent you from enjoying the real taste of pu-erh. In addition, in combination with sugar or any sweetener, it will no longer contribute to the cleansing of the body.
2. good tea depends on the cookware. For making tea puer is better use dishes made of glass or porcelain, but in ceramic dishes he loses his taste. Brew tea in small portions - at one time, as it does not retain its properties in the finished form for a long time. After you have drunk your tea, teapot wash (without dishwashing detergent) and dry it well. If you do not plan to treat anyone, but brew tea for yourself, then it is better to do it in a glass or cup so that the dishes can then dry and get rid of the smell of drunk tea. If you want to get more aesthetic pleasure, brew tea in a glass, and you can watch how the tea leaf, twisted at the beginning, unfolds, takes in water and settles to the bottom.
3. Clean and soft water. According to Chinese traditions tea drinking, in order to get a truly tasty and worthy drink, you should use rain or well water for it. Since neither one nor the other is available to us, we can use the water passed through the filter, put shungite stones in it and leave for a day. The water becomes soft and filled with the energy of the stones. To brew pu-erh, use water with a temperature of 80 to 90 degrees, but not boiling water.
4. Amount of tea leaves. One brewing container requires from 4 to 7 grams of tea. This amounts to one to one and a half teaspoons. Do not forget to pre-wash the tea leaves.
5. Brewing process. Before using the teapot, rinse it with boiling water so that it warms up from all sides. Then pour into it hot water by a third, and after a few seconds, drain it. From now on, your tea "breathes". Now pour water up to half of the kettle and wait five minutes. Ready drink should be poured into small cups.
6. Number of brews. Surprisingly, pu-erh tea leaves can be used 4 to 7 times.
Brewing time. The first use requires forty seconds, the second fifty, the third one one minute, and then each brew does not require ten seconds more than the previous one. It should be noted that the taste of each of them is different. The first turns out to be more saturated, and the last, without losing the rich smell, is lighter.
If you overexpose the first tea leaves, then your drink will be tart. If pu-erh is brewed more than an hour ago, it should not be consumed, as the tannins contained in the leaves will give it a bitter and bitter taste. bad taste. And the Chinese generally consider such a drink harmful to the body.
There is another way to brew pu-erh tea, it can be boiled. To do this, you will need a burner and a glass teapot. Thus, you can see the moment when the water starts to boil. Once this has happened, start stirring the water in a circular motion. And pour tea (washed and soaked) into the formed funnel. Once the tea is in the water, lower the heat to stop the simmer for a few seconds. When you see brown foam and bubbles on the surface, turn off the burner. Cover the pot with a lid and let the tea steep. And at this time, enjoy the dance of opening tea leaves. When they settle to the bottom, tea can be drunk.
You can also cook pu-erh in milk. Milk softens the taste of tea, but increases its consistency.
Which type of pu-erh tea and how you choose to brew it depends on your taste, and skill is a matter of time.
Also, read the website.
- the essence of the same plant - Camellia sinensis (Camellia sinensis). It all starts with collecting primary processing green tea leaf or buds (tips), which, as a result of a special technological process and become those teas that we choose according to our taste and color, depending on preferences.The basis of the technological process for the production of any kind of tea is the process of fermentation and oxidation. In fact, in tea production, the term "fermentation" is not used in the literal sense. In biology, this is the process of activity of microorganisms without the participation of oxygen. Tea fermentation is a biochemical transformation inside the tea leaf, taking place with the participation of oxygen and oxidative enzymes of the tea leaf. The task of fermentation is to maximize the accumulation of valuable flavor and aroma properties of tea by changing chemical composition tea leaves and ultimately obtaining high-quality tea from the raw materials.
Biochemical transformations of the tea leaf begin immediately upon its collection. Green tea leaves are harvested, dried in the sun or in ovens, crushed, rolled and allowed to lie down so that the leaf releases juice, salt and essential oils, which, when interacting with air, cause chemical transformations. This starts the process of enzymatic oxidation. Then the tea leaf is again steamed or heated, poured with water, dried, crushed again and heated, etc. in various variations. The more manipulations, the higher the degree of fermentation.
The processes of fermentation and oxidation proceed in parallel in tea, and therefore they are often replaced, meaning one under the other. There is no big trouble in this, but to define this mutual process, it is rather more correct to use the term "enzymatic oxidation". Different varieties teas are also fermented and oxidized in different ways, that is, the time of stopping the oxidation process and fixing the degree of its fermentation depends on what kind of tea they want to get.
Yes, the process of oxidation green tea stops or due to hot drying immediately after the collection of the sheet or treatment with hot steam. Therefore, this tea retains its natural fresh fragrance and taste. The category of non-fermented teas and lightly fermented teas also includes white and yellow teas.
The goal of oolong fermentation and oxidation is to achieve only partial fermentation. To do this, the tea leaf is crushed and stirred in such a way that the leaf gives juice only on a small area of the leaf, most often along the edges. Masters strive to ensure that the sheet remains intact and does not break. From time to time, the collected raw materials are sprayed with water. Humidity retards leaf drying and enhances and speeds up fermentation. After a few hours, the oolong fermentation process is stopped by rapid roasting at a temperature of 100 degrees. Then, a still warm soft sheet is twisted and finally dried. Partially fermented and oxidized teas include some green teas and many oolongs. Their aroma is subtle, but rich.
Black (red) tea refers to fully fermented teas. For fermentation and oxidation, tea is laid out on racks or grates in a well-ventilated area. Under conditions of high humidity and a certain air temperature, chemical reactions begin in the cells of the tea leaf. As a result of fermentation of cell sap, new substances are formed in tea. They give it tea infusion fruity-spicy dense aroma and rich color from ruby to red-brown.
The peculiarity of post-fermented teas is that they undergo a fermentation process, which can be stopped at a certain moment and then resumed again. Mature pu-erh is a post-fermented tea. It is heavily fermented at the factory, but not fully oxidized like red tea. In this case, one should distinguish between the post-fermentation of Shu and Shen Pu-erh. Accelerated aging, strong oxidation and post-fermentation of shu pu-erh takes place in factory fermentation warehouses. At a certain temperature, a wet tea stack is laid tightly on a concrete floor in the form of a semicircular roller. Thus, contact of the stack surface with air is minimized. Then, to create necessary conditions for the development of the necessary microflora, which ensures maximum fermentation, the stack is covered with a tarpaulin. In order for beneficial bacteria to multiply, hygienic conditions are strictly observed during fermentation. Of course, during the fermentation of tea, its oxidation also occurs in parallel. Pu-erh fermentation is stopped by drying, often after the tea has been steamed and pressed. If we are talking about the post-fermentation of sheng pu-erh, then they mean its ability to oxidize and ripen for years during storage due to internal natural processes. Shen pu-erh only becomes post-fermented some time after the young fermented sheng pu-erh is produced and leaves the tea factory.
And lastly, the degree of fermentation of tea is determined not by the color of the tea leaf, but by the color of the infusion that you drink. The darker it is, the more fermented the tea.
