How Tea Works

Serving saffron tea from pot into tea cup
Tea is one of the world's most sought-after drinks, more popular than Coca-Cola, coffee or wine. Sergio Amiti/Getty Images

Tea is the second-most consumed beverage on the planet, right after water. Every culture has its own unique customs involved with tea. The Japanese, for instance, hold tea in extremely high regard and developed the Japanese Tea Ceremony, or Chanoyu, as a ritualistic celebration of the drink. Many Americans drink iced tea, and Southerners are well-known for downing endless amounts of sweet tea. "Tea time" or "afternoon tea" is an indispensable part of English society, and numerous novels and films have immortalized the act as a distinctly British tradition.

Although it's largely a social drink, scholars have recognized tea as a medicinal substance for thousands of years. Recent research appears to confirm these claims, suggesting that tea carries several health benefits. Apart from providing you a pleasing sense of calm, drinking tea may also play a part in reducing the risk of cancer or heart disease.


We know very little about the origins of tea. Humans may have consumed tea for tens of thousands of years, but records that make reference to tea are only about 2,000 years old. One legend has endured -- that of mythical Chinese emperor Shen Nung, who allegedly ruled more than 5,000 years ago. Shen Nung was known as a skilled scientist and artist, and in order to enforce sanitation throughout China, he required everyone to boil all drinking water.

During a visit to a distant region of China, he stopped with his court to rest. As his servants prepared water, a gust of wind blew some leaves from a nearby bush into the water, turning the liquid an amber color. An inquisitive scientist, Shen Nung decided to experiment with the water and drank the infusion. He found the drink to be refreshing, and tea was born.

Maybe you've never experienced tea and want to learn more about it. Maybe you're a coffee addict looking to curb your addiction with tea, which contains much less caffeine on a per cup basis. Or maybe you're simply a tea lover and want to find out more about your favorite drink. In this article, we'll talk about the origins of tea and the different types of tea. We'll also discuss the health benefits of tea and the steps involved in tea preparation.

Growing and Producing Tea

© Photographer: Craig Hanse | Agency:

There are four main types of tea: green tea, black tea, oolong tea (pronounced wu-long) and white tea. There are even more varieties, including flavored, scented and "herbal infusions," but for the sake of simplicity we'll focus on the big four right now. What many people don't know is that these four types of tea come from one plant, not four different species of plant.

All tea begins as the plant known as Camellia sinensis. It's the way the tea leaves are processed that gives us the different teas and their specific taste, color and scent.


Tea is similar to wine in that the atmosphere in which it's grown determines much of the flavor and quality. Tea plants typically fare best in acidic soil and regions with heavy rainfall (around 40 inches per year), although they can be grown anywhere from sea level to altitudes as high as 1.3 miles above sea level.

Mass-produced tea is grown on large plantations in more than 30 countries, but the four biggest producers are China, India, Kenya and Sri Lanka. Most tea is picked by hand for better quality -- machines tend to be too rough and end up damaging too many leaves. There are generally two harvests throughout the year -- "first flush" in early spring and "second flush" in summer. Growers keep the tea plant in the early stage of growth with constant pruning and pick only two leaves and a bud from the tops of the plants.

© Photographer: Bayu Harsa

Once workers gather enough quantities of tea leaves, their stash is quickly carried over to a tea factory located right on the plantation. The factory is placed close to source of the leaves because once the tea is plucked, oxidation immediately begins. The oxidation process is important in understanding tea -- it must be closely monitored during production and is essential in determining the type and quality of the tea. Before we go any further we'll talk about oxidation.

Oxidation is what happens when you cut up a piece of fruit and leave it out for too long -- the color of the fruit changes, usually turning brown or black. Oxidation is also a fancier name for what happens when your car rusts. Oxygen molecules react with any kind of substance, from the metal on a bicycle to the inside of an apple. Normally, the skin of an apple protects the inside from oxygen, but when the fruit is exposed to the air, oxygen molecules actually "burn" it. Oxidation isn't great for fruit or the hood of your car, but, depending on the type of tea you want, it can be a necessary part of processing tea leaves.

Processing Tea

Cup of tea
© Photographer: Scott Karcich

We know that there are four main types of tea -- green, black, oolong and white. They all look and taste differently, yet they all come from the same tea plant. This plant is capable, like anything with living tissue, of succumbing to oxidation. In this section we'll find out the role of oxidation by looking at the different steps of processing tea.

Black Tea

You are probably most familiar with black tea. It's the world's most popular type of tea, and it accounts for 75 percent of all production. Names such as "English Breakfast Tea" or "Earl Grey" commonly stock the shelves in grocery stores. Without milk, the drink has a reddish brown color and a particularly bold taste.


There are two ways to make black tea -- the orthodox method and the CTC ("Cut, Tear, Curl") method. Both are similar in the five steps they take, except the orthodox method is mostly done by hand, while the CTC method is done by machine. Remember, the workers have just transported the tea leaves from the plantation to the factory where the following steps will take place:

1. Withering - Tea leaves are spread out in large groups and left to wither, losing some of their moisture.

2. Rolling - In the orthodox method, the leaves are now rolled so the remaining moisture is released, coating the surface of the leaves with its juices. This method is particularly gentle, so the tea leaves are usually left whole and unbroken. The CTC method, however, chops the tea leaves into tiny pieces, and you're left with a more dust-like substance.

3. Oxidation - The leaves are spread out again, this time in a cool, damp atmosphere, and the oxidation process continues. The color of a tea leaf is originally green, but as oxygen reacts with the cell tissues, it begins to turn a copper color. This is very similar to tree leaves turning from green to brown in the fall.

4. Drying - The leaves are dried with hot air, and the color changes from copper to brown or black.

5. Sorting - The final process involves sorting the tea leaves by size and grade.

Other Types of Tea

© Photographer: Katarzyna Malecka

Green Tea

It's difficult to imagine green tea coming from the same plant as black tea. The color of green tea is much different -- hues range from green to yellow -- and the taste and smell of the drink are very grassy and natural.

Like black tea, green tea also has five steps in its process, and, when written out, they look nearly the same. The five steps for processing green tea are: withering, steaming, rolling, drying and sorting.


The big difference here is the inclusion of steaming and the removal of the oxidation process. After the leaves wither and lose some of their moisture during the first step, they are immediately steamed or pan fried. This stops the oxidation process before it can really get started -- in a way, it's almost like putting car wax on your car to keep it from rusting. Steaming "freezes" the tea leaf in its current state, keeping the color green. After steaming, the leaves are cooled and rolled to release the remaining moisture, dried with hot air and sorted according to size and grade.

Oolong Tea and White Tea

Oolong tea falls right between green and black. It's only partially oxidized, so it never quite reaches the same stage as black tea.

White tea is a specialty tea and somewhat rare, picked only two days out of the year when the buds haven't fully opened. It's similar to green tea in color as the oxidation process is stopped early on, but the taste is smoother and less grassy. The rareness of white tea makes it slightly more expensive than others -- it has only been available outside of China for a few years, as the leaves were only reserved for Chinese nobility.

Herbal "Tea"

Some teas can have scent or flavor added to them. Chai tea, for example, is black tea brewed with several spices, including cinnamon, cloves, pepper and ginger.

A common misconception surrounds herbal "teas," however. Drinks labeled "herbal tea," "herbal infusion" or "tisane" actually have nothing to do with the tea plant. They are simply dried fruits or herbs infused in hot water. People generally associate herbal infusions with tea, though, and each has its own unique qualities. Here are a few major kinds:

  • Rooibos - Grown in South Africa, this "tea" comes from the plant Aspalathus linearis. Rooibos is red in color -- the name is Afrikaans for "red bush" -- and the flavor is described as sweet and nutty.
  • Herbs such as chamomile, mint, sage, thyme and rosemary are commonly used as infusions.
  • Mate (pronounced mah-tay) - Made by steeping the leaves of the yerba mate plant in hot water, this drink is popular in South America, especially Argentina and Uruguay. A cup of mate contains the same amount of caffeine as a cup of coffee, and the drinking tradition is unique to other teas and infusions. The brewed leaves are left in the cup, and a filtered straw is used to drink the liquid.

Tea Preparation

Do you want convenience or quality? Bagged tea is a little easier,
Do you want convenience or quality? Bagged tea is a little easier,
© Photographer: Shuttlecock | Agency:

When you're in a grocery store, you might notice that most of the tea is bagged, the kind you simply drop into a cup of hot water and let steep for a few minutes. Yet if you've ever been into a specialty tea shop, nearly all of the tea is loose leaf -- shopkeepers measure out a certain amount of leaves from bins and put the tea in a larger bag or tin. You then take your tea home and prepare it with a tea pot or tea strainer. What's the difference between bagged tea and loose leaf tea? Is one better than the other?

Tea lovers claim that the best kind of tea is loose leaf. Loose leaf tea is traditionally picked and processed, whereas bagged tea is normally produced by the CTC method described earlier. Because of the tiny, dust-like quality of bagged tea, many of the nutrients available in the bigger leaves are lost. The small bag also causes some problems with tea experts. To get the most in flavor and nutrients out of tea, more space and water circulation is needed for the leaves to expand and unfurl. This isn't very easy with bagged tea since the tea is "trapped."


This isn't to say bagged tea is terrible. You can still produce a decent cup from bags, and it's slightly more convenient (and much less expensive) than drinking loose leaf tea.

A simple tea strainer, so you’re not swallowing any loose leaves
A simple tea strainer, so you’re not swallowing any loose leaves
© Photographer: Agg | Agency:

Once you've chosen your tea, how should you prepare it? How long should you brew the tea? Does it matter how hot the water is?

Most people take water for granted when brewing their tea, but the temperature at which tea is prepared can affect the quality of the tea. The water used for black tea is the only water that should be completely boiled at a temperature of about 200 degrees Fahrenheit. Oolong tea is typically brewed with water heated to a slightly lower temperature of 190 degrees Fahrenheit (almost boiling), and green and white teas are steeped in steaming water, or water with a temperature of about 170 degrees Fahrenheit. The length of steeping time also varies depending on the type: black and white teas take 4-5 minutes to steep, oolong takes about 3-4 minutes, and green can take as little as 30 seconds to 2 minutes.


The Health Benefits and Science of Tea

© Photographer: Hans-jürgen Oertelt

Research findings about the health benefits of tea shouldn't be surprising -- the Chinese have praised tea for its medicinal qualities for thousands of years. Only much more recently have Western scientists begun to explore what's inside tea.

A single tea leaf contains a wide variety of substances, including amino acids, carbohydrates, lipids, minerals and vitamins. The two substances receiving the most attention in tea, however, are antioxidants and caffeine.



We learned about oxidation a few sections ago. Just like tea leaves, apples and car hoods, humans are susceptible to oxidation. Oxygen molecules create stress on our tissues and organs by introducing harmful free radicals that lead to complications such as cancer and heart disease. Free radicals are charged atoms or molecules -- they have one or more unpaired electrons. This causes the free radicals to become highly unstable, and they rush around the nearby molecules trying to find the appropriate electron and gain stability. (Think of them as obsessive-compulsive, always trying to keep an equal number of protons and electrons.) They have to steal an electron from the molecules -- this creates a chain reaction of giving and taking, and eventually an entire cell will be destroyed.

Antioxidants are substances that slow down the damaging effects of oxidation, and they are found naturally in fruits and vegetables. Once they are introduced into the body, antioxidants neutralize free radicals by giving up an electron. The antioxidant is harmless, because it is stable with or without its extra electron. Examples of powerful antioxidants are vitamin C, vitamin E and beta-carotene.

Tea contains a wide range of antioxidants. Scientists haven't agreed yet on the effectiveness of these substances, but the general consensus points toward polyphenolic compounds as the most abundant and helpful source of antioxidants in tea. Several kinds of polyphenols known as catechins -- including epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate (EGCG) -- are common in green tea and considered to provide the best protection from oxidation. Black tea offers strong antioxidants, too, but the polyphenols have different structures and are not quite as effective. The reason for this goes back once again to the different ways to process tea -- the catechins that stay in green tea transform into theaflavin and thearubigin in black teas.

Although evidence is inconclusive, results from several recent studies show that tea consumption protects against lung, breast, skin, colon and liver cancers, heart disease, high cholesterol and high blood pressure. Studies in Japan, where green tea is most popular, also pointed out EGCG as a main source of weight loss [source: Science News Online].


Like coffee, tea contains caffeine, the stimulant that wakes us up and increases concentration. The amount of caffeine in a cup of tea varies greatly -- everything from location to processing decisions affects the outcome -- but most agree that there's more caffeine in coffee than in tea. A standard cup of coffee contains anywhere from 80 to 120 milligrams (mg) of caffeine, while a cup of tea can have between 20 and 60 mg of caffeine. Most reports note that black tea is the strongest, containing about 30 to 40 mg. Green tea and oolong tea contain less, somewhere between 10 and 20 mg. White tea is thought to contain almost a negligible amount of caffeine, about 1 percent of the caffeine in a cup of coffee.

For lots more information on tea and related topics, check out the links that follow.

Lots More Information

Related Articles

More Great Links

  • Hohenegger, Beatrice. "Liquid Jade: The Story of Tea from East to West." New York: St. Martin's Press, 2006.
  • "Tea Growing." UK Tea Council.
  • "Tea Grade Definitions and Tea Production Processes." Tea Fountain.
  • "The History of Tea." Stash Tea.
  • "Tea polyphenols: prevention of cancer and optimizing health." The American Journal of Clinical Nutrition.
  • "Trimming with Tea." Science News Online.