Field to Cup: The 4 Steps in Tea Production

Those tea leaves went through a lot before they made it into your tea pot. Read on to discover the details of their journey.
Camellia sinensis tea plants.
A hedge of camellia tea ready for harvest.

Did you know that corn comes from the corn plant and apples from the apple tree? I’m sure you did.

But did you also know that tea comes from the tea plant?

Tea is a plant?

Yes, tea is a plant. Specifically, it is the tea plant, Camellia sinensis, which grows naturally as a shrubby tree and is closely related to ornamental Camellias so popular in gardens and urban landscapes.

And yes, tea is also a hot beverage. But every type of real tea—green, black, white, oolong, pu’erh—begins as leaves of Camellia sinensis and is finished by expert tea makers who process leaves for each particular tea.

Confusion arises nowadays because any herbs, flowers, or fruits that get steeped in hot liquid are called “tea.” But as a tea drinker it is important to know the difference between real tea and other types of infusions. Here today I am going to describe what Camellia-derived teas is, how it is grown, how it gets manufactured, and how it ends up on the shelves of your tea merchant.

There are four necessary steps in the process of getting tea from the field to your cup:

  1. Cultivation
  2. Harvest
  3. Manufacture
  4. Everything else

A detailed post could be written on each of these steps but for today we’ll keep things basic by focusing on the fundamental elements of making finished tea. I believe that a little information about the tea industry may help you to explore your taste sensibilities and to direct your purchases where you can get more bang for the buck. I’ll leave for a different post the discussion of how other types of “teas” such as herbals are produced.

Let’s start with the first step in this journey which begins in the field.

A vast field of Camellia sinensis
A vast field of Camellia sinensis

Cultivation

Where tea grows

Tea has growth requirements that are found within tropical, sub-tropical, and some temperate regions of the world. A healthy tea plant can tolerate high heat, seasonal drought and also occasional blankets of ice or snow. The rule of thumb is that if a particular area is hot, humid, and rainy for at least half of the year then tea might be able to flourish there.

What tea farmers do

The first thing to know about tea cultivation is that the product of interest is the leaf of the plant. This is important because the tea farmer has to make decisions that favor production of foliage over seed. Seed-containing tea fruit, when allowed to mature, is primarily used for making more tea plants and not for consumption.

To grow lots of quality leaf the farmer has to consider many different factors. The amount of rainfall and its distribution across seasons, efficiency of soil drainage, availability of minerals and nutrients, and severity of sun exposure are just a few of the considerations.

To make things even more complicated, each of the subtly different varieties of Camellia sinesis may react to the same environmental factors in divergent ways.  For instance, a treasured tea variety that thrives in high altitudes of Darjeeling, India where winters are cool, may not fare too well in the low, sub-tropical tea gardens of Yunnan Province, China. The practice of farming is to find the best combination of local environmental conditions and tea variety for a particular area.

Farmers tending their tea

In for the long haul

The other important thing to know is that tea is a long-lived creature. Good leaf may be produced from the same plants for decades and perhaps even centuries. During all these years of growth, the farmer must tend the tea like it is a part of the extended family. Among many duties, farmers must prune plants to a proper shape, weeds have to be controlled, fertilizers, composts, and amendments must be distributed, and in some cases herbicides or pesticides have to be applied. It is a lot of work to make a healthy tea plant, let alone to manage an entire tea estate containing many tens of thousands of plants.

After about two and a half years of growth since planting, farmers will begin to sample leaf for its tea-making potential. Sampling must be done lightly so as not to cause the plant to divert resources from the developing root system or distort the plant’s emerging shrubby form.

And this brings us to the next step in tea production where farmers (eventually) see the “fruits” of their labors.

Harvest

Hurry up and wait

Leaf harvest for many tea varieties can be begin in earnest in about the fifth year of growth. However, for some tea types such as pu-erh, leaf of young tea plants is not as desirable as leaf from plants (trees, actually) that are decades older. In the case of pu-erh, market value of the finished tea may vary with the age of the mother plant, with leaf from the oldest trees fetching very high prices. The ideal timing of harvest with respect to plant age just depends on the type of tea that will be made from the leaf.

Pluck, pluck, pluck

Plucking of leaf may be conducted by hand or by machine. When plucking by hand there is precise control over the qualities of material harvested but with higher labor costs. Leaf that is plucked by machine, using leaf-shearing devices operated by one or two individuals or by specialized tractors, has lower labor costs but at the expense of the quality of material.

In general, you will pay more for hand-plucked than for machine-plucked teas. There are exceptions, of course, and when researching tea for purchase it may be worth your while to dig a little deeper into the details of harvest.

Plucking tea leaves

Shoots, tips & leaves

Not all tea leaves are created equal. For one thing, a leaf at the tip end of the branch is younger than all the leaves below it. Leaf age matters because the biochemical goodies that make tea unique—polyphenols and caffeine, for example—are more concentrated in younger leaves than in older leaves. This is why so much effort in the field is dedicated to encouraging tea plants to produce as many tender young shoots as possible. In fact, harvest is often coordinated with methods of pruning that induce plants to make “tippy” foliage.

A plucking that is classified as fine includes the leaf bud at the branch tip, the next two nearest leaves, and the main stem that connects leaf stalks and bud. A plucking considered coarse may include everything from the bud down to the third and fourth leaves and perhaps all the stem in between. A fine plucking is often called “two-and-a-bud,” whereas a coarse plucking is called “three (or four)-and-a-bud.” Fine material may be more valuable than coarse, but this will depend on the type of tea that is being made.

Tea leaves ready for harvest

Timing is important during the harvest stage of tea production. If the manager waits too long to harvest then a fine plucking will transform into a coarse one and eventually lose its value altogether.

Woe to the manager who misses a harvest.

Processing

And now for the hard part

Leaf is now plucked and headed to the tea maker. Small-scale tea makers may process batches of just a few pounds of material whereas large-scale producers may be able to handle a ton or more.

The methods employed to process leaf depend on the type of tea to be made, the manufacturing facilities available, and the skills of the tea maker. Indeed, there is a bewildering number of ways to process leaf so let’s take an overview of the key stages involved. These stages may include withering, heating, rolling, oxidation, and drying.

Wither leaf?

Leaf begins to wither immediately after harvest. You have seen this same thing occur when you forget to put vegetables back into the refrigerator: a floppy stalk of celery is what you get for your neglect.

In the case of tea manufacture, however, some wither is often desirable. Teas such as the blacks may be allowed to wither up to 24 hours after harvest. Green teas such as those made in Japan, in contrast, are usually not allowed to wither any longer than the time it takes to transport the leaf from the field to the factory.

The main function of withering is to turn stiff and rubbery stem and leaf into soft and pliable material that resists breaking under stress. As you will see in the following section, however, withering is not the only way to make a leaf that bends to the tea maker’s will.

Tea leaf withers on bamboo baskets

Heating up

Heat may be applied to leaf for each of two purposes. First, leaf and stem of tea is readily softened by either steaming or pan frying. If you have steamed or pan fried vegetables then you have seen how rigid materials such as broccoli are turned limp by application of high temperatures. Heat, if applied in just the right amount, will likewise soften tea material.

The other purpose of heat treatment is to disable chemicals within the cells of the leaf. If left unchecked, enzymes that occur naturally within leaf will catalyze reactions that radically alter the flavor and color of steeped tea. In green teas these reactions are undesirable and must be nipped in the bud, so to speak.

Heat applied above a certain temperature will stop enzymatic action and preserve the grassy flavor, or “greenness,” of tea leaf. This is why leaf processed to have a green quality is either steamed or pan fried in the early stages of production.

Heat treatments therefore achieve the dual objective of softening tissues and precluding enzymatic action. The further use of heat can be quite nuanced in the production of teas such as pu-erh and oolong, but we will leave those fascinating teas for another post.

Rolling along

We now have tea leaf that is pliable enough to resist breakage. At this stage tea material may be physically manipulated, or rolled, so that cell walls and membranes are ruptured. Rolling in turn releases flavor-promoting substances normally contained within leaf tissues.

In hand-rolling a grapefruit-sized pile of withered tea is held between the palms and a table top and gently rolled in a circular motion. In machine-rolling tea material is pressed between two metal plates with the bottom plate stationary while the top plate moves in a elliptical path across the tea. The rolling and twisting forces applied in both methods cause tea juices to exude out of the internal tissues and on to the leaf surface.

The challenge here is to manipulate the leaf just enough to release the goodie inside but not so much that the leaf is mangled to a pulp. This is a tough business and especially so when material is rolled by hand. In any case, a nicely rolled leaf feels sticky and oily and has a fruity, nutty, or floral aroma. The smell of rolled tea leaf is unforgettable.

Oxidation without trepidation

The next stage of tea production is a resting period for the leaf during which oxidation occurs. Oxidation is a transformative chemical process that causes iron to rust and cut apples to turn brown.

Rolling of tea leaf induces oxidation. This is because compounds that are normally held in separate compartments within the leaf cells are now in contact with each other. A key group of compounds involved are varieties of polyphenols that react, while in the presence of oxygen, with the enzyme oxidase. It is from this oxidation reaction and its products that we obtain many different tea flavors. Colors of tea liquors (that’s the part you drink) also emerge from oxidation.

Rolled tea leaf in the early stage of oxidation. Image credit: Mike Loeb

Oxidation is usually stopped after specific durations. This takes a lot of experience and a bit of courage to execute properly because the tea maker can ruin things here if the timing isn’t right. Teas such as oolongs, for example, are not allowed to oxidize for long, perhaps an hour or two at most. These teas are referred to as semi-oxidized because the tea maker stops the process when there is still oxidation potential remaining. Black teas, in contrast, are called fully-oxidized because most polyphenols have been transformed and there is little oxidation potential remaining on the leaf.

Rolled tea leaf near the end of oxidation. Image credit: Mike Loeb

What about green teas? Recall that in the case of greens, heat was applied in order to soften the material and to cut off oxidation before it can begin. Enzymes such as oxidase are dismantled by high heat which is why green teas are considered unoxidized teas. The grassy, savory flavors of green teas emerge from compounds like theanine that are already present in the leaf at harvest. Rolling merely releases the green goodness onto the leaf surface where we can later liberate it with hot water.

Drying for keeps

The last stage in tea manufacture is drying. The goal of drying is to preserve the flavor profile that has emerged in the tea during the previous stage of processing. A dry leaf does not oxidize efficiently and so drying, conducted in either a specialized oven or in the warmth of the sun, locks in the products of oxidation.

Shelf life of finished tea will vary with the level of oxidation. This explains why under good storage fully oxidized teas will tend to hold their special qualities longer than unoxidized teas. Any exposure to moisture and air will tend to cause a little bit of oxidative change over time. In a few teas an evolution of flavor may be desirable but generally these changes diminish the quality of tea.

You will quickly learn how to protect your treasured teas from changes that lead to spoilage.

Everything else

All that is left for the tea producer is to pack and ship the product. However, finished tea leaf is not always uniform in shape and size and this variation can affect market value. Packing therefore involves a sorting and grading procedure before tea is packed into bins of loose leaf or chopped up into pieces small enough to put into individual, single-serving bags.

Finally, tea is put into boxes and shipped to middle-men who eventually put it in the hands of your local tea provider.

Summary

That’s a lot of steps, isn’t it? Indeed, making tea is a significant undertaking that is every bit as complex as making wine or cheese or any other agricultural product that requires considerable time and mastery.

I hope that this sketch of how tea makes it from the seed to the shop is useful. Please use it to inform your next selection of fine teas.

The prize that awaits: tea steeping
The prize that awaits

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