Steeping

Definition

The contact between tea leaves and hot water during which soluble compounds — caffeine, amino acids, polyphenols, pectins and aromatics — diffuse out of the leaf into the liquid. Every round of that contact is one steep, and its duration, water temperature and leaf load together determine what ends up in the cup. Longer steeps do not simply make tea stronger; they extract in a different order, pulling bitter and astringent compounds forward once the sweeter ones are spent.

Etymology

From Old English stēpan, to soak, a word first applied to grain and herbs left standing in liquid.

In use

Used both for a single immersion, as in a ninety-second steep, and for any hot-water extraction method as a whole.

What Dissolves, and in What Order

Steeping is a diffusion process. Soluble material inside the leaf moves into the water because the concentration inside the leaf is higher than in the water around it, and the process continues until the two are in balance or the leaf is removed. Temperature, time, leaf size and the concentration already in the water all affect how fast this happens.

What comes out is not a single substance but a sequence. Caffeine and the smaller amino acids, including theanine, dissolve quickly and are among the first to appear. Catechins and other polyphenols follow, and at higher temperatures they come out fast, which is where the briskness and astringency of a strong cup come from. The larger molecules — pectins, some polysaccharides and the heavier aromatic compounds — arrive later and contribute body and sweetness.

This sequence is why a long steep is not simply a stronger version of a short one. Once the pleasant material has been drawn out, continued steeping mostly adds the bitter and astringent compounds. A tea steeped for five minutes is not twice as good as one steeped for two and a half; it is a different drink with a different balance.

The Three Variables You Control

Water temperature is the strongest. Hotter water dissolves everything faster, which means it reaches the bitter compounds sooner. Green and white teas are generally steeped at around 70 to 85 degrees Celsius precisely to keep the extraction in the sweeter range; black teas, pu'er and most herbal infusions tolerate water close to boiling. The practical technique without a thermometer is to boil and let the water stand, or pour it between two vessels.

Time is the second. Shorten the steep when the water is hotter, when the leaf is fine or broken, and when the ratio is high. As a rough guide, a first infusion of green tea might be forty-five seconds to a minute, a black tea two to three minutes, and an herbal blend four to six. Later infusions can usually be lengthened because the leaf is already partly spent.

Leaf quantity is the third, and the one most often guessed badly. Weighing the leaf removes most of the variation between one cup and the next. A scale is also what makes gongfu-style brewing practical, since the ratios there are far higher than Western ones and eyeballing them is unreliable.

Leaf Size, Shape and Re-Steeping

Whole leaf steeps more slowly than broken leaf, because less surface area is exposed. That is why a whole-leaf oolong can be infused many times while a fine broken black tea gives everything up in one or two. It is also why the same tea bag can taste different from a loose-leaf version of the same tea: the bag usually contains smaller pieces.

Re-steeping works best with whole, large leaves and with teas that have been rolled or compressed, since they open gradually. Each successive infusion is usually a little longer than the last, and the character shifts from aromatic and bright toward deeper and softer. When the tea turns thin and watery no matter how long it steeps, the leaf is finished.

Compressed teas such as pu'er cakes need a longer first rinse or a second one before the leaves begin to open. This is not a matter of washing off dust, although it does that too; it is about giving the tightly packed leaf time to absorb water and separate. Skipping the rinse tends to produce a first infusion that is weak and a second that is disproportionately strong.

What Steeping Is Not

Steeping is not boiling. Boiling the leaf, or holding it at a rolling boil, damages the aromatic compounds and produces a harsh, cooked flavour. Even for teas that take near-boiling water, the water is poured onto the leaf and the leaf is then left to stand rather than kept at a boil. This applies to herbal infusions as well: a simmer is not the same as a steep.

Steeping is also not the same as decoction, in which the material is boiled to extract it, a method used for roots, barks and some medicinal preparations. Most tea is an infusion rather than a decoction, which is why the word steeping is used for it. Knowing the difference explains why some herbal blends benefit from a long steep while others turn bitter.

And steeping is not the same as brewing in the broad sense. Brewing can include pouring, filtering, pressurising or plunging; steeping refers specifically to the contact between leaf and water. When someone says a tea is over-steeped, they mean the contact lasted too long, not that the whole process went wrong.

Practical Habits

Preheat the vessel. A cold mug or pot lowers the water temperature immediately, which slows extraction and makes the first infusion weaker and blander than the same tea brewed in a warm vessel. Rinsing with hot water takes seconds and makes results repeatable.

Taste as you go rather than relying on a timer. The same tea steeped in a thin porcelain gaiwan and a thick clay pot will be ready at different moments, and the leaf itself changes from harvest to harvest. Sipping at intervals teaches you when a particular tea is at its best, which no chart can do.

Finally, remove the leaf when the steep is done. Tea left sitting in the water continues to extract, so a pot drunk slowly over twenty minutes will be noticeably more bitter at the end than at the start. If you want to keep a pot going, decant the tea into a separate vessel and refill the brewing vessel when you want the next infusion.