The Nature of Taste: To Infinitea and Beyond!

Tea is the second beverage most enjoyed by people. The first is water.

Sipping on water gives benefits of hydration to our bodies. Steeping tea leaves in water adds to the experience by releasing delightful aromas and tastes. Astringency from polyphenols and bitterness from caffeine and theanine create a beverage prized as second place for our human race.

Holding any botanical's leaf, tea included, shows the how human hands also have control over aroma and taste. Imagine comparing the aromatics of an intact leaf of any botanical to the aromatics of the same leaf cut, crushed or teared. More than likely, less aromatics are sensed from the intact leaf when compared to the crushed or teared one.

Sensing this difference shows us that precursors for aroma and tastes are found within the botanical. Cutting, crushing or tearing them allows for pathways responsible for aroma and taste to start. Factors of tea taste quality include environmental light, air and minerals, methods of harvest and control of the leave's metabolic pathways post-harvest. The work of selecting whole tea leaves, with the leaf mostly intact, is most delicately done by human hands. Mechanical harvest of tea garners more tea in less time at the expense of less control over the metabolic pathways and resulting taste.

Mechanized tea processing can take approximately one hour, resulting in a finely macerated leaf referred to as a Cut Tear Curl (CTC) tea product. Hand picking and processing can devote 24 hours to taste development and is generally reserved for the creation of whole leaf teas. Smaller particles of the whole leaf may be collected as a less expensive by product for imbibing.

How the leaf is affected throughout the stages of taste development begins with withering. Withering refers to evenly spreading field fresh leaves over large racks to air dry. As the name alludes, the goal is to allow approximately two-thirds of the fresh leaf’s moisture to evaporate. Depending on humidity levels, coal fires may be set to assist with this step and also introduce a smoky taste to the final flavor of the tea.

Withering acts on the botanical biologically to convert starches to sugars and physically to soften the leaves to allow for the next possible step in processing; rolling. In rolling the withered and pliable tea leaves are twisted by machine or by hand. The result is either a twisted spiral shaped leaf or fully rolled leaf in the shape of a ball. The physical twisting of the tea leaves causes controlled crushing, rupturing leaves and exposing flavor precursors to enzymes found in the leaf allowing for enzymatic oxidation processes to begin.

Oxidation is an important step for type, taste and appearance differentiation. White and green teas are generally not purposely oxidized while oolong teas are partially oxidized and black teas are completely oxidized.

The withered and rolled leaves are thinly spread in a cool area to oxidize. They increase in heat during the process and controlling the temperature is essential to achieving desired tastes. While some aroma chemicals are created during oxidation, a physical transformation takes place as well. The leaves trade their green fresh picked appearance for golden yellow to dark brown color. Polyphenol oxidase and peroxidase break down chlorophyll present in the leaves. Chlorophyll is responsible for the green color of fresh leaves, and as it breaks down, the fresh green color fades to the brownish hues.

Breaking or crushing of leaves in the rolling step introduces aroma chemical precursors, including fatty acids, carotenoids and polyphenols to enzymes residing within the cells or vacuoles of the leaf. The environment for enzymatic oxidation is now set.

Some carotenoids residing in the leaf are beta carotene, lycopene and neoxanthin which have the potential to enzymatically oxidize with several catalysts called carotenoid cleavage enzymes. Aroma chemicals important to tea taste recognition including beta ionone, beta damascenone and linalool can ultimately be produced by the enzymatic oxidation of carotenoids.

Fatty acids such as linolenic acid, when catalyzed by lipoxygenase, are precursors for aroma chemicals that contribute fresh green characters including T-2 hexenal, T-2 hexenol, and C-3 hexenol. Other fatty acid derived characters include 1-octen-3-ol (earthy) and herbal and floral notes are cis-jasmone and methyl jasmonate.

Removal of moisture via the next step in tea processing, drying, is essential to bringing oxidation reactions in the leaves to an end. Drying acts to stop oxidation by applying heat to denature enzymes therefore preventing further catalysis of flavor components. The drying process can be likened to preserving a snapshot of taste developed in the tea leaves.

Drying can be achieved by subjecting the leaves to heat via hot air blowers, headlamps, pan firing or coal firing. Each adds its own twist on tastes. In addition to stopping changes in taste, another goal of drying is to achieve less than 12% moisture to prevent mold growth. Two or three percent moisture is usually desired.

Given that so many factors influence the type and taste of tea, it's no wonder tea is one of the world's favorite drinks. The variation of tastes possible offers an opportunity to please many people's palates to infinitea and beyond.

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