White Tea Production
The basic principle of white tea production is very simple: gradual and sustained dehydration (withering) followed by baking or drying.
Withering
Withering is the critical stage of white tea production. In other words, the main qualities that make a tea white are formed during this phase. There are three main methods used: Natural Indoor Withering, Sunlight or Solar Withering and Heated Withering. Due to high dependence on favourable weather conditions, tea makers are often flexible in which method they employ and often use a combination of all three. The more stringent traditional methods eschew the use of heated withering and favour the natural method, whether indoor or outdoor. Early spring white teas are made using Staggered Withering; essentially a mixture of indoor and solar withering, buds and leaves are left out in the sunshine for short periods (around 20 mins) then retrieved and placed back into the shade, once cooled they are returned outside. This truncated method of withering is continued several times, but not for more than around 1-2 hours in total.
Initial production can last a few days, finished tea may take a month to be completed.
White Styles or Grades
The pick determines the type. There are two principal types of white tea: bud tea and bud and leaf teas. These are further classified into four main grades: Silver Needle, White Peony, Gong Mei and Shou Mei.
Top grade: Silver Needle made solely from buds.
Second grade: White Peony made from buds, leaves and stems.
Third Grade: Gong Mei consisting of 'looser' pick, using buds, leaves and stems from landraces not premium cultivars.
Fourth grade: Shou Mei. Lower grade than Gong Mei, but known colloquially together as "Little White" to distinguish both from cultivars "Big White"(dabai 大白) and "Big Down" (dahao 大毫) preferred for Silver Needle and White Peony grades.
These four grades also mirror the chronological development of white teas, the oldest being Silver Needle, the youngest, or newest, Shou Mei.
The tasting profile of higher grade white teas is largely determined by the unusually high concentration of furry white down (trichomes) present on the buds. Kept intact during manufacturing and high in caffeine and amino acids, they contribute decisively to the brisk and stimulating characteristics of white tea - this is especially true of Silver Needle teas, whose flavour profile and appearance is dominated by presence of these fine silver hairs. Premium cultivars used in Fuding and Zhenghe, such as Dabai or Dahao, possess trichomes of above-average length and thickness.
White tea is partially or lightly oxidised; the absence of bruising or manipulation during production first restricts, then arrests, oxidisation. This light oxidation creates the mellow flavours and yellow-almond liquors found in leafy white teas such as White Peony.
The Making of White Tea: The Craft of Simplicity.
"Although on the surface the production of white tea involves only two stages, proper control and management is extremely difficult."
The making of white tea consists of two stages used to produce the same end: dehydration. At times, the distinction between the two isn't always clearcut. Seen in comparison to other tea types, witness the finesse and finery of elegantly made wulongs, white tea production couldn't appear more straightforward. After picking, buds and leaves are placed onto withering trays, left for an undetermined amount of time, heaped together then baked or dried. One could be forgiven for thinking that anyone could make white tea such is the uncomplicated nature of its production. Nevertheless, this apparent simplicity conceals a subtle and enigmatic process, understated perhaps, but never easy. This article seeks to draw attention to this undervalued craft.
The critical stage
Withering consumes the most time and causes the main physical and chemical changes; it is during withering that most of the character and qualities of white tea are shaped. Roughly three-quarters of water loss takes place during withering.
Four main factors govern the execution of withering: temperature, light, humidity and airflow. Ambient temperatures should be warm, but not exceesively so, sunlight sparingly used, airflow not too fierce, the atmosphere neither muggy nor stale. Such is the delicate nature of white tea: only a slow and steady rate of water loss will do. Achieving this balance means relying on fair weather - northern winds are best in Fujian, for they bring slightly drier and more stable conditions - yet relying on weather is a risky business. Herein lies the complexity of white tea, something which the lack of physical manipulation conceals.
One interesting feature of white tea production is that withering does not need to be efficient. There is no need for urgency. Faster dehydration only intensifies oxidation, reddening the edges and disturbing the delicate balance needed for white tea. Discolouration of the buds and leaves is clearest sign of poorly-executed withering. Quickening the pace buys quantity at the expense of quality. Only a leisurely speed enables oxidation to begin and end naturally.
Dehydration Shock
The main theme of white tea production is the simple process of withering which causes "dehydration shock" within the leaf, triggering a series of chemical changes. These changes transform freshly-picked buds and leaves into what we know as white tea. For higher grade white teas, this low-intensity manufacturing process also maintains the integrity of the trichomes, adding lustre dry buds, briskness to infusions, and clean 'downy' aromas to teas.
The Role of the Tea Maker
The main task of the tea maker is to create and maintain consistent and stable conditions throughout the process of withering whilst at the same time monitoring minute changes in the physical appearance of the leaf. This is especially difficult for traditionally-made white teas that rely on the skill and experience of the tea maker to manage these conditions.
The unhurried nature of white tea processing seems uneventful, and in this apparent featureless drama the role of the tea maker is often downplayed. For much of the time, leaves are left to dehydrate on bamboo trays, manipulation of the leaf is strictly avoided, adding to the impression that its manufacture lacks craftmanship. In reality, craft is no less fundamental to the making of quality white teas. The tea maker does play an active role, orchestrating production, carefully watching for, and responding to, changes in the colour, shape and aroma of wilting buds and leaves.
For white tea, the devil is in the details: success or failure hinges on detecting minute changes in the shape, colouring, and scent of withering material. Being able to observe and react to the changing conditions and the subsequent impact on wilting buds and leaves the litmus test of tea makers. There is minimal margin for error, leaves cannot be unwithered, too rapid a water loss cannot be undone. It is for this reason that white tea pose the greatest risk of all tea types: small errors in judgement are writ large in the leaf and there is little recourse for recovery, baking can to a degree minimise but recover the damage.
The challenge for makers of white tea, then, is to anticipate problems and respond appropriately to any subtle changes in light, heat and humidity that may occur. To a large extent, the character of the finished white tea is shaped by these responses. High quality tea rewards nuance: just losing the appropriate amount of water is not enough. Similarly, withering for a prescribed time, say 24 or 30 hours, also lacks the subtlety needed to shape higher quality white teas. White teas that are rushed through production and strive only to lose water quickly are often characterised by insipid liquors and flat aromas. In the leaf (or bud) they will show bright leafy, almost vegetal, greens. Equally, if withering continues for too long, excessive chemical change will take place causing a darkening effect. Unfavourable weather, notably spikes or depressions of temperature, can also affect withering, spoiling the delicate colouring of white teas: "Hot weather reddens, cold weather darkens." It is the tea maker who is responsible for deciding when to stop withering; ending too early or too late can under or overcook the tea. Such is the finely poised nature of white tea production.
How long does withering take?
Withering is time-consuming even under the best conditions. Depending on the method employed and prevailing weather conditions it can take between one to three days. The slow pace is deliberate and needed to allow chemical and physical change to occur gradually. On a macro-level withering is concerned with water loss, but most of the critical and intended changes occur on a micro-level.
Withering in traditional white tea production takes between two to three days. Short-cuts are available to tea makers, such as heat-assisted withering, where specially designed rooms funnel in and funnel out warm air over rows of bamboo trays, stacked and spaced apart so heated wind can pass easily between different layers. Alternatively, withering troughs, like those used at the beginning of black or wulong production, are used to accelerate dehydration; heat-assisted withering can finish within 24 hours.
Three Stages of Withering
Withering can be divided into roughly three phases each contributing to the unique character of white teas. The first stage is characterised by rapid water loss, physical shrinking, but no lasting chemical change; the second stage is when the main character and quality of white tea is formed; the final phase is less eventful, as the cumulative effect of sustained water loss begins to undermine chemical transformation.
The Chemistry of White Tea Production
White tea production functions on a simple premise: gradual and uninterrupted dehydration. This rudimentary technique, not too dissimilar from curing, creates complex but relatively unobservable change: the majority happening at the cell level.
The rapid loss of water during the first phase triggers a series of reactions within the leaf. As water is lost from the surface, the cell-liquid becomes more concentrated. This increases the permeability which, in turn, releases enzymes. The activation of these enzymes incurs three main reactions: the balance of chlorophyll compounds is disturbed, polyphenols (mainly catechins) are oxidised, and protein is broken down into amino acids. For the most part, these three chemical changes shape the final character of white teas.
The bulk of these reactions only really get going during the middle phase. Catechins continue to oxidise, converting to Theaflavins, as well as low volumes of Thearubins. Around half the catechins are lost after this phase. Theaflavins and Thearubins are the same compounds that colour - literally and figuratively - the manufacture of black tea. Their presence in tea production confirms oxidation. Interestingly, while green tea production aims to stop this happening, for white it's an indispensable change. In terms of white tea, the oxidation of catechins during this phase yellow the liquors and mellow the flavours, reducing bitterness and astringency. That this natural oxidation begins and ends without any overt manipulation of the tea maker is another hallmark of white tea manufacture.
Physical intervention, rolling or shaping for example, or the piling of together of leaves help generate heat, accelerating and deepening oxidation - some 'New Technique' white teas have added rolling and shaping to the production of white tea. The resultant teas, in both tasting and chemical terms, are closer to wulongs than white However, in the absence of manipulation and excess heat, oxidation comes to a natural stop; without rolling the enzymes cannot connect with base material, oxidation slows, enzymic activity dwindles and eventually ceases to play a decisive role in further chemical change. Additionally, significant portions of proteins are converted into amino acids, further reducing bitterness and astringecy, while enhancing briskness and liveliness of finished teas.
As withering moves into the latter stages, sustained water loss begins to alter the colour profile of wilting material. The ebb and flow between the green and yellowish Chlorophyll compounds declines, and grayish or olive greens may be noticeable. At this point, the tea maker may notice several minute, but observable changes in the condition of the buds and leaves; perhaps a slight lifting of the hairs, or a curling of the leaf, both could indicate withering has run its course. Subsequently, bamboo trays are combined and heaped together then left for several more hours. Afterwards, the buds and leaves are considered fully withered and essentially ready for drying or baking.
Baking
Baking is a comparatively short, though not always straightforward, conclusion to white tea production. Various methods are used: from solar drying to electronic baking machines, or, in the case of more traditional white teas, and in a manner similar to Wuyi Rock teas, bamboo baskets over charcoal fires.
In general, temperatures used are quite low, between 40c to 60c, sometimes higher, but rarely exceeding 100c. Precise temperatures depend upon the moisture content after withering: the drier the leaf, the lower the temperature. Baking at low temperatures with higher moisture can trigger a secondary, and unwanted, phase of oxidation.
This final stage finishes the tea by drawing out excess moisture, dispelling any remaining green aromas, and gently 'cooking' sugars and amino acids, subtly ripening the aromas. Although considered part of traditional white tea methods, sun-dried teas are said to suffer from underwhelming aromas and, being dried rather than cooked, retain portions of undesirable 'green' aromas. In short, heat enhances the aromatic profile - an effect colloquially known generally in tea production as "提香", literally, lift the aroma. By helping to reduce bitterness and stabilising the fluctating levels of Chlorophyll, this final stage further refines the appearance and flavour of white tea.
Physical Change
If we return to the condition of freshly-picked buds and compare with those at the end of production we can observe the working of white tea production. Freshly-picked, plump, and a sprightly, lucid green, immediately begin to lose water and vigour. At turns tender and shiny, then flaccid and dull, these withering buds, through continual loss of water, gradually shrink then become taut and brittle showing a silvery sheen. Taken between the finger and thumb and rubbed gently, they may crumble into a silvery dust.
The Chemical Profile of White Teas
The incremental and sustained dehydration of buds and leaves help shape the unique chemistry of white teas. Lightly oxidised and gently baked, white teas possess clean, fruity or floral aromas, sometimes woodsy, sometimes savory, but never ripe or heavy (unless aged). Almond-yellow infusions taste mellow and fresh, two seemingly conflicting characteristics, without bitterness or astringency. These distinguishing marks of white teas are formed by the unique white tea chemistry.
Amimno Acids in White Tea
One of the unique aspects of white tea is the unsually high level of amino acids, a group of compounds responsible for brisk and umami or savory notes known to mitigate bitterness. In fact, white tea is the only tea type to contain higher volumes of amino acids than freshly-picked leaves. Of these, L-Theanine is found in particularly high quantities. L-Theanine is one chemical worthy of further investigation. Found almost exclusively in tea it has been claimed that L-Theanine promotes both relaxation and mental alertness. It has a peculiar antagonistic effect on the absorption of caffeine, which may help to explain why high-caffeine teas do not produce the same 'caffeine rush' as coffees. Research has shown that of all teas, white contain the highest volumes of Theanine.
Caffeine also increases significantly, by between 14 - 24% (according to Ye Naixing), enhancing the flavour and stimulating quality of white teas.
Another group of compounds that are increased by white tea manufacture are sugars - again, white tea contains the highest quantities - sweetening infusions and adding caramel, chestnut and other sweet aromas to finished teas.
In contrast to other tea types, most notably green, white teas contain relatively low levels of polyphenols. This is especially true of bud teas. In leaf and bud white teas these volumes increase and can add mellow and depth to the tasting profile.
