There has been extensive debate about the limits of a taxonomic approach to understanding tea processing. If the aim is to grasp what tea production is actually comprised of, is it more useful to think in terms of a sequence of independent, successive steps — or rather as a continuum, in which each step shades into the previous one and prefigures the next?

In much the same way, the lexicon that encompasses tea processing is so rich and so internally complex — so geographically, linguistically, and historically relative — that one may reasonably wonder what the advantage could be of connecting such distant points. Put differently: what purpose might be served by attempting to delineate the contours of an inevitably limited and incomplete “big picture”? I believe the principal value of such a project lies in orientation — a preliminary, navigational orientation — for those who, for whatever reason, try to cross over into a perspective on tea that belongs to a different context: Westerners and Easterners alike; readers trained chiefly in the humanities or chiefly in the sciences; professionals of the tea trade; farmers, producers, and vendors; as well as private tea devotees. That is the aim that has guided me through this research.

At the same time, I am not attempting to establish a hierarchy of terms. I do not believe that any one of the three perspectives examined should be adopted uncritically by the other two; that would be, at best, a hazardous assumption. Rather, it seems to me that merely knowing that other perspectives exist — and obtaining even a brief glimpse of their internal logic — may already provide a key to more effective communication.

As for the confusion between red tea / black tea / dark tea — that is, hóngchá 紅茶 versus hēichá 黑茶 — which still dazzles inexperienced Western chárén 茶人 today, the quirks of history and of science have long, lingering echoes in language. The aim of this project is therefore to dispel certain ambiguities related to the many context-relevant descriptions of what happens during the making of tea. It is also an attempt to create a simple comparative reference for the terms of essential tea-processing biology, to be used by people who wish to direct their gaze towards a more global tea community, whether out of personal interest or for professional reasons. Finally, it is an attempt to present an overview — certainly partial, yet still a beginning — of the evolution of the descriptors of the basic biology of tea, ultimately leading into the contemporary problem of a complex international “tea language”.

I attempted to pursue this by focusing only on two generally accepted fundamental processes, and by comparing them across three cultural and historical contexts and (in the original version of this work) ten languages. I now extend the comparison to sixteen languages, because certain linguistic corridors are historically and conceptually too central to omit: besides Chinese, Japanese, and Korean, and besides a small set of Western European languages (English, German, Dutch, French, Italian, Spanish) plus Russian, the table now also includes Portuguese, Persian, Malay, Indonesian, and Hindi, together with Bengali as an additional South Asian reference point. The underlying question remains unchanged — and its ramifications reach far beyond the scope of this small project: can three very complex and diverse worlds learn to understand one another’s perspective?

The immediate interest in this topic arose from the experience of recurrent misunderstandings that I encountered both in the East and in the West. My knowledge of Chinese and of many of the remaining languages in the table is rudimentary at best, if not altogether absent. This remains, therefore, an attempt at a compiling report, largely sourced from Western literature and assembled with the precious help of native speakers of each of the languages presented.

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A preliminary Rosetta Stone: why some languages say “tea” and others say “cha”

Before moving into processing terminology, it is worth pausing on a smaller but structurally similar problem: the word tea itself. Even a minimal philological glance reveals a pattern that is often summarised (somewhat schematically, yet usefully) as two broad families: a cha-family (forms like cha/chai/chay) and a te-family (forms like te/tea/teh). The practical relevance of this to the present project is that tea language — both in naming tea and in naming tea processes — tends to travel along routes of contact, trade, translation, and prestige vocabulary, and these routes often leave durable traces in the everyday lexicon.^{1, 2}

Language	Form (script + romanisation)	Family	Likely route (very short)	Notes
Chinese (Mandarin)	茶 chá	cha	Inland / northern routes	Core Sinitic form; widely borrowed.
Chinese (Southern Min)	茶 tê	te	Maritime routes (Fujian–Taiwan–SEA)	Often treated as the seed of European “tea/tee/thé”.
Japanese	茶 cha	cha	From Sinitic loans	Also in compounds (e.g. matcha).
Korean	차 cha	cha	From Sinitic loans	Same root family as chá 茶.
Portuguese	chá	cha	Early maritime contact (Asia–Europe)	Portuguese keeps the “cha” family despite sea routes.
Dutch	thee	te	VOC maritime trade	Key vector for many European “te/tea” forms.
English	tea	te	Via Dutch and/or seaborne trade	Standard modern English form.
French	thé	te	European diffusion	Often via Dutch / trade networks.
German	Tee	te	European diffusion	Clear “te” family form.
Italian	tè	te	European diffusion	Orthography adapts to Italian stress/phonology.
Spanish	té	te	European diffusion	Accent marks stress.
Russian	чай chai	cha	Overland (Eurasian) routes	Classic “cha” family representative.
Turkish	çay	cha	Overland / regional diffusion	Widely influential in neighbouring regions.
Persian	چای chāy	cha	Overland / regional diffusion	Often a bridge form across West/Central Asia.
Hindi	चाय cāy	cha	Regional diffusion	Very likely mediated via Persian/Urdu routes.
Nepali	चिया chiyā	cha	Regional diffusion	Common in Darjeeling/Nepal contexts.
Assamese	চাহ cāh	cha	Regional diffusion	Prominent in Assam/tea-growing discourse.
Malay/Indonesian	teh	te	Maritime / colonial-era diffusion	Likely via Dutch influence (“thee”).
Arabic	شاي shāy	cha	Regional diffusion	Often discussed alongside Persian forms.

Within the newly added languages, several occupy historically instructive positions. Portuguese chá is, in Europe, a particularly salient member of the cha-family and recalls early Portuguese contact with East Asia; it shows that European “tea” vocabulary was never monolithic, and that different channels of contact could stabilise different base forms.^{1, 3, 5} Persian chāy چای is a major relay form within West and South Asia; it participates in a vast linguistic continuum that also includes widely recognised South Asian forms such as Hindi chāy चाय and Bengali chā চা.^{2, 4} Conversely, Malay teh and Indonesian teh exemplify the te-family and point towards maritime channels of diffusion that also shaped several European forms.^{1, 2, 6, 7}

This small “tea/cha” aside is not a digression. It anticipates, in miniature, what will recur throughout the larger table: languages frequently borrow technical vocabulary through one set of channels (scientific translation, schooling, professional literature) while preserving everyday vocabulary through another (historical contact, trade, domestic use). When a single term — such as “fermentation” or its apparent equivalents — is then asked to cover multiple biological mechanisms, these layered channels of borrowing and calquing can amplify ambiguity rather than resolve it.²

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2 PROCESSES, 3 PARADIGMS, 16 LANGUAGES

The table below is intended as a compact “Rosetta Stone” for a recurring terminological problem in tea discourse: the persistent tendency — across multiple languages and publication traditions — to map a single label (often translated as fermentation) onto more than one fundamentally distinct biological mechanism.

A preliminary clarification is necessary. A very large number of diverse and complex biological processes can occur during the production of the multitude of existing teas, fostered and modulated — directly or indirectly — by even more agents and variables.^{8, 9, 10, 11, 12} For example, reactions of enzymatic as well as non-enzymatic oxidation can take place (including, under appropriate conditions, Maillard-type reactions). Many species of bacteria and fungi can initiate and promote beneficial or undesirable transformations in tea leaves under different environmental constraints (for example, jīnhuā 金花 in Ānhuà fúzhuànchá 安化茯砖茶 comes to mind — the “golden flowers”, typically associated with Aspergillus cristatus / Eurotium cristatum). In the present table, however, and for the sake of conceptual legibility, we focus only on two essential mechanisms, in deliberately broad definitions, while leaving most others unmentioned.

For a brief and accessible review of how these two processes are often framed in contemporary tea education, I recommend these introductory pieces by Tony Gebely:

• teaepicure.com/tea-leaves-oxidation¹³
• teaepicure.com/nuances-of-tea-classification¹⁴

Instead of attempting — at the very outset — to define these two processes by means of a detailed mechanistic description (and thereby risking a false sense of clarity), the table adopts a simpler principle as a working key to their distinction: the agents of one process are endogenous materials of the plant itself, whereas the promoters responsible for the other are alien organisms with an independent biology. The boundary is not always clean in practice (microbes may be present on leaves even where they are not primary drivers; endogenous enzymes remain present during microbial phases), yet as an orienting distinction it remains remarkably useful.

First process: ENZYMATIC BROWNING / OXIDATION

Language	CHINESE TRADITIONAL TERMS	COMMUNITY-ACCEPTED MODERN TERMS	SCIENTIFICALLY ACCURATE TERMS
ZH	（前）發酵・发酵 [QIÁN-] FĀJIÀO	氧化 YǍNGHUÀ	酶促褐變・酶促褐变 MÉICÙ HÈBIÀN
JA	（前）発酵 [SEN-] HAKKŌ	酸化 SANKA	酵素的褐変 KŌSO-TEKI KAPPEN
KO	（전）발효 [JEON-] BALHYO	산화 SANHWA	효소 갈변 HYOSO GALBYEON
EN	[PRE-] FERMENTATION	OXIDATION	ENZYMATIC BROWNING
DE	[Vor-] Fermentation / Gärung	Oxidation	enzymatische Bräunung
NL	[pre-] fermentatie / gisting	oxidatie	enzymatische bruinkleuring
IT	[pre-] fermentazione	ossidazione	imbrunimento enzimatico
ES	[pre-] fermentación	oxidación	pardeamiento enzimático
FR	[pré-] fermentation	oxydation	brunissement enzymatique
RU	[пре-] ферментация / брожение	окисление	ферментативное потемнение / энзимный браунинг
PT	[pré-] fermentação	oxidação	escurecimento enzimático
FA	[پیش‌-] تخمیر	اکسایش	قهوه‌ای شدن آنزیمی
MS/ID	[pra-] fermentasi	oksidasi	pencoklatan enzimatik
HI	[पूर्व-] किण्वन	ऑक्सीकरण	एंजाइमेटिक ब्राउनिंग
NE	[पूर्व-] किण्वन	अक्सीकरण	एन्जाइमेटिक ब्राउनिङ
AS	[পূৰ্ব-] কিণ্বন	জাৰণ	এনজাইমেটিক ব্ৰাউনিং

Second process: MICROBIAL RIPENING / FERMENTATION

Language	CHINESE TRADITIONAL TERMS	COMMUNITY-ACCEPTED MODERN TERMS	SCIENTIFICALLY ACCURATE TERMS
ZH	（後）發酵・（后）发酵 [HÒU-] FĀJIÀO	發酵・发酵 FĀJIÀO	微生物發酵・微生物发酵 WÉISHĒNGWÙ FĀJIÀO
JA	（後）発酵 [KŌ-] HAKKŌ	発酵 HAKKŌ	微生物発酵 BISEIBUTSU HAKKŌ
KO	（후）발효 [HU-] BALHYO	발효 BALHYO	미생물 발효 MISAENGMUL BALHYO
EN	[POST-] FERMENTATION	FERMENTATION	MICROBIAL RIPENING / MICROBIAL FERMENTATION
DE	[Post-] Fermentation / [Nach-] Gärung	Fermentation / Gärung	mikrobielle Reifung / mikrobielle Fermentation
NL	[post-] fermentatie / gisting	fermentatie / gisting	microbiële rijping / microbiële fermentatie
IT	[post-] fermentazione	fermentazione	maturazione microbica / fermentazione microbica
ES	[post-] fermentación	fermentación	maduración microbiana / fermentación microbiana
FR	[post-] fermentation	fermentation	maturation microbienne / fermentation microbienne
RU	[пост-] ферментация / брожение	ферментация / брожение	микробное созревание / микробная ферментация
PT	[pós-] fermentação	fermentação	maturação microbiana / fermentação microbiana
FA	[پس‌-] تخمیر	تخمیر	رسیدگی میکروبی / تخمیر میکروبی
MS/ID	[pasca-] fermentasi	fermentasi	pematangan mikroba / fermentasi mikroba
HI	[पश्च-] किण्वन	किण्वन	सूक्ष्मजीवी परिपक्वन / सूक्ष्मजीवी किण्वन
NE	[पश्च-] किण्वन	किण्वन	सूक्ष्मजीवी परिपक्वन / सूक्ष्मजीवी किण्वन
AS	[পশ্চাৎ-] কিণ্বন	কিণ্বন	অণুজীৱীয় পৰিপক্বন / অণুজীৱীয় কিণ্বন

Although the original version of this project compared the terms across ten languages, the present version extends the comparison to sixteen. The aim is not exhaustiveness but structural relevance: beyond Chinese, Japanese, and Korean; beyond English, German, Dutch, French, Italian, Spanish, and Russian; it is difficult to omit languages that sit at historically influential junctions of tea transmission and modern scientific vocabulary. Portuguese is a European outlier in the “tea/cha” naming history and an early contact language in East Asia; Persian is central to the overland diffusion of the chāy family (and, more broadly, to the Persianate corridor through which tea culture spread across West and South Asia); Malay and Indonesian occupy the maritime teh corridor; Hindi represents a major South Asian literary and scientific register; and Bengali is included as an additional South Asian reference point, both because of its demographic weight and because it helps triangulate the Indo-Persian chai/chāy continuum with an additional script and lexicographical tradition. The table is therefore not merely a multilingual list: it is an attempt to juxtapose languages that illuminate how tea terminology travels — across trade, translation, education, and community practice.

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FIRST PARADIGM: THE HISTORICAL CONTEXT: TEA LANGUAGE, BACK AND FORTH, FROM CHINA TO THE WORLD

The origin and evolution of the terms of Chinese tradition; the resulting evolution of the terms used in Eastern and Western publications about tea.

The origin of fājiào 發酵 / 发酵 (also encountered as 醱酵) is a non-trivial matter. To begin with, its pronunciation can elude even native speakers, who may occasionally read it as fāxiào 發酵, because the phonetic component of jiào 酵 is xiào 孝 (read xiào in standard Mandarin). Xiào 孝 is graphically and conceptually related to mǔ 母 (mother), and is often translated within the semantic field of filial / dutiful. The remaining component is yǒu 酉, a graph with a wide semantic range (including senses glossable as unitary, mature, pond, and notably wine), and with an obvious conceptual adjacency to jiǔ 酒. The logogram jiào 酵 can already be found in medieval sources and holds, as a primary sense, the meaning of yeast.¹⁵ Meanwhile fā 發 / 发 conveys a cluster of meanings such as producing, expressing, delivering, revealing.¹⁶ A related modern technical term, jiàosù 酵素 (“enzyme”), is also widely used, and is often discussed as entering Chinese through Japanese scientific translation — already a reminder of how “tea language” repeatedly absorbs scientific vocabulary through translation corridors.¹⁷

During the 1850s and 1860s, Louis Pasteur published some of his most influential works, demonstrating the critical role played by living microorganisms in food spoilage and other forms of transformation in complex organic substances.¹⁸ In that intellectual climate, it is easy to see how a general explanatory template — “microorganisms do the work” — could become persuasive far beyond the domains in which it was strictly warranted. In tea, where transformations are conspicuous, dramatic, and sensorially salient, this template has had a particularly durable afterlife. Very little specialised scientific literature existed at the time on the specific biological mechanisms of tea processing; and in such a climate, the assumption that microorganisms were responsible for the principal transformations in tea became, at least as an interpretive habit, readily available. In this sense (and without claiming a simple or linear history), one can understand how fājiào 發酵 / 发酵 could be drawn into tea discourse as a broad descriptive label, at times functioning as an umbrella term covering multiple kinds of change occurring during processing and maturation.^{19, 20, 21}

In English, the word fermentation ultimately descends from the Latin fervere, literally “to boil / to seethe”, and its history strongly reflects this phenomenological origin: a name for visible agitation, swelling, frothing, and other “boiling-like” movements in matter. In its more general and figurative definition, fājiào 發酵 / 发酵 can be described as a metaphor for something that has developed and changed under the influence of forces acting upon it.^{19, 20, 21} It is worth noting, for the multilingual scope of the present table, that the major Romance-language cognates — e.g., Italian fermentazione, French fermentation, Portuguese fermentação, Spanish fermentación — inherit the same Latin-root metaphor, which often makes their use feel “naturally equivalent” to English fermentation in translation. Yet equivalence at the level of inherited metaphor does not automatically entail equivalence at the level of scientific mechanism; and the problem becomes acute whenever one inherited metaphor is asked to cover more than one biological process.

“发酵”原来指的是轻度发泡或沸腾状态。发酵现象早已被人们所认识，但了解它的本质却是近200年来的事。

“Fermentation” originally referred to a state of light foaming or boiling. The phenomenon of fermentation has long been recognised by people, but its essence was not understood until roughly 200 years ago.

²²

廣義來說只要是酵素造成有機物的轉變都可以稱為發酵，不一定需要微生物，例如茶葉的發酵就與微生物無關。

In a broad sense, any reaction that causes the transformation of organic matter can be called fermentation, and does not necessarily require microorganisms. For example, the fermentation of tea has nothing to do with microorganisms.

²¹

The prefix hòu 後 / 后 began later to be added to fājiào 發酵 / 发酵, in an attempt to differentiate what occurs after production, during the ageing of a fully processed tea.^{23, 24} Yet the distinction is not as rigid as it appears in the modern dichotomy between yǎnghuà 氧化 (“oxidation”) and fājiào 發酵 / 发酵 (“fermentation”), and it is precisely this non-rigidity that the table tries to make visible. In other words, fājiào 發酵 / 发酵 can sometimes include — within the semantic scope assumed by its users — the transformations that other speakers would reserve for hòufājiào 後發酵 / 后发酵 (“post-fermentation”). This is why, in the table, hòu 後 / 后 is enclosed in parentheses, and why the line separating fermentation and post-fermentation is dashed: the prefix may not always be present, and when it is absent the intended meaning can remain ambiguous.

Furthermore — more rarely — one also encounters another prefix, qián 前, used to distinguish qiánfājiào 前發酵 / 前发酵 (“pre-fermentation”) when referring to the kind of “fājiào” that takes place before the end of the production process (i.e., enzymatic oxidation), rather than after, in order to eliminate further ambiguity.²³ The emergence of such prefixes is not unique to Chinese: as soon as a term becomes semantically overloaded, languages frequently deploy temporal or procedural prefixes as a pragmatic corrective. This is one reason why the table includes (as translations) both “pre-” and “post-” versions for every language considered — Portuguese pré-/pós-, Malay pra-/pasca-, Indonesian pra-/pasca-, Hindi pūrv-/uttar- — even when the idiomaticity and actual frequency of such compounds varies widely across communities.

为有别于上述那种杀青前的发酵，这种杀青后的发酵就被称为「后发酵」

In order to distinguish it from the above-mentioned pre-shāqīng 殺青 fermentation, this post-shāqīng fermentation is called “post-fermentation”.

²³

These terms survive to this day and are widely used in China and in East Asian languages, just as several of their corresponding translations remain in circulation in English and other Western languages.

Yet, as George van Driem points out, already in 1893 the intuition that a different process — namely oxidation, not caused by external agents — was responsible for the changes occurring in the leaf during the production of red teas had circulated among botanists and chemists for at least fifty years.²⁵

OXIDATION PROCESS:
“The term ‘Fermentation’ has been usually applied to this process, but ‘Oxidation’ more correctly describes the changes in the leaf that take place in the comparatively short time allowed.”²⁶
Bamber, M. K. (1893). A Text Book on the Chemistry and Agriculture of Tea: Including the Growth and Manufacture. (p. 225).

Again, from van Driem we learn that a few years later the same Bamber reported that he had isolated an oxidase enzyme from tea leaves.^{25, 27} One year later, Asō Keijirō 麻生慶次郎 confirmed those findings, attributing the changes “to the action of the oxidizing enzymes upon the tannin of the tea-leaves”, and inferring the capacity of heat to halt the process through “the destruction of oxidase in the first steps of preparation”.²⁸

However, despite these discoveries, the conflicting reality that “at one time it was actually erroneously thought that this transformation during withering was conducted by yeasts and other microorganisms” contributed to the fixation of the term 發酵 / fermentation in the jargon of the Chinese tea industry to this day, with the meaning of enzymatic oxidation.²⁵ With much greater certainty, we can state that this linguistic contrast has echoed in Western publications for more than a century, continuing in various forms to the present, often through the loose and interchangeable use of the terms fermentation (and post-fermentation), thereby contributing to widespread confusion and misinformation on the matter.

It is easy to make this manifest by listing only a few notable examples:

• Blofeld, J. (1985), The Chinese Art of Tea. Boston: Shambhala.²⁹
  “green (unfermented), semi-green (partially fermented tea generally called ‘oolong’ in English) and red (fermented tea called ‘black tea’ in English).”
  Blofeld also describes pǔ’ěr 普洱 as belonging to the categories of “white, green or red (black)”.
  
• Willson, K. C., & Clifford, M. N. (1992), Tea: Cultivation to Consumption. Dordrecht: Springer.³⁰
  Despite being a widely praised book written by two Western biologists, it still uses fermentation to describe enzymatic oxidation and semi-fermented teas to refer to wūlóngchá 乌龙茶 / 乌龙茶:
  “The withered leaf was then hand-rolled on long grooved tables and fired after fermentation.”
  “Copper is important for tea. It is an essential constituent of the enzyme polyphenol oxidase which is vital for fermentation.”
  
• Rasmussen, W., & Rhinehart, R. (1999), Tea Basics: A Quick and Easy Guide. New York: Wiley.³¹
  “The freshly plucked leaves are steamed or pan fired to halt active enzymes, which cause fermentation, or oxidation. This causes the leaves to be soft and pliable.”
  
• Rose, S. (2009), For All the Tea in China: Espionage, Empire and the Secret Formula for the World’s Favourite Drink. New York: Random House.³²
  “Black tea is fermented; green tea is not.”
  The author does add that “Although it is called fermenting, the process of making black tea is technically misnamed. Nothing ferments in a chemical sense; there are no microorganisms breaking down sugars into alcohol and gas. Black tea is, rather, cured or ripened. But the language of wine colors the language of all beverages, and so the label of ‘fermentation’ has stuck to black tea.” — but she then continues to use fermentation for the rest of the book.
  
• Jamieson, M., & McKinley, H. (2009), Handbook of Green Tea and Health Research. New York: Nova Science Publishers.³³
  “Differences of composition between green tea (popular in the Far East) and other teas (oolong and black teas, usually used in Western countries) are mainly due to the oxidation steps occurring during the fermentation process (Friedman, 2007).”

Drawing from memory, I could add many further examples of misunderstandings I personally encountered — often humorous ones, sometimes bitter ones. Speaking with tea vendors and other chárén 茶人 from both East and West, I have frequently heard them use, even in English, “fermentation” for enzymatic oxidation, and “post-fermentation” for microbial ripening.

German, Dutch, and Russian each have two terms associated with fermentation: one historically connected to the Latin-root family (fervere), and one of Germanic or Slavic descent. The meanings and figurative roots of Gärung and gisting are largely congruent with those of fermentation, yet these terms seem to include a wider range of historically sedimented connotations, especially in relation to baking. Among these connotations appears the meaning to lift, referring to the leavening action of yeast in bread and pastry. This history is particularly evident in Dutch, where gist is in fact “yeast”.^{34, 35, 36} Interestingly, in Russian, brozhéniye брожение is related with the verb brodít’ броди́ть, a term belonging to the Common Slavic family, with the meaning to roam, or to move slowly, also originally related to the expansive and apparently aleatory “movements” of food leavening.³⁷

For reference, in the table I have included a translation of both hòufājiào 後發酵 / 后发酵 and qiánfājiào 前發酵 / 前发酵 for every language considered. However, this does not imply that the terms are actually used in such languages. For example, only in very few instances have I encountered pre-fermentation in English in the context of tea.

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SECOND PARADIGM: THE CONTEMPORARY SCENE: TEA TERMS IN CHINESE, ENGLISH, & IN OTHER TEA COMMUNITIES.

The accepted language in today’s global tea communities.

In everyday (and especially food-related) English, fermentation is often used in a broad, “culinary-umbrella” sense: a transformation driven by microorganisms, regardless of whether oxygen is present or not.^[38] This wider usage easily absorbs a range of processes — alcoholic fermentation, lactic fermentations, acetic fermentations, and various aerobic “surface” ripenings — into a single lay label.

In biochemistry and microbiology, however, fermentation is commonly used in a narrower technical sense: an energy-yielding metabolism that proceeds without an external electron acceptor (classically, without oxygen), and in which organic molecules serve as terminal electron acceptors.^[39] That narrower meaning makes fermentation structurally distinct from aerobic respiration, and also distinct from “oxidation” in the everyday sense (i.e., reactions whose progress depends on oxygen as oxidant).

English dictionaries sit somewhere between these two poles: they retain the older, observable imagery (bubbling, frothing, “working”), while also adopting the biochemical register in which yeasts and bacteria are the principal agents.^[40] Historically, the scientific consolidation of the term is inseparable from 19th-century work on microorganisms and metabolism (notably the disputes that culminated in fermentation being framed as a biological process rather than a purely chemical “putrefaction”).^[41]

Tea terminology, unfortunately, re-entangles these meanings. In much Anglophone tea writing, the word fermentation is still applied to what is, in chemical terms, largely an enzymatic oxidation of polyphenols in the leaf — what older tea literature often called “fermentation”, and what many contemporary writers now prefer to call “oxidation”. The ambiguity is even reflected in some standardised vocabularies, where “aeration/oxidation” may appear parenthetically as “also called fermentation”.^[42] At the level of product definition, black tea is characterised internationally by the familiar process sequence (withering → maceration → aeration/oxidation → drying), even though everyday speech continues to waver between “oxidised” and “fermented”.^[43]

In tea processing, the core “oxidation” of black tea is best understood as a species of enzymatic browning: endogenous enzymes (especially polyphenol oxidase, and — depending on conditions — peroxidase systems) catalyse the conversion of catechins into larger oxidised polyphenols, with dramatic consequences for colour, aroma, and mouthfeel.^[44] This is not merely a terminological quibble: if one calls this fermentation, one risks smuggling microbial agency into a process that is, at least in its primary mechanism, enzymatic and leaf-internal.^[45]

On the other hand, there are tea processes in which microorganisms do most of the work (sometimes during processing, sometimes during ageing), and where fermentation in the microbiological sense is far less metaphorical. To keep the two domains conceptually separate, it can be useful to reserve a term such as microbial ripening (or, where appropriate, microbial fermentation) for those processes in which microbial communities drive the transformation of leaf constituents over time, producing distinct chemical and sensory signatures.

In contemporary Mandarin tea discourse, one also meets a vocabulary that tries — imperfectly — to cut across this ambiguity: categories such as qiánfājiào 前發酵 / 前发酵 (“pre-fermentation”) and hòufājiào 後發酵 / 后发酵 (“post-fermentation”) circulate widely, especially in discussions of dark teas and ageing. In parallel, and sometimes in tension with those older labels, a more “modern-scientific” dichotomy is increasingly deployed: yǎnghuà 氧化 (“oxidation”) for the enzymatic browning of the leaf, versus fājiào 發酵 / 发酵 (“fermentation”) for microbial transformation. This shift is not always explicit, but it is visible in how contemporary educational materials attempt to differentiate black-tea oxidation from dark-tea microbial change.

This brings us to a peculiar, but very common, contemporary confusion: the same word — fermentation / fājiào 發酵 / 发酵 — can be used to describe two almost opposite processes. In one sense it is a leaf-internal, oxygen-facilitated, enzyme-driven browning; in the other, it is a microbial ecology transforming the substrate over time, sometimes under conditions where oxygen is limited, sometimes not. The outcome is that even serious tea writing can slide between paradigms without noticing it.

「普洱茶它的前加工是属于不发酵茶类的做法，再经渥堆和后发酵制作而成。」^[46]

“Pǔ’ěr 普洱 tea’s initial processing follows the ‘non-fermented tea’ approach; it is then produced through wòduī 渥堆 and hòufājiào 後發酵 / 后发酵.”

The sentence is interesting not because it is “right” in some absolute sense, but because it reveals how classification habits can stack incompatible criteria: a product may be called “non-fermented” with reference to the absence of black-tea oxidation in the first stage, while simultaneously being described as “post-fermented” with reference to microbial change later.

「在内源酶具备活性的条件下，可以对茶叶受损细胞起发酵和氧化作用，生成前发酵茶。」^[47]

“When endogenous enzymes are active, they can exert ‘fermentation’ and oxidation effects on damaged tea cells, producing ‘pre-fermented tea’.”

Here, the slippage becomes explicit: endogenous enzymes (a leaf-internal mechanism) are said to cause both “fermentation” and “oxidation”, which in strict biochemical language would be different families of processes. Yet as tea language actually lives — across blogs, manuals, marketing, even some pedagogical materials — this kind of hybrid phrasing is not rare. It is exactly the kind of linguistic evidence that tells us: if we want to speak precisely about tea biology, we must state which paradigm we are using at any given moment.

In the rest of this article I will therefore treat oxidation primarily as the enzymatic browning of the leaf (black-tea style), and reserve fermentation for microbial transformation (dark-tea style), while noting whenever historically entrenched usage pulls the terms in the opposite direction.

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THIRD PARADIGM: THE SCIENTIFIC CONTEXT: THE TERMS OF TODAY’S BIOLOGICAL RESEARCH

How chemists and biologists, in each language, refer to the two fundamental processes and why.

Tea was made effectively long before science could explain the chemistry of the inner workings of tea production processes. On the other hand, advocates of a more naïve approach to tea experience — free from labels and structures pertaining to science — may reflect on the fact that even the modern consolidation of the six basic Chinese categories (báichá 白茶; lǜchá 綠茶 / 绿茶; huángchá 黃茶 / 黄茶; qīngchá 青茶 / wūlóngchá 烏龍茶 / 乌龙茶; hóngchá 紅茶; hēichá 黑茶) was not purely a matter of technique: the chemical composition of processed leaves (especially the quantitative profile of different classes of flavonoids) has often been treated as a criterion at least as relevant as production methods themselves.⁶⁰

These two articles by Eric Scott explain in detail how the definitional problem of the two biological processes examined here becomes particularly thorny in a scientific context:

• tea-geek.net/blog/2017/02/tea-terminology-part-1⁴⁹
• tea-geek.net/blog/2017/02/science-nomenclature-tea-processing-part-2-microbial-ripening⁵⁰

“Tea scientists seem to be as confused as everyone else. They sometimes use ‘fermentation’ with an explanation that this step doesn’t actually involve microbes. Other times they use ‘oxidation’, but explain what specific chemical reactions are going on. Still other times they use these terms without any explanation that they have a different meaning than the scientific one!”^{49, 50}

As a readily available example of this, we could recall the already mentioned paper: “Chinese dark teas: Postfermentation, chemistry and biological activities” (Zhang, L. et al., 2013).⁹

In a stricter scientific register, the Chinese equivalent of enzymatic browning is commonly expressed as méicù hèbiàn 酶促褐變 • 酶促褐变.^{51, 52} Here méi 酶 denotes enzymes (alongside the widely used synonym jiàosù 酵素), while hè 褐 foregrounds the salient sensory marker: browning. As a practical indication of how established this term is, a search for 酶促褐变 / 酶促褐變 yields a very large body of scientific literature:

• scholar.google.com/scholar?q=酶促褐变
• scholar.google.com/scholar?q=酶促褐變

As for the terms used to address microbial ripening (or, more explicitly, microbial fermentation), a robust candidate in Chinese scientific writing is wéishēngwù fājiào 微生物發酵 • 微生物发酵 (also encountered as 微生物發酵作用 / 微生物发酵作用). The compound is straightforward: wéishēngwù 微生物 (“microorganisms”) specifies the agency, while fājiào 發酵 / 发酵 supplies the familiar umbrella term — now constrained by the modifier in a way that greatly reduces ambiguity. A representative example is the integrated metagenomics/metaproteomics study of microbial communities and enzymes in solid-state fermentation of pǔ’ěr 普洱 tea.⁵³ Again, the term is easy to survey in the scientific literature:

• scholar.google.com/scholar?q=微生物发酵
• scholar.google.com/scholar?q=微生物發酵

For reference, we should keep in mind that, in biological reality, enzymes also participate in microbial processes: microorganisms produce enzymes to mediate core functions, including metabolic oxidation–reduction and substrate transformation.⁵³ As if things were not complex enough, tea-processing discourse sometimes compounds terms in ways that shift with context, and sometimes introduces additional descriptors for adjacent phenomena. In the literature on tea biology one may encounter expressions such as wéishēngwù yǎnghuà 微生物氧化 (“microbial oxidation”), shēngwù yǎnghuà 生物氧化 (“biological oxidation”), and nèiyuánxìng méicù fājiào 內源性酶促發酵 • 内源性酶促发酵 (“endogenous enzymatic fermentation”).^{54, 55} Only in regard to red teas, the controlled oxidation step is sometimes referred to as wòhóng 渥紅 • 渥红, literally “to enrich the red” — a term that foregrounds colour development as the salient phenomenological marker of the process.⁵⁶ In a related vein, Chén Chuán Chén Chuán 陈椽, in the context of hēichá 黑茶 processing, sometimes adopts the term zuòsè zuòsè 做色, meaning “colouring”.⁶⁰

Turning briefly to the other languages in the table: Japanese and Korean, when developing a scientific lexicon that needs to specify microbial agency, often retain the functional equivalent of “fermentation” (hakkō 発酵; balhyo 발효) while clarifying meaning by explicit modifiers (e.g., “microbial”). By contrast, several Western languages frequently avoid unconstrained fermentation in tea-processing contexts, preferring broader and less misleading descriptors such as ripening and maturation (or constraining “fermentation” via qualifiers such as “microbial”). Portuguese is a revealing intermediate case, since it comfortably carries the international scientific pair oxidação/fermentação while tea discourse may drift towards expressions like maturação microbiana where agency needs to be made explicit.

Finally, it is worth mentioning that Russian, spoken in an area geographically closer to China, shows an instructive coexistence of two terms for “enzyme”: ferment фермент and enzím энзи́м. Significantly, the older and more frequent фермент stands in visible morphological proximity to fermentátsiya ферментация (“fermentation”), making the Russian case unusually transparent as a linguistic fossil of older European scientific usage.^{57, 58, 59}

My attempt at investigating tea-biology terminology is, of course, constrained by limited access to sources (especially in Chinese and in many of the other languages surveyed). Yet I hope that even this necessarily partial mapping can offer a small orientation aid: it may illuminate why misunderstandings persist across communities, and why any precise discussion of “fermentation” in tea requires an explicit commitment to a paradigm.

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THANKS

A million heartfelt thanks go to the many who kindly provided answers, comments, and help for my questions and doubts:

Livio Zanini, Zhāng Wényǐng 张文颖, Nicoletta Tul, Kuge Kyōko 久下京子, Tanimoto Kōtarō 谷本宏太郎, Igor Kopylov Игорь Копылов, Marta Nazzari, Laura García Otero, Joe Myung 조 명희, Marjolein Raijmakers, Sara Cherchi, Lín Dáhàn 林達翰, Ip Wingchi 葉榮枝, Beppi Chiuppani, Kaspar Lange.

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51. Wikipedia (Chinese). Entry for 褐变 (hèbiàn).
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