An Attempt at Creating a Rosetta Stone of Primary Tea Biology

There has been a lot of debate on the topic of the limits of a taxonomical approach for understanding tea processing. With the goal of grasping what tea production is comprised of, is it more useful to think about it in terms of a series of succeeding independent steps, or as a continuum where each step blurs into the previous one and into the next?

In the same way, the lexicon that encompasses the processing of tea is so rich and complex, and it is so geographically, linguistically, and historically relative, that one could be left to wonder what the advantage might be, of trying to connect such distant points. In other words, what might be the purpose of trying to delineate the contours of a certainly limited and incomplete big picture? I believe that the main worth of such a project might be that of a general, initial orientation, for those trying to cross over onto the perspective on tea pertaining to a different context, for any reason. Westerners or Easterners alike, people with a chiefly humanistic or with a chiefly scientific education, professionals of the tea business, farmers, producers, vendors, or private tea devotees. This is the goal that guided me through this research.

However, I am not trying to establish a hierarchy of terms. I do not believe that one specific perspective among the three examined, should be adopted uncritically by the other two. That would be perhaps, a dangerous assumption. It is my opinion instead, that the mere knowledge of the existence of other perspectives, and a glimpse into their contents, might possibly hold the key to effective communication.

As for the confusion between red tea / black tea / dark tea (hóngchá 紅茶 / hēichá 黑茶), that even today still dazzles inexperienced Western chárén, the quirks of history and science have lengthy, lingering echoes on language. The aim of this project is to dispel some ambiguity 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 trying to direct their gaze at a more global tea community, either for personal interest or for business. Finally, it is an attempt to show an overview – certainly partial, but it is still a start – of the evolution of the descriptors of the basic biology of tea, ultimately leading to the issue of the complex international tea language of today.

I tried to do this by focusing only on the two generally-accepted fundamental processes, comparing them for three cultural and historical contexts and for ten different languages. The underlying question remains, as its ramifications go much beyond the scopes of this small project: can three very complex and diverse worlds learn to understand each other’s perspective?

The interest for this topic arose from the personal experience of many misunderstandings, I encountered in my experience both in the East and in the West. My knowledge of Chinese and of many of the remaining languages in the table being rudimentary at best, whether not non-existent, this is an attempt at a compiling report, mostly sourced from western literature and assembled with the precious help of native speakers of each presented language.

How to read the table:

• terms on the same column are used, often dichotomously, in the same geographical, linguistical or cultural context
• terms on the same row are used to refer to the same fundamental biological process

So many diverse and complex biological processes can occur during the production of the plethora of existing teas, fostered and modulated perhaps by even more agents and variables.^1-5 For example, reactions of enzymatic, as well as non-enzymatic oxidation can take place (such as the Maillard reaction). Many species of bacteria and fungi can initiate and promote beneficial and unbeneficial transformations in the leaves under different conditions. In this table, for simplicity, we are only focusing on the two essential mechanisms, in their broader definitions, while leaving most others unmentioned. For a quick review of what these two processes consists of, I recommend these introductory articles by Tony Gebely:

teaepicure.com/tea-leaves-oxidation

teaepicure.com/nuances-of-tea-classification

Instead of trying to define these two processes with a detailed description of their biological workings, at the beginning of this review we suggest a simpler idea as a key principle for their distinction. The agents of one of these processes are endogenous materials from the plant itself, while the promoters responsible for the other are instead alien, separate organisms, with an independent biology.

1. 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, sometimes written as 醱酵, is a non-trivial matter. For start, its pronunciation eludes even native speakers, as they sometimes pronounce it «fāxiào», because the phonetic component of 酵 is 孝, which is read xiào in Mandarin. 孝 is related to mǔ 母, mother, and sometimes translated as filial, dutiful. The other component is yǒu 酉, carrying many meanings among which unitary, mature, pond, and wine, and related to jiǔ 酒, also having the connotation of wine. The logogram jiào 酵 can already be found in medieval sources, and it holds primarily the meaning of yeast⁶. Fā 發 • 发 conveys many similar ideas, as producing, expressing, delivering, revealing⁷. It seems that a related term, jiàosù 酵素, has been introduced from Japanese after W. F. Kühne coined enzyme in 1877⁸, and this appears compatible with what we shall discuss in the following paragraphs.

During the 1850s and 1860s, Louis Pasteur published some of its most influential works, demonstrating the critical role played by living microorganisms in food spoilage and other kind of changes occurring in complex organic substances.^{9, 10} Very little scientific literature existed at the time on the subject of the biological marvels of tea transformations, and in that cultural climate the idea that microorganisms were doing most of the work became quickly accepted. As partial or as conjectural as this may be, in the second half of the 18th century – with the development of the industry of aerobic ripening of foods – the term fājiào 發酵 • 发酵 also began to be applied in China as an umbrella term to describe most of the processes that took place in tea during processing and maturation.¹⁰

In English, the word fermentation comes from the latin word fervere, literally “to be scorching”, “to seethe”. In its more general and figurative definition, fājiào 發酵 • 发酵 is instead a metaphor for something that has developed and changed under the influence of external forces.^{11, 12}

« “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。» ¹¹
«”Fermentation” originally referred to a state of light foaming or boiling. The phenomenon of fermentation has long been recognized by people, but its essence was not understood until roughly 200 years ago. »

«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。» ¹³
«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.»

The prefix hòu 後 • 后, began later to be added to fājiào 發酵 • 发酵, in an attempt to differentiate what occurred after production, during the ageing of the fully processed tea^14a. But the distinction is not as rigid as it is in the modern dichotomy between yǎnghuà 氧化 and fājiào 發酵 • 发酵.^{(see below for the next paradigm)} In other words, fājiào 發酵 • 发酵 can sometimes include, in the eyes of those who use it, the biological transformations addressed by hòufājiào 後發酵 within the scope of its meanings. That is why, in the proposed table, I have enclosed hòu 後 • 后 within parenthesis, and the line that separates fermentation and post-fermentation is dashed: the prefix may not always be present. Furthermore, more rarely someone also considers another prefix, qián 前. They use it to distinguish qiánfājiào 前發酵 • 前发酵, pre-fermentation, when talking about 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 more of the ambiguity.^{15, 16}

«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」»¹⁶
In order to be different from the above-mentioned pre-shāqīng fermentation, this post-shāqīng fermentation is called “post-fermentation”.

These terms survive to this day and are much used in China and in the Eastern languages, just as some of their corresponding translations are still in use in English and in other Western languages.

Yet, as George van Driem^14b points out, already in 1893 the intuition that a different process – namely oxidation, that was not caused by external agents – was probably responsible for the changes occurring in the leaf during the production of red teas, had already circulated among botanists and chemists for at least fifty years.

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.¹⁷

Bamber, M. K. (1893). A Text Book on the Chemistry and Agriculture of Tea: Including the Growth and Manufacture. Law-Publishing Press. (p. 225).

Again, from van Driem^14b, we learn that a few years later, the same Bamber¹⁸ reported that he had isolated an oxidase enzyme from tea leaves. And that, 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»¹⁹, and inferring about the capacity for heat to halt the process by «the destruction of oxidase in the first steps of preparation».

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. »^14b, 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.

With much greater certainty, we could state that this linguistic contrast has echoed in Western publications for more than a century, somehow continuing to this day, and taking the form of the term fermentation (and post-fermentation), being used loosely and interchangeably, thus contributing to spread much confusion and misinformation on the matter.

It is indeed easy to make this statement manifest, by listing just a few notable examples:

• Blofeld, J. (1985), The Chinese art of tea. Boston: Shambhala.
  «green (unfermented), semi-green (partially fermented tea generally called ‘oolong’ in English) and red (fermented tea called ‘black tea’ in English).»
  Describes pu’er as a tea belonging to the categories of «white, green or red (black)»

• Willson, K. C., & Clifford, M. N. (1992), Tea: cultivation to consumption. Dordrecht: Springer Science & Business Media.
  Despite being a widely praised book, written by two western biologists, it still uses fermentation to describe enzymatic oxidation, semi-fermented teas to refer to wulongs.
  «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.
  «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.
  «Black tea is fermented; green tea is not.»
  The author does indeed 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 then she keeps using fermentation for the rest of the book.

• Jamieson, M., & McKinley, H. (2009), Handbook of Green Tea and Health Research. New York: Nova Science Publishers.
  «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 to the list many examples of misunderstandings I personally experienced, often humorous ones, sometimes even bitter ones. Talking with tea vendors and other chárén from both East and West, much often I heard them use, even in English, “fermentation” for enzymatic oxidation, and “post-fermentation” for microbial ripening.

German, Dutch and Russian have two terms for fermentation, one from the Latin etymology fervere, and one of Germanic or Slavic descent. The meanings of the etymology of Gärung and gisting are quite congruent to those of fermentation, but the former terms seem to include among their figurative roots a wider range of connotations, revealing of a use that extends for many centuries, especially in the context of baking. Among those connotations, in fact, appears the meaning to lift, referring to the leavening of yeasts for bread and pastry. This history is particularly evident in Dutch, where gist is actually yeast.^23-25 Interestingly, in Russian, brozheniye 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.²⁶

For reference, in the table I have included a translation of both hòufājiào and qiánfājiào for every language considered. However, we do not imply that the terms are actually used in such languages. For example, only in very few instances I have encountered pre-fermentation in English in the context of tea.

2. SECOND PARADIGM: THE CONTEMPORARY SCENE: TEA TERMS IN CHINESE, ENGLISH, & IN OTHER TEA COMMUNITIES.
   The accepted language in the global tea communities of today.

As the Wikipedia page on fermentation states, «In the context of food production, [fermentation] may more broadly refer to any process in which the activity of microorganisms brings about a desirable change to a foodstuff or beverage». Even in this recent, broader definition, once again, the agents of transformation are microorganisms [microbes] – that is to say, exogenous actors to the plant. In its older first definition, fermentation simply referred to recognizable change in biotic substances, initiated for the manufacture of certain products, without the development of putrefactive smells and with or without the admission of air. However, these definitions both differs from the current most prevalent scientific use of the term, as proven by the fact that later in the Wikipedia page, examples are only shown of what is most commonly referred to, as fermentations: alcoholic fermentation, lactic-acid fermentation, etc. In this narrow modern definition, the term designates microbial degradation of carbohydrates for the purpose of generating energy, without the inclusion of external electron acceptors such as oxygen (O₂) or nitrate (NO₃−).⁹ That is why, in a scientific context, microbial ripening – a much more general term – is more accurate to describe the many diverse – and often aerobic – transformations occurring during tea processing. But we shall delve into this more deeply when talking about the next paradigm.

What counts is that – after more than one century and probably due to the recent growth of the tea community in the West and to the expansion of the market of Eastern tea – an important distinction regarding the browning of the leaves, has finally entered the imagination and the language of the international tea community: the process that creates, for example, wūlóng and red teas, is not chiefly attributable to external agents, but rather to components indigenous to the leaf itself (i.e. the enzymes polyphenol oxidase and peroxidase, contained in the leaves into the cellular plastids).

As I stated talking about the previous paradigm, it is not uncommon to see today, even in publications, the terms fermentation and post-fermentation still being used. However, in the international English-speaking tea community, I feel confident in saying that the terms oxidation and fermentation are today the ones most commonly used, to refer to the two fundamental biological processes occurring in tea production. Within this simplified dichotomy, the term oxidation elicits no ambiguity of interpretation, to my knowledge, as well in any of the other examined languages.

When it comes to the Chinese contemporary tea community of producers, vendors, and devotees, the terms belonging to tradition, especially in the forms of [qián-] fājiào [前] 發酵 • 发酵 and hòufājiào 後發酵 • 后发酵, are still very much in use. But a new dichotomy is slowly taking hold, and yǎnghuà 氧化 and fājiào 發酵 • 发酵^{20, 21} – fairly equivalent in meaning to the two mentioned in the previous paragraph – are now becoming adopted interchangeably, especially among experts, scholars and professionals of tea, both in the mainland as in Taiwan.

Therefore, at last and at least in principle, a form of linguistic continuity may exist today between the two communities, even if a clear linguistic and cultural segregation still endures.

That also means that, effectively, depending on the context, the terms fājiào 發酵 • 发酵 and fermentation can be used to describe the opposite biological processes: in the context of the Chinese tradition, fājiào is enzymatic oxidation but also sometimes “everything else” (including microbial ripening), while in the new dichotomy, fājiào should only be microbial ripening. No wonder much confusion endures to this day regarding the nature of these transformations!

An eloquent example of the degree of disorientation that this coexistence of partially overlapping terms can lead to, can perhaps be found in sentences such as these:

«普洱茶它的前加工是属于不发酵茶类的做法，再经渥堆后发酵而制成 »²²

«Pǔ’ěr tea pre-processing is that of a non-fermented tea. It is later obtained by piling and post-fermentation»

«在内源酶具备活性的条件下，对茶叶受损细胞起发酵和氧化作用，就制成了前发酵茶 »¹⁵

«When the endogenous enzyme is active, it can ferment and oxidize the damaged cells of the tea, and make the pre-fermented tea»

3. 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 the experience of tea, free from labels and structures pertaining to science, may reflect on the fact that even in the process of categorization that enshrined the six basic categories of Chinese tea within the modern definition in use today (báichá 白茶; lǜchá 绿茶 • 綠茶; huángchá 黃茶 • 黄茶; qīngchá 青茶 / wūlóngchá 烏龍茶 • 乌龙茶; hóngchá 紅茶; hēichá 黑茶), the chemical composition of the processed leaves – especially in relation to the quantitative profile of different classes of flavonoids – had a key role, supposedly more relevant than the one played by methods and techniques pertaining to tea production.²⁷

These two articles by Eric Scott explain in detail how the problem of the definition of the two examined biological processes can take form and why, when moving to a scientific context:

www.teageek.net/blog/2017/02/tea-terminology-part-1

www.teageek.net/blog/2017/02/science-nomenclature-tea-processing-part-2-microbial-ripening

As he points out, «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!»

As a readily available example of this, we could offer the already mentioned paper titled: «Chinese dark teas: Postfermentation, chemistry and biological activities.» (Zhang, L. et al., 2013).²

It seems that, in a scientific context, the Chinese equivalent of enzymatic browning could be méicù hèbiàn 酶促褐變 • 酶促褐变.^{28, 29} The term seems to be used extensively with that connotation, in hundreds of scientific papers. Méi 酶 are the enzymes (the already mentioned jiàosù 酵素 is also used with the same meaning). Hè 褐 refers to the brown colour.

scholar.google.com/scholar?q=%E9%85%B6%E4%BF%83%E8%A4%90%E5%8F%98

scholar.google.com/scholar?q=%E9%85%B6%E4%BF%83%E8%A4%90%E8%AE%8A

As for the terms used to address microbial ripening, a likely candidate could be wéishēngwù fājiào 微生物發酵 • 微生物发酵 (also 微生物發酵作用). It appears widely used in scientific papers. The term wéishēngwù 微生物, translatable as microorganism in the proper context, is paired with the already well know fājiào, thus it appears less likely to elicit ambiguity as for its interpretation. That may explain its academic use.

scholar.google.com/scholar?q=%E5%BE%AE%E7%94%9F%E7%89%A9%E5%8F%91%E9%85%B5

scholar.google.com/scholar?q=%E5%BE%AE%E7%94%9F%E7%89%A9%E7%99%BC%E9%85%B5

For reference, we have to keep in mind that in the complex biological reality, enzymes often take part as well to the latter of the two examined mechanisms, as they are produced by microorganisms to mediate some of their functions, for example in the metabolic processes of biochemical oxidation-reduction³⁰. As if things were not complex enough, related to this is the fact that sometimes the terms we presented cross and compound interchangeably depending on the context, and other times, different terms are also used to refer to supplementary or related phenomena. For example, in the context of the biology of tea processing is possible to find wéishēngwù yǎnghuà 為生物氧化 • 为生物氧化³¹, loosely translatable as microbial oxidation, shēngwù yǎnghuà 生物氧化³², loosely translatable as biological oxidation, and nèiyuánxìng méicù fājiào 內源性酶促發酵 • 内源性酶促发酵³³, loosely translatable as endogenous enzymatic fermentation. Only in regard to red teas, the process of controlled oxidation is sometimes known as wòhóng 渥紅 • 渥红²⁰, literally to enrich the red. The same Chén Chuán 陈椽, in the context of the fermentation of hēichá, adopts sometimes the term zuòsè 做色, meaning colouring.²⁶

In regard to the other languages being taken into consideration, it is interesting to notice how the other two Eastern ones – namely Japanese and Korean – in developing a scientific lexicon that makes it necessary to add a reference to microbes, retain the equivalent of fājiào: hakkō 発酵 and balhyo 발효. On the contrary, the examined western languages lose the relatively ambiguous fermentation, in order to adopt broader terms that are less likely to elicit confusion in the context of tea processing (ripening, maturation, etc).

It is also worth mentioning that Russian, being the language spoken in an area geographically closer to China, reveals an interesting coexistence of two terms to refer to enzymes: ferment фермент and enzím энзи́м. Significantly, the older and most frequently used one, фермент, appears related to fermentatsiya ферментация (fermentation).

My attempt at an investigation into the terms of the biology of tea was of course narrowed by my limited access to sources in Chinese and in many of the other languages that were surveyed. I consider this research nothing more than a brainstorming about these subjects, as the confines of my knowledge allow for nothing more. However, I do hope my attempt can offer a little insight into the challenges this topic presents to both Western and Eastern readers and I hope it can fuel the ongoing debate about it.

THANKS

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

Livio Zanini, Zhāng Vivian 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, Valérie Tikhonoff, 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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2. Zhang, L., Zhang, Z. Z., Zhou, Y. B., Ling, T. J., & Wan, X. C. (2013), “Chinese dark teas: Postfermentation, chemistry and biological activities”, Food Research International, 53(2), 600-607.
3. Balentine, D. A., Wiseman, S. A., & Bouwens, L. C. (1997), “The chemistry of tea flavonoids”, Critical Reviews in Food Science & Nutrition, 37(8), 693-704.
4. Yamanishi, T., Kobayashi, A., Sato, H., Nakamura, H., Osawa, K., Uchida, A., Mori, S. & Saijo, R. (1966), “Flavor of Black Tea Part IV. Changes in Flavor Constituents during the Manufacture of Black Tea”, Agricultural and Biological Chemistry, 30(8), 784-792.
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6. Jiào 酵 – Hànyǔ dà cídiǎn 汉语大辞典
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8. Jiàosù 酵素 – Bǎidù Bǎikē 百度百科
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11. Fājiào 发酵 – Bǎidù Bǎikē 百度百科
12. Fājiào 發酵 – Wiktionary.org
13. Fājiào 發酵 – Wikipedia.org
14. Van Driem, G. L., Driem, G. v. (2019). The Tale of Tea: A Comprehensive History of Tea from Prehistoric Times to the Present Day. Leiden, Boston: Brill.
    • 14a. «Consequently, these dark teas are sometimes also called ‘post-fermented’. What ‘post-fermentation’ actually means is nothing more than true fermentation with the aid of microorganisms after the process of oxidation has either been arrested or naturally come to a halt.» (p. 138)
    • 14b. pp. 133-134
15. 【普洱傳奇】普洱茶的陳化真相與秘密 – Zǐyì cháliáo 紫藝茶聊
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24. Gärung – WDW Online-Wörterbuch
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26. Бродить – Lexicography.online. Этимологические онлайн-словари русского языка
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28. Hèbiàn 褐变 – Wikipedia.org
29. Méicù hèbiàn 酶促褐变 – Bǎidù Bǎikē 百度百科
30. Zhao, M., Zhang, D.L., Su, X.Q., Duan, S.M., Wan, J.Q., Yuan, W.X., Liu, B.Y., Ma, Y. and Pan, Y.H. (2015), “An integrated metagenomics/metaproteomics investigation of the microbial communities and enzymes in solid-state fermentation of Pu-erh tea”, Scientific reports, 5(1), 1-10.
31. 你真的弄明白了茶叶的“发酵”？ – Sōuhú 搜狐
32. Shēngwù yǎnghuà 生物氧化 – Bǎidù Bǎikē 百度百科
33. 相期以茶 篇一：#原创新人# 简说中国茶叶的六大分类及十大名茶 – Shénme zhídé mǎi 什么值得买