Culture Pavilion Chronicles: Fermenting in Berlin

I. Assembling the Culture Room

Eight years ago, I created a piece centred on naturally fermented yoghurt, drying yoghurt starter cultures onto fabric. I was never particularly keen on drinking yoghurt; back then, I mainly made it because I saw natural fermentation as a potential medium for artistic expression. Consequently, maintaining yoghurt fermentation as a regular habit or hobby never really took hold.

Two years ago, when my partner and I decided to move in together, I was finally able to arrange the room layout exactly as I envisioned, carving out dedicated space for my fermentation projects. Switching to freelance work also meant shedding the nine-to-five routine. Life suddenly snapped back into focus, and hours of free time flooded in from every direction. So, I dove headfirst back into the world of microorganisms, nurturing my own fermented foods once again.

This time around, fermentation was driven by appetite and anticipation, a purely culinary pursuit: entrusted with yeast by a friend, I started baking bread; to beat the summer heat, water kefir took up residence in my kitchen once more; and after returning from my hometown, I enthusiastically set to making pickles… And so it went: a steady procession of bottles and jars coming and going through the kitchen, some settling in for the long haul, others lingering for a single season before hastily departing.

◉I transformed an unused corner of the house into a cabinet for room-temperature fermented foods, jokingly dubbing it the ‘Microbe Cabinet’ (Mikrobenkabinett). In German, *Kabinett* means both a display room and a cabinet of ministers, which perfectly captures my mental image of the microbes gathering together in one room to hold a grand assembly.

II. The Permanent Residents of the Culture Cabinet

I have experimented with countless fermented foods: yoghurt, cheese, pickles, sour soup, kombucha, water kefir, fruit and rice vinegars, sweet rice wine, bread, miso, vegetables cured in rice bran, tempeh, fermented fruit ‘tofu’, fish sauce… Merely listing them all took me aback; I had no idea I had quietly made so many attempts over the years.

Once you recognise the presence of microorganisms and come to understand which microbial communities take the lead at different stages of fermentation—lactic acid bacteria, acetic acid bacteria, yeasts, various moulds—and treat them like pets by providing a suitable habitat, failure becomes all but impossible.

Lactic Acid Bacteria

◉ Under the microscope: the starter brine for my pickles.

The production of pickles, preserved vegetables, and yoghurt all rely on lactic acid bacteria fermentation, which converts the sugars in vegetables and the lactose in milk into lactic acid. However, the lactic acid bacteria strains found in pickles can, alongside this homofermentation, also carry out heterofermentation, yielding a mix of by-products such as acetic acid, formic acid, ethanol, or carbon dioxide.

The lactic acid bacteria in pickles are anaerobic and highly tolerant of salt and acid. In a sealed, airtight jar with sufficient salt, they quickly outcompete any stray microbes to become the dominant culture. They are hands down the most low-maintenance residents in my fermentation cabinet.

Back in my hometown, a pickle jar is traditionally known as a ‘sour crock’.

During a trip home this year, I acquired a bottle of brine from a friend of my 娭毑 (āi jǐ)—a term of endearment and respect in the Hunan dialect for an elderly woman, typically referring to a grandmother. Upon returning to Germany, I poured it straight into my own jar, effectively grafting twenty years of her legacy onto mine. Accustomed to a Changsha diet of garlic, Chinese scallion buds, long beans, and white radish, the bacteria here have happily taken to a Berlin pantry of parsley root, fennel, kohlrabi, and cherry radishes. A jar fed a diverse diet only grows richer in aroma and simpler to tend.

That single scoop of brine has since become the tether for my conversations with 娭毑. Amidst our daily catch-ups and exchanges of well-wishes, I invariably find myself reporting on the jar’s state. I feel as though I have been entrusted with a precious life, a bond of affection, and a distinct flavour.

◉ Left: the crock shortly after being seasoned. Right: a vintage pickling jar from my friend’s grandmother’s home, carrying over twenty years of fermentation history.

◉ In mid-September this year, at the invitation of friends, I joined a food performance at Berlin’s museum complex. We fired up a wood-burning oven to bake bread, invited the audience to help tread sauerkraut, weave fruit garlands, and served free food to nearly ten thousand visitors. For the ten large barrels of sauerkraut, I spent the previous week cultivating ten litres of brine using our household’s mother liquid. Poured over shredded cabbage and trampled all afternoon by a pack of overly excited children, it surprisingly developed a rather authentic flavour.

◉ Alongside the classic water-pickled crock method, I began crafting bran-cured preserved vegetables this year. Since I was in a wheat-growing region and could not source rice bran, I used wheat bran to condition the fermentation bed. Seasoned with lemon and pepper, it actually produced wonderfully tasty pickled apples and cherry tomatoes.

Yeast

Yeast breaks down sugars into CO2 and alcohol, making it useful for brewing and for leavening baked goods.

I cannot drink alcohol, nor do I have much interest in brewing. Yet over the past few years, maintaining a sourdough starter and baking bread have grown into a daily companion of mine.

The yeast for my bread came from a friend. An elder in his family opened an organic shop in the early 1990s, selling bread made with their own wild yeast. Over the past thirty years, this sourdough starter has been passed between different generations of his family, finally coming into his hands a couple of years ago during a visit from a relative.

As he took up baking, he also distributed portions of the culture to other bakers in Berlin. Having been entrusted with my 100g of starter, I have tended to it with great reverence.

◉ Before I knew it, my phone was filled with an ever-growing archive of bread photographs.

Over the past two years, as I continued baking, I have kept sharing portions of the yeast with friends, who naturally passed it on further. It has even come to pass that when visiting friends’ homes, I occasionally meet the surprised gasp of complete strangers: “So you’re the original keeper of the yeast?!”

It feels as though I have unwittingly founded a quite large organisation.

◉A year ago, whilst taking part in a friend’s amateur theatre group, I wove the daily ritual of tending to dough into the stage production. The dough would be hurled against the wall, transforming into a mask. I kneaded it and spoke to it; in turn, it responded to my care with shifting expressions.

◉In Berlin, I happened upon a group of “bread obsessives”. They look down on the monolithic bread aesthetic pushed on social media (strong gluten, large holes), and instead organise annual gatherings themed around different grains. They invite researchers, millers, and bakers to share their expertise, explore flavour possibilities beyond conventional wheat, and champion the diversification of grain cultivation.

Acetic Acid Bacteria

Acetic acid bacteria are aerobic organisms that convert alcohol into acetic acid. This gives rise to the saying that wine and vinegar share the same origin—wine must come first, before vinegar can follow.

Vinegar provides the baseline for sour flavours, reflecting the agricultural output and culinary preferences of each region. In southern China, rice vinegar is the staple in rice-growing areas, while the north favours grain vinegars made from sorghum and wheat bran. Across Europe, fruit vinegars fill the shelves: wine vinegar made from wine, and apple vinegar from cider.

When I occasionally spot discounted seasonal fruit and vegetables, lactic acid fermentation and vinegar-making are the first methods that spring to mind for preserving their flavours long-term.

◉ In September, German streets are lined with trees heavy with plums of every variety. This year, following a friend’s lead, I couldn’t resist gathering a basketful to take home and turn into plum vinegar.

Mould

One of the defining features of East Asian fermented foods is the use of sauces and condiments produced with various moulds.

Every mould carries its own common names and trade labels. The constant shifting between native terms and foreign borrowings often leaves me dazzled. To keep things straight, I’ve taken to drawing up my own classification table, listing the Latin names for each strain. It serves as a handy guide to the different mould families and their respective strengths.

根霉属Rhizopus are the primary workhorses in tempeh production, with *Rhizopus oryzae* also employed in brewing; 毛霉Mucor species under the genus are frequently used to make fermented bean curd.

*Aspergillus oryzae* is often referred to as Japanese rice mould or white koji mould, while *Aspergillus sojae* is known as soy sauce mould, also called rice koji mould. The so-called black Aspergillus refers to *Aspergillus niger*, whereas red koji mould belongs to an entirely different genus, *Monascus*, comprising various species.

When speaking of moulds, one cannot fail to mention *qu* (koji). *Qu* refers to a fermentation starter in which grains (such as rice, wheat, barley, peas, or oats) serve as the substrate, inoculated or naturally enriched with mould-dominant microorganisms (such as the aforementioned *Aspergillus*, *Rhizopus*, and *Mucor*). These cultures can be used to kickstart the production of new batches of fermented foods (such as alcoholic beverages, soy sauce, vinegar, and fermented black beans).

For instance, inoculating rice flour with *Rhizopus* and brewer’s yeast yields *xiaoqu* (small koji), used to make rice wine and fermented rice. Inoculating broad beans with *Aspergillus oryzae* produces the mouldy beans used for broad bean paste. Inoculating glutinous rice with *Monascus* and *Aspergillus niger* creates *wuyi hongqu* (black-coated red koji), which can be used to brew red yeast rice wine and rose vinegar. Meanwhile, the world-renowned Japanese rice koji is simply rice inoculated with white Aspergillus mould; both Japanese artisans and the contemporary culinary world have unlocked endless applications for it, from soy sauce and shio koji (salt koji) to miso, and beyond.

In home fermentation experiments, mould-based fermentation is the only category where I rely on a fermentation chamber and commercial starter cultures. Traditionally, people would cover grain substrates with straw or leaves to inoculate them with microorganisms naturally abundant in the air and soil. However, this method of spontaneous fermentation is deeply tied to the specific temperatures and humidity levels of local environments and seasons, making it nearly impossible to replicate in urban settings with entirely different climates and microbial ecosystems. By using industrially purified single-strain cultures, each step can be precisely quantified, which genuinely lowers the learning curve for mould fermentation. This is likely why Japanese rice koji has captured the imagination of the world.

◉ Monascus purpureus (red yeast rice mould) is widely used across the coastal regions of Guangdong, Fujian, and Zhejiang for brewing wine and making vinegar. The colour-producing metabolites generated during fermentation impart a rich, deep red hue to the food. These very regions, where the mould has been cultivated for generations, were also the departure points for many early Chinese immigrants. *Red Terroir* is a 2025 still-life series of my own, drawing on fermented foods from Southeast Asia, Japan, and Europe—areas where historical Chinese migration routes have long intersected. It aims to prompt viewers to reconsider the connection between the spread of moulds and the great waves of human migration.

Co-fermentation of multiple microorganisms

Of course, many fermented foods arise from the combined action of different microorganisms. Kombucha and kefir, for instance, are fermented beverages that utilise a SCOBY (Symbiotic Colony of Bacteria and Yeast — a symbiotic colony of bacteria and yeast). Natural yeast cultures also contain lactic acid bacteria and certain moulds, while natural koji cultivation involves the interplay of yeast and lactic acid bacteria.

◉Cultivating a SCOBY is part of the kombucha and vinegar fermentation process: it is a ‘microbial pellicle’ formed by active microorganisms at the liquid–air interface.

◉When cultivated in moulds shaped like face masks, these microbial films are said to provide skincare and rejuvenating benefits.

III. I Nurture the Cultures, and the Cultures Nurture Me

In recent years, it has felt to me that fermented foods have gradually begun to gain traction and popularity among the urban middle class.

As someone who both follows and observes trends, I can’t help but reflect: guided by consumer-driven social media, when we first delve into a particular type of food, we are all too easily captivated by the techniques and tools of its preparation. Tea drinkers love to collect and display teaware; coffee enthusiasts design set after set of expensive, intricate stainless steel gadgets. When it comes to fermentation, it’s the pursuit of an open, airy crumb in bread, or the dense, fine effervescence in kombucha—after all, these are the most visually arresting elements in an image-driven media landscape.

Still, I quietly hope that the pursuit of diverse flavours will eventually lead these tasting-centred hobbies to explore varieties, genetics, terroir, and other agricultural and crop-related topics. If the fermentation trend extends beyond surface-level aesthetic appreciation and encourages urban dwellers to learn a little more about the varieties and origins of their ingredients, that would be a wonderful thing indeed.

◉The WWW (We, Wheat, Weave) project collects the various wheats and grains I have encountered in daily life and travel. With the support of local communities, traditional weaving techniques are used to weave the materials into a ‘growing’ sculpture.

For me, exploring fermented foods has reawakened my awareness of the changing seasons and deepened my appreciation for regional characteristics.

Making fermented foods has anchored my life’s rhythms: tending to yeast and nurturing koji beds by the day, refreshing kombucha by the week, and maturing vinegar, miso, and other condiments by the month or even the year… Within these cyclical patterns, I have found a pace that suits me, gradually aligning my daily routines with the microbial world.

◉The anecdote of Da Vinci ‘drawing eggs’ is widely taught in China’s basic education. This apocryphal story about a Western artistic master emphasises diligence over innate talent, stressing that art is born from day-after-day repetitive foundational practice. This monotonous, repetitive labour is not only evident in artistic training but is deeply rooted in the invisible domestic chores of everyday life—cooking, caregiving, and other forms of care work often deemed lacking in creativity. *Circle Drawing Exercises* stems from my daily bread-baking practice. In each iteration following the same recipe, the imprint left by every loaf on the baking paper ‘draws’ a different ‘circle’, revealing the subtle evolution of form and the passage of time hidden within repetition.

Through selecting ingredients and cultivating environments for microbes, I have gradually learned that fermentation should follow the seasons and adapt to local conditions: fermenting bean curd in the depths of winter, brewing wine during the first lunar month, making pastes and sun-drying white chillies during the hottest stretch of summer, pickling vegetables in rice bran at late summer’s end. Spring and autumn bring an abundance of fresh fruits and vegetables to market, providing a continuous stream of inspiration and raw materials for lactic acid and acetic acid fermentation.

Towards the end of last summer, a friend in Hangzhou and I nurtured our cultures in parallel across two locations. In temperatures exceeding 30°C, her sourdough starter languished, yet her sweet rice wine thrived with effortless ease. Meanwhile, in my 23°C flat, my koji starter either soured or dried to cracking, but my casually tended sourdough culture flourished, gifting me with more than a few delicious loaves.

The seasonal nature of fermentation has sharpened my awareness of shifting seasons and their respective harvests, making me more attuned to temperature fluctuations. Simultaneously, these comparative fermentation experiments with friends in different regions have deepened my appreciation for local characteristics. Furthermore, observing how similar fermentation techniques evolve along distinct paths and develop unique flavour profiles across different cultures offers a particular joy unique to cross-cultural fermentation practice.

Foodthink Author

Xu Xijing

Designer, fermentation enthusiast, and contemporary artist. Born in Changsha, Hunan, she currently lives and works in Berlin. Her current practice and research focus on grains and fermentation. Founder of Doubou, she co-founded the food design studio ‘TÍHÚ (TiHu)’ in 2025. Contact: info@xijingxu.com

All images in this article are provided by the author.

Editor: Xiaodan