When Noma released its lauded Guide to Fermentation in 2018, it reflected an already growing wave of enthusiasts across the industry. The processes hit the mainstream, and it became more common to see house-made kombuchas and garums on Australian menus. Seven years on and the fervour has calmed, seeing many cafes and restaurants simplify the preserves on their menus: perhaps a ploughman’s platter with a fermented pickle and sauerkraut, or a humble kimchi toasty.
But on the other side of the coin, a handful of chefs are ignoring fads in favour of exploring how fermentation has been used for centuries across continents, opting to become leaders in the field and committing to the experimental side of the art. The drivers are manifold for the daring chefs experimenting with niche ferments, from the excitement of discovering new flavour profiles and innovative applications for produce, to the ability to preserve and retain hyper-seasonal ingredients for year-round use.
Freyja Executive Chef Jae Bang stresses that fermentation shouldn’t be seen a trend. “It’s been done for hundreds of years in all different cultures and cuisines,” says the chef. Freyja opened in 2022 with Bang at the helm. The chef has an impressive resume, having worked at fine-dining restaurants internationally, including San Sebastian’s Arzak, New York’s Daniel, and one of Norway’s few three Michelin star restaurants, Re-naa.
His time in Norway shaped his approach to fermentation: “In Norway, we didn’t do this because it’s a trend or because everyone else was doing it. We were doing it because it was necessary. Having a very short spring and summer when vegetables and fruits are in season, if we didn’t do it, we wouldn’t have any access to these flavour profiles during the wintertime or even early spring.”
This approach has bled into Bang’s tenure at Freyja, where he leads the kitchen with three core tenets: minimal waste, sustainability, and regionality.
For The Mulberry Group’s recently appointed Head Chef of Molli and Group Head of Fermentation Caitlin Koether, the “magical and transformative” nature of the process is what interested her. Koether was first introduced to fermentation when she started working at Blue Hill in New York close to 17 years ago. One of the chefs there was working with whole animal butchery and preserving techniques. A self-described “massive nerd”, Koether is the type of person who finds things she doesn’t understand fascinating. At the time, fermentation was one of those things.
“I was reading Harold McGee’s On Food and Cooking at the time. And I knew that I really liked understanding the foundation of why things happen the way that they do. So when the chef was describing what fermentation was and how it’s a little bit uncontrollable and pretty magical and transformative, I found that interesting,” says Koether.
After a stint at San Francisco’s Bar Tartine (a “magical playground of fermentation and food before its time”) and time running the preservation and fermentation program at Copenhagen’s Relæ, her passion was set. Not one to do things by halves, Koether has established a big name in the world of ferments, leading The Mulberry Group to specifically craft her new role around her expertise.
Seasonality
Both chefs note that preserving seasonal produce is a major drawcard of fermentation. While preserving processes were once born out of the necessity, global supply chain networks and innovations in food production means that difficulty sourcing products isn’t a pressing problem in Australian kitchens — yet this accessibility raises concerns around sustainability.
At Freyja, the staff take an annual outing to a local strawberry farm right before Christmas. At that time of year there aren’t many ripe strawberries ready for consumption — but that’s not what the team are there for. Instead, they select unripe, green strawberries specifically for their unique flavour profile: “They’re more floral with a denser texture, higher acidity, and less sweetness. So the versatility of this product is very broad,” says Bang.
Bang adds salt to the green strawberries and puts them through a lacto-fermentation process. Once preserved, he uses them as a type of caper, because of the pleasant combination of tanginess from the lactic acid and the unripe stage of the fruit. On the current menu, Bang slices the lacto-fermented strawberries to about a half centimetre thick and uses them in a beef tartare dish.
Bang says with the weather being hard to predict in Melbourne, foraging for hyper-seasonal produce can go from successful to impossible within the span of a few days. “By preserving these items, we have longer access to them, and this helps us to support these three philosophies that we are really striving for.”
Koether says that fermentation allows her to preserve rare, hyper-seasonal produce in a variety of ways so they can be enjoyed for longer. One such product is green walnuts. The chef sources the young walnuts from Day’s Walk Farm (just outside Melbourne) in December and January. She uses them to produce Nocino, a black walnut liqueur; Glyko Karydaki, a Greek spoon sweet where the green oxidises to become totally black; and English pickled green walnuts which become a versatile, black, almost molasses-like pickle.
Process and product
When she first began her role, The chef assessed which ferments would take the longest and should be started immediately, and which could be done later. Koether breaks her ferments down into four categories: koji, dairy, pickles, and sodas. Alongside these, she’s also focussing on a range of techniques that land under the umbrella term of preservation, including dehydration, Maillard reaction, and smoking.
The longest ferments, says Koether, are the ones with higher salt — in particular, koji.
“Starting with a higher salt percentage controls the enzymatic actions. Higher salt means slower bacterial movement, which is a good thing,” says Koether. “When we do get that end result, it has a really deep, rich, complex flavour.” In contrast, the fastest are certain types of dairy ferments, which can take just two days.
Currently, Koether’s favourite ferment is her roasted corn miso. She makes it by removing fresh corn off the cob and dehydrating it at a high temperature, giving the kernels a light caramelisation. She turns these kernels into powder — a fresh-corn cornmeal — and then rehydrates it to turn it into miso. “It tastes like this beautiful umami paste of grilled corn, which is something that I grew up with and is totally nostalgic for me,” says Koether.
Bang’s range of ferments also cover a large spectrum. For Lactic fermentation, he uses between two and 20 per cent salt to determine what he wants the product to become. Then there are the koji ferments, which his team uses to produce miso, garum, and shoyu — but without incorporating standard ingredients.
“At the moment, we are using two different types of miso, among many. One of them is pumpkin seed miso. Instead of using the classic soybean like they do in Japan, we replace it with pumpkin seed. It takes about six months for us to get it ready,” says Bang.
The other is a leftover sourdough miso. The leftover sourdough comes from the loaf edges that can’t be served to guests. Following the kitchen’s minimal waste policy, they toast the scraps, mix them with koji and salt, and turn this into miso. It has a variety of uses, including as glaze on Freyja’s pork dish. The miso is layered with five or six different fermented juices, and “you can taste the actual sourdough enzyme,” says Bang.
Challenges
Despite 12 years of experience, Koether says she’s still learning from the sometimes-uncontrollable nature of fermentation. “Although you can set the same standards and processes from one batch to the next of what you’re fermenting, it can go awry at any stage.” She provides an example of her first batch of kombucha at Molli, which took on ambient yeast from the air, giving it mousy, sulphuric notes.
Through extensive years of trial and error, the chef has developed a series of troubleshooting techniques and habits to mitigate the unexpected challenges that arise. “I know that if I have a really good lacto-fermented brine that I like the taste of, then I’ll keep reusing that. Also, when you’re fermenting things, there are certain levels of salt that you use that you just know will produce the right results.”
The program at Molli itself is quite extensive, according to Koether, who during this conversation was sitting in a room with 60 litres of lacto-fermented pickles. “It’s pretty big in the sense that today I took 40 litres of milk to turn into cheese. And I’ll probably do that again next week.”
The trick to increasing production amounts is to start small and repeat the process to build muscle memory, she says. To produce at this scale, ample time, planning, and room for error are crucial. Just as important, adds Bang, is space.
“I feel like I never have enough storage because we preserve all year around. And we don’t preserve small amounts. We picked close to 80 or 90 kilos of green strawberries, which is already a big part of the space,” says Bang.
Bang has hundreds of preserved products on Freyja’s shelves — some of which they’ve had since the restaurant opened almost three years ago. “They will only develop more and more flavour as time goes, because the enzyme and the bacteria growth are going to affect the flavour profile since day one until now.”
Bang encourages chefs who wish to start fermenting to stay curious and ask themselves why they want to ferment. Koether recommends looking at fermentation as a seasoning agent.
“Fermentation and decay are actually two sides of the same coin. They are throttling down the same pathway. But when we intervene, we’re basically taking these enzymes and metabolic processes and bacteria and setting them off on a slightly different path while decay goes the opposite way,” says Koether.
“And the way that we do that is through acetification. So we add salt and sugar… When they do want to utilise it on a menu, consider it an alternative form of salt, sugar, or acidity. And it really will elevate what you’re eating and transform texture, flavour, and colour.” ■
This article was originally published in the May/June 2025 edition of Hospitality Magazine. To subscribe or learn more, click here.
