A demand for wholesome, unprocessed food has seen bakers increasingly return to the ancient technique of using sourdough starters over commercial yeast to leaven bread. Australia is rich with bakers experimenting with the techniques, flours and fermentation that have been used across time to make bread

Commercial yeast is losing its appeal and the starter is making a comeback

For centuries, bakers have daily reached for their starter—a bubbling tub of floury goop alive with microbes—so they can feed it, grow it and use it to leaven bread.

When water is added to flour, the enzymes in flour break down into sugar, and wild yeast starts to feed on this sugar. As yeast feeds, it creates gas in the form of carbon dioxide, and it’s this gas that makes bread rise.

Also alive in a starter is bacteria. Bacteria are smaller than yeasts, and they eat the sugars that the yeasts can’t (they also eat dead yeast cells).

Bacteria also kill off other organisms competing for the food source and they do this without harming the yeast. This means the yeast and bacteria form a symbiotic relationship, living happily together in the floury substrate.

The bubbles created by the yeast are responsible for creating fluffiness in bread, and the infinite variations of microflora (bacteria) for the equally variable taste of sourdough loaves.

Around the turn of the 19th century, people worked out how to isolate yeast, and commercial baker’s yeast was born. A reduction in the use of starters ensued, as many bakers preferred the speed and reliability that came with the use of commercial yeast.

But commercial yeast is losing its appeal. Call it the slow-food movement, a rise in gluten-intolerance, the popularity of wholefoods, the desire for less intervention in food production, or a general nostalgia for the past—whatever the cause—the starter is making a comeback.

We asked some of the bakers at the forefront of Australia’s sourdough culture to share their knowledge of the ancient craft and give us their tips, insights and anecdotes on that goupy, bubbly, smelly bucket of sourdough starter.

You can use fruit to infect your starter, but you don’t need to

Flour and water, without bacteria and yeast colonies, are just flour and water. To be a starter, the flour mix needs to be infected with microbes and you can grow these in a variety of ways. The two most common methods of infecting starters are to soak flour and water alone, or to soak fruit in water before mixing the infected water with flour.

Boris Gaspar, Bread Boss app creator, says the two methods are “six of one half and half a dozen of the other.

“In my experience, I found fruit takes less time and it’s probably got to do with the fact that fruit tends to be richer in sugars, but it probably also has some effect on the microbiological background.”

Boris teaches his students to soak fruit in filtered water for five to seven days (the sweeter the fruit, the shorter the soaking time) and has used everything from plums and apples to Australian Lily Pillies for fruit.

“You can smell the fermentation in it,” Boris says. “The moment it starts to smell like wine or beer, you know it’s ready for the next step.”

The next step is to drain the water from the fruit, and mix that water with flour.

The other way to infect your starter it to simply mix flour with water and, as Paul Giddings of The Bread Social says, “wait for the magic to happen.”

Paul created the starter for his Byron Bay bakery “the old school way” and says that if you create the right conditions for yeast to thrive (keep it warm, covered and in a clean container), flour and water is all you need, though he did add a bit of yoghurt to get his starter going.

Paul explains, “Once your starter’s healthy [the process used to start it] doesn’t have a great consequence on flavour.”

If in doubt, cycle

Maintaining a starter is all about cycling—but not the type you do on a bike. Cycling entails discarding about half of your mixture, and then feeding it with fresh flour and filtered water.

Bacteria and yeasts are constantly feeding on the flour (or, more precisely, the sugars in the flour) and it’s during this process that the microbes most efficient at digesting flour will come to dominate. In other words, repeated cycling of the mixture ensures that any undesirable microorganisms die, and the desirable ones thrive.

Boris says, “If you continue to cycle your starter, you reinforce that one particular group of bacteria that has a symbiotic relationship with another group of yeasts that will become so dominant that the others won’t be able to take over.”

Cycling—sometimes called feeding or refreshing—is a process sourdough bakers are forever undertaking. If you think of the bacteria and yeast as little organisms eating up the flour in your starter, then what goes in must come out, and what comes out is carbon dioxide, which, when mixed with water, creates acid. That acid is the thing that leavens, or makes rise, the bread, and it’s the reason why bakers love to see little bubbles forming in their starters. But too much acid, and the organisms will start to die in their own, ahem, waste.

Cycling the starter, then, frees the microbes from their own waste and also provides fresh nutrients for the little gals to grow and go on creating that much-desired acid.

Jordan Miller from Sonoma Artisan Sourdough Bakers says their starter is fed three times a day.

The key, he says, to keeping a starter healthy is, “A regular daily feeding schedule, a temperature controlled environment and using wheat that is milled as freshly as possible, which is much higher in nutrients, natural bacteria and enzymes.”

Keep it warm

Michael Klausen from Brasserie Bread says having a starter is “like having a baby; make sure it’s at the right temperature and make sure you feed it, and then you have less screaming.”

To grow, microflora must be kept warm. The ideal temperature for growing a starter is around 20°C. A starter growing in other temperatures will still grow, but different temperatures produce different microflora, and this will have ongoing implications on how your starter responds to things like proofing, and also affects taste.

Michael says to think about temperature as an ingredient.

“Different temperatures develop different kinds of bacteria and you get different kinds of flavour from that,” he says.

Paul Giddings agrees, pointing to the importance of temperature when creating a new starter.

“The starter needs to be kept fairly warm and you need to be monitoring it. Use a clear container so you can actually see what’s happening within your starter and make sure that activity is starting to happen, that you’re getting those air bubbles that you need.”

When it comes to keeping a starter happy, Paul says the starter at The Bread Social lives in the cool room for 18 hours a day and then sits at room temperature for six hours, but he’s hesitant to lay down ground rules.

“It’s hard to nail down rules because everything’s so volatile and seasonal. In summer, our starter might only stay outside the cool room for two hours a day and the other 22 hours it’s in the cool room. Whereas when it gets cooler and we need to get the starter more active, we leave it outside for longer.

“So it’s a lot of interaction that you do along the way and not necessarily setting timers; it’s a bit more knowledge and feel and communicating with the dough. It tells us when it’s ready.”

Keep it covered

Starters will grow a crust on the top if left exposed to air. Whether your starter’s in the cool room or on the bench, keeping it covered will prevent that crust from forming.

If your starter does develop a crust, it isn’t the end of the world, but you’ll need to throw the crust out or mix the hard pieces back through the mix before giving it a cycle.

Best keep it covered though.

Keep it clean

Keeping your storage container clean will prevent nasty things growing in your starter.

Boris says, “There was a time when I probably wasn’t as careful in terms of using a clean container and over a period of nine weeks when I didn’t use the starter, it did start to get that impure smell of sweaty socks.”

Paul adds, “It doesn’t have to be sterile but you need to work really clean to make sure you’re not incorporating any impurities. Once your starter’s strong you’ll tend to find it won’t get compromised by any other type of bacteria or mould but when you’re in those early stages of creating a starter, it definitely can.

“Just keep it clean and change the jar every couple of days.”

Don’t freakout about mould

Boris says, “Mould is on your fingers, in your mouth… everywhere. Often, after their five or seven days soaking fruit [when making a starter], people see mould growing on the top of their apple skins or their strawberry pieces and throw it away. That’s unfortunate.”

Boris says mould growing in a starter is nothing a cycle or two can’t fix.

“It’s just a matter of cycling it at the correct ratio, in the correct temperature range, and eventually the lacto bacillus will take the dominance. Starters produce lactic acid among other things, which have anti bacterial qualities to keep undesirables at bay, and that includes some moulds.”

The longest Boris has left a starter alone was for 12 weeks when he left his starter in the fridge during a summer holiday.

“When I came back it had white mould growing over the top and it smelled like camembert. I broke it open and used some of the nice glossy flour paste from underneath. I cycled it a couple of times, made bread out of it and it was absolutely fine—perfect!”

He adds. “Some moulds can grow within that type of substrate but nothing that’ll worry us, let’s put it that way.”

Starter fails

The thing about starters is, once they’re thriving with activity, they can withstand a beating.

Emma Shearer from The Lost Loaf recounts the time she left her starter in her car for a little too long.

“I was transporting my starter from restaurant to home while the restaurant closed for a few months for renovations. It was a very warm day and I had a few errands to do on the way. When I opened my boot the sourdough starter had reacted like a volcano. It was so active the lid completely burst off and the mother had spilt all through the car.

“The car never smelt right ever again.”

Luckily for Emma, there was still enough starter left in the bucket, so she didn’t lose it all.

Michael Klausen recalls a similar incident when a whole bucket of starter was tipped over.

“Luckily there was enough left in the bucket to start slowly feeding it back up again but there was a good learning from that and we have a very strict regime about education for the starter; it’s kind of the most important thing in our bakery besides the people.”

Age ain’t everything

The passing of starters from one generation to another is romantic and some bakers pride themselves on the age of their starters, but when it comes down to the science, an old starter hasn’t got that much over a newer one.

Emma says, “Some great advice my bakery lecturer gave me was you can’t always judge a good sourdough by the age of the starter. As long as the sourdough starter is active and doing well, you will produce great sourdough.”

That’s because, with starters, it’s the activity that counts and, because microflora is unique to the environment in which it’s grown, variations in starters have more to do with where they are now than where they’ve come from.

Artisan starters that are not made in a closed environment vary, which is why Paul’s starter will be different from Emma’s, which will be different from Michaels, which will be different from my little starter bubbling in the fridge at home.

Dr Bill Simpson, microbiologist and managing director of Cara Technology, tests and monitors yeast quality for the brewing industry.

He told the BBC, “If you take this sourdough culture and move to Tunisia and start baking there in the ambient temperatures, if we tested the culture after a few months, we’d find something very different.

“The strains that currently serve you well, they would begin to be lost and other strains that are there in the background would start to do well.”

So, say you’re using a starter in Australia that was created in 19th century Vienna, it’s likely your starter has changed irrevocably in its new environment and is now, biologically, a completely different starter.

Jordan says, “There are a lot of theories around starter age. In my experience, age is not relevant to a good starter or bread. A starter is only as old as its most recent feed and the fresher the starter is the better it leavens bread.”

Get started sooner rather than later

While it’s true that age ain’t everything, getting started on your starter as soon as possible is a good idea. That’s because the stronger the strains in your starter, the better it will withstand attacks from other microbiological agents.

Michael says, “Even if you’re not planning to start your bakery in the next couple of years, start your starter, because the older it gets, the more stable and the better bread it will make.”

Sourdough Starters: Back to starters

Strongly dominating strains will also ensure consistent results in your sourdough loaves.

Michael says, “Any baker that works for us that has some ambition to do their own bakery some time in the future, the first thing we tell them is to start their starter. You can’t say as it keeps getting older it will keep getting better but in the first few years it is a little bit fragile and it takes a while before that symbiotic relationship between the bacteria and the yeast gets really locked in and very strong.”

It’s complicated, and it’s also easy

Maintaining a sourdough starter is as simple or complicated as you want it to be.

Paul says learning to use a starter takes a bit of time.

“Everyone’s starters are affected by the environment, the flours they use—whether it’s rye or white flour—there’s a whole lot of variables but it’s really just about understanding how your starter’s behaving and what it looks like when it’s ready to be fed, what it looks like when it’s ready to use in bread. It’s easy but it’s complicated at the same time.”

Boris agrees.

“It’s an old-world technology that anyone can master, yet you can make it as complicated as you want and produce lots of different varieties out of it. It can be quite complicated but it doesn’t have to be—and that’s the great thing about it.”