Bakers Journal

The art of sourdough

November 11, 2010
By Julie Fitz-Gerald

History and secrecy surround many of the “mother” doughs used by bakeries to create one of the world’s most ancient breads: sourdough.

History and secrecy surround many of the “mother” doughs used by bakeries to create one of the world’s most ancient breads: sourdough.

Most sourdough products have a longer fermentation process, which breaks down more sugar.


The starter, or mother, is nurtured by it creator, fed and watered at precise times, kept at optimum temperatures and never left to die. Portions are gently removed to create mouth-watering sourdough goods and then replenished in the same delicate manner. Each bakery has its own unique sour taste as a result of every starter having different acidities and PH levels. The tangy taste and chewy texture is definite and one bite proves that this is not your regular white bread.


There are two types of sourdough starters. For those short on time, there are commercially available starters that cut down significantly on the fermentation time. But for those who really want to experience growing their own culture, there’s the old-fashioned way. Creating a sourdough starter is as simple as combining flour and water. The mixture will attract naturally occurring yeasts in the air and will begin to ferment. Brian Kirk is one of the lead bakers at St. John’s Bakery in Toronto, an organic bakery dedicated to French tradition that makes most of its breads sourdough.

“I’ve started many cultures myself and there’s wild yeast in the air, it’s all around us,” says Kirk. “So all you really need is flour and water and it [the yeast] just feeds off the sugars in the flour to get your fermentation happening.”

As the flour and water interact, naturally occurring bacteria known as Lactobacillus sanfranciscensis (named after San Francisco where it was discovered) exist symbiotically with naturally occurring yeasts, and the fermentation process begins.

“When you start a sourdough the first couple of days are critical,” cautions Kirk. “Once you see that it’s bubbling and starting to ferment and you get some foam on top, you know that you’re there.”

The mother then needs to be fed regularly with flour and water and monitored closely. At St. John’s Bakery, the mother is fed twice a day, spending half of the day at room temperature and the other half of the day in the refrigerator.

Once you have a thriving starter, you can create your leavens. “Here at St. John’s, the process is around 12 hours from when we start to when we see the first bread. We create the leavens in the morning and they’re left to rise for approximately six hours. Then the dough gets mixed and then it’s allowed to rise another two hours before it’s shaped. Then it’s allowed to rise another two hours before it’s actually baked,” Kirk explains.

Marcus Mariathas, director of product development for ACE Bakery in Toronto, notes, “The sugar content of the flour goes down the longer it sits. Most of the sourdough products have a longer fermentation process. Some of them take 20 to 24 hours before you put the bread in the oven. The longer it sits, the more sugar is broken down.”

This allows you to get exactly the flavour you’re looking for. An extended rest time will create higher levels of lactic acid, which result in a stronger sour taste. The taste is also controlled by the proportions of starter added to the dough. If you want a pronounced sour taste when the bread touches your palette, you should use a higher ratio of sour starter to dough. If you’re looking for a mild sour flavour, then you lower the ratio. ACE Bakery has found that its customers prefer a buttery flavour to their sourdough bread.

“The Canadian market is not into as strong of a sourdough, but rather a milder version,” says Mariathas. “Our focaccia breads use sourdough starters, so again, on those focaccia breads you need to experience more of a buttery flavour than the sour.”

With the nurturing and dedication that goes into sourdough starters, it’s no wonder they are so closely guarded by their owners. Some bakers travel the world to find the perfect starter, knowing that it could be used for generations, just as it has been in some of the oldest bakeries in San Francisco. Without giving away its exact origin, Brian Sisson, vice-president of operations for ACE Bakery, says, “Our starter originated in Europe. It was when ACE Bakery first started that the owners brought it over from Europe and what we do is maintain this starter.”

Father Roberto from St. John’s Bakery spent six months at a retreat in France studying the art and technique of baking. While he didn’t transport a sourdough starter back with him, the mother used at St. John’s Bakery is similar to what Father Roberto had been working with in France.

Apart from the unique taste, there is another reason to look at creating a sourdough product line. A study conducted by the University of Guelph and published in the British Journal of Nutrition has found there are added health benefits as well. The study found that sourdough breads containing lactic acid lowered the glucose response in the blood more significantly than white, whole wheat or whole wheat barley bread. The carbohydrates in sourdough breads are broken down more slowly in the digestive system, releasing glucose more slowly into the bloodstream. This is of particular interest to those with diabetes.

New research is also being done with sourdough and gluten-free grains, says John Michaelides, director of research and technology at Guelph Food Technology Centre.

“This is an opportunity for people that suffer from celiac disease to eat sourdough bread. The bacteria that are present from those grains are slightly different from the ones that you find in rye.” He adds that they are still in the research stage.

With the continuing research and development for new sourdough applications, the future of sourdough looks promising. While it’s most commonly associated with baking bread, sourdough starter can be added to a number of baked goods, depending on the flavour you are going after. However, there are a few important tips to remember when baking with sourdough. Always use unbleached, unbromated flour because it contains more micro-organisms, allowing for increased fermentation and growth. Never use hot water when replenishing the starter, as this will effectively kill the living culture. Always use cold, filtered water for best results. Do not let the dough get too warm.

“It’s a real challenge to make bread in July and August when we have a heat wave on,” says Kirk. “We have to put buckets of water in the fridge because if you’re dough gets too warm, if it goes over 27 degrees, you might as well throw it out and start over because the yeast dies.”

One last tip to remember is to be consistent with feeding the starter.

“You have to keep your starter alive,” says Mariathas. “If you’re feeding it every eight hours, then you must make sure you feed it every eight hours. Likewise, if you’re feeding it every 12 hours, make sure you’re feeding it every 12 hours so that it doesn’t have a chance to die on you or to change the acidity. When it comes to sourdoughs, you have to be careful of how much acidity you get. You don’t want too much acidity but you don’t want too little either.”

Having your own sourdough starter is a bit like being in a relationship. If you nurture your starter, giving it the time and effort it deserves, you will be rewarded for generations to come. Hey, it may even become a family heirloom!

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