An Introduction To Sourdough

An Introduction to Sourdough

What does sourdough have to do with fruits or gardening. A lot if you consider fermentation as yet another way of growing things. In fact, Stephen Facciola, the author of Cornucopia II: A Source Book of Edible Plants made sure to include a whole plethora of fermented foods starting with sourdough cultures all the way to miso and other more exotic fermented foods.

Sourdough has been a passion of mine for a while now, so I offer to you this getting started guide. Be careful, baking bread is incredibly addictive. :)

The basics of sourdough bread is simple: any bread can become a sourdough bread once you replace the yeast with a sourdough starter. So before we venture in the whole world of sourdough, let's explore what yeast is. Yeast is a one celled plant, (more exactly, a fungus) which digests the sugars and starches in flour. In the process, it produces alcohol and CO2, which causes the bread to rise.

In the old days, people did not have access to dry, or cake yeast, and the only means of leavening bread was to set out a batch of flour and water, and literally letting it rot. And the rotten batter of flour and water is what today is called a sourdough starter. From a scientific perspective, the sourdough starter is a living froth of lactobacilli and yeast which live off the complex carbohydrates in the flour. Although the lactobacilli don't contribute much to the leavening process, they do produce lactic and acetic acids which both promote a very acidic environment for the yeast to live in. While yeast loves to hang out in very acidic places, other organisms don't, and thus, the lactobacilli provide a preserving environment for the yeast. Of course, the lactobacilli and the yeast interact in a much more complex way with each other. These symbiotic interactions are what makes it possible to keep a sourdough starter around for long periods of time.

The acids in the sourdough starter are exactly what gives sourdough bread it's tangy flavor. The basics of how to make sourdough bread is straight forward once you have a starter.

For example, here's a great San Francisco Sourdough recipe for two loaves:

Sponge:

  • 1 2/3 cups unbleached bread flour
  • 1 1/3 cups warm water
  • 1/2 cups starter
  • Mix until mixture reaches batter consistency
  • Cover and let sit in a warm place until bubbly - an oven with the pilot light is usually a good place.

Dough: Add the following to the sponge:

  • 3 cups unbleached white flour
  • 1 2/3 tsp salt
  • Mix until mixture reaches a dough-like consistency
  • Knead for 10 minutes
  • Let rise until doubled
  • Punch down
  • Cut into 2 using a knife
  • shape into loaves
  • Proof until a bit more than doubled in size

Bread:

  • Bake for 50 minutes in an oven pre-heated to 400 degrees F.

Now, all you need is to learn how to make, keep, and nurture a sourdough starter. If you have read this article all the way to this point, then you are ready for the next step in becoming a sourdough guru. First, you need a starter for yourself.  You can get some from a friend, and use it to innoculate your own batch of starter, or you can buy specialized cultures. Better yet, you can make your own from scratch. There are a many different ways to get a starter going, here are a few that have worked for me:

The Purist Approach

Some people will argue that this is the only way of creating a pure sourdough starter, and they maybe right. Sourdough is like cheese: there are different cultures out there, and the only way of creating a unique culture of your own is to start with just flour and water, and invite the local micro-organisms for a royal feast.

  • Mix 1 cup of water and 1 cup flour in a bowl, cover, and put into a warm place.
  • After 1 day, add another 1/2 cup water, and another cup flour, and put into a warm place.
  • Repeat this procedure until the batter starts to smell sour, fruity and yeasty. Then, refrigerate.

The Northern European Purist Approach

Scandinavians, Russians and Germans came to recognize that certain flours produce much faster fermentation. A case in point is Rye flour, and this flour will invariably produce a very viable starter in a very short amount of time. The procedure is identical to the purist approach, exept that Rye flour is used instead of White flour.

  • Mix 1 cup of water and 1 cup rye flour in a bowl, cover, and put into a warm place.
  • After 1 day, add another 1/2 cup water, and another cup flour, and put into a warm place.
  • Repeat this procedure until the batter starts to smell sour, fruity and yeasty. Then, refrigerate.

Note that since Rye ferments so fast, it is possible to take the fermentation process too far and end up with a slurry of acedic acid. In that case, dump out 3/4 of the starter and add 1 cup flour and 1 cup water, let sit for 12 hours, and then refrigerate.

The natural innoculant approach

The idea here is to use a natural innoculant such as grape skins on which wild yeasts reside to get the starter going. The recipe is the same as the purist approach, exept that the batter is innoculated with grape skins, or other fruit skins or leaves. The assumption is that there are yeasts which reside on the skins of fruits or on the surface of leaves, and the hope is to introduce these yeasts into the batter to get it started faster. This assumption is quite reasonable since, contrary to popular belief, yeast is less likely to enter the batter through the air than on the surface of some substrate, such as flour or grape skins.

  • Mix 1 cup of water,, 1 cup flour, grape skins or other fruit skins or leaves in a bowl, cover, and put into a warm place.
  • After 1 day, add another 1/2 cup water, and another cup flour, and put into a warm place.
  • Repeat this procedure until the batter starts to smell sour and fruity. Then, sift out the grape skins, and refrigerate.

The shortcut approach

The whole point of sourdough is to savor the slow, long process of bread baking, making it into a beautiful meditative experience. But, in our fast paced world, it's understandable if sometimes we just need fast results. The idea here is to use commercial cultures to get the starter going, and then hope that the yeast organisms will evolve into a symbiotic relationship with newly developing lactobacillus. The recipe is the same as the purist approach, exept that the batter is innoculated with commercial yeast and yoghurt or buttermik cultures.

  • Mix 1 cup of water, 1 cup flour, 1 tsp active dry yeast, and 1/3 cup buttermilk or yoghurt in a bowl, cover, and put into a warm place.
  • After 1 day, add another 1/2 cup water, and another cup flour, and put into a warm place.
  • Repeat this procedure until the batter starts to smell sour and fruity, which is usually within 2 days. Then, refrigerate.

Working with an innoculent

If a friend has provided you with some starter, even as little as a tablespoon, or you bought a culture, then you can follow this recipe to start your own batch using a small batch of inoculant from your friend.

  • Mix 1 cup of water, 1 cup flour, in a bowl, and add whatever amount you got from your friend or what you bought, dried or liquid, cover, and put into a warm place for 12 hours. The oven with a lit pilot light is usually a pretty good place.
  • Then, if the batter starts to smell sour and fruity, which is almost always, refrigerate the mix. If not, add another 1/2 cup flour and 1/2 cup water, mix, and wait another 12 hours.
  • Repeat this procedure until you have a fruity and yeasty mixture, and refrigerate.

Using your starter

Now that you have a starter, it's time to use it. This short guide will explain you the many subtle and generally unknown aspects of sourdough. What you will learn here is the following:

  • The main two ways of using sourdough starter in baking
  • How to maximize the leavening and flavor of sourdough
  • The effects that using other flours has on your starter
  • The effects of SOurdough on crust and bread consistency

The traditional way of baking with a starter is to first "proof" the starter by taking it out of the fridge, and feeding it a couple of times while it sits in a warm place. Once it becomes foamy, it is ready to be used for baking. This method doesn't require the use of a sponge as described in our Introduction to Sourdough. Thus, once you have a "proofed" starter, you can then mix all the ingredients at once to make the dough.Try out this recipe:

  • 4 2/3 cups unbleached bread flour
  • 1 1/3 cups warm water
  • 1/2 cups starter
  • 1 1/2 tsp salt
  • Mix until mixture reaches a dough-like consistency
  • Knead for 10 minutes
  • Let rise until doubled
  • Punch down
  • Cut into 2 using a knife
  • shape into loaves
  • Proof until a bit more than doubled in size
  • Bake for 50 minutes in an oven pre-heated to 400 degrees F.

In general, if the starter has been used a lot, there is no need to proof the entire starter container just to make a loaf of bread. In that case, it is enough to remove the starter from the fridge just long enough to take out whatever amount you want to inoculate a sponge, let's say 1/2 cup, and then feeding the starter by replenishing what you took out, let's say 1/2 cup water, and 1/2 cup flour. After that, put the starter jar right back into fridge. Make a sponge using the half cup of starter, all of the liquids in the recipe, and half the flour, and just proof the sponge, i.e. wait that the whole batter-like mixture is nice and bubbly. Only then, add the rest of the flour, salt and other dry ingredients, and make the bread. See the recipe in our introduction to sourdough as an example.

This method also presents another advantage if you bake only about twice a week. The time it take the wild yeast to reach peak leavening activity depends on both temperature and how often you use your sourdough. If you keep your sourdough jar at room temperature, and you feed it every day, you will notice that the culture will go through its cycles ever more quickly. That also means it will go dormant much faster. With the starter being in the fridge all the time, this cycle is much slower, and feeding it once or twice a week is enough to keep the starter very active.

Maximizing the leavening and flavor

To really be successful with a starter, it's important to learn how to maximize the leavening power of the starter. To understand how the starter works, let's look at the life cycle of the starter in closer details. Assume you've not used your starter for a while, and you've just taken out 1/2 cup of it, and mixed that with some fresh flour and water. What you have done is added a bunch of nutrients, and the micro-organisms in your mixture, having noticed all the extra food, will start to multiply. First, the yeast reaches its peak activity, say within 2-3 hours. Then, the lactobacillus peak, sometimes up to 9 hours later. Eventually, the organisms run out of food, and the mixture will once again go dormant.

So the easy rules of thumb to follow are: give the micro-organisms food in the form of flour or sugar. This starts the cycle, which is 1)yeast peaks, and 2)lactobacillus peak later. Every time you feed, this cycle starts over. Every starter has different times for these cycles. The average is that it takes 3 hours for yeast to peak, and 10 hours for the lactobacillus to peak. But there are starters with yeast times as short as 1 1/2 hours, and as long as 8 hours. It asll depends on the culture you end up with. Now, let's translate all of that info into practical tips on making bread. The idea of using a sponge is simply to activate the yeast and lactobacillus. The trick is then to time it just right and add the remaining ingredients in the recipe just so that the yeast doesn't go dormant, but reactivates to give your bread that good final rise.

Example: let's say you're one of those puckering sour taste lovers. You want bread that makes your tongue turn inside out. Here's the trick: let your sponge sit long enough so that the lactobacilli really have plenty of time to reach peak activity and make all those acids that are gonna flavor your bread. Then, add the rest of the ingredients, and this time around, time it so that the final rise takes place when the yeast activity peaks.

Suppose you don't care much for too sour of a taste. Then, keep the sponge around just long enough for the yeast to reach peak activity, and then add the remainder ingredients to keep that activity going. The bread will still be sour, but much less so.

Two major factors will affect the way your culture behaves, and thus change the flavor: what you feed it, and how warm you keep it. The temperature is a real important factor: proofing at about 100 F will lead to maximizing the acetic acids in the bread, while a lower temperature around 80 degrees will generate more lactic acids.

Finally, don't forget that the enzymes produced by the starter will affect the consistency of your bread, and specially the crust. It is a well known secret among professional specialty bread bakers that the best way to obtain a chewy crust is to "age" the dough. Some bakers age their dough as long as three days at very low temperatures (78-85 deg. F). That will make the crust very hard and moist. The best way to proof your sourdough bread is to get a platic box with a semi-tight lid. Put some warm water at the bottom, and put the dough t be proofed on baking sheets. The box will retain the moisture, so that the dough won't dry out during the long, cool proofs.

Of course, not everyone bakes every single day, and in our busy world, it's not unusual to go for a few weeks without doing any baking. To keep your starter healthy long term, just follow these four guidelines:

  • Keep the starter in a glass container.
  • Feed it at least once a week.
  • Wash the glass container out every couple of months
  • and make a back up!

The first point is easy to understand. Metal containers are not a good idea because the acids in your starter will quickly corrode your container. Whatever anyone says, also avoid plastic containers. Plastic is an organic material, and so are the enzymes in the starter. The plastic will absorb whatever organic compounds your cultures produce, and conversely, your starter will absorb plastic.

As long as you feed the starter once a week, you will keep the lactobacillus active, so that they produce plenty of acids that act as preservatives for your starter. If you plan on not using the starter for an extended period of time, put all of the starter in a bowl, and wash out the jar before putting all of the starter back. That way, there will be no dried up flour caked on the insides of the jar. (The stuff caked on the sides is usually the first stuff to go moldy). Do this wash procedure every few months even if you use the starter on a regular basis.

Did I say "back up"? Hey, my starter isn't a computer. :) But still, after your starter turns to dark gray mud from months of neglect, you will be glad you have a back up. It's easy to do, you basically want to dry some starter when it's in it's most bubbly and active state, and then take the dried bits and either freeze them or refrigerate in a jar or a plastic baggie. In the case of dried starter, a plastic container is quite safe.

There are two ways to store a starter in a dried form. Either dry the starter on a sheet of wax paper, or dip a cloth into the starter, and let it dry. Either methods require you to first bring the starter to full active status. That means, feed the starter, and wait for the yeast to reach peak activity before drying it. In the case of a cloth, once the cloth is dry, fold it up, and store it away in a cool, dark place. In the case of the wax paper, scrape the dried starter into a jar, and store in a cool, dark place. Personally, I prefer the wax paper approach, it's far more hygienic given that cloth often harbors all sorts of bacteria.

Last but not least, enjoy your sourdough. It will give you endless crunchy and chewy culinary delights provided you give it plenty of love. :)