Bakers Yeast and Sourdough Starter: It Looks Alive to Me!
I have a penchant for nurturing living, growing things, whether they reside in my garden, in pots on my enclosed porch, or even in my refrigerator (though I must admit I have some rather unwelcome things growing in there; this article is not about my moldy cheese!). I've recently been introduced to the wonders of baking sourdough bread, thanks to the encouragement of a good friend, who sent a little container of sourdough starter home with my son. I keep my little culinary science experiment alive in a jar I bought for a pickle-making venture, tucked away behind the orange juice on the bottom shelf of my refrigerator.
Each week, I remove a portion, feed the rest of the little beasts, and bake up some sourdough bread. Most of us have eaten sourdough bread at some time or another, but do you know what it really is? How is it different from other yeast breads? Let me introduce you to an ages-old method of bread baking, and give you a bit of history to go along with it!
The art of bread-baking is going strong, despite the easy availability of sliced breads and bakery products lining the shelves of our grocery stores. There is nothing quite like the fragrance of homemade bread baking, or the experience of thickly slathering butter over a steaming slice of bread fresh from the oven. Most home bakers rely on the convenience of the yeast readily available in packets, jars, or cakes on the grocers shelves, but those are a very recent phenomenon, in the grand scheme of human history.
Historians have found evidence that humankind has been intentionally using yeast to leaven bread for over 4,000 years, perhaps initially using byproducts of brewing to acquire the yeasts used for leavening bread. It wasn't until 1676, when Anton Leewenhoek developed the first microscope, that the science behind the art began to be revealed. Now scientists could investigate yeast up close and really understand what it was and what it did. It was Louis Pasteur in 1859 who first discovered how yeast works, and commercial companies, such as Fleishman's Yeast, followed soon afterward. It was only within the last 150 years that individual yeast cultures were isolated and mass-produced to provide a colony, cake, or packet that contained one single strain of identical yeast cells. Yeast began to be sold by the Dutch and Germans as early as the late 1700s, though it wasn't widely available in the United States until almost a century later. So how did our ancestors worldwide make yeast breads before the advent of conveniently available commercial yeast?
Rather than purchasing a new batch of active dry yeast for each batch of bread, bakers would rely on wild yeasts, "captured" from the air and the grains used to make the flour, and grown in a suspension of flour and water, sometimes called a "sponge." It was a much slower process, as it takes a week or more for the yeasts to form a good, active, fermenting colony before it is ready to be put to use in baking bread. Rather than starting over each time, each family would carefully preserve a portion of the fermented "starter," or "sponge," feeding it with flour and water every time a portion was removed for baking. The starter might be kept in a special crock or jar, and would travel with the family when they moved to a new area. There are tales of miners in the California Gold Rush who would sleep with their starter tucked inside their shirts to prevent them from being killed by freezing temperatures.
The consistency of the starter varies widely from one baker to the next, as some add proportionately more flour and less water, giving a thick, dough-like texture, while others added much more liquid, giving a more batter-like texture. The flavor of each starter varies with the type of flour used, the local water, and the yeast cultures native to that particular area. San Francisco, in particular, is known for the sharp pungency of their sourdough breads. There is no single set way to nurture starter, as long as the cultures are kept at a comfortable temperature, and fed frequently enough to prevent them from dying. If you want to share your starter with a friend, simply put a portion in a container, then feed the remaining starter with flour and water.
Yeast is a curious creature, a type of microorganism that is found in soil, water, air, and even within the bodies of animals. It is a single-celled fungi, with more than 600 different individual species. Some are used to ferment beverages, ranging from beers and wines to fermented milks common in some Middle Eastern cultures. Others are used to leaven bread, such as the species called Saccharomyces cerevisiae, which is what is available for purchase from companies such as Red Star, Fleischmann's, and Saf-Yeast. Despite the granular appearance of the dry yeast you buy in packets or jars, the yeast cell itself is not visible to the naked eye, and is only about the size of a human red blood cell. One individual gram of baker's yeast is made up of as many as 30 billion yeast cells. Like other fungi, it reproduces by way of budding, growing a new cell out the side of the cell wall of the parent cell, producing an exact replica.
Yeast leavens the bread by feeding on the sugars in the flours. As it digests the sugars, it produces carbon dioxide, creating bubbles that force the dough to expand and rise. It also produces alcohols and acids, which affect the protein and gluten of the dough, giving it the light texture and bubbled appearance of leavened breads.
This is one area in which sourdough cultures differ from yeast breads baked with commercial yeasts. Commercial yeast is made up of many, many cells of identical yeast cultures, while sourdough starter is made up of many different "wild" yeasts and a beneficial bacteria called lactobacilli, which is what produces the lactic acid that gives it the sour flavor. As a sourdough starter ages and matures in the flour and water medium, it ferments, producing a sour, yeasty smell. A young sourdough starter will not affect the flavor of the finished bread drastically, but a more mature starter will give a distinctive sour, tangy flavor.
My particular batch of sourdough starter was shared with me by a friend, who purchased her starter from King Arthur Flour company. They claim that this distinctive starter has been nurtured and kept alive continuously in New England since the 1700s. If you don't know anyone with an established sourdough starter, and you are game for an experiment, you can search online for methods for capturing wild yeasts from the flour and air in your own kitchen. This will develop a sourdough starter unique to your own home and community. There are also many sites that show how to start your own sourdough culture, beginning with a packet of purchased yeast, though when my friend tried it, it exploded all over her kitchen counter. I've also read that some of the starters based on commercial yeasts will not survive as long, dying off after a few feedings. I haven't tried starting my own sourdough culture, so I can't give my own personal experiences there. It takes at least a week of attention, discarding half the starter and feeding it with additional flour and water, to really get the culture active and mature enough to produce true sourdough bread.
Sourdough starter alone contains enough yeast to get your bread to rise, though it takes much longer than commercial yeasts. A recipe using sourdough cultures alone might need to rise for 18 to 24 hours, during which time the yeast metabolizes some of the sugars in the dough, giving off carbon dioxide, and the lactobacilli ferments the sugars that the yeast cannot metabolize. As the proteins in the flour are gradually broken down, the gluten weakens, which is one reason slowly-leavened sourdough breads are denser than breads made with commercial yeasts. These slowly rising breads will have a more pronounced, true sourdough flavor.
Many modern bakers with busy schedules prefer to use a combination of sourdough starter and commercial yeast. With this method, a batch of bread may take 3 hours, start to finish, if you have active, recently fed sourdough starter. If your starter has been languishing in the refrigerator for some time, add a couple of hours to that time, to feed and reactivate the starter before using it in the recipe. People who bake frequently don't need to worry about this, as the starter stays more active when it is fed often. There will be a mild sour flavor from the sourdough starter, rather than the more pronounced sour flavor caused by a long, fermenting rise. These breads also tend to have a lighter texture from the comparatively brief rise-time, which preserves the gluten in the bread.
I've experimented with several different sourdough recipes, and as always, added my own variations. Below are two recipes that I developed to suit my own family's preferences. My family tends to prefer a lighter texture, rather than a heavy, dense bread, so I frequently add vital wheat gluten to encourage a higher rise and lighter texture. I'd encourage you to experiment with different flours (all-purpose vs. bread flour; whole wheat or multi-grain) and bake whatever shape of bread your family likes! Sometimes I just put the dough in a lump on a pan and let it rise into a nice round heap, and other times I divide it into two loaves and put it in loaf pans, so it will be easy to fit into the toaster in the morning. If I want a flaky, crisp crust that shatters, I spray with water just before baking, and put a pan of water in the bottom of the oven. If I want a more tender crust that browns well, I brush the surface with egg white and water before baking. I usually brush the surface of the hot bread with butter soon after removing from the oven, to give it a nice gloss and buttery flavor. There is no single "right" way to do it!
You will notice that some sourdough recipes specify "fed" sourdough, while others say you may use either "fed or unfed" starter. A fed sourdough simply means that 2to 4 hours before starting your bread, you got the starter out of the refrigerator, discarded a cup of the starter, and added a cup of flour and 3/4 cup of water to your starter, and then left it out at room temperature. This will activate the yeasts, causing them to start bubbling vigorously again. If your recipe calls for a larger amount of starter, you can discard 1 cup of starter, then add 2 cups of flour and 1 1/2 cups of water, so you don't deplete your starter too much. This is also a good plan if you want to give some starter to a friend, and still have plenty to bake right away.
White Sourdough Bread
My family preferred this recipe above all other contenders, for the tender texture, rich flavor, and light, crusty exterior.
4 to 4-3/4 cups bread flour
3 tablespoons white sugar
2 1/2 teaspoons salt
1 (.25 ounce) package active dry yeast
1 cup warm milk
2 tablespoons softened butter
1 1/2 cups sourdough starter, fed or unfed
1 egg white
1 tablespoon water
4 tsp. vital wheat gluten
optional add-ins: minced onion or garlic, shredded cheese, herbs of your choice. I particularly like garlic, sharp cheddar, and rosemary together!
1. In a large bowl, combine 1 cup flour, sugar, salt, and dry yeast. Add warm milk and softened butter or margarine. Stir in starter. Gradually add 3 to 3 3/4 cups more bread flour. My sourdough starter is about the consistency of biscuit dough, so I add about 3 cups of flour at this stage. If your sourdough starter is thinner, like pancake batter, you will likely need all 4 3/4 cups of flour. I do this in my Kitchenaid mixer, and only add flour until the dough forms a cohesive lump that cleans the side of the bowl. If you add too much and your dough turns crumbly, just add a little additional water or milk, a tablespoon at a time. If you are adding cheese, herbs, or other ingredients, add them now.
2. Turn dough out onto a floured surface, and knead for 8 to 10 minutes, or knead with a dough hook for 5 to 6 minutes. Place in a greased bowl, turn once to oil surface, and cover. Allow to rise for 1 hour, or until doubled in volume. If your kitchen is drafty or on the cool side, you can preheat your oven to around 170°F degrees, then shut it off, and place the bowl in the warm oven to rise. Some people also like to place a pan of steaming water on the lower oven rack below the bowl, to recreate the warm, moist conditions of a professional "proof box."
3. Punch down, and let rest 15 minutes. Shape into loaves. If baking in round form, I like to cover the pan with parchment paper, but you can also just grease the pan or use a baking stone. I like to slash a criss-cross in the tops of round loaves, either before rising or just before baking. If using two loaf pans, grease them well. Allow to rise for 1 hour, or until doubled. This rise typically takes a little longer for me, and I like to be sure the loaf is truly doubled before baking, so it isn't too heavy.
4. Separate egg whites from yolks. Beat egg white with 1 tablespoon water. Brush egg wash over tops of loaves for a nice, brown crust. If desired, sprinkle the top with herbs, parmesan, or minced onion.
5. Bake at 375°F (190 degrees C) for 30 minutes, or till done. I used an instant read thermometer and baked until internal temp was 190 to 200 °F. I know many bakers who can determine when the bread is done inside by the sound it makes when tapped, but I find the thermometer method more reliable.
One of my family's current favorite meals is "Patty Melts" made with the above white sourdough bread. Mix 1 pound of ground beef with a little seasoned salt, a few dashes of worcestershire sauce, and a dash of hot sauce. Make thin, ¼ pound hamburgers and cook in pan on the stovetop. Generously butter slices of this dense, chewy bread, and sprinkle with garlic powder. Place two slices of cheese and one hamburger patty between two slices, butter side out, and toast in a pan on the stove. They're like the tasty love-child of a cheeseburger and a grilled cheese sandwich! I like them with a little ranch dressing or spicy chipotle mayo, while my younger son prefers a generous dressing of barbecue sauce. You could also include carmelized onions or sauteed mushrooms, for a gourmet flair.
Multi-grain Sourdough Loaves
This is fairly light-textured for a multi-grain loaf, and makes wonderful toast!
1 cup boiling water
1 cup Hodgson Mills Multi-Grain Hot Cereal with milled flaxseed & soy
2 cups sourdough starter, fed and ready to use
¾ cup whole wheat flour
¾ cup old fashioned oatmeal
1 3/4 cups white bread flour
2 1/2 teaspoons salt
1 1/2 teaspoons instant yeast
2 tablespoons vegetable oil
2 teaspoons molasses
4 teaspoons vital wheat gluten
additional water, if dough is too dry
1) In a large mixing bowl, or the bucket of a bread machine, combine the multigrain cereal and boiling water. Let cool to lukewarm.
2) Add the fed sourdough starter and the remaining dough ingredients, adding flour gradually and mixing well after each addition, so the dough doesn't get too dry. Mix and knead (by hand, mixer, bread machine or food processor) until you've made a soft dough, adding additional water or flour as needed. I tend to leave my dough a little softer for whole grain breads, to prevent having a dry finished product.
3) Place the dough in a greased bowl, turning to oil all sides, and cover with greased plastic wrap or a clean non-terry towel. Let it rise until it's almost doubled, about 1 to 1 1/2 hours. Heavier multigrain doughs tend to take a little longer to rise.
4) Turn the dough out onto a lightly greased work surface or silicone matt, and gently fold it over a few times to deflate it. Shape it into a large round, or two regular loaves.
5) If baking a single round loaf, I cover the pan with parchment paper, or sprinkle some cornmeal on my baking stone. If making standard loaves, put in greased bread pans. Cover with lightly greased plastic wrap. Let the dough rise until it's very puffy, about 1 to 1 1/2 hours. Towards the end of the rising time, preheat the oven to 425°F for a single round loaf, or 375°F for two loaves in pans.
6) Just before baking, brush with water or spray with a spray bottle of water. For round loaves, cut the top with 2-4 slashes to allow maximum continued rising in the oven. You could also use an egg white and water wash at this point, if you like a darker brown, softer crust.
7) Bake the bread for 40 minutes, until the loaf is golden brown and an instant-read thermometer inserted into the center registers 190°F.
8) Remove the bread from the oven, let sit in the pan for 5 minutes, then turn out and cool on a rack.
Yield: 1 large round loaf, or two standard bread loaves.
Please don't be intimidated by the commitment it takes to get your sourdough starter established. Though it requires regular feedings during the first few days, it will tolerate much more neglect once it is established, just like many of the plants we nurture as seedlings, and then plant out into the garden to fend for themselves. Once your starter is healthy and mature, you can store it in a loosely covered 2 quart or larger jar or non-reactive container (glass and plastic are the preferred materials) in the refrigerator, and only attend to it once a week, or even less, if you don't bake often. Don't tightly seal the jar, or the gas given off by the digesting yeasts may cause it to explode. All you really need to do is remove a cup once a week (which you can discard, give away, or use to make quick breads like sourdough biscuits or waffles), add a cup of flour and ¾ c. of water, and let it sit on the counter for a couple of hours before baking. Remove what you need for your recipe, feed it again, and put it right back into the refrigerator to wait for the next time you want to bake.
I've read of people neglecting their starter for a month at a time, and worrying that it would no longer be active when they rediscovered it in the back corners of the bottom shelf. They stirred the separated liquid back in, discarded a cup, fed it the requisite flour and water, and left it on a warm counter to work its magic. A few hours later, they found that the starter was happily bubbling away on their counter top, ready to be used again for baking. A sour or fermented smell is normal, as is some liquid separation; pink or orange mold is NOT. If your starter develops mold, throw it out, and start over.
All pictures used in this article are my own. Please do not copy or use without permission.