Sourdough Starter Information

A sourdough starter is a living culture that needs food, water and oxygen to cultivate, ferment and multiply and takes a minimum of a couple of days or so to get started and months to become stabile. Before there was packaged yeast, all bread was leavened by a sourdough starter. Although using a sourdough starter in baking is more unpredictable than using packaged yeast, the vibrant and sour flavor as well as unique texture that results, just can't be made in any other way. It's because you are cultivating and fermenting wild yeast (often Candida milleri) and bacteria (Lactobacillus) that feed on the sugars from the hydrated flour's starches and live and multiply in the batter. A portion is used to leaven and flavor bread and other recipes.

Note: Rye flour offers some specific considerations. When baking bread that contains a high proportion of rye flour, it is necessary to acidify the rye (that is, use a portion of it in a sourdough phase) in order to stabilize its baking ability. Rye flour possesses a high level of enzymes compared to wheat flour, and when these are unregulated, they contribute to a gumminess in the crumb. The acidity present in sourdough reduces the activity of the enzymes, thereby promoting good crumb structure and superior flavor.

STARTER INGREDIENTS:

Wild yeast and bacteria are live organisms that exist all around us and the success of the starter is influenced by many variables; the degree of flavor (sourness) and texture in the final bread loaf depends on many factors including the temperature, length of fermentation, type of grains (flour), amount of water, mixing and baking techniques and most importantly, the particular strains of yeast and lactobacilli that live in the starter.

Flour: for a sourdough starter, a variety of wheat flours, such as all-purpose, organic, whole-wheat or bread and rye, with each type adding its own characteristics and flavor. Often times the very collection of micro-organisms we desire to gather resides on the grain we intend to use for flour. Rye flour is almost notorious for creating a very sour culture. A sponge starter can use any type.

Organic flours produce more of an interesting flavor than white, such as all-purpose or bread flours. I always start my starters with organic unbleached white flour. It seems to attract more interesting spores to the mix. Once a starter has become strong and healthy I feed it unbleached all-purpose flour (bleaching does not affect their nutrition, though). At this point, the yeast do not need the extra protein of a higher-protein bread flour (it is the starch they digest, not the protein), plus all-purpose is less expensive.

There are many delicious variations made with whole-wheat, rye or spelt flour, however, use a sourdough recipe specifically written for them because there will be variations. Rye and whole wheat flours are more fermentable than white. Rye flour contains a larger percentage of natural sugars, diastase and protease enzymes and is slightly higher in natural acidity than wheat flour, all of which have an acceleration effect on gas production and gas retention. Therefore, rye dough requires less fermentation time than dough containing only wheat flour. Rye flour does not contain gluten (or a different type of gluten that does not have the gas-retaining properties), so that the structure of rye bread relies mainly by a network of starches, not of gluten as in wheat bread.

There are many different types of sourdough bread that can be made by using slightly different ingredients. For example, baking with a wheat sourdough starter makes the loaf fluffy, even when combined with rye flour. The type of bread desired results from what is put into the starter. If a person is looking for a more dense center of the bread, then a rye sourdough starter is desired.

Water: For a sourdough starter, distilled and non-chlorinated water should be used. A sponge starter uses tap water. If your water is high in minerals, chlorine, fluoride, etc. and these things can damage and even kill the wild yeast. If your tap water tastes good to you the chances are it will be ok for your yeast, but it's hit or miss as to whether it will work. The only way to tell, is to try it.

Yeast: Wild yeast and bacteria (Lactobacillus) are used in sourdough starters that you cultivate yourself. Active dry, fresh yeast, sponge and/or sourdough yeast are commonly used in sponge starters. Instant Active Dry is not appropriate for use in these starters. Many times a pre-sponge starter using a small amount of packaged yeast is used to get it started and is allowed to ferment for a couple of hours. This starter is then added to another sponge starter along with more added packaged yeast and allowed to ferment again before being used in the bread recipe as the leaven. This gives bread a slow-risen and nutty flavor. A piece of a sourdough starter can be used, as well.

A starter will attract only the type of bacteria unique to where it is made. Some strains of desired micro-organisms may be more prevalent in some habitats, such as the San Francisco Bay Area or Germany. An example of this is with Lactobacillus sanfranciscans bacteria that is only found in the San Francisco area of California. It's what gives the San Francisco Sourdough Bread, its unique taste and texture. However, the only way to get an authentic version, is to culture and ferment a starter, and also bake it in San Francisco!

Unlike commercial yeast (which likes an alkaline environment), wild yeast prefers an acidic one. It has to in order to survive the lactic acids produced by the Lactobacilli bacteria. Interestingly enough, this acid also serves to lock out mold present in the air by poisoning the mixture, so it doesn't become contaminated.

HOW TO PROCURE A SOURDOUGH STARTER:

The first way is to make one yourself or get a friend who has a starter going to give you a cup. The other way is to get a packaged sourdough starter that you "activate" with water and flour in your own home.

If you make a sourdough starter yourself, it begins with a mixture of flour and water. See Sourdough Starter recipe. The ingredients are placed in a sterilized wide-mouthed mason jar or a bowl, and mixed with a sterilized spoon, so the yeast and bacteria on them don't contaminate the batter. The jar is left uncovered put in a warm, dark place, preferably 80 to 85 degrees F (but can be as low as 60 degrees F) so the natural microorganisms can settle on the surface, with the warmth encouraging their cultivation and fermentation. Over time, the starter becomes a pot of wild yeast and bacteria plus other bacteria particular to where you live.

Some bakers add grape or other fruit skins which contain a high amount of sugar that yeast can digest, which aid in fermentation. Wild yeast and bacteria also reside on them, helping to populate the starter. (It is thought that more yeast and bacteria exist on surface of flour and/or the skins of fruit rather than in the air.)

A sourdough starts with small signs of activity after about 3 to 7 or 8 days - small bubbles and a mild yeast smell - that is the yeast and bacteria are fermenting. The wild yeast and Lactobacillus are attracted to flour as a food source; the yeast converts the flour's starches to sugar and both it and the bacteria feed on it, grow and ferment.

After the starter begins to bubble, it can be remain at room temperature or be refrigerated, covered with plastic wrap. Since yeast is a living organism, it is sensitive to the temperature - warmth speeds fermentation whereas refrigeration slows it. It must be fed daily at room temperature or once a week if refrigerated. The starter must be fed as well, with more flour and water in regularly scheduled intervals and stirred, for example every 12 hours initially. The feedings consist of more flour and water continuously added to the starter after pouring some off a portion (give it to a friend or discard it - also see Excess Sourdough Starter). The pouring off and feedings help to maintain and build a stable environment. A starter is actually a concentration of the yeast by-products, which a portion of must be removed to get rid of some of the buildup of the acids and esters associated with it, which eventually kill the yeast. Pouring off also allows for a fresh source of food to be introduced to the yeast and bacteria when the new flour and water are added.

The starter can be used in a recipe, but must be activated so it is vigorously bubbling before using in a recipe. On the night before you want to make bread, for example, you take a cup of the starter from the jar and let it warm to room temperature taking a couple of hours. Then it is fed with more water and flour, stirred, and set in a warm place for 8 hours, preferably overnight. The next morning (with the mixture frothy and bubbly with carbon dioxide bubbles throughout), you use a portion to make your to make your bread recipe. You can put any left-over starter back in the jar.

The original starter, also known as "the mother", is replenished and becomes an ongoing colony of fermented microorganisms becoming more stable and sour, as well as contributing a more interesting texture, from its prolonged fermentation. It is again kept alive with regularly scheduled feedings of flour and water, until the next recipe, and so on. In fact, starters can be kept alive for years. I know someone who has had her starter for 30 years, given to her from her grandmother and it is much prized !! California Gold Rush Miners discovered that they could make sourdough starters to bake and cook with, kept alive for years while panning for gold and moving from gold.

The sourness of a given batch of starter depends on the number of generations that have passed and mutated, since the original starter was begun. Wild yeasts of fairly recent vintage usually produces a not-so-sour dough and a bread that is not as leavened. It is only when it is used and fed a couple of times that it becomes increasingly sour and active. The texture of the recipe also becomes more interesting the longer a starter ferments. If it becomes bitter, throw the starter away and start over again.

WHERE DOES THE SOUR FLAVOR COME FROM?

As byproducts of manufacturing simple sugars, lactobacilli produce flavorful organic acids: lactic acid, which adds a rich, mellow flavor to bread; and to a lesser degree over a longer period of time, acetic acid, which gives sourdough bread its sour tang.

To take a short deep dive here, there are two types of lactobacilli: homo-fermentative, which produces primarily milder-flavored lactic acid (think yogurt); and hetero-fermentative, which produces lactic acid, but also stronger-flavored acetic acid (think vinegar).

Since homo-fermentative lactobacilli do well at room temperature, dough raised at room temperature will generally yield a milder-flavored bread. Hetero-fermentative lactobacilli prefers temperatures around 50°F; so raising bread dough in a cooler spot (as cool as the refrigerator) will bring out its vinegary acidity.

By varying the liquid/flour balance of your starter, and the temperature at which it's fed; as well as the temperature and duration of a sourdough loaf's rise, you can make sourdough bread that's richly flavored, with barely a hint of sour; or one that's truly mouth-puckering.

HOW TO FEED A STARTER:

To feed a starter, first see if any off-colored liquid, often dark, has surfaced on the starter. If the liquid has not overly discolored, it is not necessary to pour it off; if it is, discard the liquid. It is called "hooch". The liquid contains alcohol and is part of what gives sourdough breads their distinctive taste. Then, stir and discard a portion of the starter, if directed. Then, feed with more flour and water and make sure you STIR well.

After feeding a starter you will notice the following lengthy cycle of activity - a starter is at its optimum strength and flavor 8 to 12 hours after it's fed, and drops off considerably in quality beyond that range. If you want it activate it more quickly, try feeding it every two hours until it is rising high in its jar.

For some period of time (perhaps up to several hours) you will see no visible activity.
Eventually you'll see just a few small bubbles on the surface of the starter, eventually rising, with a slightly domed top, and with much bubbling referred to as the starter's "peak". The average is that it takes 3 hours for yeast to peak, and 10 hours for the lactobacillus to peak, but it varies greatly depending on the type of starter. It will have large and small bubbles that are well-integrated throughout (not just on top) and smell sour and yeasty. Depending on the starter, this may go on for several hours
Then the peak will fall slightly, a stage referred to as "drop"; and,
Eventually the starter will collapse with no visible activity. At this point it is dormant.

You must always replace what you remove from the starter for the next recipe. If well maintained, a sourdough culture will last a lifetime. Each time you take a portion of the starter for a recipe, generally replace that amount with equal quantities of water and flour. However, there are many philosophies about feeding amounts. For example, if you remove 1 cup of starter to make Sourdough Bread, you must replace it with 1 cup of water and 1 cup of unbleached all purpose flour. Whisk these ingredients into the starter until blended but not completely smooth. Any remaining lumps will dissolve as the mixture ferments.

Maintain a large enough starter that you will always have at least a cup or two more than you will ever need at one time. Suppose you usually use at most two cups of starter when you bake. You should then always maintain your starter volume at three or four cups. Cover and leave the starter at room temperature for at least 12 hours or overnight. The starter is now ready to be used again, or can be refrigerated.

HOW TO STORE THE STARTER:

1. At room temperature but it will need more frequent and daily feedings.

2. An active starter can be put in the refrigerator, so it goes dormant and you can feed about once or twice a week (or every two weeks); the cold slows the metabolism of the yeast. Always feed an unused starter once more before returning it to the refrigerator. Let starter sit for 30 minutes after feeding before returning. Some say it keeps up to six months in the fridge without feeding, though I have never gone that long. But, if a starter goes unfed for too long, the yeast and lactobacilli will become more and more sluggish, conserving the nutrients they have left, the starter becoming more sour. It usually takes 48 hours and several feedings to bring a starter culture back to full "flower"; however if unfed for too long before trying to save it, it will die.

3. Starter can be air-dried on clean parchment in the following manner: Spread a thin layer of starter out on parchment paper with an offset icing or rubber spatula. Let it naturally air dry where it will flake as it dries. Store in a dark dry covered container. To activate: place starter flakes in starter container, add water and enough flour to make a good semi-stiff consistency as you would for a normal feeding. Place semi-covered container in a warm location and feed. It may take 2 to 3 days for full activity to return.

4. Freeze starter in a sterilized, air-tight plastic freezer container (not glass or stainless steel). Thaw the starter at room temperature for two or three days before you plan on baking with it, transferring it to a sterilized starter container. Refresh the starter with 1 cup each of water and flour. Cover and leave at room temperature for 12 hours or overnight before using.

STARTER CONTAINERS & OTHER EQUIPMENT:

Sterilize all equipment every time you use it when making a sourdough starter, as it prevents the starter from becoming contaminated from the wrong kind of mold spores that exist naturally in the air and soil; failure to do so could impede the growth of the starter and can be the main cause of its failure. Even sterilize a spoon or spatula each time you use it for stirring the starter. If you don't sterilize the equipment, chances are the starter will work but, you may have other microorganisms growing in there which could impede the growth of the airborne yeasts and is often the main cause of a failed starter.

Use a glass (Pyrex) or glazed ceramic container to keep your starter in that's straight-sided (easier to judge volume increases than flared-sided containers). Even stainless steel can be used as long as they, too are sterilized. Cover it with a loosely-fitting non-metal lid which allows for the gasses to escape during fermentation; if tightly covered, the gas produces enough pressure to blow the top off or break the container, especially glass, if tightly closed. However plastic wrap can be tightly stretched over the jar's opening as a cover; the wrap will just stretch from the gasses' pressure (some recipes tell you to poke holes in it just in case).

Sponge: For a sponge starter, a Pyrex glass or stainless steel bowl is perfectly fine to use - no need to sterilize.

COMMON STARTER PROBLEMS:

Starters usually encounter problems. An unhealthy starter will not make good bread and most likely won't raise it either. Here are some solutions:
PROBLEM:	SOLUTION:
My starter smells too acidy. What do I do?	First feed it with equal parts water and flour. After a few hours if it is still sour, remove 1 to 2 cups of the starter and replenish it with equal amounts of flour and water. If the starter smells off, discard. If it smells yeasty, you're in business.
My starter has off-color liquid on top. Is this a problem?	If the liquid is off-colored or somewhat dark, it should be fine. If the liquid is pinkish, discard the starter. It is probably contaminated. The separated layer of liquid on top of the starter is known as “hooch,” a clear to dark-colored, watery substance that consists of the alcohol produced as wild yeast ferments. It’s harmless to the development of a starter, but it is a clear indicator that a starter needs to be refreshed and fed. The presence of “hooch” is encouraging, a sign that yeasts were metabolizing sugar and that the starter was heading in the right direction.
My starter appears to be separating. Do I throw it out?	No. Just make sure you stir it before use or before feeding.
How do I know if my starter is active?	The starter should smell yeasty and look bubbly and foamy. If not, add flour and water. Cover lightly and let it sit at room temperature for 8 to 12 hours. AFTER that, use or refrigerate. Always let it come to room temperature before using.
My starter smells very sour and has little to no yeast smell. What happened?	Starters often change, but it can be fixed; just feed it a couple of times - do not use rye flour which will make it more sour.
My water is chlorinated. What do I do?	Use bottled, non-chlorinated water.
How do I increase my starter?	If you want to increase the amount of starter you have simply increase the amount you feed it.
I have neglected my starter. What do I do now?	If your sourdough starter has sat in the refrigerator months beyond the point of health, try reviving it: The layer of liquid on the surface will probably be very dark. Give it a sniff. If it smells exceptionally sour, it may just be sitting there in a dormant state waiting to be fed. First, blend the mixture back together and pour it into a newly sterilized glass or ceramic bowl. Mix in 2 cups of flour and 1 cup of water both to nourish and thicken it. Let it sit loosely covered in a warm area. In a couple of hours you may see some tiny bubbles appearing. If so, keep it warm and covered overnight. Give the starter another feeding, let it sit for another day to ensure its reawakened vigor. You can store in the refrigerator.
Is it possible that my bread can taste too sour?	Yes. Rye bread is the only exception: it has a naturally sour flavor more than others breads.