SOURDOUGH, FROM A TO Z

During fermentation, acetic acid is primarily produced by heterofermentative lactic acid bacteria (LAB), along with lactic acid and ethanol. Acetic acid produces both a sharp, sour flavor, and aroma.

Air pockets in the bread which are formed during mixing and fermentation and which contribute to the structure of the crumb.

Bran and germ content of flour, measured indirectly as mineral content after burning (higher ash corresponds to higher bran content).

The optional process of pre-hydrating the flour and water to allow the gluten strands to form and loosen prior to the addition of yeast and in the absence of salt. A true autolyse is performed without starter (see “Fermentolyse”), although not everyone makes this distinction. Autolysis is usually performed for 30-60 minutes prior to the addition of yeast. Longer autolysis is possible but may not add any further benefit.

Simply put, the amount of a certain ingredient in a recipe expressed as a percentage of the flour used in that recipe, which makes scaling (increasing or decreasing) a recipe a matter of easy math. Read more about baker's percentages (sometimes called baker's math here).

Also called brotform, proofing basket. Special basket used to hold bread in its final form while undergoing proofing. Shapes include round, oval and specialty shapes. Can be made of rattan, wicker, or paper mâché (among other materials). Most allow bread dough to breathe a bit while proofing. A cloth lined bowl or colander can be used in place of a banneton.

A French term meaning ‘to bathe’ or ‘to drench’. This technique is used to add water at the end of mix, and is useful for higher hydration dough.

Oval-shaped loaf.

A thin, flat tool, often made of steel, used to shape and divide dough on a flat working surface, or to transfer shaped dough to a proofing basket. 

Stiff preferment with 50% hydration or less, usually made with yeast.

Round shaped loaf.

Bulk fermentation begins with the addition of starter to a dough. It includes the period of time when the yeast are active in the dough, and ends when the dough has reached the desired level of extensibility and increase in volume through the metabolism of starches by the yeast, which release gas. Some proportion of acid is also produced during this time, which contributes to flavor. Also referred to as bulk rise, or warm proof, as it generally takes place at warm room temperature (as opposed to cold proof, see below). Many of a bread’s characteristics, including the crumb texture, can be attributed to this phase so the recognition of proper fermentation deserves extra attention in learning sourdough baking.

A gentle technique to build gluten structure in dough without tearing the existing network. Usually used at the end of the gluten building period (after a more strenuous method, like stretch and fold).

The interior structure of a loaf, as described by texture and the size and shape of the alveoli. There are many different types from tight to wild open, ie, an open crumb contains more/larger alveoli. Crumb preference varies and there is no one perfect crumb for everybody. The crumb structure is one of the most important factors in determining whether a loaf was fully and properly fermented.

The exterior surface of a sourdough loaf, including the bottom.

Can also be called diastatic malt powder or malted barley flour. Powder made from malted barley that contains amylase enzymes that help break down starches in flour, resulting in more complex flavor, darker crust, softer interior and a malty aroma. Used in baker’s percentages of 0.25-1%. Not to be confused with non-diastatic malt powder, which does not contain the enzymes that break down starch. Some breads already contain a certain percentage of malted which will be noted in the ingredients.

The portion of dough that is removed to reduce total amount of starter to be fed (and therefore the wasting of water and flour) and which can be used on its own in so-called discard recipes, also to reduce waste. Mature discard may be used for leavening, although it will take longer to rise than fed starter. However, the discard from the first 2 weeks of building a new starter should only be used as a replacement for flour and liquid and will need additional leavening in the form of commercial yeast or baking soda/powder. Discard may smell foul in the first few days of creating a starter due to high bacterial content and should not be used in that case. Discard that smells like alcohol or acetone suggests yeast activity in the starter and is ok to use.

The attractive, curved lip that forms along the edge of the score during baking and which is often indicative of good oven spring. May also occur in underproofed dough but not usually in overproofed dough due to gluten breakdown.

The ability of the dough to spring back after being stretched and contributes to the volume and structure of the bread.

Dough has been “enriched” through the addition of fats (butter or oils), sugar or egg. The opposite of “lean” dough.

The ability of the dough to stretch without tearing.

The metabolic process by which yeast convert sugars into carbon dioxide, alcohol and acids. Can be part of the bulk fermentation or final proof. Contributes to the texture and volume of the dough and final crumb.

A version of the autolyse which includes the sourdough starter but not salt.

Note that autolysis without the addition of starter does not start the clock on bulk fermentation but fermentolysis DOES as the yeast are starting to work once they come in contact with the flour and water in the dough.

A test of the liquid absorption capacity of flour, and which varies by type of flour and bran content. In general, recipes using higher bran flours (like whole wheat as opposed to all purpose) will require more hydration because of their relatively higher absorption capacity.

A loaf with apparently good oven spring from the outside, but which has a dense or otherwise disappointing crumb on the inside, usually due to underproofing. For example, the crumb may be tough and might have a few large or tunneling holes instead of evenly distributed alveoli.

A protein in flour which combines with another protein, glutenin, to form gluten and give bread its characteristic chewiness. Gluten allows the dough to stretch as alveoli (bubbles) form and create an airy, springy crumb.

Gluten is the result of the combination of different proteins during the sourdough process. The goal of the stretching, slapping, folding, and other dough manipulations during bulk fermentation are meant to create and strengthen the gluten network, to give the bread a nice structure.

The initial phase of bulk fermentation marked by manipulation of the dough through slapping, stretching, kneading, folding, coiling, or mixing, and whose purpose is to encourage the formation and strengthening of gluten strands and a web-like gluten network in the dough. This result allows dough to rise by way of trapping carbon dioxide bubbles produced by the yeast. Weak dough is recognized by insufficient rise and non-uniform crumb texture.

A protein in wheat flour (and other related Triticum species). It provides strength and elasticity to bread dough. Combines with gliadin to form gluten.

The alcohol smelling liquid by-product of yeast, often found sitting on top of hungry (not recently fed) starter. May be clear, yellowish or gray, and should be poured off for maximum starter health. Contrary to popular belief, this alcohol does not contribute to the sour taste of bread, and can be harmful to the starter in large amounts.

Hooch is not to be confused with water separation, which can also float on top of freshly fed starter, and is a sign of too high hydration in the starter (and often happens when feeding a starter by volume rather than weight).

The amount of water in a dough expressed as a baker’s percentage (i.e. the water content of the dough divided by the flour content). Dough hydration may range from 65 to 100% or even more. For beginner bakers, hydration in the range of 68-73% may be easiest, and hydration may need to be increased if whole grain flours are used (see “Flour stress test”.) To calculate hydration exactly requires diving ALL the liquid in a recipe by ALL the flour in the recipe, including the water and flour in starter, that is:

Hydration relates to starter in the same way it relates to dough in that it represents the water content of the starter as a percentage of flour content. If not specified in a recipe, 100% hydration is assumed. This is often expressed as the ratio 1:1:1 (see “Ratio”). Other options include "stiff" starter, which is taken as starter with a hydration of 65% or less. Between 65-100%, starter may be called a “sponge”.

Sweet or savory additions to bread dough for flavor and texture, for example seeds, nuts, dried fruit, herbs and spices, and cheese.

The amount of sourdough starter in a recipe expressed as a baker’s percentage. If a recipe calls for 1000g flour, 750g of water, and 200g starter, then the inoculation level is 20%, which is very common. However, that number can be lower than 20% or much higher in the case of recipes that use a large amount of preferment.

Harmless but foul-tasting yeast culture marked by geometric, wave-like, or ring-like formations on the surface of the starter, especially after long periods of not feeding.

Method of strengthening bread dough (see “Gluten development”). Technically, kneading is any form of dough manipulation used to produce a smooth and elastic dough, so stretch and fold, slap and fold and machine mixing are all forms of kneading.

One of two by-products produced by lactic acid bacteria during fermentation and metabolic processes, the other being acetic acid. Combined they give sourdough its classic sour flavor. Lactic acid is also the source of the tang flavor in buttermilk and yogurt.

The type of bacteria in sourdough which produces lactic acid and acetic acid. There are many species and strains that can be present in a sourdough culture.

A tool used to score dough just before baking in order to control the direction of expansion as it rises in the oven. Can be used to make functional as well as decorative designs, and normally consists of a double-sided razor. Alternatives to using a lame include safety razors, X-acto knives, and scalpels.

Method of gluten development that is performed by stretching the dough out thinly over a large surface area such as a countertop, usually with the help of water, in order to stretch the gluten strands and then fold them on top of themselves into a strong network. Also used as a way to incorporate inclusions evenly throughout the dough. Lamination can be done any time but can cause degassing of the dough; therefore laminating is advised to be done early in the bulk fermentation process.

A custom-built starter for a recipe that may or may not have the same ingredients and proportions as the mother starter. Building a levain allows the baker to change the flour type and the hydration % used in the preferment and to be fed at a different time or a different ratio, which allows it to peak when needed.

The degree to which the loaf springs up/rises/grows in the oven, characterized by a rounded “belly” and visible stretched gluten strands where the dough was scored.

Used to describe dough that has been fermented for too long. The gluten structure has started to break down due to acid build up during fermentation and the yeast have run out of food. The resulting crumb can be dense with ragged crumbs, or have large holes near the surface of the crust. Severely overproofed dough can collapse entirely. Generally defined by a flat shape as opposed to the pyramid shape of underproofed dough.

Stiff preferment made with a hydration level of 50% of lower, sometimes kept submerged in water. Commonly used in sweet doughs.

Mixture of mother starter, water and flour which is allowed to rise by way of fermentation in advance of the creation of the final dough. Examples include biga, polish, sponge, and levain/leaven.

Test of proper fermentation for ending the bulk fermentation phase. A finger poked into the dough should spring back slowly and not completely. If it springs back quickly, the dough isn’t ready and needs more time to ferment. If it doesn’t spring back, it has overproofed. This only works on room temperature dough, and tends to be subjective at best.

Preferment made with yeast, typically at 100% hydration.

Another name for fermentation, or used to describe the final rise of the bread. Often used to differentiate the period of rest after dividing and shaping dough from the initial bulk fermentation. Proofing/proving can be done at warm/room temperature, or at cooler temperature, in which case the fermentation slows down and the dough becomes more firm. “Cold proof” or “cold retard” describes this process also, and is used to develop more complex flavors in the dough due to increased production of acid.

A numerical way to express the proportion of flour and water used to feed a starter, in relation to the amount of starter that is being fed. For example, 50g of existing starter that is fed 50g flour and 50g water has a feeding ratio of 1:1:1 because all the parts are equal. This is the most common strategy and is assumed unless otherwise stated. A stiff starter for use in sweet bread may have a high proportion of flour. Some so-called liquid starters are fed more water than flour.

Feeding ratio may be increased to extend the rise time or to make a large amount of starter. For example, feeding 1:4:4 may take 8 hours to rise instead of 4 and be useful for creating a starter to rise overnight and be ready in the morning. The base feeding ratio should ideally be at least 1:1:1 to make sure that the yeast have enough food to thrive.

Feeding ratio is not usually used to describe a feeding strategy by volume (eg, cups, tablespoons, and fluid ounces), but rather for weight. Furthermore, feeding by weight in grams is preferred for accuracy. However, if feeding by volume, one must note the variable weight of flour and water in order to feed “equal amounts.” Specifically, a cup of flour weighs about the same as half a cup of water, so starter should be fed approximately twice as much flour as water by volume.

A very gentle, effective way of mixing ingredients together and building strength in dough. It also helps incorporate air into the dough, which tends to yield greater overall loaf volume..

The method of cutting slits or curves into the dough before putting in the oven which allows expansion of the dough in a particular direction and create an aesthetic “ear.” Can be purely functional or decorative.

Thin, often plastic, flexible tool used to help with scraping down the sides of a mixing bowl to incorporate those bits into the dough, and for removing dough from the bowl. Not to be confused with a metal bench scraper.

Aggressive method of building strength and developing gluten structure in slack, high hydration dough. Used right after mixing ingredients together to help wet, shaggy dough form a smooth, homogenous ball by way of forcing the elements together against the countertop and incorporating air into the dough.

The most common method of building strength and gluten structure into dough at the beginning of the bulk fermentation by stretching an edge of dough upwards and then folding it on top of itself. Repeated around the edges of the dough 4-6 times every hour or so for 3-4 hours. The goal is to stretch the dough without tearing it, and to build adequate strength so that dough can be stretched thin into a translucent “window” without tearing (see “Windowpane test”.)

A stable, symbiotic culture of yeast and lactic acid bacteria existing in a medium of starch and water. The term “mother starter” may be used to differentiate one that has been created as an offshoot of the original, asin the case of creating a levain or other preferment. The process of creating a starter involves the collection and cultivation of a colony of yeast and bacteria from the environment and may take 2-4 weeks to become strong and mature enough to bake with as leavening. In the meantime, the starter is fed and some portion is removed. It is not advised to use discard until the starter is mature.

The maintenance of a mature starter may optionally also involve discarding some portion before feeding, and that starter may be used for purposes of leavening, although it will take longer to rise than recently fed starter. (See “Discard”.)

A method of building a dough using a roux of flour and water or milk, often used for sweet breads and pastries, and then added into the final dough. Gives bread a softer crumb and can delay staling.

Used to describe dough that has not been fermented long enough or by a weak starter such that yeast have not sufficiently metabolized the sugars to aerate the dough The result is a dense, gummy crumb and possibly large, tunneling holes as opposed to a tender bite and evenly-spaced, homogenous alveoli. Underproofed dough can look flat (frisbee or UFO shapes), or have a pyramidal shape or even a well-rounded belly in the case of fool's crumb. Very common mistake by beginners.

Organisms in the fungus family found in the environment, the human body, and in flour. When flour and water are mixed to cultivate a starter, the naturally present wild yeast propagate themselves by eating starches in the flour and multiplying. The result is a living ecosystem of eating, breeding, and dying yeast interacting in symbiosis with various bacteria.

The most common types of yeast found in sourdough starter are Kazachstania exigua (Saccharomyces exiguous), Saccharomyces cerevisiae, K. exiguus and K. humilis (previously Candida milleri or Candida humilis) although many others exist, and the variety of yeast in a starter will vary by region and type of flour used. In fact, the microbial make-up of a particular starter may change to reflect the specific microbes present in the baker’s individual environment, regardless of where the starter originated.

Test of dough strength that ends the “gluten development” phase of making sourdough. Dough passes this test when it can be stretched thinly enough to see through, and is the result of adequate kneading, stretching, folding, and other manipulation of the dough to create a strong, supple gluten network.