'Proofing' (also called 'proving') is a step in creating
yeast breads and baked goods where the yeast is allowed to
leaven the dough. This step is not often explicitly named, and normally shows up in recipes as "Allow dough to rise".
Process

Bread dough, set aside to proof

Forty minutes later
During proofing, yeast converts
glucose and other
carbohydrates to
carbon dioxide gas which gives the bread rise and alcohol which gives it flavor. Bacteria which coexists with the yeast consume this alcohol, producing
lactic and
acetic acids. Different types of bread have vastly different requirements for proofing depending on their recipe. Some breads will only require a single proofing while others will need multiple periods. Between stages of proofing recipes will often instruct a cook to "punch down" or "deflate" the dough to allow the bubbles of gas which have formed in the dough to deflate without popping (called ''overproofing''). Length of proofing periods can be determined by time or characteristics. Often the "poke method" is used to determine if a bread has risen long enough; if the bread, when poked, springs back immediately it is ''underproofed'' and needs more time.
Proofing is divided into a number of different categories including fermentation, proofing, retarding, autolyse. ''Fermenting'' is any stage of proofing which is completed prior to the shaping of the bread. Often a third of a bread's rise will occur during this stage. ''Proofing'' is the general term for allowing a bread to rise while at room temperature after it has been shaped. ''Retarding'' is the stage in which bread is placed into a dough retarder, refrigerator, or other cold environment to slow the activity of the yeast. The retarding stage is rarely found in recipes with commercial yeast but often used in
sourdough bread recipes to allow the bread to develop it characteristic flavor. ''Autolyse'' is a period of rest allowed for dough to relax. After the initial mixing of
flour and water, the dough is allowed to sit. This rest period allows for better absorption of water and allows the
gluten and starches to align. Breads made with autolysed dough are easier to form into shapes and have more volume and improved structure.
Proofing Equipment

A banneton basket viewed from below.
To ensure consistent results, specialized tools are used to manipulate the speed and qualities of fermentation.
A 'dough proofer' is a chamber used in baking that encourages
fermentation of
dough by
yeast through warm temperatures and controlled humidity. The warm temperatures increase the activity of the yeast, resulting in increased carbon dioxide production and a higher, faster rise. Dough is typically allowed to rise in the proofer before
baking.
A 'dough retarder' is a
refrigerator used to control the
fermentation of
yeast when proofing
dough. Lowering the temperature of the dough produces a slower, longer rise with more varied fermentation products, resulting in more complex flavors. In particular, cold reduces the activity of the yeast relative to the
lactobacilli, which produce flavoring products such as
lactic acid and
acetic acid.
A 'banneton' is a type of basket used to provide structure for the
sourdough breads during proofing. Proofing baskets are distinct from
loaf pans in that the bread is normally removed from these baskets before baking. Traditionally these baskets are made out of
wicker, but many modern proofing baskets are made out of
silicone or plastic. Frequently a banneton will have a cloth liner to prevent
dough from sticking to the sides of the basket - though some have no such cloth. These baskets are used both to provide the loaf with shape and to wick moisture from the crust. Banneton baskets are also known as Brotform or proofing baskets. Alternatively, a 'couche' or proofing cloth can be used to proof dough on or under. Couche are generally made of linen or other coarse material which the dough will not stick to and are left unwashed so as to let yeast and flour collect in them, aiding the proofing process.
External links
★
The Oliver 596D Proofer
★
Proofing baskets
References
★
Nancy Silverton (1996). ''Breads from the La Brea Bakery''. Villard Books. ISBN 0-679-40907-6 (USA)