Editing Bread (section)

==Leavening==
{{See also|Unleavened bread}}
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[[File:Aberdour Castle - Dough Trough.jpg|thumb|A dough trough, located in [[Aberdour Castle]], once used for leavening bread]]

[[Leavening]] is the process of adding gas to a dough before or during baking to produce a lighter, more easily chewed bread. Most bread eaten in the West is leavened.<ref name=BAC>{{cite web|title=The Bread Leavening Process|url=http://becomingachef.co.uk/bread-leavening-agents-sourdough-starter/|website=Becoming a Chef|access-date=2 October 2016|date=15 August 2016}}</ref>

===Chemicals===
A simple technique for leavening bread is the use of gas-producing chemicals.  There are two common methods. The first is to use [[baking powder]] or a [[self-raising flour]] that includes baking powder.  The second is to include an acidic ingredient such as [[buttermilk]] and add [[baking soda]]; the reaction of the acid with the soda produces gas.<ref name=BAC/> Chemically leavened breads are called ''[[quick bread]]s'' and ''[[soda bread]]s''. This method is commonly used to make [[muffin]]s, [[pancake]]s, American-style [[biscuits]], and quick breads such as [[banana bread]].

===Yeast===
{{Main|Baker's yeast}}
[[File:Compressed fresh yeast - 1.jpg|right|thumb|Compressed fresh yeast]]

Many breads are leavened by [[yeast]]. The yeast most commonly used for leavening bread is ''[[Saccharomyces cerevisiae]]'', the same species used for brewing alcoholic beverages. This yeast [[Fermentation|ferments]] some of the sugars producing [[carbon dioxide]]. Commercial bakers often leaven their dough with commercially produced [[baker's yeast]]. Baker's yeast has the advantage of producing uniform, quick, and reliable results, because it is obtained from a [[pure culture]].<ref name=BAC/> Many artisan bakers produce their own yeast with a growth culture. If kept in the right conditions, it provides leavening for many years.<ref name="isbn0-387-38563-0-cite4">{{cite book |author1=Young, Linda |author2=Cauvain, Stanley P. |title=Technology of Breadmaking |publisher=Springer |location=Berlin |year=2007 |page=79 |isbn=978-0-387-38563-1 |url=https://books.google.com/books?id=HXtJivmeDfcC&pg=PA79}}</ref>

The baker's yeast and [[sourdough]] methods follow the same pattern. Water is mixed with flour, salt and the leavening agent. Other additions (spices, herbs, fats, seeds, fruit, etc.) are not needed to bake bread, but are often used. The mixed dough is then allowed to [[Proofing (baking technique)|rise]] one or more times (a longer rising time results in more flavor, so bakers often "punch down" the dough and let it rise again), loaves are formed, and (after an optional final rising time) the bread is baked in an [[oven]].<ref name=BAC/>

Many breads are made from a "[[straight dough]]", which means that all of the ingredients are combined in one step, and the dough is baked after the rising time;<ref name=BAC/> others are made from a "[[pre-ferment]]" in which the leavening agent is combined with some of the flour and water a day or so ahead of baking and allowed to ferment overnight. On the day of baking, the rest of the ingredients are added, and the process continues as with straight dough. This produces a more flavorful bread with better texture. Many bakers see the starter method as a compromise between the reliable results of baker's yeast and the flavor and complexity of a longer fermentation. It also allows the baker to use only a minimal amount of baker's yeast, which was scarce and expensive when it first became available. Most yeasted pre-ferments fall into one of three categories: "[[poolish]]" or "pouliche", a loose-textured mixture composed of roughly equal amounts of flour and water (by weight); "[[biga (bread baking)|biga]]", a stiff mixture with a higher proportion of flour; and "pâte fermentée", which is a portion of dough reserved from a previous batch.<ref>{{cite web|title=Artisan bread baking tips: Poolish & biga|url=https://www.weekendbakery.com/posts/more-artisan-bread-baking-tips-poolish-biga/|website=Weekend Bakery|access-date=2 October 2016}}</ref><ref>{{cite web|title=Preferments|publisher=King Arthur Flour}}</ref>

<gallery mode="packed">
File:Breaddough1.jpg|Before first rising
File:Breaddough2.jpg|After first rising
File:Risen bread dough in tin.jpg|After [[proofing (baking technique)|proofing]], ready to bake
</gallery>

===Sourdough===
{{Main|Sourdough}}
[[File:Sour dough loaves03.jpg|thumb|Sourdough loaves]]

Sourdough is a type of bread produced by a long fermentation of dough using naturally occurring yeasts and [[Lactobacillus|lactobacilli]]. It usually has a mildly sour taste because of the [[lactic acid]] produced during [[Anaerobic respiration|anaerobic]] [[fermentation]] by the lactobacilli. Longer fermented sourdoughs can also contain [[acetic acid]], the main non-water component of vinegar.<ref name=DavidsonSourdough>{{cite book | first=Alan | last=Davidson | year=1999 | title=The Oxford Companion to Food | publisher=Oxford University Press | isbn=978-0-19-211579-9 | pages=[https://archive.org/details/oxfordcompaniont00davi_0/page/756 756–57] | url=https://archive.org/details/oxfordcompaniont00davi_0/page/756 }}</ref><ref>{{cite book | editor1=Gobbetti, Marco |editor2=Gänzle, Michael |date=2012 |title=Handbook on Sourdough Biotechnology |publisher=Springer |isbn=978-1-4899-9189-8}}</ref><ref>{{Cite journal |last=Ng |first=Henry |date=June 1972 |title=Factors Affecting Organic Acid Production by Sourdough (San Francisco) Bacteria |journal=Applied Microbiology |language=en |volume=23 |issue=6 |pages=1153–1159 |doi=10.1128/am.23.6.1153-1159.1972 |issn=0003-6919 |pmc=   380523 |pmid=5042265}}</ref>

Sourdough breads are made with a sourdough starter. The starter cultivates yeast and lactobacilli in a mixture of flour and water, making use of the microorganisms already present on flour; it does not need any added yeast. A starter may be maintained indefinitely by regular additions of flour and water. Some bakers have starters many generations old, which are said to have a special taste or texture.<ref name=DavidsonSourdough/> At one time, all yeast-leavened breads were sourdoughs. Recently there has been a revival of sourdough bread in artisan bakeries.<ref>{{cite news|last1=Mesure|first1=Susie|title=Supermarkets cash in on sourdough bread craze as popularity surges |url=https://www.independent.co.uk/life-style/food-and-drink/news/supermarkets-cash-in-on-sourdough-bread-craze-as-popularity-surges-a6844101.html |newspaper=[[The Independent]] |access-date=2 October 2016|date=30 January 2016}}</ref>

Traditionally, peasant families throughout Europe baked on a fixed schedule, perhaps once a week. The starter was saved from the previous week's dough. The starter was mixed with the new ingredients, the dough was left to rise, and then a piece of it was saved to be the starter for next week's bread.<ref name=BAC/>

===Steam===
The rapid expansion of steam produced during baking leavens the bread, which is as simple as it is unpredictable.  Steam-leavening is unpredictable since the steam is not produced until the bread is baked. Steam leavening happens regardless of the raising agents (baking soda, yeast, baking powder, sour dough, beaten egg white) included in the mix. The leavening agent either contains air bubbles or generates carbon dioxide. The heat vaporises the water from the inner surface of the bubbles within the dough. The steam expands and makes the bread rise. This is the main factor in the rising of bread once it has been put in the oven.<ref>{{cite book |author=Edwards, W.P.|title=The science of bakery products |publisher=Royal Society of Chemistry |location=Cambridge |year=2007 |page=68 |isbn=978-0-85404-486-3 |url=https://books.google.com/books?id=oCVPjK0mSfkC&pg=PA68|quote=When bread expands in the oven the resulting expansion is known as oven spring.  It has been calculated that water expansion was responsible for some 60% of the expansion. |access-date=8 December 2012}}</ref> [[Carbon dioxide|CO<sub>2</sub>]] generation, on its own, is too small to account for the rise. Heat kills bacteria or yeast at an early stage, so the CO<sub>2</sub> generation is stopped.

===Bacteria===
[[Salt-rising bread]] does not use yeast. Instead, it is leavened by ''[[Clostridium perfringens]]'', one of the most common sources of food-borne illness.<ref>{{cite web|url=http://home.comcast.net/~petsonk/ |archive-url=https://archive.today/20120630212428/http://home.comcast.net/~petsonk/ |url-status=dead |archive-date=30 June 2012 |title=Susan R. Brown's Salt Rising Bread Project |publisher=Home.comcast.net |access-date=3 June 2010 }}</ref><ref>{{Cite journal |last1=Juckett |first1=Gregory |last2=Bardwell |first2=Genevieve |last3=McClane |first3=Bruce |last4=Brown |first4=Susan |date=2008 |title=Microbiology of salt rising bread |url=https://pubmed.ncbi.nlm.nih.gov/18646681/ |journal=The West Virginia Medical Journal |volume=104 |issue=4 |pages=26–27 |issn=0043-3284 |pmid=18646681 |archive-date=13 April 2021 |access-date=20 April 2023 |archive-url=https://web.archive.org/web/20210413134225/https://pubmed.ncbi.nlm.nih.gov/18646681/ |url-status=live }}</ref>

===Aeration===
[[Aerated bread]] is leavened by carbon dioxide being forced into dough under pressure. From the mid-19th to mid-20th centuries, bread made this way was somewhat popular in the United Kingdom, made by the [[Aerated Bread Company]] and sold in its high-street [[Aerated Bread Company#Tea shops and early women's issues|tearooms]]. The company was founded in 1862, and ceased independent operations in 1955.<ref name=memoir>[[Benjamin Ward Richardson|Richardson MD FRS, Benjanmin Ward]]. ''[https://books.google.com/books?id=5gEAAAAAQAAJ&q=%22john+dauglish%22 On the Healthy Manufacture of Bread: A Memoir on the System of Dr. Dauglish]''. Baillière, Tindall, & Cox, 1884. pp. 18, 20–21, 34, 62–63, 67–70, 74.</ref>

The Pressure-Vacuum mixer was later developed by the Flour Milling and Baking Research Association for the [[Chorleywood bread process]]. It manipulates the gas bubble size and optionally the composition of gases in the dough via the gas applied to the headspace.<ref>{{cite book |editor1=Kilcast, D. |editor2=McKenna, B. M. |title=Texture in food |publisher=Woodhead |year=2003 |page=448 |isbn=978-1-85573-724-2 |url=https://books.google.com/books?id=u-K8UuyKT48C&pg=PA448}}</ref>