Sourdough

Sourdough is a dough for making baked goods, which is usually held permanently by lactic acid bacteria and yeasts in fermentation. The carbon dioxide produced thereby loosens the dough. The typical species of lactic acid bacteria Lactobacillus plantarum ( homofermentative ) and Lactobacillus brevis ( heterofermentative ). A typical strain of yeast in the sourdough is Saccharomyces cerevisiae.

Leaven is added as a leavening agent to loosen pastry and makes rye dough breadmaking quality. Improve digestibility leaven, aroma, flavor, shelf life and cut the pastry. Likewise, nutritional properties are improved.

• 3.1 flavor and aroma
• 3.2 volume, texture and pore structure
• 3.3 processing properties
• 3.4 freshness
• 3.5 Shelf life

• 4.1 leaven by spontaneous acidification

• 5.1 starter cultures 5.1.1 Classification of starter cultures for sourdough standard
• 5.1.2 cultures

• 6.1 Anstellgut from the mature sourdough
• 6.2 leaven errors and their causes

• 7.1 Germany
• 7.2 Austria
• 7.3 Switzerland
• 7.4 France

• 9.1 Christianity 9.1.1 practice
• 9.1.2 symbolism

General

Sourdoughs contain a community of lactic acid bacteria and yeast, used by the person for several thousand years for the production of corn cakes, bread and bread-like food. The metabolic products of these microorganisms loosen the dough and improve the digestibility, the aroma, the taste and shelf life of baked goods. Has a special meaning in the use of sourdough rye flour. While wheat flour, pure yeast can be used as a leavening agent, with the use of rye flour, the supply of acid is required, so that the bread does not remain flat. The lactic acid bacteria of the leaven produce these in the form of lactic acid and acetic acid.

While in the past, processes and methods were sought for inexpensive and efficient preparation of bread, today the taste and nutritional properties of sourdough baked goods out in the foreground. Especially whole grains obtained by leaven an improved " mouth feel" and better taste, nutrition determining which substances are preserved.

Types of leaven

Usually sourdough bread is made from grain flour ( wheat or rye), but it can be replaced either partially or wholly by other cereal products or flour similar products. Very widely used in Africa teff bread in Ethiopia and, for example Laxoox in Somalia.

Wheat Sourdough

Wheat Sourdough is a dough made from wheat flour, water, yeast ( Saccharomyces cerevisiae mostly ) and often a small proportion of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus brevis ssp. Lindneri ). Some traditional baked goods with wheat sourdough ciabatta are, Panettone or the Hermann dough.

Rye sour

Rye sour is a mixture of rye flour, water and lactic acid bacteria (Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus fructivorans ) and most yeasts (Saccharomyces cerevisiae). Not all sourdough rye contain enough yeast for the relaxation. That is why sourdough yeasts ( acid-resistant and drove strong yeasts) are often added.

Durable products

Crumbs Auer

With a lot of flour to dry crumbs processed leaven is used as crumb Auer (also Gerstl ) and are used for storage.

Dry Auer

• Main article: Art Auer
• This includes sourdough concentrates. Such concentrates are often sold under the name of natural fermentation starter. They are prepared by a sourdough of wheat flour, yellow Saaterbse and honey is gently dried. This leaven form is well suited for private households because no complicated sourdough is necessary, but the dough by adding water is gäraktiv and yeasts and lactic acid bacteria and is suitable for producing bread from bread grains and non- bread cereal varieties.

Effects of leaven

Flavor and aroma

Sourdough breads contain many odors and flavors. There are known more than 300 flavors, but only a few are aroma and taste -determining. Many of the substances involved are already present in the flour, but give a faint aroma impression. Through fermentation and formation of esters ( from ethanol and acids) with the leaven such flavoring substances are strongly developed. Wearing aroma compounds such as methyl butanol and diacetyl take in concentration, but it will also reduce undesirable flavors; so is decomposed such as the grassy flavoring hexanal in sourdough.

Volume, texture and pore structure

Leaven by the specific volume is increased. The pore structure of the crumb is finer. In addition draws a higher moisture and elasticity from a sourdough, making the pastry is cut resistant. When consuming the mouth feel is pleasant, because all fractions of the flour are digested better: an effect that is particularly wholemeal products. Rye breads can be better chewed by lowering the pH. While chewing the unleavened crumb on the teeth is liable, causes an unpleasant mouthfeel; with decreasing pH increases the elasticity of the crumb.

Processing properties

• Wheat dough from sourdough - especially whole wheat doughs - trap moisture and ensure good by swelling a better and easier processing. This probably because the solubility of pentosans increases. Developing the adhesive is improved, the dough is extensible.
• In contrast to wheat doughs require rye doughs of the acid to be back capable. In rye dough prevents the - compared to wheat flour doughs - higher proportion of water-binding pentosans the formation of an adhesive scaffold, whose task is the ( Krumenbildung ) during the baking process. Instead, store swollen pentosans and rye starch together to form after pasting ( Heat One effect ) the stable crumb. Without acid, the strength of the flour amylases would be degraded, could not gelatinize and the bread would remain flat and would be inedible. The acids of sourdough effect at a pH value of 4.1 suspend most of the enzyme activities and thus the degradation of starch.

Freshness

This staling is complex and not fully understood. The bread loses flavor and mouthfeel, it is harder and more brittle; the strength releases moisture and turns into a crystalline state. The moisture migrates from the crumb to the crust, where it exits. So far, only ensures that the formation of exopolysaccharides caused by lactic acid bacteria in sourdough fermentation, it has significant influence.

Shelf Life

Sourdough bread moldy Guided slower than non-acidified or chemically leavened breads. Causes and effects are manifold. Leavened breads are less susceptible to:

• Mold. Caused the decreased susceptibility to spoilage by lowering the pH and the formation of caproic acid or phenyl - lactic acids. During the acidification also occur antimicrobial metabolites, which act together with the lowering of the pH value. Undissociated acids penetrate the cell nucleus and destroy the vital transmembrane. There are also diacetyl, acetaldehyde or hydrogen peroxide formed, which also have an antimicrobial effect, but affect smell and taste of the product.
• " Stringing ". In recent years, the old, almost forgotten, bread disease of the stringing is again more common. It occurs only in wheat breads and is prevented by the addition of sourdough.

Extraction

Sourdough by spontaneous acidification

This procedure is quite old and secure. It is still used today to attract the basis of ( sour) for sourdough.

Lactic acid bacteria are found everywhere. They can be found in the flour in the air and in the water. Therefore, a leaven be prepared that you can ever have the same amount ( rye ) flour and water mixed and covered at room temperature with each other for about two days. Smells of dough then pleasantly sour, often with a hint of fruit, one can assume that the lactic acid bacteria have prevailed. Smells of the approach, however, rotten eggs, so one must assume that putrefactive bacteria have prevailed.

The result is, however, strongly dependent on the state of the raw materials. Much the storage of raw materials (temperature, humidity ) and the infestation of pests affect the number and types of microorganisms. Thus, a certain type of bacteria or yeasts can safely develop enough germs of this type must be present. Success and quality are highly dependent on chance. It is a cut-throat competition which decides which cultures evolve.

Biology and chemistry of the leaven

Leaven is a stable symbiotic culture of lactic acid bacteria and yeast in a dough of flour and water. Lactic acid bacteria convert the sugar, which can not reduce the yeast, and on the other side products of the yeast to metabolize the lactic acid fermentation. Generally one can say that the yeast produce the gas that the dough rise and the lactic acid bacteria produce lactic acid, which is responsible for the sour taste and the enzyme inhibition. Lactic acid bacteria work anaerobically, that is, You can proliferate in the absence of oxygen. Hammes and Vogel 1995 have distinguished three different metabolic groups of lactic acid bacteria:

• Obligate homofermantative lactic acid bacteria: build hexoses via the Embden - Meyerhof - cycle ( the glycolysis) to two molecules of lactic acid ( C3H6O3 ) on. However, they do not form carbon dioxide (CO2). You can not tolerate oxygen. Lactobacillus delbrueckii and L. acidophilus are typical representatives.
• Facultatively heterofermentative lactic acid bacteria: metabolizing hexoses to lactic acid, and pentose to lactic acid and acetic acid. They tolerate and use oxygen. Examples are Lactobacillus casei and L. plantarum.
• Obligate heterofermentative lactic acid bacteria: build from hexoses via the Embden -Meyerhof cycle to lactic acid, acetic acid and CO2. Pentoses they break down to lactic acid and acetic acid. Typical representatives are Lactobacillus fermentum, L. brevis, L. kefiri, and L. sanfranciscensis. The often - wrongly - held view, the acetic acid formed came from a vinegar fermentation, is not true.

The lactic acid bacteria decompose some of the sugars in the flour to lactic acid to acetic acid and a small proportion of carbon dioxide. The yeast form carbon dioxide and small amounts of alcohol ( ethanol). The alcohol is converted by acetic acid bacteria in acetic acid. Through different conditions ( fermentation time, mixing ratio, temperature) can influence the proportions of the individual fermentation products and thus on properties (effect) and taste of sourdough. By temperature control can be achieved that more acetic acid ( 24-28 ° C) is formed in the dough, so the bread tastes sour. Lactic acid is milder in taste. If, therefore, more lactic acid are formed, the dough must be performed at about 30 ° C. In the final leaven prevail pH values ​​from 3.8 to 4.3. The alcohol formed during fermentation connects to the part with acids in the dough to form esters that contribute to odor and taste of the pastry. Another portion is converted to acetic acid. The ratio of lactic acid to acetic acid in the dough should be between 3:1 to 4:1. If the ratio in the direction of acetic acid shifted, so the flavor is usually considered to be too acidic.

Starter cultures

Starter cultures are the basis of a standardized leaven. In the production of a flour -water mixture is seeded specifically to particular cultures, resulting in a sourdough developed. Again, a residual Anstellgut is canceled for the next sourdough. At certain intervals, the acid is often completely re-arranged with pure breeding Auer, with other producers rely again on its own, proven, stable cultures for years.

Classification of starter cultures for sourdough standard

• Starter for pure breeding sourdough
• Starter for Silosauerteig
• Starter for stockpiling, deep freeze compatible
• Starter for the bread fermentation
• Starter for Anfrischsauer

Cultures

• Enforced has the strain Lactobacillus sanfranciscensis, which is heterofermentative. In addition to acetic acid lactic acid, ethanol and carbon dioxide are formed. It also peptides, amino acids and sugars, which are raw materials for the subsequent formation of aroma in bread produced.
• For many years Candida humilis is used as Sauerteighefe.

Starter cultures are available for the following cereals:

• Sourdough
• Wheat sourdough
• Rye and wheat sourdough
• Spelt sourdough
• Rice starter
• Backfermente for rye, wheat and other grains

No significance is the type of grain for the development of the desired microorganisms. More important is the supply of the necessary nutrients, with dark flour considerably better results.

The outer layers of rye and wheat grains contain phytic acid, which promotes the development of the young cereal grain and protects against predators. Dark flours contain much phytic acid, while the share for light meals and decreases in white flour is insignificant. Phytic acid is considered to be anti-nutritive: binds minerals (Ca, Mn, Mg, Fe) by protein complexes ( phytates ), by which the absorption in the intestines is reduced, or made ​​more difficult. Basically, phytin is in the bread for the human organism insignificant because it is not thermally stable; however minerals remain bound. In sourdough - by the low pH - build grain 's own enzymes from phytate.

Sourdough guides

Main article: sourdough

As a leader, one refers to the production of sourdough on one or more stages of different temperature is being tried a product corresponding to the desired ratio of the micro-organisms ( yeasts and lactic acid bacteria ) to reach.

Anstellgut from the mature sourdough

If a mature sourdough not completely consumed, the rest can be renewed as Anstellgut. Purpose flour and water are added. If in certain circumstances the acid formation is no longer satisfactory, undesirable microorganisms can multiply in the dough. Possible consequences:

• Sour vinegar stitch
• Bitter taste bread
• Inelastic, soggy crumb
• Porung unevenly

To avoid this, a pure culture Auer should be used as an approach regularly.

Sourdough errors and their causes

Due to errors in the sourdough amount and maturity can occur bread typical errors:

General public's perception of sourdough

By the term leaven of the consumer connects the product with high quality and natural origin. Different countries have therefore adopted policies and product for the protection of the consumer:

Germany

In the German Food Code Guidelines (§ 15 LFGB ) over the current business practice for many foods are described. These principles have been developed and maintained by consumers, economists, researchers, food control and the authorities. But principles are not rules of law. They could be described as anticipated expert opinion. Products may vary from these guidelines and be brought in the appropriate identification in traffic.

2006 definition (excerpt):

• " 1:11 Sourdough is a dough, the microorganisms (eg lactic acid bacteria, yeasts ) from sourdough or sourdough starters are in an active state or be reactivated. They are qualified by the addition of cereal and water for continuous acid formation. Parts of a leaven be used as Anstellgut for new leaven. The life activity of the microorganisms will only be terminated by baking or hot extrusion. The acid increase the leaven is based solely on his fermentations. "

The Guidelines also sourdough bread is defined:

• " 3.1 sourdough bread is prepared so that the total added amount of acid from sour dough comes. In point 1.11 is referenced. Notes on the concomitant use of sourdough are only common when the added amount of acid to more than two -thirds comes from sourdough. In Bauern-/Landbrot with a rye content above 20%, the added amount of acid originates at least two thirds of leaven. "

Austria

The guiding principles of the German Food Code corresponds, in Austria the " Austrian Codex Alimentarius ". excerpts:

B9: baker's yeast, yeast, baking powder, leavening agent for special purposes:

• Section 5: Sourdough is made ​​from flour or meal brewed befindlicher with water in an acid fermentation dough. The fermentation and acidification can occur either spontaneously or induced by the addition of an induced via a pure breed mixed culture of sourdough yeast and acidifier. After the kind of inception are therefore different nature Auer and Auer purebreds.
• Section 7 (excerpt): sourdough, which is caused by the parallel process of spontaneous fermentation and Spontansäuerung by itself, is called nature Auer. [ ... ] In the nature Auer have the desired Herführungsmaßnahmen that promote their development, are increased, thereby simultaneously the increase of undesirable microorganisms is inhibited.

In Austria so natural Auer is quite narrowly defined. Its use is required in the production of agricultural and peasant bread (Codex Chapter B18 ).

Switzerland

In Sect. 16 of the Swiss Food Manual leaven is defined (excerpt):

• Leaven is specifically guided by spontaneous or by starter cultures ( lactobacilli) fermentation through several stages approach guided dough of rye or wheat flour with an active, operating performance micro- flora. [ ... ] The pH of a mature sourdough, depending on the type (rye / wheat) and extraction rate in the range of 3.2 to 4.5, the acidity of 10 to 30 The Sour Share ( mature full Auer ), depending on bread type and desired flavor 15-50 %.

France

On September 13, 1993, Decree No. joined. 93-1074 for the protection of breads: Pain Maison, Pain de Tradition Française and pain au levain in force. excerpts:

• Article 3: bread that is brought under the name " Pain au Levain " on the market, must be made ​​with a sourdough accordance with Article 4 and at most have a pH value of 4.3 and more than 900 ppm of acetic acid.
• Type 4: Sourdough is a dough composed of wheat or rye flour, drinking water and possibly salt which undergoes a natural fermentation acid-forming and whose function is to let the dough rise. Leaven contains mainly consisting of lactic acid bacteria or yeast leavening microflora. The addition of yeast (Saccharomyces cerevisiae ), which is intended for use in the bread dough is allowed to 0.2% ( based on the total amount of flour ). The leaven can also be dried if it contains one billion bacteria per gram and 10 million yeasts per gram. After addition of water and possibly the addition of baker's yeast (Saccharomyces cerevisiae ) it must provide sufficient Teigtrieb according to the above conditions. The leaven can also approved species of microorganisms are added.

History

Pliny the Elder described by 79 AD, the production of sourdough by mixing wheat bran with three -day-old grape. Also, the method Spontansäuerung and the continuation of sourdough were known to him. In the Middle Ages the diverse knowledge of agriculture and bread making, however, turned again into oblivion. Only at the courts and monasteries of this knowledge was still maintained.

In Germany delivered in the 15th and 16th centuries, brewers and distillers bakers yeast the first. In France, this technique has long been controversial, since the population feared a health risk due to this new food. Only in 1670 the use of brewer's yeast was allowed, where they had to be previously mixed with leaven. In Europe, the first Hefezüchtungen were known around 1700. End of the 18th century, the factory-like production of yeast had established. Buoyancy brought the development of the baker's cooling machine of Carl von Linde. The brewers increased after 1877 from top fermenting to bottom-fermented beer. This was possible only by refrigeration, but not a viable yeast for bakeries was incurred more. Must ensure that the development of special baking yeasts was promoted. The yeast the brewer and distiller were of poor quality. The strain Saccharomyces cerevisiae has been specifically selected and produced, since this yeast with excellent baking results were obtained.

Rye sour was first replaced in 1900 by citric acid, but the baking results were not optimal. Around 1920, it was recommended in the rye to simplify the preparation of bread, the addition of acids, which made ​​sense based on current knowledge, because then flours possessed a high enzyme content. In parallel, we developed sourdough starter cultures and offered it as a " pure breed Auer " on. 1930 reached the first finishing Auer on the market. They consisted of swelling flour and fermentation lactic acid. Also in 1930 was offered dried leaven, which, however, due to the process only had a low acid. 1970 Dry Auer was brought as " leaven extract rye " on the market.

Thereafter, the development did not stop. Innumerable methods and baking agents have been developed and continuously improved in order to optimize the existing leaven and simplify procedures.

Cultural dissemination

Christianity

Practice

In the religious practice of Christianity sourdough plays no significant role. The wafers for the Eucharist are indeed produced in the Western Church since the 11th century from unleavened wheat dough, but this tradition has no religious commitment. In the Eastern churches, except Armenians since ancient times, leavened bread is used always.

Symbolic content

Sourdough has in the writings of the New Testament has a different meaning than in Judaism: The leaven is a symbol of a dynamic, whose quality is determined in each case from that of the pulse.

The most important positive image is the parable of the leaven (Mt 13,33 EU ), in which the kingdom of God is described as an event, like a leaven steadily and inexorably creates change, even if the beginning seems small. As a negative gewertetes example is the dynamic that of the Pharisees, Sadducees (Mt 16.6 EU), and of Herod ( Mk 8,15 EU) goes out.

In (1 Cor 5.6 ff EU) Paul writes that believers are to be cleaned by the cast teachings and ways of life, how to clean a house for Passover from the old leaven, that they may take the new way of life as unleavened dough:

" Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth. "