Sourdough Breads
These are some of my sourdough bakes from three years ago.
I had compiled this article almost three years ago when I had just started my first sourdough journey. But somehow didn’t post it as I felt that it was not the right time to do so given my limited experience and knowledge. But this lockdown has made many of us try bread baking at home. Also the shortage of yeast especially in the earlier months of the
lockdown has made many of us to turn to sourdough breads using natural yeast. Well, better late than never 🙂 so here we go….
Disclaimer: This is just a compilation of what I have understood after reading a lot on sourdough bread and it’s baking. My practical knowledge is very limited and I have just typed down this article for my better understanding of the theory behind sourdough and I am sharing it with you all, thinking that it might be interesting to read. I intend to modify the contents and maybe add something more as I gain some more practical experience. All information are taken from the internet. I shall correct my mistakes as I progress in the sourdough journey.
So, what is actually sourdough?
From the wiki: Sourdough is a dough containing a Lactobacillus culture in a symbiotic combination with yeasts. It is one of the principal means of leavening (fermenting/rising) in bread baking.
The origin of bread baking dates back to several centuries and people depended on sourdough for leavening (causing fermentation) of these breads. The use of commercial Baker”s yeast (the dry and fresh yeast) is quite recent (maybe around 150 years or so). Though the usage of sourdough was superseded by the introduction of these commercial yeast in bakeries, this is stil a favourite amongst many any artisan bread bakers and is considered to be an art 🙂
Fermented foods are often preferred for their numerous health benefits, due to the presence of beneficial bacteria. These bacteria maintain the acidity level of the intestine and aids in good digestion. Lactic acid fermentation not only helps to preserve food and maintains its freshness, but it also increases the amount of nutrients available for our body to absorb.
There are numerous ways by which a Sourdough bread preparation improves nutrition:
- pre-digesting the starches and thereby making the bread more easily digestible
- lowering insulin response/improving glucose tolerance
- protecting Vitamin B1 from damage due to the high heat at which breads are baked
- breaking down gluten, which may result in a bread that gluten-sensitive people can also eat
- activating phytase ( phytase is any type of phosphatase enzyme that catalyzes the hydrolysis of phytic acid – an indigestible, organic form of phosphorus that is found in many plant tissues, especially in grains ) to hydrolyze (dissolve) the phytates, thus freeing up minerals such as: zinc, iron, magnesium, copper and phosphorus.
All about starter:
So now how do you start preparing a sourdough bread. Well, it often starts with the preparation of a starter also called as “chief“, “chef“, “mother“, “head“, “sponge” etc, which is basically a fermented mixture of flour and water containing a huge colony of micro organisms. According to the ratio of flour and water used, starter can be of various kinds. The objective of the starter is to make a healthy and potent leaven and to make the bread more flavourful. A starter can be in the form of a liquid batter or even like a stiff dough.
Flour naturally contains many types of yeast and bacterial spores. So, now when the flour comes in contact with water, the naturally occuring enzyme amylase (it is the catalyst which helps in hydrolysis of starch into sugar) breaks down the starch into various sugars like glucose, sucrose, galactose, raffinose and maltose. Now some of these sugars are metabolized by the sourdough’s natural yeast and some are not. When this flour and water mixture is subjected to a favourable temperature, time and fresh amount of flour and water, it develops a stable culture. This culture will then help in risening or leavening of the flour if adequate amount of gluten (the protein in grains) is developed in the flour. The sugar which is not metabolized by the sourdough’s yeast (maltose) is then fermented by the bacteria present.
The byproducts of this reaction is further metabolized by the yeast which results in the formation of carbon di oxide gases which will help the dough to rise. However this is a slow process as these natural yeast are not as vigorous like the baker’s yeast. So, unlike breads which uses commercial yeast, these breads will take more time to ferment and proof.
To keep the starter active, we feed it regularly with fresh flour and water (called refreshments) in a definite ratio. The ratio of fermented starter to fresh flour and water (called refreshment ratio) is critical in the development and maintennace of a starter. Higher this ratio, greater is the microbial stability in the sourdough and lower acidity of the dough. A drier and cooler starter has less bacterial activity and more yeast growth, which results in the production of more acetic acid as compared to lactic acid. Conversely, a wetter and warmer starter has less yeast growth, with more lactic acid as compared to acetic acid.
A dry and cool starter produces a sourer loaf than a wet and warm one. Refreshment intervals of longer than three day makes the dough more acidic and may change the microbial ecosystem. Generally, if the starter is fed only once in three days, the percentage amount of starter in the final dough should be reduced to obtain a satisfactory rise during proofing.
Unbleached, unbromated flour contains more micro-organisms than more processed flours. So, if possible, try to source these kind of flours. You can check out unbromated and unbleached flour from www.wildpep.com
Bran-containing (wholemeal) flour provides the greatest variety of organisms and additional minerals. So whole wheat flour ferments faster than refined flour. Basil leaves or water from boiled potatoes help in increasing the bacterial activity.
Bakers often use a part of fermented dough from a previous batch to make fresh loaves of bread rather than making new starter every time. The original starter culture may be many many years old. Because of their pH level and the presence of antibacterial agents, such cultures are stable and able to prevent colonization by unwanted yeasts and bacteria. For this reason, sourdough products inherently keep fresh for a longer time than other breads, and are good at resisting spoilage and mold formation without adding any additives unlike breads with commercial yeast.
The flavour of sourdough bread varies from place to place according to the method used. The hydration of the starter and the final dough, the refreshment ratio, the length of the fermentation period, ambient temperature, humidity, and elevation, all of these contribute to the microbiology of the sourdough.
The starter is mixed with flour and water to make a final dough of the desired consistency. The starter weight is usually 12-25% of the total flour weight, though the formula may vary from baker to baker.
The dough is shaped into loaves, left to rise, and then baked. Because the rise time of most sourdough starters is longer than that of breads made with baker’s yeasts, sourdough starters are generally unsuitable for use in a bread machine.
Sourdough does not require much gluten, in contrast to factory-made bread which often has gluten added to it. People with gluten intolerance may therefore find sourdough bread more comfortable to eat. Sourdough bread produces a smaller surge in blood glucose than other types of bread. Thus it is suitable for coeliac patients too.
Difference bewteen Commercial Bread and Sourdough Bread:
Commercial Bread:
- It uses an artificially laboratory made yeast called the Baker’s yeast.
- It gets used up and have to be replenished. So it turns out to be more expensive.
- It depends a lot on the evnvironment, temperature, humidity and other weather conditions to work efficiently.
- One has to work quickly with commercial yeast as other microorganisms will start acting otherwise.
- Commercial breads stale very easily.
- Due to the absence of lactobacilli, the phytic acid found in grains is not neutralized.
Sourdough Bread:
- Sourdough bread uses naturally occuring wild yeast available free in nature.
- Starters can last for hundreds of years. So it is cost effective.
- Starters form an ecosystem with a host of useful micro organisms which add B-vitamins to the bread, breaks down the gluten and helps in digestion and neutralizes the phytic acid found in grains.
- The organisms in the starter are more versatile and helps to maintain the freshness of the bread for a longer time.
The science behind sourdough starter:
This occurs at a microscopic level with the help of wild yeast and lactobacilli that are present naturally in flours and everywhere around us.
These yeast are single celled fungi which feed on the simple sugars in the flour and they require oxygen to survive. When the yeast feed on these sugars, they release small amounts of ethanol, acetic acid and lot of carbon di oxide gas which is seen as the bubbles in the starter and this helps the bread to rise. The acetic acid and ethanol imparts the tangy and sour taste to the bread and the acetic acid also helps to retain the freshness of the bread for a long time.
The bacteria are the lactobacilli which also eats up the sugar, but they do not need oxygen unlike the yeast. They neutralize phytic acid and release lactic acid, ethanol and some carbon di oxide. Like the case in yeast, acetic acid and lactic gives the sour taste to the bread, carbon dioxide helps the bread to rise, lactic acid acts like a natural antibiotic preventing the growth of any harmful organism.
Some terminologies involved in sourdough baking:
The world of sourdough baking is both an art and science and it will be helpful to familiarize oneself with some terminologies commonly used here.
Sourdough: A type of bread made from a natural leavening agent known as a sourdough starter. Sourdough is made tangy by the lactobacilli present in the sourdough starter, hence its namesake.
Yeast: A component of the sourdough starter contributing lift to breads. During the fermentation process, yeasts and bacteria feed off the starch and oxygen present and create carbon dioxide. This gas is trapped in the matrix of the bread dough, creating a risen bread dough.
Lactobacilli: The bacteria present in many fermented foods that produce lactic acid which gives sourdough bread its characteristic tang. Lactobacilli also work to raise the bread through the production of carbon dioxide, a by-product of the fermentation process.
Gluten: It is a group of seed storage protein found in certain cereal grains especially wheat. Gluten comprises 75–85% of the total protein in bread wheat. It has unique viscoelastic and adhesive properties, which give dough its elasticity, helping it rise and retain its shape while baking. However, gluten can trigger adverse inflammatory, immunological and autoimmune reactions in some people.
Starter / Starter Culture / Sourdough Starter: A mixture of flour and water used to leaven bread that contains bacteria, yeast, and organic acids. Made either by inoculating with an established colony of bacteria or by capturing wild bacteria and yeasts over a longer period.
Feeding: The process of adding flour and water to the sourdough starter to keep it active and healthy. This is usually done at least once per day, if the starter is kept at room temperature. For starters kept in the refrigerator, it only needs to happen once a week or more.
Hydration: The ratio of water to flour in a sourdough starter or bread dough. The hydration is calculated by dividing the total amount of water by the total amount of flour.
Hooch: A layer of liquid that sometimes accumulates on the top of the sourdough starter. It often has a component of alcohol to it due to infrequent feedings or stress on the sourdough starter. It can be poured off just before a feeding to rid the starter of any off flavors.
Leaven / Levain: A sourdough leavening agent made from a sourdough mother culture. Simply put, this is the part of the starter that is actually going to be used in the bread. This technique is used to boost the yeast activity of the sourdough starter by feeding a larger quantity of flour and water to a small amount of starter.
Autolyze: This is a step in which flour and water are mixed just until combined and allowed to rest before adding salt, leavening or further ingredients. The autolyze step provides several benefits through the hydration of the flour and the enzyme activity that follows. These enzymes work to soften the dough and helps in gluten development. It is done before any kneading is introduced, thereby improving both the flavor and the texture of the bread while cutting down on the kneading time that will follow.
Bulk Fermentation: This terminology is generally used when a big batch of dough is fermented, which is then divided and shaped to form individual loaves or boules. This step is the first fermentation period of the dough after the initial mixing of flour, starter, and water and often comes after a period of kneading. The bulk fermentation generally takes place at room temperature, unless otherwise noted in the recipe and is a longer period of time (4 -12 hours) than the final proofing period. This step may be listed as proofing, rising, or bulk fermentation in a recipe but is always the first period of fermentation.
Long Fermentation: This refers to a slower, cooler fermentation over a longer period. This is often 8-24 hours but, with refrigeration, can be even longer. Preferable for those who prefer a tangier bread or the health benefits that go along with a longer fermentation. This often coincides with a small quantity of starter being used in the recipe.
Stretch-and-Fold: An alternative to traditional kneading used to develop gluten. This method is often used in high hydration doughs and is performed periodically throughout the bulk fermentation. The concept is to take a corner of the dough, fold it upon itself, rotate the dough, and repeat. Once all four corners of the dough have been stretched and folded, gluten development and a smooth, elastic dough is just a step away.
Resting: A common step in bread baking, often occurring directly after a kneading or shaping of the dough. A rest period allows the gluten in the dough to relax before a final shaping. This is especially important for stiffer doughs like those used in making pizza and bagels. This may also refer to a period of fermentation or an autolyse step in which the dough is left alone, covered, at room temperature.
Proofing: This is the final rise of the bread before it sees the oven. It generally, happens after the final shaping of the loaf.
Retard: In layman’s terms, retarding dough is the process of slowing down the final rising in the bread-making process. This is done by proofing the bread overnight in the refrigerator since the cold slows down the rise. This step adds flavor to the bread and allows you to bake the bread at a later time according to your convenience.
Slashing: Cutting the outside of the dough with a very sharp razor or knife just before baking. This practice accomplishes two things. First, it can be used as a decorative element on breads, to create a signature look, or to create a design to help bakers of many loaves to tell one from the other. More importantly, however, slashing is used to help a bread expand in the oven without exploding, cracking, or creating unsightly bulges. Slashing reduces the unpredictability and increases the loaf’s ability to expand once it meets a hot oven.
Oven Spring : Refers to the final burst of expansion of a dough upon being introduced to a hot oven. At approximately 140 degrees, the yeast is killed off but up until that point, a dough can expand in the oven in the first phase of baking. Many factors can impact oven spring including the length of fermentation, the gluten development, and the hydration of the dough.
Crumb: This term refers to the texture of the inside of a loaf of bread. Often based on the size of the holes produced by the carbon dioxide or the moisture (or lack thereof) in the loaf.
Crust: Crust is the hard, outer part of a loaf of bread, or a layer of pastry covering a pie, or a hardened layer on something.
Boule: Boule: (“ball” in French) is a traditional shape of French bread resembling a squashed ball.
Batard: It’s a short loaf of French bread having an oval or oblong shape.
Dutch oven: A Dutch oven is a thick-walled cooking pot with a tight-fitting lid. Dutch ovens are usually made of seasoned cast iron. It retains heat quite well and traps moisture inside, rendering it ideal for slow cooking or baking.
Banneton: It’s a bread proofing basket, ideally used for proofing the dough and also for plating and presentation. … The basket helps keep the dough rising upwards, with its sturdy sides, rather than spreading out during its final rise.
Lame: It’s a is a double-sided blade that is used to slash the tops of bread loaves in artisan baking. It is used to score/slash bread just before the bread is placed in the oven.
References:
- https://www.theperfectloaf.com/
- https://thebreadguide.com/
- https://www.theclevercarrot.com/
- https://breadtopia.com/