This time last year, people were going crazy looking for flour, after deciding they wanted to make sourdough from scratch. It sounds easy, just three ingredients – flour, salt and water, but this is a process that takes time and patience. With no added yeast involved it takes days of ‘leavening’ or rising and adjusting the starter. It is fermented using naturally occurring bacteria ( which is good for you). The end result is a beautifully soft, tangy and chewy bread. Below we go into the science behind this process. This is why it takes 72 hours to make a loaf of bread.
What is wheat leaven?
Leaven, also known as levain is the mixture of flour and water. Wheat leaven is sourdough made from 100% wheat, usually wholemeal flour. Sourdough is a mixture of water and flour (in our case wheat flour), in which wild yeast and lactic acid bacteria (Lactobacillus) grow. It is thanks to the latter that sourdough bread has a distinct taste and smell, while having a higher nutritional value than regular bread. Sourdough is also responsible for the structure of bread, because it is a natural raising agent.
What is wheat leaven fermentation?
One of the oldest biotechnological processes that is used in the production of bread is the use of sourdough. Wheat leaven is obtained by spontaneous fermentation of wheat flour and water as a result of the action of microflora that is present both in the raw materials and in the air. Fermentation is initiated by yeasts of the Saccharomyces genus and lactic acid bacteria, which use the carbohydrates present in the flour to produce natural lactic acid, carbon dioxide and ethanol. Many chemical changes that occur during fermentation which leaven the dough, are responsible for its distinct taste, aroma and texture. In addition they protect the dough against the growth of undesirable microflora extending its longevity. The length of the fermentation process depends on the temperature and the amount of water used. A warmer environment and slightly smaller amount of water, which promote the multiplication of lactic bacteria, are more favourable. Wheat leaven is less acidic than rye and has a milder taste and smell.
What are the properties of wheat leaven?
Bread made with the use of sourdough is considered the best in terms of taste and health:
- Sourdough bread has lower glycemic index and higher satiety compared to other types of bread.
- The use of sourdough in the preparation of bread reduces the amount of phytic acid, thus improving the bioavailability of certain elements, like iron, zinc and magnesium.
- Wheat leaven, due to the presence of bioactive peptides that are formed during fermentation by lactic acid bacteria has antioxidant properties – bioactive peptides have greater ability to bind free radicals.
- Sourdough bread is characterised by more beta-glucans like polysaccharides with many health benefits, including being responsible for lowering cholesterol, and more B vitamins, including folates – extremely important for women during the reproductive period.
- Thanks to the fermentation process, lactic acid bacteria has the ability to digest gliadin; thanks to which part of the gluten is pre-digested, lowering the amount of gluten in the bread.
- The latest research also shows that natural leaven fermentation reduces the amount of carcinogenic compounds (e.g. nitrates) in the dough.