The rising popularity of sourdough has been one of biggest trends in baking over the last few years. There are increasing numbers of consumers buying the bread and more and more manufacturers, large and small, looking to capitalise on the ever-growing demand. Generally people love the sour flavour and chewy texture, but is it worth the significantly higher price tag?
Below I explain what makes it different to conventional bread and why it’s worth it!
What is sourdough?
Sourdough is one of the oldest forms of grain fermentation. A widely accepted technical definition of sourdough describes it as a mixture of flour and water, spontaneously fermented by lactic acid bacteria and wild yeasts, which have the ability to acidify and leaven. Sourdough is one of the oldest examples of natural starters, compared with the modern day alternatives of baker’s yeast and chemical leaveners.
History of sourdough
Leavening bread by fermentation is a central element of the history of feeding the human race. Experts believe it originated in ancient Egypt around 1500 B.C. and remained the main method of leavening bread until baker’s yeast replaced it a few hundred years ago In the Egyptian dialect, the pronunciation of ferment and bread uses the same Arabic term aish, which means life.
How does it compare with other types of breads?
A basic bread recipe comprises cereal flour, such as wheat or rye, tap water, salt and a leavening agent. The leavening agent is responsible for gas release and consequently dough expansion. The choice of the leavening agent is important for a number of factors such as, costs and time of processing and also the effects on sensory, texture, nutritional and shelf life features.
Commonly, three types of leavening agents may be used: chemicals, baker’s yeast, e.g. commercial preparations of Saccharomyces cerevisiae cells, and sourdough. While the production and commercialization of the first two types takes place at industrial levels, the sourdough is a natural starter.
Sourdough is fermented by naturally occurring lactic acid bacteria and wild yeasts that grow during back slopping, this is a traditional procedure in which the sourdough from the previous fermentation cycle is used as the starter to ferment a new mixture of flour and water.
Wild yeast is more resistant to acidic conditions than baker’s yeast, which allows it to work together with lactic acid bacteria to help the dough rise.
During the bread-making process, the starter ferments the sugars in the dough, helping the bread rise and acquire its characteristic flavour. Sourdough bread also naturally contains varying levels of acetic acid bacteria, a group of bacteria that give sourdough bread its particular vinegar-like aroma. Starters with high levels of acetic acid bacteria take longer to ferment and rise, giving sourdough bread its characteristic texture.
What are the health benefits?
Research has shown that the yeast naturally found in traditionally made sourdough bread is able to increase the bread’s nutrient content and make it easier for the body to digest than bread that’s made using baker’s yeast. However, it is important to note that not all store-bought sourdough breads are made using the traditional sourdough method, and this may reduce their health benefits.
Sourdough bread is often made from the same flour as other types of bread. However, the fermentation process used to make it improves its nutrition profile in several ways:
- Mineral absorption
Whole grain breads contain good amounts of minerals, including potassium, calcium, magnesium, iron and zinc. However, the body’s ability to absorb these minerals is limited by the presence of phytic acid, also known as phytate.
Phytate is naturally found in grains, and is often referred to as an antinutrient because it binds to minerals forming insoluble complexes, decreasing their bioavailability and making them more difficult for the body to absorb.
The lactic acid bacteria found in sourdough bread lower the bread’s pH, Which activates phytase enzymes in the flour and helps to deactivate phytate.
Research shows that the most suitable level of acidification is in the range pH 4.3–4.6 and results in a 70% decrease in phytate, allowing a large spectrum of minerals to become bioavailable and absorbed by the body.
- Anti-nutritional factors
Research has shown that the dough’s low pH, combined with the lactic acid bacteria increases the level of other nutrients and antioxidants in sourdough bread, particularly if chickpea, lentil or bean flours are used.
These flours contain anti-nutritional factors, which include raffinose, tannins, saponins and trypsin inhibitors. The lactic acid bacteria and wild yeast contain enzymes such as α-galactosidase, β-glucosidase and tannases that neutralize these antinutrients and help the body to digest the grains more easily.
- Fibre content
Sourdough fermentation produces resistant starch, this is a type of prebiotic indigestible fibre that feeds the beneficial (friendly) bacteria in the gut, in turn improving gut health and boosting immunity.
The sourdough fermentation process also helps break down large compounds found in grains, in particular gluten, making it easier to digest. Gluten is a type of protein found in certain grains. It can cause health problems in people who are sensitive or allergic to it.
Gluten tolerance varies from person to person. Some people have no noticeable issues digesting gluten, whereas in others it can cause stomach pain, bloating, diarrhoea, or constipation.
Sourdough bread’s lower gluten content may make it easier to tolerate for people who are sensitive to gluten, making sourdough a potential option for them. However, sourdough fermentation does not degrade gluten completely. People with coeliac disease should always strictly avoid any breads containing wheat, barley or rye.
- Blood sugar control
Research has shown that sourdough bread has a better effect on blood sugar and insulin levels than other types of bread. The fermentation process changes the structure of carbohydrate molecules which reduces the bread’s GI (glycaemic index), a measure of how quickly carbohydrates are digested and absorbed into the bloodstream. The acids produced by the lactic acid bacteria also help to prevent a spike in blood sugar levels.
Several other studies have compared the effects on blood sugar of eating sourdough bread compared with bread fermented with baker’s yeast. The results showed that those who ate sourdough bread had lower blood sugar and insulin levels than those who ate the breads fermented with baker’s yeast.
Sourdough bread is often easier to digest than bread that’s been fermented with baker’s yeast. This is mainly related to proteins in the bread with research showing that people eating sourdough absorb more amino acids compared with other types of bread.
When compared with other types of bread, sourdough scores highly for satiety, the effect of feeling fuller for longer. Ultimately, this can help with weight control and prevent unnecessary snacking.
Is it worth it?
Although more expensive, sourdough bread is a great alternative to conventional bread. It’s richer in nutrients, less likely to spike your blood sugar, and easier to digest.
If you’re worried about the cost, it’s worth having a try at making your own. As you can make sourdough bread from any type of flour chose a wholegrain rather than a refined flour to get the maximum health benefits.