Our sourdough is bread made entirely with organic flours, water and salt. We use our starter which is 4 years old, and was born out a bit of honey and olive oil mixed to water and flour. It took 5 weeks to be active and ready to be baked with.
This starter (who now finally has a name, Leonard) is a colony of lactic acid bacteria (LAB) and wild yeast and its job is to ferment the dough and make it rise: it produces organic acids that transform the taste, the nutritional value and digestibility of the final product, the bread.
These microbes work together in the pot to produce enzymes that break down the flour in all its components (different types of sugars) that then feed the microbes and LAB and make them reproduce and grow. They make these sugars ferment into CO2 that causes the dough to rise and also produce ethanol which flavours the bread (that's why the starter has a slight fermented-alcohol smell).
This starter needs to be fed every day, so we add fresh water and flour to it to keep it alive.
"Well this is very interesting and a bit weird, but how does this contribute to my daily diet?" you might ask.
Slow-fermented bread transforms the flour and this increases nutrients and fibres good for us and for our microbes (the ones responsible for our health and well-being) too. Sourdough is a prebiotic: the prebiotics feed the friendly bacteria in our bodies and help them proliferate. These microbes are the same found in soil and in the sourdough starters. Isn't this fascinating?
Talking about fibres, eating sourdough can increase our daily fibre intake by 10-15% compared to yeasted bread, specially if in it you can find wholemeal kinds of flour (and in ours we always use a percentage of it), which are already higher in fibres than traditional white flour.
We don't want to get too much into the details and chemical components of fibres, you can research it easily yourself if you're a bread-nerd as we are, (or we're happy to answer your questions with what we know) but we'll give you a quick guideline here. There are two types of fibres: soluble and insoluble. These two groups are both in our bread and can be manipulated depending on how long the bread is fermented for. Soluble fibre helps to lower cholesterol levels and stabilise the glucose in our blood, plus they slow the emptying process in our stomach which makes us feel fuller for longer. Insoluble fibres help us also feel full, plus they keep our bowels healthy: they absorb water that help soften the contents in our bowel and help us to have regular bowel movements. The longer the fermentation, the higher are the levels of organic acids and fibres in the sourdough, the easiest will be to digest it (note that breads made using only yeast can be fermented and ready to bake in as little as 3/4 hours, whilst sourdough from feeding the starter to baking can take up to 36 hours), that's why every baker will tell you that time is the most important ingredient in bread.
A quick word on wholemeal flours: many people don't know this, but organic flours have a high content of vitamins (E, B2, B12 and many others), minerals (calcium for our bones, iron for our blood, magnesium for our muscles, zinc for our immune and digestive system, to mention a few) and anti-oxidants. By slow-fermenting these flours, we help producing extra fibres and increasing these nutrients.
We are not doctors, we give here a small guideline on the chemistry and benefits of Sourdough Bread, info that are available on the internet and in specific baking books. For more specific information and intolerance queries please we invite you to seek professional help.