On the Table: Cambridge Cookery’s Tine talks sourdough

“Is it that different from normal bread? What makes it sour? Is it really a superfood?” As we mark Sourdough September, Cambridge Cookery MD Tine Roche demystifies the not-so-humble loaf

When I established the cookery school in 2008, I knew that the backbone of our future programme had to be the health benefits - and joy - of real bread. Bread Making for Beginners and Sourdough were the first two classes I designed - and they have remained intact for 15 years. Always fully booked and, to our team’s never-ending delight, always resulting in guests leaving in a state very close to euphoria.

There is no lack of hype, myth and confusion around sourdough. Is it that different from normal bread? What makes it sour? Is it really a superfood? The short answers, which I will elaborate on below, are: utterly, lactic acid and emphatically yes.

Sourdough bread is made without the addition of commercial yeast. Commercial yeast, whether fresh, with a putty-like texture, or freeze-dried and sold as little granules, is a beer-brewing derivative. It is a fast-acting, reliable yeast from which the baker can expect consistent results over and over again.

Sourdough, on the other hand, has no such yeast added. Instead it begins with a ‘mother’ or starter. This is simply a mix of strong, organic flour and water left to ferment at room temperature. Each time a new starter is made, it will have its own unique flora of good yeast bacteria derived from natural spores present in organic flour and from spores in the air around us. Non-organic flour, made from cereals sprayed with various chemicals won’t work, as the good guys will have perished along with the bad ones. The individuality of natural, ambient, live yeast cells makes them considerably less predictable - which can be a challenge for the home baker.

Natural yeast works at a much slower pace than brewery-derived commercial yeast, which is the key to understanding the slow sourdough process, which creates acidity and makes gluten more digestible. The acidity means that sourdough scores very low on the Glycaemic Index. GI measures the speed with which starches and sugars are broken down by the digestive system. A high GI indicates ‘fast’ carbohydrates which will be taken up by the blood very quickly, causing an immediate increase in blood sugar followed by an equally rapid drop in blood sugar. A low GI, based on fibre and/or acidity, indicates food that releases its energy slowly into the system, stabilising blood sugar levels and leaving us feeling sated and energised for longer. This is important for both wellbeing and stamina.

In addition, when a dough ferments - as it does when baking sourdough but not in any other dough - the gluten proteins become more water soluble through a reaction called hydrolysis, involving the breaking of a bond in a molecule using water. Scientific tests have shown that the consistency of dough changes entirely with fermentation - something that any sourdough baker can vouch for, having fought to keep the shape of a slack sourdough loaf before baking it.

A bag of flour contains gliadin and glutenin; proteins which give bread its ability to rise properly and to gain its structure. When flour is mixed and kneaded with a liquid, these two proteins form what is commonly known as gluten. In a fermented sourdough both these proteins undergo drastic hydrolysis and are broken down in a way which means that the gluten is easier for the gut to digest.

The other, much less-mentioned, benefit of sourdough is its chewy texture and tough crust. This really deserves to be flagged up as it is vital for our digestion. Unlike normal bread, which we can consume almost without registering that we are eating, sourdough gives our jaws and teeth a thorough workout. When we chew, saliva is released. Saliva contains important substances for effective food digestion. These include enzymes and anti-bacterial compounds. The enzymes are crucial for successful digestion of starches and fats and are released when we chew a slice of sourdough - and not when we consume soft white bread. This goes for all soft, non-fibrous foods as compared to those that need a full set of teeth. Almost all ultra-processed food belongs in the former group - it is not an issue for commercial bread alone.

If you are not already a convert, do have a go at making sourdough and if you end up in a sticky place, book yourself on to one of our classes!

Vist cambridgecookery.com for more.