Sourdough - an open crumb to maximise your chances of 'holes'!

Everybody seems to judge a sourdough loaf by one or more of four attributes.

Does it have...

1. A thick dark crust? 

2. An attracive scoring on the top?

3. That distinctive 'sour' taste?

4. A sufficiently open crumb - that is to say, lots of holes? 

Let's deal with each of these in turn. 

A thick dark crust

The darker the bake, the longer it's been in the oven and the higher the temperature. Sourdough is a strange bread. The 'oven spring' - the magic of it reacting to the heat of the oven and the 'growth' of the loaf as it meets the heat - is largely to do with placing it into an oven that is as near to 230 degrees C as you can achieve. Unlike the usual 'yeast' bread, it thrives on heat and, rather than simply going black as a piece of coal, it develops an armour-plated crust and that distinctive golden to dark brown finish. Any additional coarse flour on the loaf scorches artistically! 

If you can apply steam during the bake, all the better. Some people place a small metal tray at the bottom of the oven and pour hot water into it just before the loaf goes in. Others spray the inside of the oven with a mist of water. 

I can't do either on pain of severe reprimand - we have two new ovens! 

An attractive scoring on the top

The markings on the sourdough serve two purposes.

The first is to allow the loaf to expand upwards, through the slashes in the dough, rather than simply bursting out sideways or producing unslightly lumps and bumps. 

The second, is historical. In the olden days, people would take their unbaked loaves to the village baker who would put them into his oven for a small fee. Personal markings on the loaf would make later identification easier. 

There's an interesting video on varieties of lame or slash marks at

That distinctive 'sour' taste

The 'sour' taste that gives sourdough its name and its distinctive quality comes from the acetic acid within the dough. 

A basic rule of thumb is that the lower the hydration level of the starter, the higher the level of acetic acid. Therefore, open crumb sourdough - that is to say those loaves with plenty of holes, tends to have less of a 'sour' taste. The more dense the crumb, the stronger the taste. 

A sufficiently open crumb - that is to say, lots of 'holes'

Bearing in mind what you've just read about the distinctive 'sour' taste of sourdough, you will understand that it's all to do with hydration levels. The higher the hydration, the more loose the dough and the more it leads itself to an open crumb and, therefore, more holes. 

A low hydration means that the dough is easier to work and less 'gloopy' (what a great word!). 

There is a really good guide to hydration levels at,multiply%20the%20result%20by%20100. 

And another guide at

There's also another factor to consider when you think about 'holes' and an open crumb. The dough has to be encouraged for 'holes' to form. This is about working the dough. This is a method I haven't covered before so watch you don't miss it. 

Right, let's get on with it. 

Today, I'm going to walk you through a specific combination of the four attributes. When you feel confident enough to wander away from this and change the quantities / processes to suit your own taste, by all means experiment until you find your favourite combination. Write it down and keep it handy. You can't be going through all these formulas every Bake Day. 

Stage 1

I'm using 

160 gms of starter. My starter has been made using equal portions of flour and water so it's at a 100% hydration. 50:50 = 100%. I feed the starer last night with 100 gms of rye flour and 100 ml water. 

5 gms sea salt

400 gms of flour Today, I'm using strong white flour. As a rule of thumb...the coarser the flour, the more water you'll need. 

280 mls water I'm working on a 70% hydration level. I have 400 gms of flour  70% of 400 is 280 (0.70 x 400 = 280) So, I need 280 mls of water. 

You'll read about all sorts of formulae that incorporate both the flour and water from your starter as well as from the main body of flour and water. A safe 'short cut' is to presume that if can pour your starter into your bowl or pan then it's likely to be at least 50:50 flour to water. Therefore, just work out 70% or whatever of your main body of flour - as I have done above. If your starter is very stiff - and I mean stiff - then add 10 - 15 mls more water to your mix. 

If you're using a more coarse flour - for example, rye flour, increase your water by 10 - 15 mls or as you wish. 

Below 70% hydration and you're in basic sourdough territory. Above 70% is usually classed as 'Artisan Sourdough'. The gas bubbles that form the 'holes' in sourdough appear when the dough is loose and at 65 - 100% hydration. Remember, the looser the mix - the more difficult it is to handle. If you're new to sourdough - choose a 65% hydration and experiment as you feel more assured. To be honest, I usually work around 70- 75%. 

Mix your ingredients together and knead to form a dough, place it in an oiled bowl and leave, covered with a tea towel for ONE hour. 

As usual, I'm using a pizza dough setting on a machine (45 minutes) but which ever route you take, you need to reach the point where your dough has had its first prove. 

Building tension into your dough - here's a brief video of the stretch, fold and turn technique. 

Stage 2

At the end of the first hour, or when the machine has finished, take out the dough and place it on an oiled board. 

Now, we're going to work tension into the dough. Tension helps the dough to rise rather than spread when it feels the heat of the oven - or 'oven-spring'. 'Rise' also allows the gas bubbles to form holes within the crumb. 

We've covered this method every time we've made sourdough. Watch the video above and then follow the technique...

Form the dough into a slab in front of you. 

Take the far side of the dough and pull it away from you whilst holding the near side to the board. 

Fold the far side back into the middle. 

Turn the dough through 90 degrees

Pull the far side out away from you whilst holding the near side to the board.

Fold the far side back into the middle

Turn the dough through 90 degrees....and repeat....and repeat.....and repeat for 30 seconds. 

Bring the dough together and place it back in the oiled bowl, Cover it with the tea towel and return it to its warm place (22 - 24 degrees C).

After the first hour
Ready for Stretch....Fold and Turn

Wait an hour and do this process of stretch, fold and turn again. Leave it again in the warm place. 

Wait and hour and repeat. 

In the end, you will have stretched, folded and turned the dough three times in the three hours. 

Stage 3

After a final stretch, fold and turn, place the dough in a proving basket, Dutch oven or whatever you're using. 

Once the dough is in your proving basket, dust it with flour and put it back into your 'warm place' - in my case, the airing cupboard - covered in a tea-towel for two and a half hours. 

After two and a half hours, preheat your oven to 230 degrees C. By the time the oven has come up to heat, the loaf will have had the best part of three hours.

Stage 4

Your oven should be at 230 degrees C

If you're using a non-oven proof container, carefully tip the loaf out onto a baking sheet or parchment paper (if you're using a Dutch oven or pizza stone - remember to preheat them)

Dust the top of the loaf with coarse flour (spelt, rye or rice) and slash in a pattern to suit yourself. 

Place the loaf on a lower shelf for 45 - 50 minutes. 

When the loaf is done - it'll be a good colour and will sound hollow when tapped on the bottom, place it on a wire rack to cool. 

Happy baking......


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