Experiment Two: Hydration

Like bad 1980s football, baking is a game of percentages. When listing bread recipes, it’s common to see them expressed not in absolute quantities, but written in baker’s percentages – with each ingredient expressed as a percentage of the total weight of flour. As an example, my standard pizza dough would be written as follows:

  • 100% strong white flour
  • 65% water
  • 2% salt
  • 1.5% yeast
You’ll notice that the total adds up to much more than 100%. This is always the case with baker’s percentages, and it’s just one of many things that people can find offputting about writing recipes like this. When I first saw a recipe set out in this way, I thought it was needlessly obscure – if you need 10g of salt to make a loaf, surely the simplest way of
Chris Waddle's pet mullet

1980s football was a game of percentages. And also mullets. Percentages and mullets.

writing that is to say “you need 10g of salt to make a loaf”? Stating that you need 2% of your total weight of flour in salt seemed deliberately obtuse. However, there are two big advantages with this notation. First, and of most use to bakers, is that it means you can easily make any amount of a particular bread: whether you want to make one loaf or a thousand loaves, the formula will let you figure out precise amounts for each ingredient easily. The second advantage is that it makes it very easy to compare different bread recipes at a glance. Once you’ve learned to interpret BP, you can quickly work out what sort of loaf a recipe will produce. (For more on baker’s percentages, see the excellent Wild Yeast blog.)

Arguably the most informative line of a recipe is the percentage of water a loaf contains. Changing the hydration of a dough – that is, how much water it contains – can have major effects on the crust and the crumb; wetter doughs tend to give a more open texture with bigger holes, whereas drier doughs tend to have a tighter crumb structure. Drier doughs are generally easy to work with, whereas very wet doughs can tend to spread, slowly and menacingly, like a horrifying yet delicious B-movie monster. What all this means for the pizza maker isn’t immediately obvious. Pizzas, being flat, aren’t really noted for their crumb, so aiming for a ciabatta-like dough would seem to be a bit of a waste – if your pizza rises sufficiently high to show off your wonderful lattice of large air-holes, it’ll be much too bready to be a decent pizza. Nevertheless, changing the hydration of the dough will change the final product, somehow. Precisely how it changes it will be what we set out to discover in Experiment Two.

Hydration

It's important to get the amount of water exactly right

Given the rather arbitrary amount of water in the baseline pizza recipe, a useful first question to explore the effect of changing the amount of water would be to compare two doughs with different hydration. One dough, which I am going to call the “Wetter Dough” includes 70% water. The other dough, which I am going to call “Dame Margaret Harrington”, includes 60% water*. Both amounts feature in plenty of bread recipes, so both should give perfectly edible pizzas. The aim of this experiment is to put down a marker to show how different hydration affects the final products: our experimental question is “Which is preferable for pizza – a wetter dough or a drier dough?”.

[*On second thoughts, I’m not going to call this dough “Dame Margaret Harrington”. I’m going to call it the “Drier Dough”, as this may be slightly clearer for some readers. You may, if you wish, continue to call it Dame Margaret Harrington.]

Wetter dough:                                                              Dame Margaret Harrington:

500g strong white flour                                                500g strong white flour
350g water                                                                   300g water
7g instant yeast                                                            7g instant yeast
10g salt                                                                        10g salt

The doughs were made up by hand, kneaded for five minutes, covered with oil and left to prove for two hours. They were then made into pizzas, flatbreads, and dough balls.

Results:

Eyeball test: There was a striking visible difference between the doughs. The wetter dough had risen more, felt a little cooler, and looked more glossy. Although the surface of both doughs was relatively dry after proving for two hours, the wetter dough was noticeably stickier under the surface than the drier dough. It had also risen more, and had more obvious air pockets inside. The drier dough felt more putty-like, and tighter – when it was pushed, it had much less give. With the wet dough, in contrast, when it was pushed, the whole top of the dough moved, not just the part of the dough immediately local to the prodding. In other respects, the doughs look identical. This difference was so obvious that even when I accidentally mixed up two dough balls I made from these doughs, it was easy to work out which was which.

70% vs 60%

From the air, the two pizzas looked almost alike. (70% water on left, 60% water on right.)

Pizza Test: When making the pizzas, the wetter dough was noticeably more stretchy. The drier dough did stretch a little bit, but tightened up after it had been rolled. But the difference between them was most noticeable when I tried to roll out the pizzas: the drier dough was easy enough to form into a flat disc, whereas the wetter dough was too sticky to roll properly. However, the wetter dough was supple enough to be pulled out into a pizza shape without using a rolling pin. My skills as a pizzaiola are non-existent, but I still managed to form a decent-looking pizza – it had a raised outer crust (what Peter Reinhart assures me is called a cornicione), and generally looked cool. My impression from forming the pizzas is that the wetter dough was much more alive. It’s much more responsive and fun to work with. The dry dough is like Ed Miliband. It’s prim, and dull, and you want to try to like it, but it’s a struggle.

Whatchoo talking about, Willis?

My pizza-shaping skills are so refined that the differences between the two pizzas are barely perceptible to the naked eye. Ahem.

After baking, the pizzas were visibly different. The wetter dough pizza had risen more (partly because my shabby efforts in shaping it by hand meant that it was much thicker than the drier dough pizza, but partly too because it showed more oven-spring). It tasted a little bready, chewy, almost naan-like, because of its thickness. It had risen nicely, and I liked the shape of the pronounced cornicione, though I think it would have been better if I’d managed to make it thinner. The drier pizza was flatter, and because the edges were thinner, they had browned more. It had a crunchier texture, and I liked the flavour added by the slight caramelisation of the crust. This aside, the pizzas tested very similar. The major differences were in the texture and thickness.

Ed Miliband is 60% water

A picture is worth a thousand words. In this case, seven hundred of them are "Noooooo!".

Flatbread Test: As with the pizzas, the drier dough was much easier to work with. It behaved itself, held its shape, and didn’t stick. The wetter dough was much more delicate – it took a good spray of olive oil on the work surface and rolling pin before I was able to roll it into a disc. During baking, the drier dough puffed up and was more pitta-like, whereas the wetter dough was a little tighter and less puffy. As a result, the drier dough was a little more crunchy. The wet dough had a softer texture, a little like untoasted pitta. That aside, there was no great difference in taste, and only a slight difference in texture.

Dough Ball Test: The wetter dough was easier to shape into a boule than the drier dough; the extra stickiness helped when trying to seal the base of the dough balls. After proving, the wetter dough seemed to have risen a little more. It was more airy, with a little more give when you squeeze it. Both looked and tasted fine after baking, though the wetter dough had risen a little more, and had a little more airiness to it. The dry dough was a little tighter, and more claggy due to the tighter crumb. Both tasted good though, and any differences between the two doughs were pretty minor.

The Verdict

The Verdict

"Mr Waddle, you have been found guilty of crimes against hair. Also, 'Diamond Lights' was shite."

Changing the amount of water in the dough doesn’t seem to make much difference to the taste. It does, however, change the physical qualities of the dough a lot. The wetter dough, with 70% water, rose more during proving, and was stickier and more elastic during shaping. The drier dough, with 60% water, was stiffer, less adhesive, and could be rolled out more easily. Because of this, there were some interesting incidental differences in flavour between the two pizzas: the drier-dough pizza had a thinner crust, and so it caramelised more, was more crunchy, and had a more varied mouthfeel. The wetter-dough pizza had a thicker, raised crust. This tasted quite bready, which wasn’t unpleasant but didn’t seem so appropriate for a pizza. For the purposes of these side-by-side experiments, a drier dough actually has the advantage that it’s easier to make into two identical pizzas, using a rolling pin – the wetter dough is harder to shape consistently (at least with my shaping skills), as it needs to be formed by hand. But I think that if you were able to shape the wetter dough into a thinner pizza, that’d be the best of both worlds – it’d give you a crunchier raised crust, and would be easier to shape into the classic raised-crust pizza shape than the drier dough.

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