The Fresh Loaf

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How hydration % affects stretchability

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frostious's picture
frostious

How hydration % affects stretchability

I had been wondering precisely how dough hydration affects a dough's ability to stretch to form a membrane, so this morning I did a quasi-scientific experiment to get a rough idea of how this works.


I made five batches of dough, at different hydration levels, using the following recipe:


525g bread flour


15g sugar


10g salt


8g yeast


The hydration levels were 50%, 57%, 64% and 71%


The sugar, salt and water were added to a 6qt KA mixer bowl, and the flour and yeast were floated on top. The mixture was then kneaded with a spiral dough hook for 15 minutes on setting 2, and then a 200g ball from each batch was set to rise for two hours in an air conditioned environment (~74 deg).



It should be noted that the spiral dough hook wasn't able to form a proper ball with the 64% and 71% batches, so I imagine that the kneading that they received wasn't quite as rigorous as the others.



After rising, the dough was given a french fold, and left to rest for 5 mins, after which, three 10g balls were plucked from each 200g ball. These 10g balls were then rolled out in to as thin a membrane as I could manage using a rolling pin and dusting flour. The 64% and especially the 71% doughs were tricky to handle.


The rough average area that I managed to produce from each batch is as follows:


50%: 20.5"


57%: 25"


64%: 25.6"


71%: 26"


To make the most of the experiment, I also made a 57% batch where I substituted 10% of the water for oil (270g water, 30g olive oil). I was able to get an average membrane of 23.3" out of it.


There has to be a point where adding more water will do more harm to the extensibility than good (soup doesn't make a very good membrane), but it looks like I didn't quite reach it in this experiment. Seeing as the gains past 57% were modest, and the increase in difficulty of handling was significant, I probably wouldn't go much past it for stretchiness sake alone. My go-to pizza dough recipe uses 62% hydration, and as a result of the results found here, I might experiment with lowering it for practicality sake. On the other hand, it could be that if the 64 and 71% batches balled-up properly in the KA, they might have proven to be even more extensible.


I do have pictures, and more procedural data if anyone wants it.

PMcCool's picture
PMcCool

That's an interesting experiment, frostius.  I wonder how the results might have come out if the 10g balls were allowed a 10 or 15-minute rest?  A 5-minute rest doesn't give the gluten much opportunity to relax, which might have masked the real extensibility gains associated with the higher hydration levels.


Then again, maybe the flour used for your experiment has an upper limit on extensibility, regardless of hydration.


There are so many factors that affect extensibility that I wonder if it really is possible for the home baker to isolate those that have the biggest impacts.  Even if we buy the same brand from the same store, we have no assurance that today's purchase will have the same characteristics as those of the previous purchase.


You may already have established an important datum for your own baking with that brand of flour: more hydration leads to greater extensibility.  Your next round, if you want to take it, might be to establish an autolyse/mixing/kneading routine that effectively develops the gluten in doughs of varying hydration levels.  That would let you resolve your question about whether the higher-hydration doughs were adequately developed and the resulting effects on hydration.  At first blush, it seems that an under-developed dough might be more extensible, but, who knows?


Thanks for posting your observations.  I'd be interested to hear more.


Paul

intelplatoon's picture
intelplatoon

i did a stage at a bakery in Portland, Oregon once and they baked with very hydrated dough, (maybe 77% i dont remember exactly). but they did what i believe they called a delayed hydration, where they would mix most of the dough at around 72% and then add in the last 5% of water after gluten began to develop. too much water will coat the proteins and act as a lubricator for the gluten strands to slip right on past each other. 

rubber-side-down's picture
rubber-side-down

Hello. I am delurking with this post. I've taken the hydration/stretchability data supplied by the OP and fit them to yield this result:

66.3% hydration produces an optimal stretchability of 26.2" given the conditions.

Yes, I'm a hopeless dork, and to further my dorkdom I provide my method:

Used a least-squares regression to fit the data to the 2nd degree polynomial model y = ax^2+bx+c. The coefficeints are -0.0209183673, 2.7754081633, -65.7894897959, respectively. I used a 2nd degree polynomial because the OP assumed that there was a finite optimal value.