The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Second Hydration: why?

Mason's picture
Mason

Second Hydration: why?

I regularly make bread by using a 66% hydration sourdough starter and a fairly stiff cold-autolyse soaker of all the rest of the flours I'll be using, so all the flour is somewhat hydrated for at least 8-12 hours.  

Usually it's about 40% whole wheat and 10% rye. I generally aim for a reasonably high hydration; often about 80%, but the whole wheat absorbs more, so it isn't totally liquid, but it is a sticky dough then needs a light touch.It needs the S&F to develop some dough strength. The photo above is from my last batch like this, with a wonderfully cool and chewy crumb and paper-thin crackly crust.

I reserve about 100g of the total water, adding that as a second hydration when I mix the soaker and sourdough starter together. I mix it in my Kitchenaid for a minute or so until it's evenly wet and mixed. I then let it sit for for about 30 minutes before I add the salt.

With the salt added, I mix about 3 minutes more. Then build final dough strength with 4-5 S&Fs over a couple of hours or so, before leaving for bulk rise (overnight in the fridge sometimes, depending on my schedule).

I do this "second hydration" because I read a few people on this site doing it.  TxFarmer, DonD, and David Snyder have attributed this to Anis Bouabsa.  I don't know much about him or his reasons for this technique.

I accept their expertise as a reason to save some water and give the dough a second hydration (I have made fairly good bread following their formulae and methods).

But I have no idea why this is supposed to be a good idea  

I like to understand the why as well as the how of bread making.  Not understanding why, I'm not sure if I'm doing it right.  

Is it just so the salt you add after hydration is incorporated easier, without the crystals cutting the gluten?  Or is there more to it than that?  

Explanations or corrections would be appreciated, please.

 

tgrayson's picture
tgrayson

At high hydration levels, the gluten develops slowly. You can cheat by developing the gluten at lower hydration levels, then add the extra water later.

Mason's picture
Mason

So the real trick is the initial autolyse with less water, rather than the extra water later?  Not what I expected.

tgrayson's picture
tgrayson

Well...the only reason that you need to add the extra water at all is that it's part of the trick. You want the extra water, but you don't want to have to work so hard to develop the gluten.

Mason's picture
Mason

I usually add the water, mix it for a minute or so, then leave it to fully hydrate for 20-30 minutes before adding the salt and mixing.  Is there no need to do that, if the gluten development happened in the long cold autolyse overnight in the soaker?

tgrayson's picture
tgrayson

It does seem to be overkill to me, since all the flour spent a long time hydrating. You might consider skipping it and see if you notice any difference.

bikeprof's picture
bikeprof

what you describe doesn't really fit the description of a double hydration...you're adding your water when starter and other ingredients (all but salt) are mixed...if you were keeping that last 100g of water out until after you had mixed for gluten development, then that would be more in line with the idea.  Doing that would make sense if the dough was too loose otherwise to get the gluten development that you were looking for during your mix...but that doesn't seem to be a concern with the long auto doing most of the work for you, and only a couple minute mix being sufficient even with all the water added.

Second, or double, hydration is really about gluten development during mechanical mixing, and how to achieve that and (eventually) high levels of hydration.

Very nice looking loaf, btw...

 

Mason's picture
Mason

Thanks.  So the point is that initial gluten development is best done by mixing with less water?  

So I should mix the starter and soaker together for a few minutes, to begin developing the gluten with a stiffer dough? And then add the extra water after most of the mixing?  With the salt?

Some people have described using the extra water in the rising container, and doing the S&F in the container, incorporating extra water during that process.  Is that the basic idea?

If anyone knows of a good explanation of how/why this helps develop the gluten, and when one should use this second hydration method, I'd appreciate a link or book reference.  

I'm still kind of flying blind here.

tgrayson's picture
tgrayson

I'd mix the starter and soaker together, along with the salt, and then add the extra water after the gluten is developed.

Well, actually, *I* wouldn't do that because I don't use the double hydration method. I would just do stretch & folds over the course of a few hours at whatever hydration I found useful.

If you want to research the scientific basis for this technique, it follows from the observation that high hydration doughs require a lot of mixing to develop the gluten. I suppose that it has something to do with the fact that the proteins which combine to form gluten, gliadin and glutenin, have trouble getting together when they are widely separated by water, but I won't fall on my sword over the correctness of that explanation.

tgrayson's picture
tgrayson

BTW, I didn't read your original post carefully enough...I agree with bikeprof that you aren't currently using the double hydration method.

bikeprof's picture
bikeprof

Generally...gluten can form passively over time once water is added (so the long autolyse is working passively to develop gluten), but that process is facilitated by mechanical mixing as the proteins pass by each other they have more opportunities to form bonds.  That process is less effective in really wet doughs (think about really extreme cases of something like a thin batter...those proteins are all swimming around and you can mix and mix and mix and they still have so much water around them they won't be effectively brought into contact with others as much as in a solid dough).

So IF you wanted more gluten development during mixing, then hold back some water during the initial mix...but why do you want that when you appear to get great results without doing it?  Adding the water with the initial mix and letting time and folding do the work can be very effective.

If you are curious, try it both ways and compare

Mason's picture
Mason

I'll do an experiment, and try mixing the soaker and starter and salt as a more stiff dough for a while to get the initial gluten development going.  Then mix in the last 50g or so of water at the end.  

I could even add it while I S&F (e.g. add it to the container, and S&F in the container).  I have seen some people recommending it that way.

That's more along the lines of this method, right?

I was basing my method on formulae by others on this site, who were all adding extra water to the mixer, after a soaker or cold autolyse, as a "second hydration".  

e.g. DonD's 36 hour baguettes.   He describes adding a liquid levain to a cold-autolysed flour soaker as functioning as a second hydration.  

Like I said.  I was/am flying a bit blind here, replicating formulae without understanding the why of it.

bikeprof's picture
bikeprof

I hope I'm not coming off like the language police on the use of the term "second hydration"...plenty of room for multiple interpretations/uses.  Just trying to explain what the double hydration method is typically trying to do...

Many, including Chad Robertson, suggest holding back a bit of water to help incorporate the salt when it is added...but that is clearly for a different purpose.

leslieruf's picture
leslieruf

her potato water blister crust sourdough uses double hydration and gives a good demonstration of this technique.  a couple of years ago I watched her video but I am not sure of where to find it now.  Basically she makes a low hydration dough then after a 2 hour autolyse adds the remainder of the potato water and this is slowly incorporated by stretch and folds every hour for 3 - 4 hours.