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Don't understand difference between Strength & Tension

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Bread Head's picture
Bread Head

Don't understand difference between Strength & Tension

In the Tartine book under Shaping and Bench Rest (pg75)

I don't understand what he means with this statement;

"Should I give the dough a long bench rest to develop more strength, or should I shape the dough twice to give more tension?

Can someone explain to me in the most simplest terms what he means by this?

 

Thanks for you time!

phaz's picture
phaz

 sounds like strength is referring to gluten development.  creating tension when shaping should develope the gluten strands on the outer layers of the dough, thereby creating strength so the dough will better retain its shape.  tension develops gluten, and the gluten creates strength.  hope I got that right!

yy's picture
yy

That's a great question! 

One way to think of it is to envision an unshaped batch of dough that has reached optimal gluten development - the dough is smooth and you can gently stretch it into a nice, smooth windowpane without tearing it. This dough has STRENGTH, but if you pour it out onto a table surface, it will spread out into an amorphous blob. This is because no TENSION has been created to help it retain its shape. It's kind of analogous to a balloon (not perfectly so, of course). A deflated balloon has STRENGTH, in the sense that the latex walls have a certain structural integrity that enables it to stretch without breaking. However, it is limp and unshapely. Filling in the ballon with air creates TENSION. The walls stretch out and become taught, and the balloon gets a nice round shape. 

Fatmat's picture
Fatmat

YY - Great explanation - thanks very much. 

imaloafer's picture
imaloafer

yy,

That was a very good example!

 

mwilson's picture
mwilson

A nice description. Although what you are calling strength is actually extensibility. Substitute Strength for extensibility and it's fine.

Strength is more to do with resistance / tension. In the extreme doughs that are overly strong tear when stretched.

yy's picture
yy

Great point. My description doesn't distinguish between extensibility and elasticity. I kind of think of dough strength as a combination of the two - the ability to relax and stretch while staying intact as a continuous membrane and the ability to resist elongation as well. I find it hard to divorce elasticity and extensibility sometimes, as properties of the dough are constantly in flux depending on how much it's been agitated, how long it's relaxed, etc. A very strong dough can be highly elastic and not at all extensible shortly after kneading, but after a 30 minute rest, it regains extensibility, but I'd still consider it "strong". Wonder if this is off base? 

I like how these questions such as "what is strength" reveal the gaps in my understanding :-). There must be a lot of other terms I take for granted. 

mwilson's picture
mwilson

Good points. And it's good practice to consider all properties of dough together.

Strength really is resistence and it's best jugged in a relaxed state.

If you havent read it this article is a great read http://www.sfbi.com/images/pdfs/NewsF04a.pdf

I also found having an understanding of the Alveograph helped make things clearer for me.

Bread Head's picture
Bread Head

Great Explanation.

Thank you!

FlourChild's picture
FlourChild

My read on it is that he is referring to is the fact that a dough develops gluten as it rises, and this happens everywhere, all through the dough.  So if he is talking about allowing the dough to rise (during a long bench rest), that would further develop the gluten, bind up a little more water in the dough (gluten needs water to form), and give a crumb with smaller holes, less oven spring and more chew.  The bread would also hold its shape better and spread out less.

The other option, shaping twice, would stretch the outer layer of dough very tightly so that it provided a firmer frame to help the slack, wet dough hold its shape.  The goal with that option would be to have a more open crumb, bigger oven spring and a little more tenderness in the crumb.  But there would need to be a certain amount of structure already present in the dough for that to work- enough to allow the outer layer of dough to be stretched without tearing, but not too much or it will not stretch very well (it will be too elastic).

Does that fit with the context of the quote?

Bread Head's picture
Bread Head

Yes, thank you! This also helps.

mariana's picture
mariana

Longer bench rest simply means more time to restore broken gluten links here. Dividing< punching down, and preshaping pieces of dough breaks some of the links in gluten and during longer bench rest they are restored

Tension in dough relates to the process of applying mechanical stress to dough, as if it was a tightly wrapped elastic band which resists further stretching: for example, folding a piece of dough, until a tight smooth surface is developed. The more dough is manupulated manually (cut, shaped, rolled, all kinds of mechanical stress), the tighter it becomes. So, tense dough will contract if stretched, i.e. it resists changing its shape. Relaxed (left alone) dough is easily shaped. For the hearth breads we want them to hold their shape, not to go from round balls to flat pancakes during proofing or during baking, so we develop tension in bread dough during shaping or preshaping of the loaves.

developing strength and developing tension are two different processes in dough. One has to do with chemically reinforcing  gluten bonds in dough or restoring gluten links after tearing gluten strands apart, another - with physical manipulation of the dough that stresses it.

FOrmal definition of dough strength is 'the balance between extensibility, elasticity and tenacity'. This point of balance is unique for each baked goods: pizza dough must be more extensible, hearth bread - more elastic. Too strong dough is too elastic, i.e. when stretched, it comes back to its original shape immediately - such pizza dough is impossible to stretch into a thin pizza round. Too weak dough is flowing like pancake batter, too extensible, cannot hold shape at all. Too tenacious dough resists stretching action. I.e. when you roll out your tenacious baguette dough, it is difficult to elongate the piece of tenacious dough, it resists.