The Fresh Loaf

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stretch and fold magic

kendalman's picture
kendalman

stretch and fold magic

Hi

something different

                                                             Two Glues and a Foam

The general descriptions of what happens when a stretch and fold is carried out  are usually misleading or  wrong.  It is nothing short of magic to explain dough strengthening in terms of gluten strengthening and strands of gluten being straightened or surface tension effects.  The real fun science is missing, everywhere, even in the bread makers’ books.  That is a shame because it is hard to improve on magic, unless you have a better spells book and I have not seen any.

All bubbles produce a restoring force when their shapes are distorted, so when you poke a finger against the surface of a balloon you feel this force as your finger pushes in, take away your finger and the balloon surface goes back to the original shape.  We use this restoring force when a stretch and fold is done on dough foam.

The problem is how to describe something that is more like a liquid than a solid, is extendible and elastic, and grows into a foam that can support its own weight.  What is done to the foam makes the dough stronger.  The proofing/proving is about waiting for the bubbles of the foam to grow large enough and round enough to support the weight and shape of the dough and the tool to use is the stretch and fold technique.

 You can feel the restoring force produced by the bending distorted bubbles when you do your stretch and folds.  It is not noticeable at first, the bubbles are too small, but as they grow each stretch and fold is harder to make to distort the bubbles against the viscous gluten.  The gas in a bubble pushes against the gluten and tries to keep it’s shape nearly round.  Nearly round bubbles packed together keep the shape of their gluten foam better than any other bubble shape and the bigger the bubbles the better because that spreads the dough weight over a bigger surface area and so makes it easier to hold up.

At the end of the knead the two important glues in the gluten are ready for use.  The glue that holds everything together is working throughout the dough and keeps working all the time.  The other glue that only works for about 25 minutes is also working.  Pull a lump of new dough into a log and put it on the work surface.  It shrinks a bit, that  is the 25 minute glue in action.  The fact that the shrunken log stays as a shrunken log is due to the first glue.  Remaking the 25 minute glue just means stretching/bending the dough, what you do when you stretch and fold.

 As the newly kneaded dough starts to prove/proof the foam starts to grow.  But the dough is sinking into a flattening blob.  So you fold it back on itself and stretch it a bit in the process and pin it down on the dough still sticking to the work surface to get it back to a useable lump, an obvious natural movement.  

 That short life glue is essential for sticking/pinning your fold down onto the remaining dough and leaving a small amount of tension. This helps to support the new dough shape whilst the newly distorted bubbles have time to reshape to their normal ‘round’ shape in the viscous gluten.  The dough gets stronger than it was and keeps its shape better because the bubbles have grown a bit and are nearly round. (They are all trying to be round but geometry stacking and gravity mess them up a bit).  

The point of the stretch and fold is to reshape the dough using the properties of the foam to make it stronger and hold its shape better each time.. You could say, as you work your dough, ‘mine’s got bigger rounder  bubbles than yours’ rather than ‘mine is stronger than yours’...

The glue that holds everything together reaches peak glueiness at the window pane test time. It is all to do with breaking/making of disulphide bonds that cannot be used again.  The 25 minute glue uses hydrogen bonds that are electrostatic so make and break as many times as you want.  Both types of bonds are between gluten chains etc.

Taken time to pluck up courage.  thanks for reading, comments?

GaryBishop's picture
GaryBishop

Thanks for posting.

JonJ's picture
JonJ

I like your analogies. Well written, thank you!

Foam makes more sense to my brain than bags of balloons.

-Jon

Rock's picture
Rock

kendalman, hope you don't mind if I add some pictures. I've been using the method for decades and an aggressive stretch is how I learned. I mix only long enough to fully combine the ingredients, usually about 3 minutes in my Bosch Universal. The actual dough development is done over the period of an hour with a series of four stretch and fold every 20 minutes.

Dave

sf1

sf2

sf3

sf4

sf5

sf6

 

happycat's picture
happycat

Some interesting ideas in your draft. I did have some trouble following but I am intrigued. Always a fan of imagery.

I was sort of following along until the glue part.

I have the impression that you have two main concepts and are building an explanation. I would benefit from an overview at the start of the piece outlining the main concepts, like a roadmap.

I would also benefit from some definitions up front to set the stage. Glue. Foam. etc. Then when those terms are used, I will know what you mean.

I would benefit from having the pieces of the explanation signposted with headings with an intro statement of the concept to be covered in the section and how it relates to / builds on the other ones.

Maybe that sounds like too much work. Depends on your goal. I've received my share of criticism for my writing and have come to realize that I get excited about a topic and forget to provide some handholding and signposts and examples and summaries etc. to my readers :)  

The bummer of that is people who don't have very interesting ideas get a lot of attention because they've mastered some structure while people with exciting ideas don't get the exposure they deserve.

I'm quite interested in the topic and would benefit from an explanation with a few basic diagrams. I think it would be a great resource.

Just my 2 cents.

albacore's picture
albacore

Perhaps a relevant question is whether better bread (or similar bread) is produced by:

a) develop gluten either in a mixer - or by eg French folds or Rubaud method - to windowpane, followed by one or two folds.

or

b) stretch and fold magic?

 

Lance

kendalman's picture
kendalman


Hi

I just assumed the article would be under my ‘kendal roll work’, but it is a separate topic.  The article came about because when I found the kendal roll I realised that I could not explain how it worked.  When I read about strengthening dough I realised that the usual descriptions could not work.  So I started to look into the science and found none on the physics behind stretch and fold but the excellent book ‘Bread Science’ helped a lot with the chemistry.  It is two years along from finding the kendal roll to being ready to go properly public, sometime in the next few weeks if nothing else crops up.

I hoped the work could stand alone but realise that it needs some background for clarification.  So here goes:

Do look at the kendal roll video on youtube named ‘basicskendalroll’ the one where the old guy complains he cannot pull the dough apart!  At last I can explain that and I can explain how the kendal roll works and why it enables me to make free standing high hydration bread in an ordinary oven etc...  I can strengthen my dough when there are much bigger bubbles in my foam. Its one hell of an advantage.  I make large volume light weight loaves from small amounts of flour every day always high hydration.

FOAM   like on a beer or on the beach after a storm  the bubbles are different sizes but fit into a shape

GLUE holds things together in this case not only the starch granules but also the bubbles.  But it is a viscous liquid, it will not hold its shape until is mainly holding large bubbles.  On baking the closed foam becomes an open foam (the bubbles burst in the baking)  I like the idea of eating what I have just glued together.

THE TWO GLUES I have to use the model idea to get these over.  I don’t want to have to describe how the protein strands link in the different ways to produce the glue effects.  They do and you can see this in action when you stretch the fresh dough.  On the model standard it is better than a wooden train set and possible around the clockwork standard.  I’m not a chemist.

All the development routines have to involve sliding dough content over dough content to speed up the formation of the bonds.  There are two points, overdoing it and effort, I go for the least effort.  The exposure to oxygen is essential but it affects the chemicals causing the flavour, a question for the chemists!

My glues are fully developed at the end of the knead in a bread machine. My stretching and folding routines are kendal rolls carried out in the proof simply to give me, in the end, the shape I want.  That is the only time I handle the dough.  I don’t know the effects on dough quality but I do prefer the overnight version of my recipe.

I need to make another video because I have recently learnt how to make my dough even stronger and have an excellent over night routine.  I am getting too old for this!  

Best wishes to you all.

joe_n's picture
joe_n

I watched the YouTubes and will I will definitely try your method for a lean whole wheat dough.  If I can get it to work, it would be a lot less clean up than for working through a lamination.

joe_n's picture
joe_n

Is the baking temp 200C (400F) and no steam?

Does this method work for breads with no butter or oil?

I hope you will have time to make a video on your new technique!