Question from a newbie

Hi Kim,

There are degrees of vigour, obviously, but the dough really does need to be knocked back after bulk ferment to some extent, unless you are making breads such as ciabatta where you are actively trying to create big random holes in the finished crumb.

The reason is that when the dough has proved up to this extent there are large pockets of carbon dioxide gas within the dough.   Bakers yeast requires oxygen to move around, so the presence of lots of carbon dioxide hampers the yeast activity.   Knocking back the dough expels all the carbon dioxide and creates favourable conditions for the yeast to work again.   This tends to induce a renewed rapidity to gas generation through the fermentation process.

However, over vigorous knock back will tighten up the gluten network in the dough and make it difficult to shape the dough to the final shape required without greater periods of rest to allow the gluten network to relax.

Best wishes

Andy

Kim,

To Andy's comments I would add that "punching" down the dough is something that is commonly inflicted upon white bread in order to bring about a uniform crumb.  I would generally recommend that you lean towards gentle handling of dough and controlled degassing rather than any sort of punching, slapping or banging.  

Jeff

Most instructions for shaping a loaf will result in you having to flatten the risen dough to some extent.  Otherwise you can't fold the edges and ends under as instructed.  Here is a link to a TFL video on how to shape sandwich loaves.  They are sourdough, which takes longer to rise, so don't get thrown off by the comment about a 4-hour bulk fermentation.  You can see how perforce his dough must be flattened a bit by what he is doing, but it is not actually punched down.

instant yeasted dough, then by all means let loose and punch the heck out of it.  Hit it baby, one more time!  As Britney likes to say!  (That song could only be applied to dough and cards.)   My favorite technique is dropping the bowl hard.  "Whack!"  Love to make the kids jump.  And everyone knows what I'm up to.   Love to watch it fall as the shock wave rips thru the dough and a big smile spreads across my face.  (simple pleasures)  By the time I turn the dough upside down on my work bench it's pretty flat and begging for mercy and fine treatment which it dutifully gets.  Twice punching is also allowed so just letting you know it can happen.  

My ryes on the other hand are all sourdoughs and they don't get bashed around in my kitchen once I let them start to rise.  Nor do any of my home grown yeasty beasties.   They're above all that and get gently squished and folded.  :) 

Instructions to "punch down" the dough were almost universal a few decades ago, perhaps partly because doing it feels good and partly because fairly uniform very small holes were the goal.

Recently, "punching down" has to some degree gone out of fashion  ...so much so that some recent bread books suggest you don't do it with any recipe, not even the (mostly older) recipes that explicitly mention it. Why?

• The fashionable wording has changed to "knock back" (that isn't really quite fair - not only the words but also a trend toward less vigorous action have changed)
• There are other ways besides punching down to eliminate large gas bubbles: flattening with the fingers, another stretch and fold, dropping the bowl a few inches, ...
• The new fashion of highly varied hole sizes including some very large holes militates against knocking back