From Cookipedia(Redirected from Knock back)
Knocking back, knocking down, punching back or punching down are terms used to describe the stage in bread making when dough that has risen and is full of tiny air pockets is quite firmly punched, slapped or knocked. This usually results in the dough deflating immediately and returning to its pre-risen stage. The aim of this is to remove any large air pockets which have formed in the dough, create an even texture in the bread and redistribute the nutrients for the yeast, thus allowing fermentation to continue. The dough can then be proved a second time.