What steps couls be taken to prevent round doughnuts shirking or collapsing within a few minutes of leaving the fryer?

What steps couls be taken to prevent round doughnuts shirking or collapsing within a few minutes of leaving the fryer?

The collapse of doughnuts after they the fryer is associated with the transition of the dough from a ‘foam’ to a ‘sponge’ (in the genetic not specific cakemaking sence). In foams the gas bubnles or cells are sparated from one another by a stabilizing film of one form of another, e.g. protein, fat, emulsifier, while in sponge the cells are interconnected and gases and liquids can readily pass though the matrix.

In the oven most baked products undergo the form foam to sponge and the gas contained withing the individual cells difuses out of the product into the surrounding atmosphere. The transition occurs at different parts of the dough piece at different times, depending on the head transfer rate. Before conversion the pressure inside the air bubbles is greater then that of the product. At the moment of conversion from foam to sponge there is equalization of gas pressure with that in the surrounding atmosphere and is seen as a slight shrinking of the volume of the baked product just before the end of baking.

Addition of some ingredients can delay the convertion of the foam to sponge to a leter time during the wheat starch and subsequeantly the temperature at which the foam to sponge conversion is made. In some formulations the transition may not take place within the center of the product before baking is compled. As a consequence the internal pressure. At some point the externl pressure on the product becomes greater than the internal pressure of the cells and the product shrinks. This is the collapse and wrinkling of the product that you see.

To avoid the problem you should reduce the sugar level in the formulation or reduce the ability of the dough to remain gas. It is well known that a mechanical shock delivered to many such products can be used to eliminate the problem, so simply banging the trays as you remove them from the fryer can reduce or even eliminate this problem.