Side wall collapse is a common defect in pan loaves. It is also known as ‘keyhole’ because the bread forms a keyhole shape. 

This results from excessive gas retention, which can be caused by overly strong flour, high levels of improver, or excessive enzymatic activity (cereal alpha amylase).

Excessive expansion during baking compresses the bread’s cell layers into the side of the pan. This reduces the density of the centre to such an extent that the loaf is unable to support itself as it cools, and so collapses, particularly once de-tinned and handled.

Kate Woods, bakery technologist, Campden BRI

Campden BRI provides technical support to the food, drinks and allied industries worldwide. Its activities are built on a programme of industrial relevant research and innovation steered by industry. See or telephone 01386 842000