Crumbles rumbled.

SCIENTISTS have worked out why biscuits are so easily broken before the packet has been opened.

A study group led by a Ph D student at Loughborough University, Leicestershire, looked at the way rich tea biscuits disintegrate after they have been baked.

Using a laser beam to show up cracks, the team discovered that cooling biscuits expand and contract, resulting in tiny cracks.

They become more fragile and can easily break up when handled, moved or packaged.

The results, published today in the Institute of Physics journal Measurement Science and Technology, will help manufacturers work out how to stop crumbling.