Innovation: Damp-busters tackle pies

SOGGY crisps and pie crusts are being put under the microscope at Nottingham University in a research project aimed at improving the quality and extending the shelf life of food products, writes Nuala Moran.

Using techniques more commonly applied in materials science, the researchers are exploring how molecular behaviour in food influences its flavour, texture and presentation.

The pounds 1m project, which began this month, is backed by 13 food companies including Cadbury Schweppes, Kraft, General Foods, Allied-Lyons, Nabisco, Nestle and Weetabix. 'The overall objective is to look at the mobility of molecules in food systems,' says John Blanshard, the project's director.

Pie crusts and crisps have to be kept in 'a glassy state', where the molecules do not have enough energy to rearrange themselves and move into a 'rubbery state' - in other words, become soggy. If food products can be kept in the glassy state, they are less prone to deterioration. 'For bacteria to grow, the molecules they feed on must diffuse towards them, and this can't happen in the glassy state,' Professor Blanshard explains.

The structural changes and transitions that Prof Blanshard and his colleagues are studying have been well known in the field of synthetic polymers for 40 to 50 years. 'Their significance in the food area was recognised five or so years ago, but it is only now being translated into food manufacturing,' he says.

This is Nottingham University's second programme of research into food shelf-life. The first produced several patents, including one for a process that slows down the rate at which bread becomes stale, allowing food companies to cut costs by reducing wastage.

Ending the problem of the soggy pie crust will involve finding a way to stop water molecules diffusing from the wet filling into the crisp glassy-state crust.

Prof Blanshard suggests that this could be done by using some form of impermeable barrier.

Such a process is already used in the production of Cornetto ice-creams. The wafer cornet is protected from the high moisture content of the ice-cream it contains by being sprayed with chocolate.