A variety of new options on the menu from the latest X-ray inspection technology

'Ensuring a tart is cut into equal slices is a challenge for all of us - let alone at the rate of 200 tarts per minute on a production line.

- Dr. Richard Parmee

But the latest inspection technology is rising to that challenge for the food industry - ensuring equal slices every time. It is also making sure fragile toppings such as the meringue on lemon meringue pies are not damaged. Along the way it can also check that each tarte au framboise on the production line has enough raspberries on the top.

The stakes are high as many bakery products are luxury items, often in transparent packaging which allows the purchaser to see the item so damaged and non-uniform products will be left on the supermarket shelf. This not only adds to food waste dealing with such issues results in additional costs and disruption for manufacturers.

The use of low-energy X-ray imaging to detect foreign objects in food products is an established technique to detect unwanted fragments of metal or glass, for example, before products leave the factory.

It is based on being able to detect material that is substantially denser - higher in atomic number than the food matrix.

But guarding against cosmetic issues in luxury food items involves more than just looking for contrasting densities. It also requires looking at levels of contrast the difference between soft fruit and the background filling, for example, as well as the crevices in the surface of a dessert created by a cutting tool. This requires enhanced detection capabilities and higher resolution.

Taking inspection to this level involves detecting differential greyscales in the inspection image which are considerably smaller than the variation in the normal range of greyscales in a standard product.