(Photo: Dickson Lee)Polytechnic University scientists have developed a method that can rapidly distinguish between so-called "gutter oils" at the centre of a series of food safety scandals and safe edible oils. Traditionally, testing can take hours and is labour-intensive, but the PolyU team has adopted a technique that uses lasers to ionize samples. They then analyse the oil spectra - broadly speaking, a comparison of the oil components and the intensity with which they are found.