LONDON - A scientist has calculated the optimum thickness for a slice of cheese to make the perfect cheese sandwich, according to a study. In a bite-sized sandwich using pre-sliced white bread lightly buttered with margarine, a slice of cheddar needs to be at least 2.8 mm thick, the study found. Dr Len Fisher from Bristol University was commissioned by the British Cheese Board to work out how to maximise the "cheesy" aroma in a sandwich. "After a certain thickness, no increased amount of cheese will increase the 'cheesy aroma' impact of the sandwich," said Fisher. Tests done on the contribution of tomato and pickle found that tomatoes boosted the cheesiness flavour whereas pickles did not. reuters