GulpEating is the most pleasurable, gross, necessary, unspeakable biological process we undertake. But very few of us realise what strange wet miracles of science operate inside us after every meallet alone have pondered the results of the research. How have physicists made crisps crispier? What do laundry detergent and saliva have in common? Was self styled 'nutritional economist' Horace Fletcher right to persuade millions of people that chewing a bite