China’s food regulator has visited close to 600 restaurants, businesses and food distributors as it investigates a fast-spreading food safety scare that has dragged in a number of global brands and hit food outlets as far away as Japan. Shanghai police detained five people on Wednesday, including the head and the quality chief of Shanghai Husi Food, a Chinese-based supplier to foreign fast-food brands including KFC, McDonald’s Corp and coffee chain Starbucks Corp over allegations it supplied out-of-date meat. Shanghai Husi Food is owned by Illinois-based OSI Group.