Jimmy's Food Factory is back to unravel the secrets of supermarket food. Farmer Jimmy Doherty sets up his own food factory in a barn. Using farmyard and household junk, he is creating his own supermarket production line to find out what they are really doing to our food. Jimmy creates the foods that provoke extreme reactions, and nothing divides the nation more than yeast extract. To find out the factory's secrets, Jimmy must force all his yeast cells to self-destruct, but they aren't playing ball. People either love it or hate it, but is chewing gum a food? Jimmy has one of the most bizarre lists of ingredients ever as he tries to make his own. Part of the lure of chocolate is its glossy appearance, and so Jimmy heads off to discover how factories make it so shiny people can't resist. And people might love the taste, but nobody likes the way onions make you cry. So Jimmy meets a farmer who's harvesting a no-cry onion - will it end in tears?