Jimmy Doherty asks what makes a London dry gin a London dry gin. He also finds out about a threat to British juniper berries that could spell the end of gin's recent resurgence. Kate Quilton heads to tropical Hawaii to find out why macadamia nuts aren't sold in their shells. She ropes in some Hawaiian muscle in the Big Island shipyards to help crack the case. At a Food Unwrapped party, Matt Tebbutt grosses out the crew with his notorious habit of double dipping: going back for a second dip in a communal salsa with a tortilla chip that's already been in his mouth. In a laboratory, Matt investigates what germs he may be transferring to the dips, and whether he needs to change his mucky ways.

Jimmy Doherty wants to know why jelly won't set if you add chopped papaya to it. In South Africa, Jimmy discovers that the exotic fruit contains enzymes that can also help tenderise meat. But could they also help the human gut? Jimmy quizzes Holland and Barrett, who sell papaya extract as an after-meal supplement. In Hawaii, Kate Quilton visits America's only tuna auction to find out why some fish have dangerous levels of mercury, while others don't. She also visits a ground-breaking tech start-up in San Francisco who hope to feed the world by growing fish flesh in a dish. And Matt Tebbutt wants to know why homemade ice cubes are always cloudy, when the ones that you buy in shops are always clear. They're all made with tap water, so what's the trick?