Jimmy finds out if prunes can help the Food Unwrapped team stay regular. After a trip to southern France for the prune harvest, Jimmy puts plums, prunes and prune juice to the test, and heads to Kings College London where he's tasked with making his own 'poo recipe'. A global surge in demand for black pepper has transformed the lives of farmers across Vietnam, where Kate learns the difference between black and white pepper, hears the secrets of peppercorn quality control, and discovers the remarkable lengths to which producers go to guard their valuable crop from thieves. And Matt visits Switzerland to find out why there are holes in Swiss cheese.