Kate looks into coloured crisps. In Chile she finds out how these rainbow snacks get their colour, and discovers why the common white potato is king of the crop, despite the other fantastic options on offer. Meanwhile, Jimmy investigates one of the trendiest items on our shelves: avocados. But the rapidly rising demand for these fantastic fruits has led to alarming reports of a crime wave hitting growers. A trip to an avocado farm in Spain reveals the extent of the problem, and also sheds light on the secret to making a lovely green guacamole. And in Belgium Matt finds out about one of the tangiest tipples on our supermarket shelves: sour beer.