Gelato bars are popping up everywhere in the UK, but what exactly is gelato? Is it just ice cream? At the oldest gelato parlour in Rome, Kate learns some important differences. And a gelato flavourist who's been dubbed the Heston Blumenthal of the ice cream world shows Kate the surprising reason why Italian gelato is famed for its staggering range of flavours. Jimmy visits Mauritius to find out what the difference is between white and dark rum. Are they made from different ingredients? Back on home soil, he learns where the term 'proof' originally came from: the answer is explosive, and it nearly blows Jimmy away! And why does Matt's mouth go cold when he sucks on a mint? To find out, he visits a traditional sweet factory in Blackburn, full of mouth-watering treats... and an unexpected encounter with a very hot chilli.