Trade secrets are jealously guarded by the food industry – and confidentiality is becoming ever more important. The Food Chain is on a mission to find out why. Emily Thomas explores the best way is to protect a secret recipe, and finds out just how hard that is to do when thousands, even millions of people, have tried the dish. Plus, a so-called 'food hacker' recreates one of the world’s most iconic secret recipes, and a nose around a chocolate factory reveals the secrecy behind a good truffle. This programme was first broadcast on 15 March 2018.(Picture: Security camera on building, Credit: Getty Images)

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