Tesco this week unveiled its latest  weapon in the foodie arms race in the small but deadly form of the world's hottest chilli - the Dorset Naga.

This potent pepper originates from Bangladesh but has been soup up by West Country farmer and part-time evil scientist Michael Michaud.

"We trialled them in our test kitchens and even the hardest blokes were brought to their knees," bragged Tesco exotic veg buyer Jonathan Corbett, who recommended only those with "asbestos-lined stomachs" give them a try.

Whatever next? Will Sainsbury's hit back with a mind-expanding peyote fajita sauce?