Long lunch? This sandwich stays 'fresh' for two weeks

At a time when retailers fall over themselves to assure customers that their food is fresh and locally-sourced, one company has bucked the trend by offering a "gas-flushed" sandwich with a two-week shelf life.

The food and drink wholesaler, Booker, is launching chicken tikka and cheese ploughmans sandwiches, among others, it insists will remain fresh for 14 days.

"The product is as good on day 14 and it is on day one," said Ray Boggiano, a food technologist who has spent almost a year developing the sandwich.

The secret behind the sandwich's anti-ageing is a process of gas flushing, Boggiano explained, where oxygen is replaced by CO2 and nitrogen as part of the protective atmosphere packaging.

Highly perishable foods such as lettuce are not used, while the sandwiches include specially developed fillings such as a slightly more acidic mayonnaise with a low pH, as well as oatmeal bread to make them more micro-biologically stable.

The manufacturers will have a long way to go, however, before they catch up with the delicacies on offer to the world's frontline troops. British military ration packs are designed to have four-year shelf life.