Airline passengers are being urged not to take their own food on flights.
New Department for Transport (DfT) guidance states that "food or powders should be packed into hold baggage where possible".
Many passengers take their own food when they fly to avoid paying the premiums charged by airport retailers or airlines.
British Airways is among the legacy carriers which have recently stopped offering complimentary refreshments to economy passengers in a bid to compete with low-cost airlines.
The DfT says storing food in hand luggage can "obstruct images on the x-ray machine or may be mistaken for suspicious items", leading to additional checks.
Passengers will not be stopped from travelling with food, but those that do should "allow extra time at security", the guidance warned.
There are already rules banning travel with liquids, gels and pastes of more than 100 millilitres, sharp items and tools.
Large electrical items such as laptops or tablets can be taken into the cabin, but must be removed from hand luggage at the search area and placed in the tray.
Aviation minister Baroness Sugg said: "We have some of the strongest aviation security measures in the world, and the restrictions are in place for a good reason - to keep passengers safe.
"By simply checking the guidance before they set off for the airport, passengers can have a smoother and less stressful start to their journey."