As many have said check what is allowed, declare it and as long as it is in the main lugage, no great problem.

Regarding UK Security, I frequently get exhasperated - for some reason known only to the "highly trained and customer-focused security operative" on one occassion my M&S BLT sandwich was declared a "security risk". When challenged, the said highly trained, wonderfully eloquent and polite security operative muttered something about the mayonaisse content (I jest not). Given the incredulity of the other passengers behind me and in order to vent my anger without resorting to physical violence, I downed laptop bag and backpack (while blocking the queue) and proceeded to eat said security risk while discussing the relative merits of excessively mayonnaisey sandwiches with the (fortunately) good-natured passengers behind me. I then handed said now rather sheepish-looking highly customer-focused securrity operative the empty packet before marching through the detector gate, willing it not to beep. By some miracle it didn't and I marched off to the lounge for a calming G&T and a minor gloat at getting one over the jobsworth muppets for whom I spend so many hours impatiently queuing annually.

On another occasion it was my wife who was unceremonially stopped, this time in PIK. At the time she was pregnant with arctic cub #1, and suffering from morning sickness and for some bizarre reason the only thing which seemed to help with the morning sickness was Marmite. She was duly apprehended carrying a quarter-full jar of the stuff. Since the jar was 125ml, it was duly identified as a dangerous substance and confiscated (in spite of my wife's explanations and warning of the consequent risks of vomiting without notice.

For once, I was on the side of the security guard !!!

Marmite - you either hate it or are beyond all hope.....