Burgers have become a symbol of recent food scares, but even when they contain harmful bacteria they do not necessarily make you sick.

Health experts say that it is the way burgers are stored and cooked which is responsible for most food poisoning cases.

If they are properly cooked on both sides and there is no raw pink meat inside most infectious agents they may contain should be killed off.

Some burger chains have changed the way they cook their meat in the light of the recent food scares, including E.Coli and BSE.

McDonalds, for example, now grills its burgers on the top and bottom to ensure they are cooked all the way through.

It has also dispensed with batch cooking and now makes burgers to order.

However, although most bacteria are killed off by thorough cooking, it appears BSE may be able to survive high temperatures.

Research is still continuing in this area. The government says beef now on sale does not present a health risk.

The law

UK regulations governing the labelling of burgers divides them into three types:

• Burgers: which must contain 80% of the meat or food named in the title, eg, beef or chicken. Some 65% of the meat must be lean;
• Economy burgers: they must contain at least 60% of the meat or food named in the title. Some 65% of the meat must be lean;
• Hamburger: the meat used must be pork, beef or a mixture and the burger must contain 80% meat with 65% of that being lean meat.

Meat includes muscle tissue, fat, skin, rind and gristle.

Mechanically Recovered Meat (MRM) is also regarded as meat and is used in many of cheaper brands of beefburgers.

Until recently, MRM contained the spinal columns of cows.

This was banned after concern that the spinal chord contained BSE which could be passed to humans.

MRM is regarded as meat recovered from beef, lamb, pig and poultry bones, excluding the bones of the feet or head.

High pressures are used to break down the structure of the meat so that it becomes a pur�e.

The major burger chains, including Burger King, McDonalds and Wimpy, say their beefburgers are 100% beef.

McDonalds advertises that its burgers contain only prime cuts and that it does not use offal or MRM.

A spokeswoman for MAFF said: "MRM can go into hamburgers. It is up to the food producer.

"It depends what sort of quality they are providing and what the consumer is prepared to spend. It is up to consumer choice."

Health groups say another problem is the regulation of food legislation.

They say the dual role of the Ministry for Agriculture, Fisheries and Food in both promoting and monitoring the UK food industry leads to "conflicts of interest".

They believe the setting-up of an independent food standards agency will help improve regulation.

History

Burgers are a 20th century phenomenon, although the beef cake is believed to date back to ancient times.

The first hamburger steak - named after the Baltic port of Hamburg - did not reach the UK until 1889, but its popularity soared after a 1904 World Fair in St Louis, USA.

The first UK food chain selling burgers was the White Castle chain which began business in 1921.

Following the Second World War, when meat was rationed, the burger became a symbol of the UK's growing prosperity.

By the 1980s - the age of convenience food, summed up by Michael Douglas' claim that 'lunch is for wimps' in the film Wall Street - the burger had become one of the world's most popular snacks.

The industry was then hit by BSE, but, after a temporary dip in UK sales following the scare, burgers were soon back on the menu.