Experts spent 1,000 hours testing different bacon variations

Experts at Leeds University discovered the secret to the ideal sandwich lay in how crispy and crunchy rashers were.

They found that two or three back bacon rashers should be cooked under a preheated oven grill for seven minutes at about 240C (475F).

The bacon should then be placed between two slices of farmhouse bread, 1cm to 2cm thick.

Cooking times

Four researchers at the Department of Food Science spent more than 1,000 hours testing 700 variations on the traditional bacon sandwich.

They tried different types and cuts of bacon, cooking techniques, types of oil and a range of cooking times at different temperatures.

A shortlist was then tested with computers to measure the texture of each sandwich.

Fifty volunteers also judged each sandwich according to its taste, texture and flavour.

'Turn-off'

Dr Graham Clayton, who led the research, said: "We often think it's the taste and smell of bacon that consumers find most attractive.

"But our research proves that texture and the crunching sound is just - if not more - important.

"While there was much debate within our taste panels on the smoked or unsmoked decision, everyone agreed that tough or chewy bacon is a turn-off."

The formula is: N = C + {fb (cm) . fb (tc)} + fb (Ts) + fc . ta, where N=force in Newtons required to break the cooked bacon, fb=function of the bacon type, fc=function of the condiment/filling effect, Ts=serving temperature, tc=cooking time, ta=time or duration of application of condiment/filling, cm=cooking method, C=Newtons required to break uncooked bacon.