It is the fashionable cooking technique favoured by many MasterChef contestants.
But now Government scientists have found the 'sous-vide' method of simmering vacuum-packed foods in a water bath could increase the risk of food poisoning, reported the Daily Mail.
Tests showed that water temperatures in sous-vide cooking were too low to kill potentially deadly bugs such as salmonella, E.coli and campylobacter.
Experts from Public Health England analysed 34 meals from restaurants, hotels and pubs which were mostly made up of chicken or duck breast cooked in a water bath.
The results, in the journal Epidemiology and Infection, showed ten had 'unsatisfactory' levels of bacterial contamination and another eight were borderline.
Sales of sous-vide machines, which can cost up to £400, are reported to have increased by around 300 per cent in recent years in the UK.
The technique, pioneered by celebrity chefs like Heston Blumenthal, is lauded for its ability to preserve flavour and texture, but it braises food well below the 100C boiling point of water.
Microbiologist Professor Hugh Pennington, who investigated the deaths of 21 people in Scotland in 1996 from an outbreak of E.coli, said: "I would not want to eat anything that had not been heated through properly."