Spanish and Portuguese researchers said worries concerning the presence of furans in food have risen in recent years due to their toxic and carcinogenic effects in animals.
The International Agency for Research on Cancer, part of the World Health Organisation, has now listed them as possible carcinogens for humans.
Researchers from the University of Porto and the University of Extremadura found there were three times as many furanic compounds (furan, 2-furfural, furfuryl alcohol, 2-pentylfuran and 5-hydroxymethylfurfural) when the fishfingers were fried with olive oil and twice as many with sunflower oil.
The results, published in the journal Food and Chemical Toxicology revealed that fish fingers fried in olive oil contain about 30 micrograms of furans per gram (µg/g) and about 20µg/g when sunflower oil is used.
“The number of furans is lower when the temperature is lower and frying time is shorter, and also decreases when a longer time elapses after cooking,” said María Trinidad Pérez-Palacios, one of the authors.
“The formation of furanic compounds can be reduced by adjusting the conditions of cooking and post-cooking, for example by using the oven instead of the deep fryer, lowering the frying time and temperature – four minutes at 160ºC is sufficient – or leaving a suitable amount of time (10 minutes) between cooking the product and eating it.”
The researchers found that by following these recommendations the formation of furans could be reduced, although the volatile compounds associated with the aroma and flavour of the cooked products decrease along with them.
“Furans enhance the organoleptic characteristics of food, but as there is scientific evidence of their potential toxicity and carcinogenicity, new research is channelled towards reducing the formation of these compounds without impairing our sensory enjoyment of what we are eating,” added Pérez-Palacios.
There is currently no legislation on the maximum permitted levels of furans in food. The European Food Safety Authority is working on this issue and recommended analysing these substances in heated products, such as cooked foods or drinks such as coffee, both when purchasing and when cooked for consumption.
Pérez-Palacios believes that it is also important to educate consumers to read the labels on ready-to-cook food products, which often recommend oven baking as the method of preparation.
“As such, manufacturers should also make progress, for example by putting information on packaging relating to the possibility of oven-cooking the product or even recommending it as the sole method of preparation,” concluded the researcher.