The scientists from the University of the Basque Country (Spain) were the first to discover the presence in food of hazardous substances, called aldehydes and associated with neurodegenerative diseases and some cancers.
Toxic aldehydes, in particular, are contained in sunflower oil, which is often used for frying. These substances are formed in the oil after the degradation of fatty acids. They react with proteins, hormones and enzymes from the human body and prevent their proper functioning. Until now, it has been believed that aldehydes, which are associated with different types of cancer and neurodegenerative disorders (Alzheimer’s and Parkinson’s diseases), enter the body from the external environment. The Spanish researchers conducted the first study that attempted to determine whether they remain in food after heat treatment.
Three types of oil (olive, sunflower and linseed) were heated in an industrial deep fryer up to 190 degrees Celsius. Olive and sunflower oils were subjected to heat treatment during a total of 40 hours (8 hours per day), and linseed oil was heated for 20 hours. The latter is not commonly used in Western cooking, but it was chosen because of the number of omega3 fatty acids it contains. The results showed that the aldehydes produced in sunflower and linseed oils (especially in the first one) were much more toxic and produced in less time, than in the olive oil.