Detect toxic aldehydes re-heated oil.
The study is published in the magazine ‘ Food Chemistry ’.
-Researchers at the University of the Basque (UPV/EHU) country have discovered for the first time in foods the presence of certain aldehydes suspected of being behind disease, neurodegenerative and some types of cancer. These toxic compounds appear in some oils, such as sunflower, when heated at frying temperature
Spain, February 2012.- “ it was known that the oil to frying temperature emits aldehydes which pollute the atmosphere and can be inhaled, so we decided to investigate whether these compounds remain in the oil after heating it and effectivelyso is â€, drew SINC MarÃa Dolores Guillén, Professor in the Department of Pharmacy and food technology of the UPV.
The researcher is also the co-author of a work which confirms the simultaneous presence in oil frying of several toxic aldehydes of the Group of the ‘ oxygenated α, β Unsaturated ’, such as 4-hydroxy-[E] – 2nonenal. In addition, two of them are described for the first time in food (4-oxo-[E] – 2 – year and 4-oxo-[E] – 2 – undecenal).
So far these substances only had cited in biomedical studies, where its existence in the body with various types of cancer and neurodegenerative diseases, such as the Alzheimer and the párkinson relates.
Toxic aldehydes are generated as a result of the degradation of fatty acids of the oil and, although some are volatile, others remain therein after frying. In this way they can be incorporated to cooked food. As they are very reactive compounds can react with proteins, hormones and enzymes in the body and prevent its proper functioning.
The research, which publishes the journal Food Chemistry, has been heated to 190 ° C in an industrial Fryer three types of oil: olive, sunflower and flax. The operation was carried out during 40 hours (8 hours per day) in the first two and 20 hours in the case of flax oil. The latter is not commonly used for cooking in the West, but has been selected for its high content in groups omega 3.
More toxic in sunflower oil aldehydes
After applying techniques of gas spectrometry and nuclear magnetic resonance mass chromatography, the results reveal that the oils from sunflower and flax – especially the first –, are those that generate more amount of toxic aldehydes and in less time. These oils are rich in polyunsaturated fatty acids (linoleic and linolenic).
On the contrary, olive oil, showing greater concentration of monounsaturated acids (such as oleic), generates less and more afternoon these harmful compounds.
in previous studies, the same researchers found that oils subjected to frying temperature also form other toxic substances, the alquibencenos (aromatic hydrocarbons), and concluded that the olive oil is that fewer generates among those who studied them.
The dose makes the poison
“ Is not alarm the population, but the data are and must be taken into account â€, stresses Guillén, pointing to the need for further research to establish clear limits on the toxicity of these compounds. “ Sometimes the dose makes the poison â€, recalls the researcher.
The Spanish legislation which regulates the quality of oils and fats heated establishes a maximum value of 25% for the content of polar components (degradation products that originate during frying). However, according to the new study, rather than some of the analyzed oils reach this limit already contain “ significant concentrations †of toxic aldehydes.
Labour quantifies all aldehydes – not only the harmful – appearing during frying. In addition, their authors presented a model that allows to predict how any hypothetical oil which is known its initial composition of fatty acids will evolve under the same conditions.
Bibliographic reference:
Maria D. Guillen, Patricia S. Uriarte. “ Aldehydes contained in edible oils of a very different nature after prolonged heating at frying temperature: Presence of toxic oxygenated α, β-unsaturated aldehydes â€. Food Chemistry 131 (3): 915-926, April 2012 (available online from September 2011). DOI: 10.1016/j.foodchem.2011.09.079.
