Model studies on benzene formation from benzaldehyde

The carcinogenic aromatic hydrocarbon benzene has recently been detected in drinks with added cherry flavour, and it was suggested that benzene could be formed from benzaldehyde used as flavouring. To get a deeper insight into parameters favouring benzene formation, the influence of light, pH, oxygen, temperature as well as presence of transition metal ions was studied in model solutions of benzaldehyde. It was found that in particular irradiation with light increased benzene formation. However, this was not observed in a cherry juice most probably due to absorption of light by the red colour. Therefore, the benzene detected in commercial cherry juices may have been added as contaminant of the benzaldehyde used in the flavouring. The assumption was confirmed by the analysis of commercial flavourings. Thus, to avoid benzene formation in flavourings, amber glass vials must be used during production, storage and sale.