Benzaldehyde in cherry flavour as a precursor of benzene formation in beverages

• Benzene contamination was found to be high in cherry flavoured beverages.
• The cherry flavour constituent benzaldehyde may act as a benzene precursor.
• Model experiments confirmed benzene formation at increased temperatures in the presence of ascorbic acid.
• Industry should include benzaldehyde as a control point to mitigate benzene formation.

During sampling and analysis of alcohol-free beverages for food control purposes, a comparably high contamination of benzene (up to 4.6 μg/L) has been detected in cherry-flavoured products, even when they were not preserved using benzoic acid (which is a known precursor of benzene formation). There has been some speculation in the literature that formation may occur from benzaldehyde, which is contained in natural and artificial cherry flavours. In this study, model experiments were able to confirm that benzaldehyde does indeed degrade to benzene under heating conditions, and especially in the presence of ascorbic acid. Analysis of a large collective of authentic beverages from the market (n = 170) further confirmed that benzene content is significantly correlated to the presence of benzaldehyde (r = 0.61, p < 0.0001). In the case of cherry flavoured beverages, industrial best practices should include monitoring for benzene. Formulations containing either benzoic acid or benzaldehyde in combination with ascorbic acid should be avoided.

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