Flavor research for consumer protection
Flavorings containing benzaldehyde can develop benzene under the influence of light
Freising, March 26, 2020
In 2013, the Stiftung Warentest found harmful benzene in drinks with cherry flavor. But how did the substance get into the drinks? Was the source benzaldehyde, an essential component of the cherry flavoring? And if so, how could the problem be solved? A new study by the Leibniz-Institute for Food Systems Biology and the Technical University of Munich (TUM) is now able to answer these questions.
According to the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR), benzene is mainly absorbed by our bodies via the air we breathe. Non-smokers take in an average of 200 micrograms of benzene per day. Smokers take in around ten times as much. But our food can also contain traces of this harmful substance and thus contribute to the exposure.
When the Stiftung Warentest examined soft drinks in 2013, they came across small quantities of benzene. One drink contained just under 4.6 micrograms of benzene per liter. For comparison: In Germany, one liter of drinking water is allowed to contain only 1 microgram of the substance. At that time, experts at the Stiftung Warentest supposed that the odorant benzaldehyde was the cause of the benzene contaminations observed.
“As our research is specialized on odorants, we followed up on this supposition in the interest of consumer protection and at the suggestion of the German Association of the Flavor Industry (Deutscher Verband der Aromenindustrie, DVAI),” says lead author Stephanie Frank from the Leibniz-Institute for Food Systems Biology at the Technical University of Munich.
To do this, the team of scientists first established a reliable, highly sensitive quantitation method of benzene. Then, they carried out experiments with various model solutions which contained benzene-free benzaldehyde. The team also examined cherry juice produced under laboratory conditions, to which they also added the pure odorant.
Light is the crucial factor
“Our findings confirm the assumption of the Stiftung Warentest and also explain how the formation of benzene occurs. An important requirement in solving the problem in the long term,” reports food chemist Stephanie Frank.
As the study proves, the longer the odorant is exposed to light, the more benzaldehyde is converted into benzene. But the light intensity is also decisive. In contrast, the pH value, the oxygen content, the presence of metal ions or the temperature did not affect the benzene production in the model solutions.
To the surprise of the researchers, no benzene was formed in the cherry juice produced under laboratory conditions during light exposure. Frank reasons that it is possible that the dark red color of the drink acts as a light protection filter and prevents the formation of benzene. The benzene found in a few soft drinks sold commercially is probably the result of added cherry flavoring which has already been contaminated with benzene.
“This is why we must be sure to protect flavorings containing benzaldehyde from light, from when the substance is produced to when the product is sold, for example, by storing them in amber glass vials,” recommends Peter Schieberle, Professor for Food Chemistry at the Technical University of Munich.
Publications:
S. Frank, A. Dunkel, P. Schieberle
Model studies on benzene formation from benzaldehyde
Eur Food Res Technol, 22. Feb. 2020 – DOI: 10.1007/s00217-020-03455-6.
S. Frank, T. Hofmann, P. Schieberle
Quantitation of benzene in flavourings and liquid foods containing added cherry-type flavour by a careful work-up procedure followed by a stable isotope dilution assay
Eur Food Res and Technol, 245(8): 1605-1610 – DOI: 10.1007/s00217-019-03267-3.
More information:
Initiated by the research association Forschungskreis der Ernährungsindustrie e.V. (FEI), the research work in project AiF 18813 N was funded by the German Ministry of Economics and Energy based on a decision made by the German Bundestag as part of the program for promoting cooperative industrial research (IGF) via the German Federation of Industrial Research Associations “Otto von Guericke” e.V. (AiF).
Contacts to this article:
Dr. Gisela Olias
Leibniz-Institute for Food Systems Biology
at the Technical University of Munich
Press & Public Relations
Lise-Meitner-Str. 34, 85354 Freising, Germany
Tel.: +49 8161 71 2980
g.olias.leibniz-lsb(at)tum.de
Dr. Stephanie Frank
Leibniz-Institute for Food Systems Biology
at the Technical University of Munich
Section I / work group Sensory Systems Chemistry
s.frank.leibniz-lsb(at)tum.de
Prof. Dr. Peter Schieberle
Technical University of Munich
Department of Chemistry
Lichtenbergstr. 4, 85748 Garching, Germany
peter.schieberle(at)ch.tum.de
About the Institute
The Leibniz-Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM) has a unique research profile. Its researchers combine methods of basic biomolecular research with analytical methods of bioinformatics and analytical high-performance technologies. Their goal is to decode the complex ingredient profiles from raw materials to the final food products and to elucidate their function as biological active molecules on humans. Based on their studies, the scientists develop products, which are as healthy as they are tasty. These foods will help to provide a sustainable and sufficient stream of food for future generations. In addition, the new scientific findings will be used to develop personalized nutritional concepts that, for example, help people with food intolerance without compromising quality of life and endangering their health.
The Leibniz LSB@TUM is a member of the Leibniz Association, which connects 96 independent research institutions. Their orientation ranges from the natural sciences, engineering and environmental sciences through economics, spatial and social sciences to the humanities. Leibniz Institutes devote themselves to social, economic and ecological issues. They conduct knowledge-oriented and application-oriented research, also in the overlapping Leibniz research networks, are or maintain scientific infrastructures and offer research-based services. The Leibniz Association focuses on knowledge transfer, especially with the Leibniz Research Museums. It advises and informs politics, science, business and the public. Leibniz institutions maintain close cooperation with universities - among others, in the form of the Leibniz Science Campuses, industry and other partners in Germany and abroad. They are subject to a transparent and independent review process. Due to their national significance, the federal government and the federal states jointly fund the institutes of the Leibniz Association. The Leibniz Institutes employ around 20,000 people, including 10,000 scientists. The entire budget of all the institutes is more than 1.9 billion euros.