The food flavouring beef thiophene in doubt

A hazardous substance but a low risk. That is the conclusion of the European Food Safety Authority (EFSA) when assessing the food flavouring called beef thiophene (3-acetyl-2,5-dimethylthiophene). It is a substance that occurs naturally at low levels in cooked beef. As a synthesised food flavouring, beef thiophene is a colourless to yellow liquid that can be used to strengthen the roast and smoked flavour of processed meats but also to give a burnt, nutty flavour to confectionery, baked goods and some other savoury products. So what is the potential danger? Let me explain.

Hazardous or not

Europe reviewing safety of food flavourings (Photo: Xavier Häpe)

Europe reviewing safety of food flavourings (Photo: Xavier Häpe)

The European Union adopted a regulation on flavouring substances in October 2012, with the aim of providing a list of flavouring substances that are deemed safe and thus may be used in food in the EU. At the time of announcing the list, 2100 flavouring substances had already been assessed by EFSA or other equivalent organisations and included in the list. Any flavouring substances not in the list will be prohibited after a phasing out period.

Now the turn came to assess the safety of beef thiophene. Initially there was a lack of genotoxicity information on which to make an appropriate safety assessment. However, EFSA requested additional information from industry. The missing information was provided by the European Flavour Association. The data submitted consisted of a bacterial gene-mutation assay and an in vivo study on mice. The studies were deemed appropriate since they were performed in compliance with Good Laboratory Practice and complied with the OECD Guideline 471 and 488, respectively.

Unfortunately, the bacterial mutation assay showed a dose-dependent positive outcome and it was possible to conclude that the observed mutagenicity indicated that it was due to a metabolite of the substance. Similarly, the in vivo mice study showed dose-related mutations in the liver, with results further supporting the hypothesis that the mutagenicity observed was due to a metabolite of the beef thiophene. Therefore, since the substance was genotoxic (that is, it can damage DNA, the genetic material of cells) both in vitro and in vivo, EFSA considered that its use as a flavouring substance raised safety concerns.

Potential risk

It is clear that genotoxic substances should not be intentionally added to food. However, EFSA found that the overall use of beef thiophene was low with total annual sales in the EU estimated to be 2.3 kg. It is produced as a flavouring by a small number of manufacturers and only used in a limited number of foods. While no exposure assessment was carried out by EFSA, should you have been exposed to this substance in food any risk to your health is expected to be very small. Thus, although it is deemed to be a hazardous substance with genotoxic potential and inappropriate as a food flavouring, public health risk from past use is low.

EU risk managers will now have to decide whether to remove beef thiophene from the EU list of authorised flavoring substances. Other countries might follow. The substance is on the GRAS (generally recognised as safe) list in the USA and, although difficult to get use levels, might be more commonly used there. Since beef thiophene has been approved as a food flavouring by JECFA (the Joint FAO/WHO Expert Committee on Food Additives) it might also be used in many other parts of the world. It’s going to be interesting to see the world-wide reaction to the new findings.

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