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Liquid smoke food flavouring is an alternative to traditional food smoking. Ageing treatment of liquid smoke can remove tar to improve a consistent sensory experience but traditionally takes months by storage. This study proposed a thermal treatment approach to accelerate the ageing process. Liquid smoke samples from kānuka and hickory woodchips were prepared by fast pyrolysis. The obtained liquid smoke samples were subjected to ageing by storing them at ambient temperature for 18 months. Accelerated ageing of liquid smoke was carried out by heat treatment at 80 °C for 24 and 48 h. Tar formed during the ageing process, with a yield ranging from 2.2 to 4.1 wt.%. Both ageing treatments resulted in decreases in bioactive content and their activities in terms of total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power assay (FRAP) and 2,2-diphenyl-1-picrylhydrazyl scavenging activity (DPPH). Chemical composition and principal component analyses indicated that liquid smoke chemical compositions were influenced by wood type and ageing conditions. It was found that thermal treatment at 80 °C for 24 h was sufficient to age liquid smoke. [ABSTRACT FROM AUTHOR]

The exposure of humans to the aromatic hydrocarbon benzene should be minimized due to its carcinogenicity. Previous studies have reported on the presence of benzene, in particular in foods with added cherry aroma compounds, in particular benzaldehyde. To allow a reliable quantitation of benzene, a stable isotope dilution assay using (2H3)benzene as the internal standard was developed and solid phase microextraction (SPME) was used for volatile isolation followed by GC × GC–TOFMS analysis. Care was taken to avoid any exposure to light and to use materials during work-up, which were free of benzene contamination. The method, applied on 22 liquid foods with added flavour showed that benzene did not exceed a concentration of 1 µg/L in any sample (i.e. the limit established for drinking water). Furthermore, flavourings containing benzaldehyde and the corresponding raw material were analysed. The major source of benzene in flavourings turned out to be benzaldehyde itself. First insights into parameters supporting the formation pathway of benzene from benzaldehyde were obtained indicating that the presence of light and either acidic or alkaline conditions favoured benzene formation. [ABSTRACT FROM AUTHOR]