Investigation of an Iodine-Like Taste in Herring from the Baltic Sea

Abstract

Marinated herring from the Baltic Sea was found to have an offensive odour and taste described as iodine-like and phenolic. This taint appeared similar to the ‘Jodgeschmack' reported previously in herring. Fat isolated from herring was found to contain this taint. The volatiles were isolated from the fat, using a molecular distillation and were subsequently fractionated by gas chromatography. A fraction containing the taint was obtained and submitted to mass spectrometric analysis to identify compound(s) of interest. By this procedure, the tainted herring was found to be contaminated with o-bromophenol. This compound was not found in good quality herring or only at a concentration level below its odour and flavour threshold values. The odour and taste thresholds of this compound and its isomers were determined. The thresholds of o-bromophenol were very low, while the character of the taste was in agreement with that of the taint observed in the herring. o-Bromophenol is thus believed to be responsible for the taint. Finally a discussion is given of the various possible sources, which might give rise to the contamination with o-bromophenol. Various bromophenols have been reported in algae, but no monobromophenols. Also, the harvest period of the herring does not correspond to the period that algae are their major food supply. Likely, the iodine-like taint is not associated with the consumption of algae, as has been suggested elsewhere. o-Bromophenol may be an industrial pollutant but is not reported to be used to any extent in industry. However, a trace amount of this compound in the sea can be bioaccumulated to produce this taint. On the other hand, a chemical reaction between bromide and phenol might occur during marination, but no evidence was found to support this.