Fish quality assessment with ion mobility based gas detector.

Measurement of the mixture of extractable volatile compounds of the gills of vendace was used in the fish freshness evaluation (Coregonus albula L.). MGD-1 gas detector was used for the detection of volatile compound profiles of hexane extracts of gills. The measuring principle of MGD-1 is ion mobility distribution and is based on IMCELL technique. A 2.5 microl sample of hexane extract was heated on a ceramic plate and the vapour was carried with a constant flow (2.5 I/min) of active carbon filtered air to the detector. The ion mobility distribution spectrum was measured every 1 second for 2 minutes. For reference, the microbial counts of gills, ATP-breakdown products (K-value) of fish flesh, electrical properties (Torrymeter scores) of fish skin and sensory evaluation scores were measured. The ion mobility distribution profiles of gills changed significantly during the 7 days storage period The findings related to freshness evaluation were supported by the reference methods. There is, however, a seasonal difference in the freshness probably due to seasonal variation of microbial flora. Besides the evaluation of fish quality, ion mobility distribution based technique provides a new analytical tool for food quality assessment.