An Instrumental Method for Determining Rancidity in Frozen Catfish Fillets

A dynamic headspace sampling method was developed to sample and concentrate volatile, rancid flavor aldehydes from frozen stored catfish fillets for gas chromatographic (GC) quantification. This instrumental method involved entrainment of tissue headspace volatile aldehydes onto Tenax adsorbents and subsequent thermal desorption of these aldehydes directly onto the gas chromatographic column for separation and quantification. Results indicated that reproducibility was excellent for quantification of the rancidity related aldehydes, pentanal, hexanal, cis-hexanal and nonanal from catfish fillets. The Procedure proved to be an effective tool for documenting overall fillet rancidity development during frozen storage. Volatile aldehyde concentrations, particularly hexanal and total volatiles, correlated well with sensory flavor scores (r = 0.930 and 0.952, respectively).