Exploration of volatile compounds causing off-flavor in farm-raised channel catfish (Ictalurus punctatus) fillet

Off-flavor is a major challenge to the quality of farm-raised catfish fillet. In this work, headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was employed to analyze volatile compound profile of catfish fillet to find the volatiles which might be responsible for the off-flavor. Ten volatile compounds were identified, and their concentrations in on-flavor and musty off-flavor fillets were compared. The off-flavor fillet contained significant larger amount of geosmin (GSM), 2-methylisoborneol (MIB), hexanal, 1-octen-3-ol and nonanal, indicating they might be related to the musty off-flavor. Sensory evaluation of the five compounds and their combinations suggested that GSM and MIB might be mainly responsible for the musty off-flavor, while the presence of hexanal or 1-octen-3-ol might notably intensify the off-flavor. This research suggested that besides GSM and MIB, some small aldehydes and/or alcohols might also need to be considered for controlling off-flavor in catfish fillet. This work also provided a useful chemistry-based objective method to evaluate the effects of treatments and/or managements in reducing catfish off-flavor.