Identifying volatile compounds in rabbit fish ( Siganus fuscescens ) tissues and their enzymatic generation

摘要

The volatile compounds associated with unpleasant smells in rabbit fish tissues, including muscle, skin, viscera and stomach contents, were studied using solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). A lipid oxidation model system was used to demonstrate how volatile compounds formed. In the model system, crude enzymes extracted from rabbit fish viscera were incubated with dominant polyunsaturated fatty acids (PUFA), including n-6 PUFA (arachidonic acid (ARA), linoleic acid (LA)) and n-3 PUFA (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)). The key odour compounds contributing to the overall smell of rabbit fish meat were hexanal and 1-octen-3-ol, which were also the main volatile compounds generated from the reaction of crude enzyme and ARA. In addition, various volatile compounds were generated in the model system, indicating the presence of lipoxygenase (LOX) in rabbit fish tissue. The highest level of enzymatically generated compounds was observed with an ARA reaction, suggesting the highlighting substrate specificity of rabbit fish viscera LOX and ARA. Our findings indicate that volatile compounds associated with the unpleasant smell in this herbivorous species are due to PUFA oxidation, particularly ARA, initiated by LOX.