Off-Flavours in Crustaceans Caught in Australian Coastal Waters

Australia is a major producer of crustacean sea-foods for local consumption and export. Species harvested in commercial quantities from estuarine and ocean sources include prawn, lobster and crab. The common off-flavours encountered in these species are described as garlic, garlic-metallic, rotten onion, solvent and iodoform-like. Chemical studies, including the application of GLC, GLC-MS, micro-NMR spectrometry and microreaction GLC, have led to the identification of most of the compounds responsible for these off-flavours. Compounds identified include bis-(methylthio)-methane, dimethyl trisulphide, (5Z)-octa-1,5-dien-3-ol and a number of aromatic hydrocarbons. Studies related to the biological origin of the offending compounds indicated that microbial spoilage, environmental pollution and diet were the most likely sources of the off-flavours. The paper describes the identification of the off-flavour compounds, indicates their likely biological origin and lists the species affected.