FOOD CONTROL BY APPLIED BIOCHEMISTRY OF MARINE ORGANISMS - COMPARISONOF PROTEINS AND METABOLITES FROM FISH AND INVERTEBRATE MUSCLE

Most fishery products consist of muscle tissue from fish and invertebr ates. Differences in the molecular structure and in metabolism of musc les can be utilized to characterize and identify various seafood. Crea tine and arginine were found to be useful for the differentiation betw een imitation crab/shrimp meat and real crustacean meat. Octopine serv ed as an indicator for the meat of cephalopods and mussels. In order t o identify the animal species of a fishery product, several electropho retic methods were used. It depended on the type of product, whether s arcoplasmic or myofibrillar proteins were better suited. Raw products were best analysed by isoelectric focusing of sarcoplasmic proteins. T wo types of sarcoplasmic calcium-binding proteins, parvalbumins of fis h and soluble calcium-binding proteins of invertebrates, were especial ly useful for species identification. Due to their thermal stability, these proteins gave species-specific patterns for cooked products, too . Two other techniques were also investigated: urea gel isoelectric fo cusing and sodium dodecyl sulphate - polyacrylamide gel electrophoresi s. These methods were applied in the analysis of products where the sa rcoplasmic proteins had been removed by washing steps, i.e. imitation crab meat made from surimi, and of other raw and cooked products. The myosin light chains gave protein patterns that were characteristic for many species. Paramyosin, which is absent from vertebrate muscle, ind icated the presence of mollusc muscle. It was shown that the determina tion of arginine kinase activity enabled differentiation between raw f ish muscle and invertebrate muscles.