ALTERATION OF THE ELECTROPHORETIC PATTERN OF MYOFIBRILLAR PROTEINS INFISH MINCE DURING FROZEN STORAGE

A study was made of the variations in the electrophoretic profile of m yofibrillar proteins in the muscles of blue whiting (Micromesistius po utassou R.), horse mackerel (Trachurus trachurus L.) and mackerel (Sco mber scombrus L.). It was shown that all species presented different d eterioration patterns during frozen storage. The fish were caught at t wo separate times of the year (winter and summer) and were stored froz en at -18-degrees-C for 1 year. The results indicate that during froze n storage, electrophoretic patterns varied according to species. Compa rison of myosin heavy chain/actin (MHC/A) ratios indicates that blue w hiting is the species that undergoes most alteration, and that this is more intense in fish caught in the summer than in the winter. Alterat ion of the MHC/A ratio was similar in horse mackerel and mackerel caug ht in the winter, whereas in the summer horse mackerel proved to be th e most stable species. In all cases, the reduction of the MHC/A ratio was due essentially to alteration of the MHC, an effect which was part icularly marked in blue whiting. Tropomyosin remained stable throughou t the storage period in all three species.