Copper induced lipid oxidation during salting of cod (Gadus morhua L.)

Yellow/brown discoloration of the muscle surface was investigated in downgr aded heavily salted cod fillets from a processing plant. The results showed that discolored areas were relatively evenly distributed on the muscle sur face and that lipid oxidation correlated with the copper and not the il on content in the muscle. A model system for studying lipid oxidation and yell ow discoloration of salted cod muscle was established and used for investig ating the effect of including transition metals in the process. The model s ystem confirms that copper is particularly pro-oxidative. Of the redox stat es, the reduced form of copper was most potent. It appears that copper conc entrates in the muscle during the brining. The results also indicate that c opper induced lipid oxidation was increased by low pH of the fish muscle po stmortem. The model system seems well suited for detailed studies of the sa lting process and may be useful for developing methods which can inhibit li pid oxidation in salted products.