Spoilage of Haddock in the Trawlers at Sea: The Measurement of Spoilage and Standards of Quality

During a period of eight months, 850 haddock were taken from a trawler from the Nova Scotian and Grand Banks. Immediately after landing, the fish were filleted and the fillets were examined organoleptically and tested for pH and trimethylamine.The results indicate a rather close correlation between the development of early spoilage odours and the increase of trimethylamine. One marked exception was the development of "bilgy" odours which can become very offensive without an increase in the trimethylamine content of the muscle.Sixty-five per cent of the fillets without perceptible spoilage odours had trimethylamine values of less than 1 mg. per 100 g.; 83 per cent had values of less than 1.5 mg., 92.5 per cent of less than 2 mg.; only 0.5 per cent had trimethylamine values of between 3 and 4 mg. and none above that level. Conversely, only 10.5 per cent of the "smelly" fish had trimethylamine values below 1 mg.; 89.5 per cent had values above 1.0 mg., and 66.5 per cent above the 1.5-mg. level. For the purpose of grading freshly cut haddock fillets, the following standards are suggested: trimethylamine values of 0 to 1 mg. per 100 g.–fresh; 1 to 5 mg.–doubtful or spoiling; above 5 mg.–spoiled.In spite of its usefulness as a measure of spoilage, it seems very unlikely that trimethylamine contributes to the early spoilage odours that develop in haddock muscle before the pH reaches 6.9.The pH of the homogenized muscle is not a good indication of the extent of deterioration that takes place in the earlier stages of spoilage of these fish.