A process risk model for the shelf life of Atlantic salmon fillets
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Rasmussen, SKJ and Ross, T and Olley, J and McMeekin, TA, A process risk model for the shelf life of Atlantic salmon fillets, International Journal of Food Microbiology, 73, (1) pp. 47-60. ISSN 0168-1605 (2002) [Refereed Article]
The shelf life of Atlantic salmon (Salmo salar) portions produced for retail distribution is examined and the dominant aerobic spoilage organism is identified. Characterization of the harvesting and processing operations allow the development of a stochastic mathematical model, a process risk model (PRM), which predicts the range of the possible shelf life for the portions under normal retail and distribution. The considered risk is the failure to achieve the nominal 'use by' date. Bacterial counts from surface swabs, water, ice, and fish samples, collected over a period of 9 months, are fitted to distribution functions for use within the model. Comparisons are made between the distributions fitted to the observed bacterial levels and the predicted levels for the slurry water, initial surface contamination on the fish, and for the predicted and observed shelf life. Storage temperature of the packaged salmon portions has the greatest influence on shelf life, with contamination from contact surfaces and other sources being the next most important. The range of bacterial counts on the portions was between - 0.6 and 5 log 10 cfu/cm 2. The model predicts bacterial counts in the slurry water to have an average value of 3.36 log 10 cfu/ml, whereas the observed slurry water bacterial counts were 3.35 log 10 cfu/ml. The predicted average initial bacterial contamination is 3.31 log 10 cfu/cm 2 on the fish surface and 3.23 log 10 cfu/cm 2 on the observed. The average predicted shelf life is 6.5 days, compared to an observed value of 6.2 days at 4°C. © 2002 Elsevier Science B.V. All rights reserved.
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