APPLICATION OF AN ITERATIVE APPROACH FOR DEVELOPMENT OF A MICROBIAL MODEL PREDICTING THE SHELF-LIFE OF PACKED FISH

An iterative approach was used to develop a microbial model for shelf- life prediction of cod fillets packed in modified atmospheres. The eff ect of temperature (0-15 degrees C) and CO2 (0-100%) on growth of the specific spoilage organism, Photobacterium phosphoreum, was studied in packed cod and in liquid media. P. phosphoreum was a dominant part of the spoilage microflora of packed cod stored at the extremes of the r ange of conditions studied. The organism is therefore likely to be imp ortant for spoilage and the development of a microbial model within th is domain seems relevant. A liquid medium was developed to provide gro wth kinetics of P. phosphoreum similar to those observed in packed cod . Using this medium, the effect of temperature and CO2 on the maximum specific growth rate of Photobacterium phosphoreum was determined by a bsorbance measurements and modelled by a square root equation and by a polynomial equation. Product validation studies were carried out duri ng summer and winter using naturally contaminated packed cod fillets w hich were stored at constant and at changing temperatures. The shelf-l ife of the packed fillets was predicted on the basis of the initial nu mbers of P. phosphoreum, product temperature profiles and the level of CO2 in the modified atmosphere. The average deviations between shelf- life determined by sensory evaluation and shelf-life predicted by the square root equation and by the polynomial equation were 17% and 9%, r espectively. (C) 1997 Elsevier Science B.V.