Application of a systematic experimental procedure to develop a microbial model for rapid fish shelf life predictions.

A systematic experimental procedure for fish shelf-life modelling was used to develop a model for predicting the quality of fish in the chill chain. For this, the growth of the naturally occurring bacteria pseudomonads, Shewanella putrefaciens, Enterobacteriaceae, lactic acid bacteria and yeasts, on gilt-head seabream (Sparus aurata), was studied at temperatures from 0 to 15 degrees C. The results from the microbiological, organoleptical and chemical analysis conducted on naturally contaminated fish as well as on inoculated sterile fish blocks identified pseudomonads as a good spoilage index. Growth of pseudomonads was modelled as a function of storage temperature and correlated to organoleptical shelf life. To reduce the time required for the enumeration of the initial pseudomonads number, which is crucial information for shelf life prediction, a conductance assay was established. Compared with the conventional microbiological tests, this method gave results in one-fourth of the time.