Time temperature integrators for monitoring the shelf life of ready-to-eat chilled smoked fish products

Abstract

Abstract The aim of the study was the selection of appropriate enzymatic TTIs for quality and shelf life monitoring of ready-to-eat smoked fish products during refrigerated storage. The response of different types of enzymatic TTIs was kinetically modelled and correlated with the quality decay and shelf life of vacuum packed hot smoked eel and trout and cold smoked salmon fillets in the cold chain. The kinetics of shelf life determining quality indices for the tested smoked fish products were established via isothermal experiments. Mathematical models which describe the effect of the enzyme concentration, storage time and temperature on the response of the TTI were developed and validated at variable conditions. The effect of the temperature on the response change of the TTIs was expressed through activation energy and the values were calculated in the range of 80-150 kJ·mol−1. Applying the developed models, the required TTI design to reliably monitor the shelf life of the respective smoked products was determined. Shelf life of vacuum packed smoked eel, trout and salmon at 5 °C was 7.5, 11 and 2 weeks, respectively. LP-17U, M-17U and M-5U enzymatic TTI adequately monitored shelf life of vacuum packed smoked trout fillets, smoked salmon slices and smoked eel fillets, respectively.