Optimization of shelf life distribution of frozen fish products based on modelling and TTI monitoring

摘要

The objectives of the present study were the determination of the response function of two types of UV activated photochemical and one type of enzymatic TTI labels, the development and validation of kinetic models for the quality indices deterioration of the frozen fish products and the evaluation of the applicability of a TTI based system to improve frozen fish product quality. For the determination of the response function, the photochemical OnVu Logistics and F4 TTI labels charged at different UV levels from 0.2 s to 2.5 s and the M-type enzymatic TTIs were exposed to temperatures from -4°C to -15°C. The response of the labels was measured vs time by using the X-rite Eye1pro colorimeter. For the modelling of the photochemical TTIs response rate constant as a function of activation level and storage temperature, two composite mathematical equations were developed. A mathematical model which describes the effect of the concentration of the substrate and the storage temperature on the response of the enzymatic TTIs was also developed. For the fish products, selected quality indices such as colour, texture, oxidative rancidity, totalvolatile- nitrogen(TVBN) and trimethylamine-nitrogen(TMA) analysis, aerobic plate count, pH and sensory evaluation were studied at appropriate time intervals. The quality indices were kinetically modeled and the temperature dependence of the quality loss rates was modeled by the Arrhenius equation. Applying the developed models, the required charging levels for the photochemical TTIs and the required substrate concentrations for the enzymatic TTI labels were estimated to effectively monitor the shelf life of frozen fish products.