Monitoring the Time and Temperature History of Frozen Hake (Merluccius merluccius, L.) Muscle by FTIR Spectroscopy of the Lipid Fraction

The objective was to model the time and temperature changes of the lipid fraction of hake muscle by mid-infrared spectroscopy. Fillets of a total of 90 hake (Merluccius merluccius, L.), stored at −10, −20, −30 or −80 °C for up to 150 weeks, were used and lipids analysed by attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR). Three spectral regions corresponding to ν(C-H) vibrations (3,100–2,750 cm−1), ν(C=O) vibrations from ester and carboxylic groups (1,800–1,670 cm−1) and νas(PO2−) phospholipid vibrations (1,330–1,127 cm−1) were studied separately. Principal component scores were used as the response variables for the kinetic modelling. Three models were obtained, each per region, and the best one resulted from the region corresponding to the phosphorous moiety of the phospholipids with R2 = 0.93. They kept a close relationship with other reported quality parameter such as Kramer shear resistance which suggests their potential for the estimation of frozen storage time and temperature in fishery products.