NIR spectroscopy: A non-destructive fast technique to verify heat treatment of fish-meat gel

Attempts have been made to assess previous heat treatment of fish-meat gels prepared from walleye pollack and horse mackerel surimi, since surimi-based products have been gaining popularity for their protein quality, law fat content and convenience in consumption. Visible–NIR spectra of gels (30–90 °C) were collected from 650 to 1100 nm with a surface interactance fibre optic accessory. Partial least squares (PLS) and multiple linear regression (MLR) techniques were employed for data analysis. Spectral changes upon heat treatment were related to the heating temperature which reflected the changes in the environment of the secondary structure due to the denaturation of proteins, and to changes in the state of water. A promising linear relationship (R = 0.98) was observed between NIR-predicted temperatures and the actual heating temperatures with prediction error of 1.85 °C.