Endpoint temperature of heat-treated surimi can be measured by visible spectroscopy

From a microbiological point of view thermal processing is useful to preserve food and keep it safe. Assessing endpoint temperatures (EPT) enables effective temperature control throughout processing, but assessment methods have so far been labour-intensive or sensitive to water associated with the sample. The aim of this study was to develop a non-invasive method able to deal with the water levels of fresh samples. Visible spectroscopy measurements were combined with multivariate analysis for EPT prediction of surimi samples. No measures were carried out to control the water on the surface or the water content of the samples. In the range from 400 to 700 nm an apparent correlation between temperature treatment and spectra intensities was observed. The spectral changes reflect the changes in relative scattering intensities caused by protein denaturation. A similar correlation was not observed for the near infrared (NIR) region. By excluding the NIR region, where water absorbs strongly, we present a model in range from 400 to 700 nm that show a prediction error less than 2 °C in the temperature range 46.6-74.4 °C. This model is robust (r2 = 0.96) and covers the temperature range for mild surface pasteurization, thereby showing potential for use in the food processing industry.

► Visible spectroscopy measurements were used for EPT prediction of surimi samples. ► This is a non-invasive method able to deal with the water levels of fresh samples. ► A correlation between temperature treatment and spectra intensities was observed. ► Near infrared region was excluded due to waters strong absorption in this region. ► A model for predicting temperatures up to 75 °C is presented.