Use of mid-infrared spectroscopy to monitor shelf-life of ready-made meals

The objective of this work was to use mid-infrared spectroscopy as a rapid analytical method to monitor the change in stored ready-made meals over time. Six ready-made meals were packaged in two plastic bags, Alu and Alox, and stored at 23  °C at a partial oxygen pressure of 96 kPa. After thawing, samples were directly measured in attenuated total reflectance mid-infrared spectroscopy between 4000 and 650 cm−1. Multivariate analyses applied on spectral data highlighted some changes in the global profile, particularly in Bolognese soup and in mashed potatoes with cheese. Indeed, the Bolognese sauce samples were clearly discriminated (i) according to the storage time and (ii) according to the packaging type presenting a greater oxidation in the Alox packaging. The eigenvectors allowed for the identification of clear absorption bands at 2918, 2850, 1741 and 1164 cm−1 which increased over storage. These absorption bands could be attributed to fats, which thus appeared to have a major effect in sample discrimination. Mid-infrared spectroscopy was shown to be a relevant tool for discriminating the oxidation state of canned ready-made meals and might be used to determine their shelf-life.