Moisture migration during storage at different humidity conditions in fresh-packed pasta

Moisture migration is a common problem for most composite foods, especially for those at high moisture content and high water activity. Moisture loss, gain and transfer can affect texture and quality stability by enabling chemical reactions as well as microbial growth. For packaged composite foods, moisture migration continuously occurs between different food domains and between the food and the environment, until a thermodynamic equilibrium is reached. Therefore, choosing the correct food composition as well as appropriate packaging characteristics are key elements to ensure that all quality requirements are met during shelf life. In this study, the moisture migration phenomena of a composite food consisting of fresh egg pasta and a ricotta filling added with citrus fruit fiber. According to the product shelf life, samples were stored for 49 days in refrigerated conditions at two different relative humidity conditions. A relative humidity sensors system was created to constantly monitor the relative humidity inside and outside the package. This allowed to confirm the existence of a humidity gradient inside the package, which resulted of great importance in driving the moisture exchange through the package. Pasta and filling weight profile was assessed weekly, and the application of a packaging fitting model to evaluate the moisture loss over time resulted in good agreement with the experimental data. The evaluation of the unaccomplished moisture ratio between pasta and filling at different relative humidity storage conditions confirmed the importance of capillary phenomena, on which is based moisture migration. Particularly, the unaccomplished moisture ratio of the food model stored at lower relative humidity expressed a higher perturbation, with respect to the one obtained at higher humidity, probably due a greater difference in water vapor partial pressure between inside and outside the package. This can be confirmed by the almost unchanged unaccomplished moisture ratio after 49 days of the product stored in a sealed environment. Finally, the tested filling composition allowed to reduce the moisture migration compared to the filling used in a previous study at the same experimental conditions. Further studies are being carried out by the company to choose the best ingredients for controlling moisture migration.