Monitoring the drying process of lasagna pasta through a novel sensing device-based method

The desiccation process of lasagna pasta is usually accompanied by bending and breaking of the dry pasta slices, due to self generated internal stress. The diffusive transfer of water through the slice bulk is responsible of these phenomena, leading to excessive product reject. The water sorption equilibrium and kinetics of drying were measured for different pasta mixtures. Measurements have been performed by means of a novel equipment based on a raw alumina substrate (3 x 3mm sized) equipped with gold interdigitated electrodes, and a strict analogy exists between current and water diffusion data. Moreover, in situ measurements have been performed in an Italian pasta factory with an on line system assembled on the desiccation apparatus. Results of the sorption studies show a Case II diffusion mechanism, with the formation of a glassy shell around the pasta sample during desiccation at low water vapour activities, which prevents the further desiccation of the internal humid core. Thus, an accurate control of the humidity both in the sample and the external environment was performed to avoid stress generation in the material and cracks formation. The measuring device provided an accurate control of the sample humidity and a fast response to external environment modifications during desiccation. (c) 2004 Elsevier Ltd. All rights reserved.