An experimental study of the local evolution of moist substrates under jet impingement drying

Jet impingement can be successfully and efficiently employed in drying or dehydration of moist substrates, like food slices or plates, among other applications. With this intensification technique, a great deal of the available water is removed by applying heat under controlled conditions, but excessive or nonuniform local drying may cause local deterioration (i.e. in case of foods, the eating quality, the nutritional value, the mechanical consistence and so forth). In this paper the thermal, water activity and moisture depletion histories have been measured in a food substrate, due to localized heating by a turbulent air jet impingement, to infer on the inherent driving forces and transport phenomena. It is evident that strong non-uniformity may exist in the substrate so that a local analysis as the reported one is necessary to help reach optimal processing. (C) 2010 Elsevier Masson SAS. All rights reserved.