Jet impingement is commonly used to attain high local heat exchange coefficients in several industrial frameworks. Both cooling and heating air jets can be used, where precise and rapid thermal control is required. This paper focuses on the air impingement cooling of cylindrical foods, the use of which has been devised and analyzed numerically during the initial stage of cooling/chilling operations. Results include the temperature distributions within the food and at its surface, as well as the associated flow field due to the jet-food interaction. Results have also been compared with available literature data and with classical heat transfer solutions. The local, time-dependent Nusselt number distribution in jet impingement cooling has been shown to be strongly dependent upon the conjugate effect, i.e. the heat transfer rate is altered by the conduction in the food, which is neglected in the associated studies available so far. Slowest Cooling Zones (SCZs) have also been found to lie off-center, depending upon the given thermal boundary conditions. The knowledge of transient temperature distributions within the processed food and related local heat transfer is important in cold treatment of foods, in order to achieve the desired system performance in the most efficient manner. (c) 2006 Elsevier Ltd. All rights reserved.