Advances in temperature validation of foods

Abstract Whereas the major purpose of cooking is to increase the palatability of food, the heating of many foods is essential to kill bacteria thereby increasing the foodstuff's safety and storage life. In practice, pasteurization and other sterilization processes require stringent assurance that all parts of the food product have been heated above a certain temperature for a defined period of time; unfortunately this often means that parts of the product have been overheated, resulting in loss of product quality. As a consequence much research has been carried out to optimize the quality and safety of many heating processes. As the complexity of heating methods increase, so too does the need for more innovative measurement techniques to monitor the efficiency of heating, particularly since some measurement methods may interfere with the heating process itself. Hence, despite the ever-increasing sophistication of models for heat transfer and the increasing power of computers to deal with them, there continues to be a need to validate models by in situ measurement, ideally with capability for on-line process control. At present in situ temperature monitoring still remains a challenge. Ideally the temperature measurement technique should be easily incorporated into the process without disturbing it; be non-contact because of the need for stringent sterile conditions; and have good spatial- and temporal-resolution: those requirements suggest use of some kind of tomographic technique 1 , 2 . Fortunately, several such technologies have been developed for medical applications and this review outlines previous work in this area and more recent developments of magnetic resonance imaging (MRI) temperature mapping [3] . Particular emphasis is devoted to temperature measurement in new processing methods (such as microwave sterilization) since that topic has not been adequately covered elsewhere.