Dosimetry And Process Control
Control of food processing in all types of facilities involves the use of accepted methods of measuring the absorbed radiation dose, the distribution of that dose in the product package, and of monitoring of the physical parameters of the process.
Dosimetry for food irradiation is analogous to temperature monitoring in thermal processing, with dose meters being the analogs of thermocouples in that they are employed to provide an accurate measure of the rate of energy delivery, total energy delivered or absorbed and the over dose ratio. There are several types of dose meters, the most common ones being based on a chemical change that is linear within a practical dose range. Dosimetry is the keystone of the proper radiation processing. Careful dosimetry is required to ensure that a technologically useful dose has been applied, while maintaining the best possible dose uniformity ratio. Therefore, prior to commissioning of the plant, extensive dosimetric calibrations of the irradiator are carried out and followed during the processing by routine dosimetry.
Because it is not possible to distinguish irradiated from non-irradiated products by sight, smell or taste, it is important that appropriate indicator devices which undergo radiation induced colour change be attached to each container/package, and that physical barriers be employed in the radiation plant to keep processed and non-processed products separated from each other.