Investigation of methods for logging and recording the temperature of food samples submitted for microbiological analysis

Abstract

The quality of results from the microbiological examination of foods is affected by the quality of the sample taken and the provision of effective transport systems which prevent temperature deterioration of the samples during transit. This project has investigated and evaluated the factors which affect transportation of food samples for microbiological analysis e.g. type of transport container, cooling agents, insulation agents and the influence of the sample load. The effect of these variables was determined using two calibrated, multi-channel temperature logging systems. This will lead to the evaluation of temperature logging devices for use in routine sampling.
Results from these studies have been used to assess the existing guidelines in Code of Practice No 7:Sampling for Analysis or Examination.
The use of a Thermos 2700 cool box or a Coleman 28 Quart cool box with a modified insulated lid proved to be the best transport container. The volume and position of cooling agents was found to be very important when transporting food samples. A minimum 10% volume of ice packs: volume of cool box should be used, half the volume of ice packs should be placed below the food samples and the remaining ice packs placed above. An insert should be used to prevent contact between food samples and ice packs. Overloading of the cool box should be avoided therefore allowing adequate air circulation. Studies showed that if an insulated transport container was set up properly, ambient food samples could chill to 5°C within 4 hours and be maintained at this temperature for 24 hours.