Identification of gamma-irradiated ingredients in liquid seasonings by thermoluminescence analysis: an interlaboratory blind trial

Abstract

An interlaboratory blind trial was conducted to validate the thermoluminescence (TL)-based identification of gamma-irradiated (0, 1, and 10 kGy) ingredients (garlic powder) in liquid seasonings. Two kinds of forty (20 each) coded samples containing irradiated ingredients at blending ratio of 0–3 % were processed in a food industry and sent to two different irradiation detection laboratories. The garlic powders were also analyzed by both laboratories as reference materials. Irradiated garlic powder provided a strong TL peak at about 200 °C, which was absent in the non-irradiated ones, and the results were also confirmed by determining the TL ratio (TL1/TL2). In the blind trial of sauces containing an irradiated ingredient, 75–80 % validated results were reported. The problematic results were observed for the samples containing low quantities of 1 kGy-irradiated ingredients. The TL ratios of all sauce samples were <0.1 irrespective of their irradiation history, where the evaluation was made using the glow curve shapes and intensities. Low amounts of irradiated ingredients could be effectively detected; however, the lower detection limits need to be established after getting a better understanding of the complex TL glow curve results.