Abstract：
Irradiation is widely used worldwide to sterilize and kill insects in food, and prevent the germination of agricultural products. However, in Japan, food irradiation is prohibited except to prevent potato sprouting. Herein, 5,6-dihydrothymidine (DHdThd) residue-a damaged nucleoside generated from the thymidine (dThd) residue in DNA contained in food upon irradiation-was used as a detection indicator. Eight dried plant-based food samples were gamma ray-irradiated in the range from 3.2 to 8.3 kGy. Subsequently, DNA was extracted from the irradiated sample and digested into nucleosides by the three enzymes, and the test solution was analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Evidently, in all samples, the concentration ratio of DHdThd to dThd in the test solution (DHdThd/dThd) was dependent on the irradiation dose; moreover, during storage under frozen conditions for at least 890 d post-irradiation, this concentration ratio was equal to that immediately after irradiation. The irradiation histories of the eight types of dried plant-based food samples were correctly detected.
摘要：
辐射在世界范围内广泛用于消毒和杀死食物中的昆虫，防止农产品发芽。然而,在日本,除了防止马铃薯发芽外，禁止食物辐照。在这里，5,6-二氢胸苷（DHdThd）残基-在辐照时从食品中所含DNA中的胸苷（dThd）残基产生的受损核苷-用作检测指标。八个干燥的基于植物的食品样品在3.2至8.3kGy的范围内进行了伽马射线辐照。随后，从辐照过的样品中提取DNA，用这三种酶消化成核苷，并通过液相色谱-串联质谱(LC-MS/MS)分析测试溶液。显然,在所有样品中，测试溶液中DHdThd与dThd的浓度比（DHdThd/dThd）取决于辐照剂量；此外，在冷冻条件下储存期间，辐照后至少890d，该浓度比等于照射后立即的浓度比。正确检测了八种干燥植物食品样品的辐照历史。
