Abstract
Over the last decade, numerous cases of illness and death in dogs, which consumed imported irradiated chicken jerky
treats, and in parallel outbreak of neurological disorders and deaths in cats in Australia, which fed irradiated food, raised
attention to the safety of the irradiated pet food products. Although the actual cause is still unknown, determining the total
irradiation dose is invaluable to ensure the products are processed within the safe limits. Among the methods established
for the detection of irradiated foods, analysis of 2-alkylcyclobutanones (2-ACBs) with GC-MS and analysis of cellulosic
and carbonate radicals with electron paramagnetic resonance (EPR) spectroscopy serve as the most promising approaches
to determine the irradiation history in pet food products. The goal of the proposed research is to develop GC-MS and EPR
techniques coupled to quantify the formation of specific irradiation markers and to determine the total amount of
irradiation treatment in pet foods and treats. We will carry out the project in two parts: the first three years will be
dedicated to development and validation of testing methods; the last two years will be the comparison and field-testing of
the validated protocols for evaluation of the irradiation history in pet food products. In the first part of the project pet food
products, including chicken jerky treats, sweet potato treats, dog chews (beer, lamb), bones, hoofs and pig ears, will be
irradiated from 0.1-75 kGy with either a Cesium-137 source and electron beam (e-beam). The formation and stability of
various 2-ACBs (i.e., 2-DCB, 2-TCB, 2-TDCB) will be evaluated using GC-MS techniques based on our previous works
in collaboration with Vet-LIRN and USDA labs. In parallel, formation and stability of carbonic and cellulosic radicals
will be evaluated by using EPR analysis in both low mobility and high mobility environments. Complementary to EPR
measurements, irradiation-specific DNA damage will also be investigated by using qPCR analysis. The analytical and
physical methods will be validated for different product formulations with varying lipid composition, moisture content,
presence of glycerin, vegetables, phytochemicals etc., and extraction methods, such as hexane extraction, solid phase
extraction (SPE), solid phase microextraction (SPME), soxhlet extraction. The chemical and thermal stabilities of the
specific irradiation markers will be analyzed over a temperature range (20-80 °C) and at least one year of storage at room
temperature. In the second part of the project, validated protocols will be tested on commercial irradiated pet food
products available in the market. Eventually, we will compare and contrast the results obtained from physical and
analytical techniques. Overall, at the end of the project we will propose validated and tested protocols, which can be used
as standardized techniques to quantify the irradiation doses in various pet food products.