Estimation of absorbed dose in irradiated dates (Phoenix dactylifera L.). Test of ESR response function by a weighted linear least-squares regressionanalysis

Food spoilage is caused by infestation by insects, contamination by bacteri a and fungi and by deterioration by enzymes. In the third world.. it has be en estimated that 25% of agricultural products are lost before they reach t he market. One way to decrease: such losses is by treatment with ionising r adiation and maximum permitted doses have been established for treatment of a wide variety of foods. For dates this dose is 2.0 kGy. Detection of irra diated foods is now essential and here we have used ESR to detect and estim ate the dose received by a single date. The ESR spectrum of unirradiated da te stone contains a single line g = 2.0045 (signal A). Irradiation up to 2. 0 kGy induces radical formation with g = 1.9895, g = 2.0159 (signal C) and g = 1.9984 (signal B) high field. The lines with g = 1.9895 and 2.0159 are readily detected and stable at room temperature for at least 27 months for samples irradiated up to this dose. The yield of the radicals resulting in these lines increase linearly up to a dose of 5.0 kGy as is evidenced by th e linear increase in their intensity. In blind trials of 21 unirradiated an d irradiated dates we are able to identify with 100% accuracy an irradiated sample and to estimate the dose to which the sample was irradiated to with in similar to0.5 kGy. (C) 2001 Elsevier Science Ltd. All rights reserved.