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

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2001, Vol.60 (1), p.143-147
• Main Authors: Ghelawi, M.A., Moore, J.S., Bisby, R.H., Dodd, N.J.F.
• Format: Article
• Language: English
• Subjects: Absorbed dose; Dates; ESR; Irradiation; Regression analysis
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/S0969-806X(00)00309-1

Food spoilage is caused by infestation by insects, contamination by bacteria and fungi and by deterioration by enzymes. In the third world, it has been estimated that 25% of agricultural products are lost before they reach the market. One way to decrease such losses is by treatment with ionising radiation 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 irradiated foods is now essential and here we have used ESR to detect and estimate the dose received by a single date. The ESR spectrum of unirradiated date 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 the linear increase in their intensity. In blind trials of 21 unirradiated and 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 within ∼0.5 kGy.