Detection of Irradiated In-Shell Peanuts (Arachis hypogaea) by Screening PPSL and Confirmatory TL Luminescence Methods

In this work, the luminescence methods of pulsed photo-stimulated luminescence (PPSL, as screening) and thermoluminescence (TL, as confirmatory) were used for identification of non-irradiated and low-dose irradiated (1–5 kGy) in-shell peanuts from light emissions of silicate minerals incorporated in the shell. The minerals were irradiated with ⁹⁰Sr beta particles, ⁶⁰Co and ¹³⁷Cs gamma rays. Screening PPSL response detected peanut shell as irradiated from 80 Gy for ⁶⁰Co and 30 Gy for ¹³⁷Cs gamma rays. Irradiated (⁶⁰Co and ¹³⁷Cs) peanut shell samples were positively detected with PPSL after 4.5 and 14 months. A complex TL glow curve composed of at least two maxima was exhibited by the minerals. Using the TL₁/TL₂ ratio, the in-shell peanuts were identified as irradiated from 50, 120, and 100 Gy of ⁹⁰Sr, ⁶⁰Co, and ¹³⁷Cs radiation, respectively. Moreover, the TL glow curve shape was also used to identify the peanut shell minerals as irradiated at lower dose of radiation. After 34 days of storage, the peanut shell minerals showed enough TL emissions for their identification as irradiated.