Presentation on theme: "ELECTRON SPIN RESSONANCE IDENTIFICATION OF IRRADIATED FOOD LIN/COPPE/UFRJ Prof. Edgar Francisco Oliveira de Jesus * Prof. Ricardo Tadeu Lopes * Prof."— Presentation transcript:
ELECTRON SPIN RESSONANCE IDENTIFICATION OF IRRADIATED FOOD LIN/COPPE/UFRJ Prof. Edgar Francisco Oliveira de Jesus * Prof. Ricardo Tadeu Lopes * Prof. Ricardo Tadeu Lopes * Dr. Alexandre Malta Rossi ** Dr. Alexandre Malta Rossi ** *Laboratório de Instrumentação Nuclear (Escola de Engenharia/COPPE/UFRJ) **Centro Brasileiro de Pesquisas Físicas (CBPF)
LIN/COPPE/UFRJ H. Delincée - Analytical methods to identify irradiated food ¯¯ a review Radiation Physics Chemistry; 63, 3-6; p , 2002
Electron Spin Resonance (ESR) Electron Spin Resonance (ESR) LIN/COPPE/UFRJ
Radiation Sources LIN/COPPE/UFRJ Brokhawen Portable Cesium Development Irradiator (BPCDI) - IPE, CETEX., Guaratiba, RJ. Césio-137 with 3,99 x Bq ( Ci), in 1969 Actual dose rate Gy/min Gammacell 220 Excel - Nordion - Laboratório de Instrumentação Nuclear COPPE/UFRJ Cobalto-60 with 3.08 x 10 6 Bq (12,000 Ci), in 2000 Actual dose rate - 90 Gy/min
LIN/COPPE/UFRJ IPD Irradiator - Frontal view.
LIN/COPPE/UFRJ Gammacell Irradiator
ESR Measurements LIN/COPPE/UFRJ Bruker ESP300E spectrometer (CBPF) Bruker EMS104 spectrometer (LIN)
Alcoholic Extraction Treatment Alcoholic Extraction Treatment LIN/COPPE/UFRJ Compact the pulp without seeds and skin, in a uniform sample; About six grams of the pulp is treated with 40 ml 80% ethyl alcohol solution in de-ionized water; The insoluble solid fraction is then separated by filtration; Remove the excess of water and left to dry at ambient temperature for one hour; 100 mg of the dry matter is then pressed in an acrylic matrix by a steel stick; The resulting sample, consisting of a cylinder 2.5 mm in diameter and 15 mm high, is measured by ESR in a quartz tube.
LIN/COPPE/UFRJ ESR Signal Intensity Variation with Dose
LIN/COPPE/UFRJ ESR Spectra of tomato irradiated with additive doses
(Intensity/Gy) MDDose (Gy) * Cellulose (g/100g) Kiwi Papaya Tomato Strawberry Apple Pineapple Pumpkin Carrot * Calculated as the dose necessary to introduce a signal twice the background intensity for non-irradiated samples. LIN/COPPE/UFRJ ESR Sensitivity for Different Products