Detection of irradiated potatoes and onions using photo-stimulated luminescence (psl) measurements

Abstract

ABSTRACT

Photo-stimulated luminescence (PSL) measurement was conducted to detect irradiated potatoes and onions after dark storage for 1 week, 3 and 6 months.  Using screening and calibrated PSL, all the samples were correctly distinguished between non-irradiated and irradiated samples at doses 50, 150 and 500 Gy based on photon count values.  The PSL signal stability of irradiated samples (150 and 500 Gy) appeared to fade upon 6 months storage but remained well above upper threshold values of 5000 photon counts/60 s (PCs) for irradiated potatoes and onions. The PCs of irradiated tubers and bulbs showed a general trend of increase with the increase in doses up to 500 Gy. Samples showed highest intensity after irradiation.  The differences in intensity to irradiation are possibly attributed to the varying quantity and quality of silicate minerals present in each tuber sample. Tubers irradiated at doses higher than 150 Gy, showed sensitivity index ratio of less than 10. Sensitivity Index was suggested for irradiated samples at doses slightly above 150 Gy.  Irradiated samples at doses less than 150 Gy should be subjected for further investigation using thermoluminescence (TL) analysis. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated tubers and bulbs.

ABSTRAK

Teknik PSL digunakan untuk mengesan kentang dan bawang yang disinar selepas penyimpanan selama 1 minggu, 3 dan 6  bulan  dalam keadaan gelap. Hasil pengukuran secara saringan dan kalibrasi PSL berjaya membezakan antara kentang dan bawang yang tidak disinar dan disinar pada dos 50, 150 dan 500 Gy.  berdasarkan nilai kiraan photon/60s.  Kestabilan signal PSL umbisi disinar (150 dan 500 Gy) menunjukkan sedikit penurunan selepas 6 bulan penyimpanan tetapi masih melebihi nilai nilai ambang 5000 photon counts/s (PCs) untuk kentang dan bawang yang disinar. Nilai PCs mempamerkan kecenderungan peningkatan dengan dos sinaran sehingga dos 500 Gy. Sampel menunjukkan intensiti yang tinggi apabila disinar. Perbezaan intensiti mungkin disebabkan oleh perberbeza kandungan dan kualiti mineral silikat yang hadir pada sampel. Kedua-dua umbisi yang disinar melebihi dos 150 Gy menunjukkan nisbah indeks sensitiviti kurang dari 10. Indek sensitiviti dicadangkan untuk sampel tersinar melebihi dos 150 Gy. Sampel kurang dari dos 150 Gy dicadangkan untuk penganalisaan lanjut menggunakan analisis termoluminesens (TL). Hasil kajian ini menyediakan pangkalan data ke atas kesesuaian teknik PSL untuk mengesan umbisi disinar di pasaran Malaysia.