Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the...Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the world,compliance of different regulations relating to use of technology in different countries and demand of consum- ers for clear labelling of irradiated foods,there is need for the development of analytical methods to detect radiation treatment of food.Among several methods studied so far,thermoluminescence (TL) is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles.In this study,the irradiated and unirradiated wheat and rice samples were analyzed using the TL method.The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture (NIFA),Peshawar.The mineral contaminants were isolated by jet water,ultrasonic treatment,and density gradient.TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50—500℃using a TL reader.Generally,the glow curves for irradiated samples showed much higher TL intensities (TL_1) than the unirradiated samples.The results were normalized by re-irradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves (TL_2).The ratio of the area of first glow curve to that of second glow curve (TL_1/TL_2) was calcu- lated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples.Finally,the shapes of the glow curves for irradiated and unirradiated samples were also analyzed.On the ba- sis of these results (comparison of TL-intensities,TL_1/TL_2 ratios and shapes of the glow curves),all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.展开更多
Dosimetric characterization of aqueous solution of basic fuchsin was studied spectrophotometrically for possible application in the low-dose food irradiation dosimetry. Absorption spectra of unirradiated and irradiate...Dosimetric characterization of aqueous solution of basic fuchsin was studied spectrophotometrically for possible application in the low-dose food irradiation dosimetry. Absorption spectra of unirradiated and irradiated solu- tions were determined and the decrease in absorbance with the dose was noted down. Radiation-induced bleaching of the dye was measured at wavelengths of maximum absorption λmax (540nm) as well as 510nm and 460 nm. At all these wavelengths, the decrease in absorbance of the dosimeter was linear with respect to the absorbed dose from 50 Gy to 600 Gy. The stability of dosimetric solution during post-irradiation storage in the dark at room temperature showed that after initial bleaching during first ten to twenty days, the response was almost stable for about 34 days. The study on the effect of different light and temperature conditions also showed that the response gradually decreased during the storage period of 34 days, which shows that basic fuchsin dye is photosensitive as well as thermally sensitive.展开更多
文摘Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the world,compliance of different regulations relating to use of technology in different countries and demand of consum- ers for clear labelling of irradiated foods,there is need for the development of analytical methods to detect radiation treatment of food.Among several methods studied so far,thermoluminescence (TL) is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles.In this study,the irradiated and unirradiated wheat and rice samples were analyzed using the TL method.The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture (NIFA),Peshawar.The mineral contaminants were isolated by jet water,ultrasonic treatment,and density gradient.TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50—500℃using a TL reader.Generally,the glow curves for irradiated samples showed much higher TL intensities (TL_1) than the unirradiated samples.The results were normalized by re-irradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves (TL_2).The ratio of the area of first glow curve to that of second glow curve (TL_1/TL_2) was calcu- lated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples.Finally,the shapes of the glow curves for irradiated and unirradiated samples were also analyzed.On the ba- sis of these results (comparison of TL-intensities,TL_1/TL_2 ratios and shapes of the glow curves),all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.
文摘Dosimetric characterization of aqueous solution of basic fuchsin was studied spectrophotometrically for possible application in the low-dose food irradiation dosimetry. Absorption spectra of unirradiated and irradiated solu- tions were determined and the decrease in absorbance with the dose was noted down. Radiation-induced bleaching of the dye was measured at wavelengths of maximum absorption λmax (540nm) as well as 510nm and 460 nm. At all these wavelengths, the decrease in absorbance of the dosimeter was linear with respect to the absorbed dose from 50 Gy to 600 Gy. The stability of dosimetric solution during post-irradiation storage in the dark at room temperature showed that after initial bleaching during first ten to twenty days, the response was almost stable for about 34 days. The study on the effect of different light and temperature conditions also showed that the response gradually decreased during the storage period of 34 days, which shows that basic fuchsin dye is photosensitive as well as thermally sensitive.
