Abstract

CRUZ-ZARAGOZA, E. et al. Thermoluminescence response of the polymineral fraction from hibiscus sabdariffa L foodstuffs. Rev. mex. fis. [online]. 2011, vol.57, suppl.1, pp.44-49. ISSN 0035-001X.

Food processed by ionizing irradiation is a safe technology and has been recognized by the FAO/WHO Codex Alimentarius Commission. It is an excellent method to prevent food spoilage and foodborne diseases by inhibiting the growth of microorganisms and slowing down ripening. The widespread use of food irradiation treatments that include spices, dry vegetables, grains and fruits make relevant the developing of methods for identification and analyses of foodstuffs processed by irradiation. The present work focuses on the thermoluminescence property of Mexican Roselle flower previously irradiated for detection purposes. The polymineral content of irradiated commercial Roselle flower (Hibiscus sabdariffa L.) was extracted and analyzed by thermoluminescence (TL). The X -ray diffraction analyses showed that quartz and albite composition of the polymineral fraction. Different grain sizes; 10, 53, 74 and 149 μm, were selected for the TL analyses. The TL glow curves depended on the grain sizes. The glow curves depicted two peaks around 92 and 120°C. The first peak was ascribed to quartz and the broad part of the glow curves (120-250°C) seems to correspond to the albite. Because the complex structure of the TL glow curves from polyminerals the kinetic parameters were calculated by a fitting process using a deconvolution method based on a non-linear least-squares Levenberg-Maquart. The values ofthe activation energy were found to be at 0.79-1.05 eV and 0.79-1.04 for 53 μm and 250 μm, respectively. The TL properties ofthe samples were determined including dose response, reproducibly, fading and UV light bleaching.

Keywords : Food irradiation; Roselle flower (Hibiscus sabdariffa L.); polyminerals; kinetics parameters.

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