Thermally (TL) and Infrared Stimulated Luminescence (IRSL) analysis of polyminerals from commercial spices

E.CRUZ-ZARAGOZA; J. MARCAZZÓ; S. GASTELUM; S. GUZMAN; V. CHERNOV

Hermosillo, Sonora

Congreso; XVI Reunión Universitaria de Investigación en Materiales; 2011

Radiation processing improves the hygienic quality and extends the shelf life of the foodstuffs. Although the wholesomeness of irradiated food is no longer a question there is a need for their irradiation detection in the trade of food [1,2]. In this frame, irradiated food detection research program at ICN-UNAM, the luminescence properties of the inorganic polymineral separated from the commercial black pepper (Piper nigrum) and Jamaica flower (Hibiscus sabdariffa L.) are reported. The similarities and differences between thermoluminescence (TL) and infrared stimulated luminescence (IRSL) behavior are pointed out for both spices. Fine grain powder, 10 and 149 µm, was analyzed by XRD. Quartz mineral phase was identified as the main component in the mineral fraction of black pepper, while the components for Jamaica flower were quartz (45%), plagioclase (35%), and Illite (20%). After-glow (AG) and infrared stimulated luminescence (IRSL) measurements show high decreases in the intensity of the first glow peak (100 °C) which could be related to the quartz present in the polymineral samples. The traps that give rise to this peak (100º C) seem the responsible for the IRSL signal of the black pepper. A broad glow peak appears about 150 to 370 °C in both spices. The thermal cleaning (Figures) of TL peaks reveals a possible continuous distribution of traps may be present. The complex structure of the glow curves were deconvoluted by six peaks by using the General Order Kinetics model and the kinetics parameters with a good Figure Of Merit (0.8%) were calculated