Irradiacao de especiarias. Metodos de deteccao do tratamento e estudo das alteracoes em que se baseiam

Five spices purchased from portuguese retailers were studied: white and black-pepper, sweet-paprika, cinnamon and turmeric. They were chemically and microbiologically characterised. The pre-packed spices were treated by #gamma#-radiation (cobalt-60), with the doses of 3,5,7 and 10 kGy, and the changes of microbiological load evaluated. The maximum absorbed dose recommended by the Codex Alimentarius (10 kGy) was effective in the decontamination. Two methods of identification were studied: electron paramagnetic resonance (EPR) and viscosity. Paramagnetic species detected by EPR, formed during the ionising irradiation, are shorter lived than the shelf-life of the spices which constitutes a limitation for this methodology. The viscosity of alkaline heat-treated aqueous suspensions had presented promising results for the spices with high starch content - White and black-pepper. Under the conditions of the methodology developed, it was possible to estimate with an accuracy of #+-#1.5 kGy for white-pepper and #+-#2.5 kGy for black-pepper the previous dose of irradiation. Another rheological approach was used for the five spices which allowed the observation of different behaviours. The starch from #gamma#-irradiated white and black-pepper was characterised by size exclusion chromatography (SEC) and compared with that from non-irradiated samples. The results obtained could be attributed to the formation of few cross-links between chains of amylase and amylopectinAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga