Browsing by Author "Teubig, P."
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- Influence of gamma radiation on the antioxidant properties of edible chestnutsPublication . Antonio, Amilcar L.; Ferreira, Isabel C.F.R.; Bento, Albino; Teubig, P.; Botelho, M. LuísaAs seasonal products chestnut have to be postharvest treated to increase the shelf-life. Several problems are associated with traditional preservation methods. These are a decreasing in quality due to dehydration and contamination with insects and microbes including secondary metabolites, e.g.: mycotoxin. The most common preservation method for chestnuts is the use of chemical fumigation with methyl bromide. Methyl bromide is a toxic agent and has been banned according to the Montreal Protocol due to its adverse effects on human health and the environment. Following the recommendations of a scientific committee of the United Nations Environmental Program (UNEP), Methyl Bromide Technical Options Committee (MBTOC), food irradiation is a possible feasible option. This pre1iminary study evaluated the influence of gamma irradiation in the antioxidant potential of chestnut fruits and skins. Results showed that irradiation of chestnuts at low irradiation doses, 0.27 kGy and 0.54 kGy, could affected the skin and fruit properties differently.
- Radiation technology: processes and products: concepts and applicationsPublication . Cabo Verde, Sandra; Melo, Rita; Marcos, H.; Silva, Tânia Cristina; Nunes, I.; Dores, V.; Antonio, Amilcar L.; Reis, J.; Teubig, P.; Santos, Pedro M.P.; Botelho, M. LuísaThe radiation technology process is based on the physics and chemistry of radiation interactions with matter and the quantities that are used for monitoring radiation energy depositions. The modifications in a material exposed to ionizing radiation are caused by deposition of energy such as in thermal or chemical processes. However in any thermal or chemical process the energy transfer is relatively small. Taking into account that the binding energies are generally below 12 eV any chemical bond may be broken and/or potential chemical reactions happen during the exposure to ionizing radiation. The impact of primary radiation energies (>10 keV, <10 MeV) could lead to the degradation and complex interactions with matter wich produce a cascade of reactions of secondary lower energies. Ionizing radiation with wavelengths less than 10^-10 m, such as gamma-rays, X-rays and electron beams have a higher energy, causing electron transitions and atom ionization, but the energy imparted in the system is not eneough to change the nucleus into a radioactive isotope. The primary radiation energies are produced by electron beam accelerators and electromagnetic radiation (X and gamma rays) are produced by machines or by radioisotopes such as Cobalt-60 or Caesium-137. Ionizing radiation is a clean and environment friendly energy and could be applied to a large range of applications on biology and chemistry fields. Some applications and their ranges of absorbed doses usually applied will be discussed.
- The implementation of radiation technology program in PortugalPublication . Botelho, M. Luísa; Cabo Verde, Sandra; Melo, Rita; Marcos, H.; Silva, Tânia Cristina; Nunes, I.; Dores, V.; Antonio, Amilcar L.; Reis, J.; Teubig, P.; Santos, Pedro M.P.The development of ionizing radiation pplications for Industrial purposes in Portugal began near of 1982 with the support of IAEA. The main steps to put forward prior to the implementation were the sitting and the design study in order to build up the facility. Subsequently, the main parameters to be achieved were the construction, the commissioning, the operation, the maintenance and the foreseen decommission. Once a quality system for the gamma facility was established, the following stage is to develop, validate and control the terilization/disinfection process. The research activities carried out in the UTR have been closely related with the main applications of this technology namely, the sterilization of medical devices and pharmaceuticals and other products’ decontamination. Recently, a research Cobalt-60 equipment was upgraded and a LINAC was implemented in order to sustain the R&D. Fundamental and development research is ngoing in order to understand the irradiation mechanisms of action and to apply the technology with safety and quality patterns.