EDUARDO DE MOURA
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Resumo IPEN-doc 26555 Effect of ionizing irradiation on tilapia (Oreochromis niloticus) skin2011 - FROSE, C.A.P.; MOURA, E.; YAMAGUISHI, R.B.; SOMESSARI, E.S.R.; SILVEIRA, C.G.; LEME, E.; GERALDO, A.B.C.; MANZOLI, J.E.The culture of tropical tilapia (Oreochomis niloticus), as a non-native freshwater fish specie in Brazil, have had importance in the last decade due its fast growing, fast reproduction characteristics, high tolerance of climate variations in our country and high disease resistance. The high demand of whole fish or fillets is related to its good taste. Althought, its skin, that represents from 4.5 % to14 % of fish weight, is a byproduct that is generally discared or sold at low cost to feed mills. The general animal skin composition comprises protein, water, minerals and fatty matter where the relative portions of these materials depends of upon animal specie, age, breed, feeding and other animal habits. The putrecible raw animal skins can be chemically and physically treated to make it in non-putrecible stabilized material; it results in a soft and flexible polymeric material. The chemical process to obtain this material generally involves a crosslinking of carboxyl groups or amino groups of skin proteins and the chemical reactive specie [1]. Also, physical process as UV irradiation have been successfully employed to crosslink collagenous biomaterials and thus, improved some mechanical characteristics [2]. The goal of this work was to study the tilapia skins exposed to ionizing irradiation from electron beams. The raw skins and the chemically degreased skins were the studied materials. The tensile strenght and elongation at break were the mechanical parameters evaluated. The optical microscopy was used to evaluate some histological characteristics in irradiated and non-irradiated samples. Also, the polymeric product obtained when skins are treated with oxidizing ions were used to compare some results. The tilapia raw skins were kindly available by APTA, a governmental agribusiness technological agency. These skins were scales free, slighted and frosted. The skins were irradiated in atmosphere air on a Job 188 Dynamitron® Electron Beam Accelerator with 1.5 MeV energy under comprised doses of 20 kGy and 40 kGy and dose rates of 2.2 kGy/s and 7.4 kGy/s. The mechanical parameters were measured at a Lloyd LXR tensile tester at a crosshead speed of 10.00 mm/min. Irradiated samples shows high integrity and high tensile strength in comparison to the polymeric product obtained by oxidizing ions reaction. These results are discussed.Artigo IPEN-doc 26276 Ionizing radiation applied to one step conversion from different sources of chitin2019 - FERREIRA, MAIARA S.; MOURA, EDUARDO; GERALDO, AUREA B.C.Chitosan is a polyssacharide obtained from chitin’s molecule deacetylation which is the main constituent of some fungi species and the exoskeleton of crustaceans, insects and mollusks. Frequently the production of chitosan is from the crab shells and shrimps that are byproducts of the fishing industry, so it is highly dependent on seasonality. Therefore, finding new chitin’s sources become important. The amino groups present in chitosan give important biological properties such as biodegradability and biocompatibility, activity/immunological effects and antibacterial healing. The chitosan deacetylation process is an aggressive reaction since it requires the attack of chitineous substrate in hot and high concentrated alkalis solution by 1 to 17 hours. It is possible to reduce reagent concentration and time using high-energy irradiation (gamma rays and electron beam). The advantages of radiation use in high-energy include: the absence of chemical initiators, the process can be performed at room temperature and there is no need for the use of solvents. In this work, crab shell, shrimps, squid glads and blattaria were used in order to compare the quality of chitosan found in each animal source. After pretreatment, which include the steps of demineralization and deproteinization, the samples were irradiated at a dose of 20 kGy (gammacell) in order to reduce the deacetylation time. The chitosan from the used chitin sources was characterized by FTIR analysis and its degree of deacetylation was determined.