Browsing by Author "Melo, Rita"
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- Assessment of gamma radiation effects on antioxidant activity of cork wastewaterPublication . Madureira, Joana; Pimenta, Andreia I.; Dias, Maria Inês; Melo, Rita; Santos, Pedro M.P.; Falcão, António N.; Cabo Verde, Sandra; Ferreira, Isabel C.F.R.; Margaça, Fernanda M.A.Cork cooking wastewater results from the process of boiling cork planks. It is an aqueous and complex dark liquor with high concentration of phenolic compounds such as phenolic acids and tannins [1, 2], which are known for their high antioxidant activity. The aim of this work is to perform a compreensive assessment of the effects of gamma radiation on the antioxidant activity of cork cooking water. The irradiation experiments were carried out at room temperature in a Co-60 experimental equipment (Prescisa 22, Graviner, Lda, UK), with an activity of 140 Tbq (3.77 kCi) and at a dose rate of 1.5 kGy/h, located at the Centro de Ciências e Tecnologias Nucleares (Portugal). Samples of wastewater were irradiated at. three distinct. doses (10, 20 and 50 KGy) and the antioxidant activity was evaluated by in vitro assays based on different mechanisms of action: DPPH radical scavenging activity, reducing power and inhibition of β-carotene bleaching. Antioxidant capacity was compared with the physico-chemical characterization [3) of cork wastewater - Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS) and Total Phenolic Content. (TP) - when exposed to gamma radiation. The obtained results point out that gamma radiation induces changes in complex compounds leading to an increase in the antioxidant capacity. These results demonstrate the potential of this technology in order to increase the added value of cork wastewaters.
- Degradation of compounds present in cork boiling water by gamma radiationPublication . Madureira, Joana; Barros, Lillian; Melo, Rita; Santos, Pedro M.P.; Falcão, António N.; Cabo Verde, Sandra; Ferreira, Isabel C.F.R.; Margaça, Fernanda M.A.Cork boiling water is an aqueous and complex dark liquor with high concentration of phenolic compounds such as phenolic acids and tannins [1, 2], which are considered biorecalcitrants [2]. Ionizing radiation has been widely studied as an alternative technology for the degradation of organic contaminants without the addition of any other (e.g.: Fenton technologies). The aim of this work was to identify the compounds present in cork boiling water and further evaluate the resulting stable degradation products after gamma irradiation. The irradiation experiments of standard solutions were carried out at room temperature using a Co-60 experimental equipment. The applied absorbed doses were 20 and 50 kGy at a dose rate of 1.5 kGy/h, determined by routine dosimeters [3]. The identification of radiolytic products was carried out by HPLC-DAD-ESI/MS. The phenolic compounds were identified by comparing their retention times and UV–vis and mass spectra with those obtained from standard compounds, when available, as well as by comparing the obtained information with available data reported in the literature. Concerning the obtained results and the literature review, the main cork wastewater components are: quinic, gallic, protocatechuic, vanillic, syringic and ellagic acids. Based on this, we used protocatechuic, vanillic and syringic acids as model compounds to study their degradation by gamma radiation in order to identify the corresponding radiolytic products. Standard aqueous solutions were irradiated and the derivatives of each model compound are represented in figure 1. The obtained results seem to demonstrate that the derivatives of the parent compounds could also be phenolic acids, since it was observed the loss of 44 u (CO2) from the [M-H]- ions. Gallic and protocatechuic acids are identified as derivatives of vanillic and syringic acids, and gallic acid as a protocatechuic acid derivative. Compound 5 ([M-H]- at m/z 169) was tentatively identified as 2,4,6-trihydroxybenzoic acid, since its fragmentation pattern (m/z 151, 125 and 107) is similar to that previously reported in literature [4]. The structure of compound 7 was proposed based on the molecular ion and its fragmentation and compound 6 remains unknown.
- Degradation of phenolic acids by gamma radiation as model compounds of cork wastewatersPublication . Madureira, Joana; Barros, Lillian; Melo, Rita; Cabo Verde, Sandra; Ferreira, Isabel C.F.R.; Margaça, Fernanda M.A.The degradation by gamma radiation of four phenolic compounds (gallic acid, protocatechuic acid, vanillic acid and syringic acid) present in cork wastewaters was studied in several treatment conditions. The irradiations were performed under different pH (natural, 3, 7 and 10) and atmospheres (aerated, N2O and O2) for isolated and aqueous mixture solutions of standard phenolic acids. The degradation of the compounds was higher in isolated than in the mixture solutions indicating a protective effect in the quaternary mixture solution. The saturation with N2O promoted the highest degradation rates for all phenolic acids in the mixture. However, at natural pH and in air it was achieved degradation efficiencies>50% for gallic, vanillic and syringic acids in isolated and mixture solutions for a treatment dose of 20 kGy. It was verified that some of the compounds are a degradation product of the others, for example gallic acid was found to be a radiolytic product of syringic, vanillic and protocatechuic acids. Two different compounds were identified as radiolytic products of the studied phenolic acids, and their fragmentation pathways were proposed. The results highlighted that ionizing radiation could be used as clean technology for pollutants degradation using doses of 20 kGy.
- Effects of gamma radiation on cork wastewater: Antioxidant activity and toxicityPublication . Madureira, Joana; Pimenta, Andreia I.; Popescu, Larisa; Besleaga, Alexandra; Dias, Maria Inês; Santos, Pedro M.P.; Melo, Rita; Ferreira, Isabel C.F.R.; Cabo Verde, Sandra; Margaça, Fernanda M.A.A comprehensive assessment of the toxicity and antioxidant activity of cork boiling wastewater and the effects of gamma radiation on these parameters was performed. Antioxidant activity was evaluated using different methodologies as DPPH radical scavenging activity, reducing power and inhibition of ß-carotene bleaching. The results have shown that gamma radiation can induce an increase on the antioxidant activity of cork boiling wastewater. Toxicity tests were performed to access the potential added value of the irradiated wastewaters and/or minimization of the impact for discharge in the environment. Two different methods for toxicity evaluation were followed, bacterial growth inhibition test and cytotoxicity assay, in order to predict the behavior of different cells (prokaryotic and eukaryotic) in the presence of cork wastewater. Non-treated cork boiling wastewater seemed to be non-toxic for prokaryotic cells (Pseudomonas fluorescens and Bacillus subtilis) but toxic for eukaryotic cells (A549 human cells and RAW264.7 mouse cells). The gamma radiation treatment at doses of 100 kGy appeared to increase the toxicity of cork compounds for all tested cells, which could be related to a toxic effect of radiolytic products of cork compounds in the wastewaters.
- Gamma irradiation effects on microbial inactivation and antioxidant activity of Melissa officinalisPublication . Meneses, Márcia; Madureira, Joana; Melo, Rita; Antonio, Amilcar L.; Cabo Verde, SandraMany herbal products are traditionally being used as medicines and nutraceuticals in different regions of the world (Kumar et al., 2010). This increased consumption of natural products has become a public health problem. The concern in the safety of these products is due, in part, to the possible presence of pathogenic bacteria and fungi producing mycotoxins (Prado et al., 2009). The medicinal plant, also known as lemon balm, analysed in the present study is used in traditional medicine to treat or to relieve nervous disturbance of sleep and functional gastrointestinal disorders although there are a great variety of phytopharmaceutical preparations containing this plant or its extracts (Kennedy et al., 2002; López et al., 2009). Consequently the evaluation of the hygienic quality of medicinal plants, as well the use of decontamination methods are significant steps towards the consumer safety and therapeutical efficiency (Soriani et al., 2005). The obtained results suggested that the gamma irradiation treatment could be advantageous in improving microbial safety of M. officinalis with the potential added-benefit of increasing its antioxidant content. The effect of higher irradiation doses on M. officinalis will be further investigated, in an attempt to augment the reduction of the microbial population.
- Gamma radiation induces degradation of phenolic acidsPublication . Madureira, Joana; Barros, Lillian; Melo, Rita; Cabo Verde, Sandra; Ferreira, Isabel C.F.R.; Margaça, Fernanda M.A.The aim of this work was to study the degradation by gamma radiation of four phenolic acids (gallic acid, protocatechuic acid, vanillic acid and syringic acid) that are recalcitrant pollutants present in cork wastewaters [1]. The irradiations were carried out at room temperature using a Co-60 experimental equipment, under different pH (natural, 3, 7 and 10) and atmospheres (aerated, N2O and O2) for isolated and aqueous mixture phenolic acids’ solutions. The applied absorbed doses were 5-20 kGy at a dose rate of 1.5 kGy/h. The degradation of phenolic acids was analyzed by HPLC-DAD and the identification of radiolytic products was carried out by LCDAD- ESI/MS. The obtained results indicated that the degradation of the compounds was higher in isolated than in the mixture solutions suggesting a protective effect in the quaternary mixture solution. The N2O saturation promoted the highest degradation rates in the mixture, at natural pH, however in aerated conditions it was achieved degradation efficiencies >50% for a treatment dose of 20 kGy. Concerning the identification of the radiolytic products two different compounds were identified (trihydroxybenzoic acid, [M-H]- at m/z 169, and methyl gallate, [M-H]- at m/z 183) as radiolytic products of the studied phenolic acids (Figure 1). The degradation mechanisms of the studied phenolic acids was proposed. The results highlighted that ionizing radiation could be used as clean technology for pollutants degradation using doses of 20 kGy.
- Impacto reológico na descontaminação microbiológica de uma emulsão alimentar: pasteurização vs radiação gamaPublication . Oliveira, Beatriz; Lima, Maria Gabriela; Dores, V.; Cabo Verde, Sandra; Marcos, H.; Silva, Tânia Cristina; Nunes, I.; Melo, Rita; Antonio, Amilcar L.; Botelho, M. LuísaO presente trabalho teve como objectivo comparar o tratamento de emulsões alimentares por radiação ionizante (e.g. radiação gama) com o tratamento térmico pasteurização. Para tal, foram avaliados parâmetros microbiológicos (e.g. caracterização da carga microbiana da fase aquosa e produto final), reológicos (e.g. viscosidade na fase aquosa e textura no produto final) e sensoriais (no produto final). Os resultados obtidos sugerem que não existem diferenças significativas entre o produto pasteurizado e o produto irradiado, quer em termos de viscosidade, quer a nível de textura. Também na análise sensorial se denotou uma aceitabilidade semelhante entre os produtos. Ambos os parâmetros têm elevada relevância na aceitabilidade do produto por parte do consumidor. Relativamente à avaliação microbiológica, o tratamento por radiação gama demonstrou uma maior eficiência de inactivação microbiana mais eficaz que o tratamento térmico por pasteurização. Os resultados obtidos evidenciam a potencialidade da aplicação da radiação gama como tratamento de conservação para as emulsões alimentares. This study aimed to compare the treatment of food emulsion by ionizing radiation (e.g. gamma radiation) and heat treatment (e.g. pasteurization). It were evaluated microbiological (e.g. bioburden of aqueous phase and the final product), rheological (e.g. viscosity of the aqueous phase and texture in the final product) and sensory (final product) parameters. The results obtained, from viscosity and texture analysis point out to no significant differences between the product pasteurized and irradiated. Also in the sensory analysis were observed a similar acceptability between products. Both parameters have high relevance in the acceptability of the product by the consumer. The microbiological evaluation indicated a higher microbial inactivation efficiency by, by gamma radiation treatment than by pasteurization. The obtained results highlight the potential application of gamma radiation as a treatment for the conservation of food emulsions.
- Impacto reológico na descontaminação microbiológica de uma emulsão alimentar: pasteurização vs. radiação gamaPublication . Oliveira, Beatriz; Lima, Maria Gabriela; Dores, V.; Cabo Verde, Sandra; Marcos, H.; Nunes, I.; Melo, Rita; Antonio, Amilcar L.; Botelho, M. LuísaO presente trabalho teve como objectivo comparar o tratamento de emulsões alimentares por radiação ionizante (e.g. radiação gama) com o tratamento térmico pasteurização. Para tal, foram avaliados parâmetros microbiológicos (e.g. caracterização da carga microbiana da fase aquosa e produto final), reológicos (e.g. viscosidade na fase aquosa e textura no produto final) e sensoriais (no produto final). Os resultados obtidos sugerem que não existem diferenças significativas entre o produto pasteurizado e o produto irradiado, quer em termos de viscosidade, quer a nível de textura. Também na análise sensorial se denotou uma aceitabilidade semelhante entre os produtos. Ambos os parâmetros têm elevada relevância na aceitabilidade do produto por parte do consumidor. Relativamente à avaliação microbiológica, o tratamento por radiação gama demonstrou uma maior eficiência de inactivação microbiana mais eficaz que o tratamento térmico por pasteurização. Os resultados obtidos evidenciam a potencialidade da aplicação da radiação gama como tratamento de conservação para as emulsões alimentares.
- 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.