The purpose of this research was to determine the concentrations and bioaccessibility of metals in urban playground soils in the province of New Brunswick. Ten parks each were selected for sampling in Fredericton and Saint John, and a duplicate sample was taken from one park in each city. Metal bioaccessibility was determined by an in vitro physiologically based extraction test (PBET). The risk associated with exposure to selected metals (including As, Ba, Cd, Co, Cu, Pb, Ni and Zn) in soil from the urban parks in New Brunswick studied was fairly low based on the total metals concentrations and bioaccessibility data obtained in this study.

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Determining accurate exposure estimates and subsequent risk of hydrophobic organic contaminants (HOCs) in aquatic sediments requires measuring the bioavailable and/or bioaccessible concentration in sediment; as total extractable concentrations have not been found to produce accurate results. Organic carbon normalization was originally proposed as a means of accounting for the bioavailable concentration by estimating the chemical activity of the contaminant expressed as the freely dissolved chemical concentration in the interstitial water, thus correcting exhaustive extractable concentrations for the sorbing phase of sediments. Organic carbon normalization often fails, however, to accurately reflect exposure as other environmental variables (i.e. organic carbon composition, aging time of contaminants in the environment) alter desorption, such that changes in chemical activity as represented by the interstitial water concentrations are not controlled by organic carbon alone. Desorption-based samplers, such as single-point Tenax extractions (SPTE), provide a clearer estimate of bioaccessibility than organic carbon normalization by serving as a sink for desorbing compound for the length of the extraction. In this way, SPTEs account for all the factors affecting desorption and the resulting interstitial water concentrations, providing estimates of the chemical concentration that will become available for exposure in a given time frame. The utility of SPTEs as an exposure metric has been demonstrated many times in the literature through estimates of bioaccumulation and development of toxicity benchmarks. The simplicity, accuracy, and robust nature of this technique suggests this tool could serve as an ideal means of evaluating exposure and risk of HOCs, and more specifically acutely toxic compounds, such as pyrethroids, during environmental sampling and risk assessments of aquatic sediments. However, the use of this method is limited within the scientific literature and absent from most risk assessment protocols. The reasons for its limited use are linked to poor methodological standardization, an absence of understanding of environmental and methodological variation on estimates of bioaccessibility provided by SPTEs, and only a vague idea of how Tenax extractions relate to other exposure metrics, such as passive samplers. Therefore, the dissertation goals were to: evaluate the effects of variation in the SPTE, specifically the Tenax mass to organic carbon mass (Tenax:OC) ratio, on exposure estimates of pyrethroids (Chapter Two); understand how methodological and environmental variation affect the relation of SPTEs to bioaccessibility represented by desorption of pyrethroids from the labile desorbing fraction (Frap) (Chapter Three); and, determine how bioavailability and bioaccessibility are linked through evaluation of chemical activity expressed as the freely dissolved chemical concentrations provided by SPTEs, passive sampler concentrations, and Frap (Chapter Four). The most variable aspect of the SPTE within the Tenax literature is the Tenax:OC ratio used during 24 h SPTEs. Yet, no study has evaluated how altering this ratio may affect 24 h SPTE concentrations and thus, biological exposure estimates provided by Tenax extractions. Manipulating the Tenax:OC ratio used during 24 h SPTEs of pyrethroids from laboratory-spiked and field-contaminated sediments revealed the effect of this variation was such that Tenax extractable pyrethroid concentrations varied between 0.85 to 3.91-fold between the highest and lowest ratios examined. The results of this experiment suggest most of the variation in toxicological endpoints derived using Tenax extractable concentrations is due to toxicokinetic and toxicodynamic variation in biological responses across sediments and not due to methodological variation of the Tenax extraction (Chapter Two). The utility of the SPTEs as an estimate of exposure is linked to the ability of SPTEs to reflect the chemical concentration that desorbs from sediment. As many factors, such as the organic carbon content, aging time of sediments, and hydrophobicity of the compounds, can impact desorption, understanding how these factors affect the relationship of SPTEs to biological exposure is needed to evaluate the consistency of the Tenax extraction. The relation of SPTE concentrations to Frap was proportional despite changes in organic carbon content of the sediment being extracted, the hydrophobicity of the pyrethroids, or the Tenax mass used during the extraction, such that the SPTE concentration was equal to 1.46 ± 0.03 times the pyrethroid concentration in Frap (Chapter Three). Only the aging time of the pyrethroids in the sediment significantly affected this relationship, as desorption from longer aged sediments slowed, reducing the 24 h SPTE concentration to Frap ratio by -0.0027/d (Chapter Three). The results of Chapters Two and Three demonstrate the consistency of the Tenax extraction as a representation of biological exposure of pyrethroids in sediment. However, other aspects limit the widespread use of the Tenax method, particularly the relation of this technique to more widely accepted bioavailability-based metrics, such as passives samplers. Tenax extractions are often disregarded in favor of passive samplers as the link between bioavailability-based metrics, chemical activity, and exposure is well understood. However, as SPTEs and passive samplers both demonstrate a clear relation to bioaccessibility through estimates of Frap, it was hypothesized that both exposure metrics represent the same chemical fraction of sediment, and as such could be considered complementary tools for evaluating biological exposure through estimates of the freely dissolved interstitial water concentration. This was confirmed when comparisons of the chemical activity expressed as the interstitial water concentration at equilibrium were done using the chemical concentration estimated by Frap, a passive sampler, and SPTEs. Strong linear relationships (p<0.0001) were found among all three metrics, such that Frap, passive sampler, or 24 h SPTE concentrations of pyrethroids from sediment provide comparable estimates of the freely dissolved interstitial water concentration in sediment. Thus, Tenax extractions and passive samplers, which describe the bioaccessible and bioavailable concentrations, respectively, describe the same chemical fraction in sediment; the labile desorbing fraction. This dissertation provides further concrete evidence that the SPTE offers a robust, rapid, and cost-effective means of evaluating exposure of acutely toxic compounds in sediment. With data that link this exposure metric to more widely accepted methods, such as passive samplers, and demonstrate the robust character of the SPTE, the research presented here should further the use of the SPTE within the scientific and risk assessment communities.

MELO, Luciana Sousa. Avaliação da bioacessibilidade “ In Vitro” de macro e microminerais em Amaranto, Multimistura e Quinoa. 2015. 86 f. Dissertação (mestrado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2015. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-04-05T18:34:04Z No. of bitstreams: 1 2016_dis_lsmelo.pdf: 1492346 bytes, checksum: 5af6196da0a229a248b591312c11c8fe (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-05-23T17:28:15Z (GMT) No. of bitstreams: 1 2016_dis_lsmelo.pdf: 1492346 bytes, checksum: 5af6196da0a229a248b591312c11c8fe (MD5) / Made available in DSpace on 2016-05-23T17:28:15Z (GMT). No. of bitstreams: 1 2016_dis_lsmelo.pdf: 1492346 bytes, checksum: 5af6196da0a229a248b591312c11c8fe (MD5) Previous issue date: 2015 / For the proper functioning of the human body are essential various nutrients, among these are the macro and micro. The minerals are important in the physiological and biochemical functions of the human body. Insufficient intake can cause deficiencies, on the other hand excessive intake may be toxic. For the recommended doses of each mineral we need to consume fruits, vegetables, grains and vegetables. The food supplement is useful when selecting foods in a diet has some nutrient deficiencies. However, not all nutrient contained in a food supplement can be made available to be absorbed by the body, ie bioaccessible. Thus, the study of mineral bioaccessibility in this array is necessary. Thus, the aim of this study was to evaluate the in vitro bioaccessibility of macro and micro minerals in samples of amaranth, and quinoa multimixture, used as a food supplement. To determine the total content of minerals, samples were digested in oven with microwave cavity and the content of mineral measured by ICP OES. To evaluate the bioaccessibility, the samples were subjected to in vitro gastrointestinal digestion. The bioaccessible fraction was digested in the digester block prior to analysis by ICP OES. The three studied food supplements, as the total contents, are rich in Cu, Fe, Mg, Mn and P, and only multimixture is a source of Ca and Zn, with respective contributions of 19.1% and 20.1%, considering : source (15-29% of RDA) and rich (at least 30% of RDA). However, the amount of Cu and Mn amaranth and quinoa multimixture exceeded the UL (upper tolerable limit intake). After in vitro digestion, there was a marked reduction in the contribution to the RDA of all the three minerals and food supplements. The bioaccessibility study results show that the amaranth is a source of Fe, Mg and Mn-rich P and Cu; multimixture is the source of Fe, Mn and high in P and quinoa source of Mn and high in P and Cu. The application of PCA (principal component analysis) showed that multimixture has higher content of K, Cu, Mg, Zn, Fe and Ca and amaranth Mg and P (total contents) and the bioaccessibility, amaranth was more bioaccessible of Ca, Fe and Mg; multimixture K and Zn; and amaranth and quinoa, similarly, Cu, Mn and P. Regarding the content of phytic acid in the samples was observed that the greater the anti-nutritional content of such lower bioaccessibility of Ca, Cu, Fe and Mn. This work shows that the study of bioaccessibility and anti-nutritional factors performed to amaranth, and quinoa multimixture were relevant, since they can be inserted more precise information on the absorption of minerals in nutritional composition tables of these foods. / Para o bom funcionamento do corpo humano são essenciais vários nutrientes, dentre estes estão os macro e microminerais. Os minerais são importantes nas funções fisiológicas e bioquímicas do corpo humano. A ingestão insuficiente pode causar deficiências, por outro lado a ingestão excessiva pode ser tóxica. Para obter as doses recomendadas de cada mineral é preciso consumir frutas, verduras, cereais e hortaliças. A complementação alimentar é útil quando a seleção de alimentos em uma dieta possui carências de algum nutriente. Contudo, nem todo nutriente contido em um complemento alimentar pode estar disponível para ser absorvido pelo organismo, ou seja, bioacessível. Logo, o estudo da bioacessibilidade de minerais nessa matriz faz-se necessário. Desse modo, o objetivo deste trabalho foi avaliar a bioacessibilidade in vitro de macro e microminerais em amostras de amaranto, multimistura e quinoa, usadas como complemento alimentar. Para a determinação dos teores totais dos minerais, as amostras foram digeridas em forno de micro-ondas com cavidade e o teor dos minerais medidos por ICP OES. Para avaliação da bioacessibilidade, as amostras foram submetidas à digestão gastrointestinal in vitro. A fração bioacessível foi digerida em bloco digestor antes das análises por ICP OES. Os três complementos alimentares estudados, quanto aos teores totais, são ricos em Cu, Fe, Mg, Mn e P, e apenas a multimistura é fonte de Ca e Zn, com respectivas contribuições de 19,1% e 20,1%, considerando: fonte (15-29% da RDA) e rico (no mínimo 30% da RDA). No entanto, a quantidade de Cu e Mn no amaranto, multimistura e quinoa excedeu a UL (Limite superior tolerável de ingestão). Após digestão in vitro, houve uma redução acentuada na contribuição para a RDA de todos os minerais e nos três complementos alimentares. Os resultados do estudo de bioacessibilidade mostram que o amaranto é fonte de Fe, Mg e Mn e rico em P e Cu; a multimistura é fonte de Fe, Mn e rica em P e a quinoa fonte de Mn e rica em P e Cu. A aplicação da PCA (análise de componentes principais) mostrou que a multimistura possui maior teor de K, Cu, Mg, Zn, Fe e Ca e o amaranto de Mg e P (teores totais) e com a bioacessibilidade, o amaranto foi mais bioacessível em Ca, Fe e Mg; a multimistura em K e Zn; e o amaranto e a quinoa, de forma similar, em Cu, Mn e P. Quanto aos teores de ácido fítico nas amostras observou-se que quanto maior é o teor desse antinutricional menor a bioacessibilidade de Ca, Cu, Fe e Mn. Este trabalho mostra que o estudo de bioacessibilidade e dos fatores antinutricionais realizados para amaranto, multimistura e quinoa foram pertinentes, uma vez que podem ser inseridas informações mais precisas quanto à absorção de minerais em tabelas de composição nutricionais desses alimentos.

Vitamin D deficiency is an epidemic issue in all age groups in Western countries and that affects both skeletal and non-skeletal functions. Even with the wide application of food fortification, vitamin D deficiency tends to increase continuously. Being hydrophobic in nature, vitamin D has poor solubility; thereby it negatively affects its absorption and bioavailability when compared to other hydrophilic dietary compounds. The need to develop a novel strategy is of greater importance to enhance its bioavailability and thereby improving vitamin D level in the body. In this study, lipid-based delivery of oil-in-water nanoemulsion (diameter < 200nm) was utilized to improve the bioaccessibility and oral bioavailability of vitamin D3. First, we examined the in vitro relative bioaccessibility of nanoencapsulated vitamin D3 using a simulated gastrointestinal system. The study results showed that nanoemulsion-based delivery system significantly increased the relative bioaccessibility by 3.94 fold when compared to the coarse emulsion (diameter >200nm), as indicated by the concentration of vitamin D3 in the mixed micelles. To evaluate the in vivo bioavailability of vitamin D3 an animal study was conducted. Mice were assigned randomly to three groups: vitamin D3 nanoemulsion (n=6), coarse emulsion (diameter > 200nm) (n=6) and vehicle (nanoemulsion without vitamin D3) (n=3), which is the control group. After 3-days of feeding emulsion by mixing in drinking water, the serum 25(OH)D3, a biomarker of vitamin D availability, was measured using immunoassay. We found that serum 25(OH)D3 level in animals fed with vitamin D3 nanoemulsion was significantly higher than in those animals fed with coarse emulsion (22.7 ± 1.10 ngmL-1 vs 17.92 ± 2.82 ngmL-1). It indicated that nanoemulsion improved the in vivo bioavailability by 28%. These results showed that the nano-based delivery systems can be utilized to improve vitamin D level, and further human studies are warranted for its application to the human population in order to improve the vitamin D status.

This study investigates the interactions between dissolved trace metals and plastic debris under controlled laboratory conditions by using polyethylene pellets as a model plastic particle. Specifically, the study compared virgin pellets sourced from a local moulding plant with those collected from local beaches and subjected to aging, attrition and deposition of extraneous material. Pellets collected from the coastline of Southwest England were mainly polyethylene according to Fourier transform infra-red spectroscopy (FTIR), although occasional polypropylene pellets were present. Additionally, FTIR was used to identify the extent of degradation of pellets according to a photo-oxidation index derived from the relative magnitudes of specific absorbance peaks, and suggests pellet colour may give an indication of polymer degradation. Acid extractions of pellets collected from the coastline of Southwest England yielded metal concentrations ranging from low ng g-1 for metals such as Cd, Ni and Cr, to 7.7, 10.3 and 290 g g-1 for Cu Pb and Zn, respectively, while Al, Fe and Mn were present on beached pellets at concentrations of up to 171, 314 and 308 g g-1, respectively. Metal concentrations exhibited a high degree of inter- and intra-site variability. Correlation of metal concentrations with the photo-oxidation index indicates that pellet age is not a reliable indicator of metal concentrations. Batch experiments where metals (Cd, Co, Cr, Cu, Ni, Pb, Zn) were added to suspensions of pellets in seawater and estuarine water were performed in order to understand the extent and rates of trace metal adsorption to pellets. Langmuir modelling of adsorption isotherms in seawater indicated a range of maximum values for the accumulation of trace metals on beached pellets from 10 ng g-1 to 720 ng g-1 for Cd and Pb, respectively, in seawater spiked with 5 g L-1 of each trace metal. Langmuir constants for these relationships ranged from 0.140 (Cd) to 2.67 (Ni) mL g-1. Differences between trace metal affinities for pellets collected from the environment (beached) and those obtained directly from a plastics processing facility (virgin) were also identified. Adsorption maxima for virgin pellets ranged from < 1 ng g-1 (Cd) to 300 ng g-1 (Cr) with corresponding, respective Langmuir constants of 0.413 and 0.127 mL g-1. Adsorption of trace metals to beached pellets exceeds that to virgin pellets owing to the development of viable surface sites by photo-oxidation, biofouling and deposition of fine sediment particles on the former during exposure to environmental conditions. Adsorption kinetics were modelled successfully using a pseudo first-order reversible model. Chemical response times derived from kinetic constants ranged from 1.5 – 12 h for beached pellets and 0.2 to 4.5 h for virgin pellets, and were generally lower in seawater than in river water. Applying a similar batch approach to a system simulating an estuarine salinity gradient, the controlling effects of ionic strength and pH on the adsorption of trace metals to pellets were identified. Partitioning of Cd, Co and Ni exhibited inverse relationships with salinity, with partition coefficients (KD) decreasing from values of the order 101 to 10-1 or 10-2 mL g-1 (for beached pellets) as salinity is increased from < 0.05 to 33. Chromium exhibited contrasting behaviour within the estuarine gradient, with partitioning increasing with salinity, while Pb appears to be independent of salinity within this system. Chemical modelling was used to explain the results in context of changes in trace metal speciation which occur through the estuarine gradient. The bioaccessibility of metals on beached pellets to avian species was determined using an in vitro approach. Metal bioaccessibility in a simulated avian gastric environment comprising 10 g L-1 pepsin, 0.1 M NaCl and HCl at pH 2.8 indicated metals on pellets are labile (bioaccessibility ranges from < 10 % (Cr) to > 80 % (Mn)) and may be released readily within the digestive tract. Dissolution kinetics were modelled using the Noyes-Whitney equation, from which rate constants were determined in the range 3.1 x10-4 (Cr) to 8.7 x10-1 %-1 h-1 (Mn). This study has shown, for the first time, that plastic pellets have the potential to accumulate and transport trace metals in the marine environment. Furthermore, metal accumulation on plastic pellets is controlled by estuarine master variables such that conditions which favour or limit adsorption can be defined. Pellets present a previously unreported vector for the transport of metals in the environment, and have the potential to convey metals to organisms upon ingestion. The findings of this thesis have implications for interactions between metals and plastics more generally in the marine environment.

No Brasil, principalmente na região Amazônica, o pescado representa uma importante fonte proteica, especialmente para as populações indígenas e ribeirinhas. Por outro lado, estudos demonstram altos níveis de mercúrio (Hg), nos pescados desta região. O Hg é conhecido por ser altamente neurotóxico e por possuir efeito bioacumulativo, sendo os peixes a principal via de contaminação pelo homem. Neste trabalho, foi realizado um estudo de bioacessibilidade in vitro de Hg total em espécies originadas da Amazônia central. O Hg foi determinado utilizando-se o analisador direto de mercúrio (DMA-80, Milestone Inc) com limite de detecção de 0,003 ng. Neste trabalho foi realizada a validação da metodologia e a validação da bioacessibilidade, juntamente com os cálculos de incerteza de ambos os processos. A validação analítica seguiu o DOQ-CGCRE-008-004 (INMETRO, 2016), tendo uma incerteza de 14,7%. Já a bioacessibilidade foi validada através da análise do material de referencia certificado: Dourada 1 (Brachyplatystoma Flavicans) (IPEN-Brasil), certificado para mercúrio total (0,271 &plusmn; 0,057 &mu;g g-1) considerando a quantidade de Hg recuperado em cada etapa do processo e o balanço de massa final do processo. Os resultados obtidos demostraram a robustez do procedimento com uma recuperação >90%, coeficiente de variação < 10%, limite de detecção de 0,01 &mu;g g-1 e o limite de quantificação de 0,1 &mu;g g-1 e incerteza de 25%. O estudo indicou que a média bioacessível do mercúrio total é de 60%, para as espécies carnívoras, e 45% para os não carnívoros, demonstrando que o mercúrio presente no tecido não é absorvido pelo organismo em sua totalidade. A especiação do MeHg, indicou que do total bioacessível apenas uma parcela de 80% é MeHg demonstrando que a absorção de Hg pelo corpo pode ser ainda menor. Estudos como esse são fundamentais para influenciar nas decisões regulatórias, agências de controle dos níveis permissíveis de contaminantes nos alimentos, visto que, somente avaliar a concentração total do contaminante e não considerar a sua bioacessibilidade pode levar a um equívoco quanto à segurança de consumo do alimento. / In Brazil, mainly in the Amazon region, fish represent an important protein source mainly for the indigenous and riverside populations. On the other hand, studies showed high levels of mercury in the fish of this place. Hg is known to be highly neurotoxic and bioaccumulative. Fishes are well known for being the main source of Hg for humans. In this work, an in vitro bioaccessibility of total Hg was carried out in species originating from Amazonia central. Mercury was determined using the mercury direct analyzer (DMA-80, Milestone Inc) with a detection limit of 0.003 ng. In this work, it was performed methodological and bioaccessibility validation, and the calculation for uncertainty in both processes. Analytical validation followed the DOQ-CGCRE-008-004 (INMETRO, 2016), presenting uncertainty of 14.7%. Validation for bioaccessibility considered the recovery Hg in each step of the process and mass balance from each stage of the process. The certified reference material: Dourada - 1 (Brachyplatystoma Flavicans) (IPEN-Brazil), certified for total mercury (0.277 &plusmn; 0.057 &mu;g g-1). The result obtained show a great robustness, a recovery> 90%, the coefficient of variation <10%, limit of detection of 0.01 &mu;g g-1 and limit of quantification of 0.1 &mu;g g-1 and a uncertainty of 25%. The study indicated that the mean bioaccessible fraction of total mercury is 60% for carnivorous species and 45% of non-carnivorous species, demonstrating that not all is absorbed by the human body. The speciation of MeHg indicated that from the total bioaccessible only a portion of 80% is MeHg demonstrating that the uptake of Hg by the body may be even lower. Studies like this are fundamental to influence the regulatory decisions by agencies to control the permissible levels of contaminants in food, since evaluating the concentration of contaminants and not considering their bioaccessibility may lead to a misunderstanding regarding the safety of food consumption.

A ervilha é considerada uma fonte nutritiva de proteína vegetal de alta qualidade, sendo também reconhecida como boa fonte de vitaminas, minerais, compostos fenólicos e carboidratos. Considerando que nem todos os nutrientes presentes no alimento tornam-se acessíveis para absorção pelo organismo e considerando ainda que a irradiação é uma técnica que permite garantir a segurança e a qualidade de um alimento, controlando microrganismos patogênicos, sem afetar significativamente qualquer atributo organoléptico e sensorial, estudou-se comparativamente os efeitos gerados na bioacessibilidade de Fe e Zn, tomando como base, uma amostra controle, o processo tradicional de ervilhas congeladas e o processo utilizando radiação gama na dose de 1 kGy. As ervilhas foram avaliadas em duas condições de tempo: tempo inicial, correspondente ao tempo após o término do processamento e tempo após quinze dias de armazenamento. Verificou-se que para as amostras controle e irradiada, a bioacessibilidade do Fe foi inferior à das amostras congeladas. A bioacessibilidade do Zn para as amostras de ervilhas analisadas (controle, irradiada e congelada), apresentou um teor médio de 71%, de acordo com os testes estatísticos de ANOVA e Tukey, não houve diferença significativa entre as amostras. Este trabalho avaliou também os aspectos sensoriais (cor, textura e sabor), microbiológicos e a composição centesimal dos produtos obtidos por esses tratamentos. Nos aspectos sensoriais observou-se pela análise de variância (ANOVA) em um nível de significância de p>0,05, que não houve diferença significativa entre as amostras analisadas. Nos aspectos microbiológicos, para as análises de bolores e leveduras, contagem de aeróbios mesófilos, coliformes a 45°C, E. coli e Salmonella, verificou-se que a irradiação trouxe melhor preservação microbiológica às ervilhas quando comparadas com o congelamento e com as ervilhas apenas refrigeradas (controle). Em relação à composição centesimal, constatou-se que os resultados encontrados estão alinhados aos referenciados na literatura. / The pea is considered a nutritious source of high quality vegetable protein and is also recognized as a good source of vitamins, minerals, phenolic compounds and carbohydrates. Considering that not all the nutrients present in the food become accessible for absorption by the body, and also considering that irradiation is a technique that ensures the safety and quality of a food by controlling pathogenic microorganisms without significantly affecting any sensory attributes, this work evolved the effects generated in the bio accessibility of Fe and Zn. The study performed the comparison between the control sample (the traditional process of frozen peas) and those submitted to the process using gamma radiation at 1 kGy dose. The peas were evaluated in two conditions: initial time, corresponding to time after processing, and after fifteen days of storage. For both samples - control and the irradiated - the bioaccessibility of Fe was lower than that of the frozen samples. Considering the initial time and after 15 days of storage, the bioaccessibility of the Zn to the analyzed (control, irradiated and frozen) pea samples, was about 71% and according to the statistical tests of ANOVA and Tukey there was no difference between the samples. This work also evaluated the sensory aspects (color, texture and flavor), microbiological and the centesimal composition of the products obtained by these treatments. Sensory aspects presented no statistical differences among analyzed samples (p> 0.05). Microbiological aspects (for yeast and mold counts, aerobic mesophilic counts, Salmonella, coliforms organisms and Escherichia coli) demonstrated that the irradiation brought better microbiological preservation to the peas when compared with the freezing and the chilled peas (control). In relation to the centesimal composition, results found are in agreement with those referenced in the literature.

O ferro é um nutriente essencial para quase todas as espécies vivas e desempenha muitos papéis essenciais nos sistemas biológicos, como transporte de oxigênio, respiração, metabolismo energético, destruição de peróxidos e síntese de DNA. A deficiência de ferro no organismo pode acarretar diversas desordens fisiológicas, como por exemplo, a anemia ferropriva, que está relacionada com os níveis de hemoglobinas no sangue. Uma das maneiras de se obter as necessidades diárias desse nutriente e, dessa forma evitar as desordens fisiológicas ocasionadas pela deficiência do mesmo, é o consumo de frutas, hortaliças e carnes na dieta, uma vez que esses alimentos são ricos nesse elemento. Dessa forma, foram feitas determinações para avaliar as quantidades totais e a bioacessibilidade (através de métodos in vitro) de ferro, e de outros macro e micronutrientes, em diferentes tipos de alimentos. Além disso, visando buscar correlações com os resultados obtidos, a composição centesimal e o conteúdo de ácido fítico dos alimentos analisados também foram determinados. A concentração de ferro heme foi determinada para as amostras de fígado bovino. As quantidades totais e bioacessíveis dos elementos permitiram constatar que dentre todos os alimentos analisados, o espinafre foi o alimento que apresentou a maior quantidade de ferro total, porém verificou-se que a bioacessibilidade deste nutriente é muito baixa, sendo inferior a 20%. Isto pode estar relacionado ao elevado teor de oxalatos e fitatos (que possuem capacidade complexante) presente neste tipo de alimento. Ainda com relação a bioacessibilidade deste nutriente, o fígado bovino cru foi o alimento que apresentou a maior quantidade de ferro bioacessível. Porém, quando o mesmo é submetido ao processo de cocção, o valor da bioacessibilidade deste nutriente diminui consideravelmente, o que está correlacionado com a quebra do complexo de ferro heme presente em maior parte neste alimento, transformando-se em ferro iônico, que possui uma menor biodisponibilidade no organismo humano, pois é absorvido de forma menos eficaz que o ferro heme. Além disso, com relação aos alimentos de origem vegetal, os resultados mostraram que o potássio (K) possui as maiores quantidades totais e bioacessíveis para os alimentos analisados, resultado que se encontra em concordância com o fato deste elemento ser fundamental no crescimento de qualquer espécie vegetal. A determinação do conteúdo de ácido fítico (fitatos) permitiu evidenciar que os mesmos possuem diferentes intensidades de ligação com os cátions dos nutrientes presentes nos alimentos avaliados, e desse modo a influência dos fitatos na bioacessibilidade dos elementos analisados é maior para alguns e menor para outros, dependendo da estabilidade dos complexos formados entre os minerais e os fitatos. As concentrações de ferro heme obtidas para as amostras de fígado bovino demonstraram que o aquecimento provoca uma diminuição considerável na porcentagem de ferro heme presentes nas amostras, variando entre 33 e 43 %. Esta diminuição está relacionada à clivagem oxidativa do anel porfirínico em que o Fe está coordenado, e essa redução é relativamente alta uma vez que a liberação do ferro do complexo heme só ocorre em temperaturas elevadas, de 85 a 100 °C. / Iron is an essential nutrient for almost all living species and plays essential roles in many biological systems, such as oxygen transport, respiration, energy metabolism, destruction of peroxides, and DNA synthesis. Iron deficiency in the body may cause various physiological disorders, such as anemia, which is related to hemoglobin levels in blood. One way to obtain the daily requirement of this nutrient and thus avoid the physiological disorders caused by its deficiency is to ingest fruits, vegetables, and meat, because they are rich in this element. This work evaluated the bioaccessibility (by in vitro methods) and the total amounts of iron and other macro and micronutrients in different types of food. Seeking correlations with the results, the percent composition and phytic acid content of the analyzed foods were also determined, and the concentration of heme iron in samples of bovine liver was analyzed. The total and bioaccessibles amounts of elements allowed to observe that among all foods, spinach contained the highest amount of total iron, but the bioaccessibility of this nutrient was low, below 20%, probably due to the high levels of oxalates and phytates (which have complexing capacity) in this type of food. Still regarding the bioaccessibility of this nutrient, bovine liver was the food with the highest amount of bioaccessible iron. However, cooking considerably reduced bioaccessibility of this nutrient. This decrease is correlated with the breakdown of the heme iron complex present in bovine liver, wich generated the less bioavailable and the less efficiently absorbed ionic iron. Concerning plant species, the results showed that potassium (K) had the highest total and bioaccessible amounts for the analyzed foods, a result that agreed with the fact that this element is essential for the growth of any kind vegetable. Determination of phytic acid (phytates) content showed that they correlated with the cations of the nutrients in the tasted foods differently; i. e., phytates affected the bioaccessibility of the analyzed elements to different degrees, depending on the stability of the complexes formed between the minerals present in a given food and phytic acid. The heme iron concentrations in bovine liver samples revealed that heating significantly lowered the percentage of heme iron present in the samples, which ranged from 33 to 43%. This decrease was related to the oxidative cleavage of the porphyrin ring. The reduction in heme iron was relatively large, since the release of heme iron complex only occurs at elevated temperatures from 85 to 100 ° C.