FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / PaÃses tropicais, como o Brasil, sÃo depositÃrios de uma grande variedade de fontes de polissacarÃdeos vegetais conhecidos e outros ainda nÃo explorados que possuem grande potencial em aplicaÃÃes industriais. A goma de cajueiro pode ser citada como um desses polissacarÃdeos. Algumas pesquisas reportam a possibilidade do uso da goma de cajueiro em vÃrios setores e por sua semelhanÃa estrutural com a goma arÃbica, tem sido sugerida como substituta. Sendo assim, este projeto se propÃe a aumentar o conhecimento existente sobre as propriedades tecnolÃgicas da goma de cajueiro e avaliar o real potencial de substituiÃÃo da goma arÃbica. Para tanto, serÃo realizados os diferentes mÃtodos a secagem apÃs a purificaÃÃo da goma, e anÃlises fÃsico-quÃmicas, reolÃgicas e tecnolÃgicas . A liberaÃÃo do uso industrial da goma do cajueiro seria um grande avanÃo, especialmente para a indÃstria de alimentos, onde o material encontraria inÃmeras aplicaÃÃes, substituindo (com vantagens econÃmicas) a goma arÃbica, e podendo ser utilizada em aplicaÃÃes para as quais a goma arÃbica nÃo à usada por razÃes econÃmicas. Eventualmente, a produÃÃo industrial da goma de cajueiro poderia proporcionar ao Brasil a independÃncia de importaÃÃo de goma arÃbica, e tambÃm inserir um produto altamente competitivo em sua pauta de exportaÃÃes. Este trabalho teve como objetivo o estudo diferentes mÃtodos de secagem da goma do cajueiro (Anarcadium occidentale L), avaliando suas propriedades tecnolÃgicas . Observou-se que algumas caracterÃsticas da goma do cajueiro os teores de umidade, cinzas, atividade de Ãgua e pH foram determinados para a goma nos vÃrios mÃtodos de secagem. Os teores de minerais (Na, Ca, K, Mg) presente na goma foram analisados atravÃs do mÃtodo de raio X. O teor de proteÃna, no entanto nÃo diminuiu significativamente ao longo da secagem, o que pode ser um indicativo de que ela se encontra agregada ao polissacarÃdeo. O teor de solubilidade, higroscopicidade, viscosidade, capacidade de absorÃÃo de Ãgua e Ãleo foi determinado ao longo de todos os mÃtodos de secagem. / Tropical countries such as Brazil, are deposits of a variety of sources of plant polysaccharides known and others not yet explored that have great potential in industrial applications. The cashew tree gum may be cited as one of these polysaccharides. Some studies report the possibility of using cashew gum in various sectors and for their structural similarity to the gum arabic, has been suggested as a replacement. Therefore, this project proposes to increase the existing knowledge on the technological properties of cashew gum and evaluate the real potential replacement of gum arabic To do so, will perform the different drying methods after purifying the gum, and physical-chemical, rheological and technological. The release of industrial use of cashew gum would be a breakthrough, especially for the food industry, where the material would find numerous applications, replacing (with economic advantages) gum arabic, and can be used in applications for which gum arabic is not used for economic reasons. Eventually, the industrial production of cashew gum could give Brazil independence from imports of gum arabic, and also enter a highly competitive product in its exports This work aimed to study different methods of drying of cashew gum (Anarcadium occidentale L), evaluating their technological properties. It was observed that some characteristics of cashew gum the moisture, ash, water activity and pH were determined for the starch in the various drying methods. The levels of minerals (Na, Ca, K, Mg) present in the gum were analyzed using the method of X-ray The protein content, but did not decrease significantly during drying, which may indicate that it is aggregated to the polysaccharide. The level of solubility, hygroscopicity, viscosity, water absorption capacity and oil was determined over all drying methods.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-15T11:47:50Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese.nelson certa.pdf: 11814547 bytes, checksum: 2cbb2aad17bbcac9f45275deb527071a (MD5) / Made available in DSpace on 2016-04-15T11:47:50Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese.nelson certa.pdf: 11814547 bytes, checksum: 2cbb2aad17bbcac9f45275deb527071a (MD5) Previous issue date: 2015-07-31 / A ocorrência de tolerância por parte dos micro-organismos contaminantes de alimentos a agentes e/ou tratamentos antimicrobianos clássicos, impõe a busca de tecnologias alternativas para emprego na conservação de alimentos, a exemplo dos óleos essenciais, em especial aqueles obtidos da espécie Rosmarinum officinalis L. (OERO). A ação antimicrobiana do OERO tem sido atribuída ao 1,8-cineol (CIN) frequentemente citado como seu constituinte majoritário. O objetivo deste estudo foi investigar o efeito da exposição a concentrações subinibitórias do OERO e CIN na modificação da tolerância direta e cruzada de algumas bactérias contaminantes de alimentos (Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa e Salmonella Typhimurium). Ainda, foi avaliada a influência dos fatores sigma alternativos σS e σB na tolerância de E. coli MG1655 e L. monocytogenes EGDe, e seus mutantes isogênicos E. coli MG1655 ΔrpoS e L. monocytogenes EGD-e ΔsigB, frente ao OERO e ao óleo essencial de Origanum vulgare L. (OEOV) bem como na modificação da tolerância bacteriana direta e cruzada ao campo elétrico pulsado (CEP). Para isso, foram realizados ensaios de determinação da Concentração Inibitória Mínima (CIM) e de modificação da tolerância direta e cruzada após exposição das cepas às concentrações subinibitórias (sub-CIMs) (1/2 CIM e 1/4 CIM) do OERO ou do CIN em caldo base carne (18 h) e em modelo base carne (72 h). Para os ensaios de verificação de injúria subletal e interferência dos fatores sigma na tolerância bacteriana, células de E. coli MG1655 e L. monocytogenes EGD-e foram expostas a concentrações inibitórias do OERO ou OEOV para, em seguida, serem cultivadas em meios adicionados de agentes seletivos (NaCl ou sais de bile). Os valores de CIM variaram entre 20 e 40 μL/mL e 40 e 80 μL/mL para o OERO e CIN, respectivamente. Os ensaios de modificação de tolerância não revelaram aumento de tolerância direta e cruzada nas cepas bacterianas testadas. A CIM do OERO e OEOV frente às células mutantes foi menor daquele encontrado frente às células parentais. As células mutantes também apresentaram maior diminuição da sua viabilidade quando tratadas com os óleos essenciais (OES) em relação às células parentais, bem como maior proporção de células apresentando lesão subletal. Ainda, as células mutantes mostraram maior sensibilidade ao CEP quando comparadas as parentais. A ausência dos fatores sigma diminuiu a tolerância direta e ao CEP nas células pré-expostas ao OES em sub-CIMs. Os resultados obtidos neste estudo demonstram que: i) a exposição das cepas bacterianas a sub-CIMs do OERO ou CIN não aumentou a tolerância direta e cruzada; ii) os fatores sigma σS e σB influenciaram a sensibilidade das cepas de E. coli MG1655 e L. monocytogenes EGD-e, respectivamente, frente ao OERO e OEOV ao CEP; e iii) os fatores sigma não influenciaram no aumento da tolerância bacteriaia direta e cruzada ao CEP. Estes resultados demonstram o potencial do OERO e do CIN para uso como antimicrobiano na conservação de alimentos, quando considerado o seu efeito inibitório sobre bactérias contaminantes de alimentos e a ausência de indução de aumento na tolerância bacteriana direta e cruzada. / The occurence of tolerance in food contaminant microorganisms to agents and/or classic antimicrobial treatments has required the search of alternative technologies for use in food preservation, such as essential oils, especially those obtained from the specie Rosmarinum officinalis L. (ROEO). The antimicrobial action of ROEO has been attributed to 1.8-cineol (CIN), frequently cited as its main constituent. The aim of this study was to investigate the effect of exposure to subinhibitory concentrations of ROEO and CIN on the modification of direct tolerance and cross-tolerance of some food-contaminant bacteria (Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella Typhimurium). Still, the influence of alternative sigma factors σS and σB on tolerance of E. coli MG1655 and L. monocytogenes EGD-e, and its isogenic mutant E. coli MG1655 and L. monocytogenes EGD ΔrpoS and ΔsigB to the ROEO and the essential oil of Origanum vulgare L. (OVEO), as well as direct on the modification of the bacterial direct tolerance and cross tolerance the pulsed electric field (PEF) were investigated. For this, assays to determine the Minimum Inhibitory Concentration (MIC) and the modification of the direct tolerance and the cross-tolerance after exposure of the strains to subinibitory concentrations (sub-MICs) (1/2 MIC and 1/4 MIC) of ROEO or CIN in meat broth (18 h) and model based meat (72 h) were performed. For verification of sublethal injury and interference of sigma factors on bacterial tolerance, E. coli MG1655 cells and L. monocytogenes EGD-e were exposed to inhibitory concentrations of ROEO or OVEO and further cultivated in media added selective agents (NaCl or bile salts). The MIC values ranged between 20 and 40 μL/mL and 40 to 80 μL/mL for ROEO and CIN, respectively. The tolerance modified assays revealed no increase in either the direct tolerance or the cross-tolerance in the tested bacterial strains. The MIC of ROEO and OVEO against the mutant cells was lower than that found against the parental cells. Mutant cells showed also a greater decrease in viability when treated with essential oils (EOS) compared to the parental cells, as well as a higher proportion of cells with sublethal injury. Still, the mutant cells showed higher sensitivity to PEF when compared to parental cells. The absence of sigma factors decreased the direct tolerance and tolerance to the PEF in cells pre-EOS exposed to sub-MIC. The results of this study show that: i) exposure of the bacterial strains to sub-MICs of ROEO or CIN did not increase the direct or the crosstolerance; ii) the sigma σS and σB factors influenced the sensitivity of strains of E. coli MG1655 and L. monocytogenes EGD-e, respectively, to the OVEO and ROEO and PEF; and i) the sigma factors did not influence the increase in direct bacterial tolerance and cross tolerance to the PEF. These results demonstrate the potential of ROEO and CIN for use as antimicrobials in food preservation, when considering their inhibitory effect on bacterial foodcontaminants and the absence of induction to direct or cross bacterial tolerance.

Thesis (D. Tech. (Biomed. Tech.)) -- Central University of Technology free State, 2010 / Consumer demands for fresh, microbiologically safe foods with high organoleptical and nutritional quality has led to the development of novel food preservation technologies as alternatives or enhancements to traditional preservation techniques. An example of these novel preservation technologies is high hydrostatic pressure (HHP) processing. It involves the applications of static pressure of 50 to 1 000 mega Pascals (MPa) to solid or packaged liquid foods, with varying holding times. The combination of factors to enhance preservation is increasingly being used in industry, e.g. the use of different temperatures and additives (hurdles) can enhance the preservative effect of HHP. In this study the influence of HHP on organism viability and growth response was assessed. The organisms evaluated included Escherichia coli O111, Listeria monocytogenes (UAFSBCC) and Staphylococcus aureus (ATCC 25923), in peptone water, which was subjected to HHP of 200 MPa for 15 minutes at 8 and 50 ºC respectively. Subsequent to the mentioned pressurisation, sub-culturing was performed and growth responses were evaluated at 0, 6, 18, 24, 30, 42 and 48 hours. Bacterial survival and growth response was measured by means of intact cell count, colony forming units and optical density. From the results it was eminent that bacterial cells were only sublethally injured and were able to repair within 48 hours of enriched sub-culturing. E. coli O111 proved to be most sensitive to HHP with Staphylococcus aureus (ATCC 25923) most resistant. This study also proved that bacterial concentration and inactivation rate are inversely proportionate to each other. Subsequent to growth and cell repair assessments, E. coli O111 was selected as a model to evaluate the effect of sublethal HHP on the liberation and toxicity of bacterial endotoxins (free and cell wall bound). It is also known that different extraction procedures extract different lipopolysaccharides (LPS) fractions and therefore LPS was extracted from the test broth by a combination method of Folch, Lees & Sloane-Stanley, and Venter and Ivanov. The extraction yielded a biphasic system, LPS with reduced lipid content in the upper phase (aqueous) and LPS with increased lipid content in the lower phase (organic). Following extraction the Limulus amebocyte lysate (LAL) test was performed to quantify the concentration (assumed) of LPS in the aqueous and organic phases. Free LPS was detected within six hours in the supernatant in the high and low bacterial loads, moreover the toxicity response of post HHP cell damage was more pronounced at 50 ºC (hurdle) than that observed for the treatments at 8 ºC (hurdle) and more so in the organic phases. The latter implied that HHP not only resulted in quantity LPS variation but also in structural change. However membrane repair was apparently complete after 48 hours, as differences in toxicity were no longer evident. Furthermore, the use of a porcine IL-6 ELISA assay was evaluated as an alternative for the customary LAL as a biomarker for pyrogenic substances in matrixes. Porcine whole blood was challenged for IL-6 production by LPS in the samples from the organic and aqueous systems. A porcine IL-6 enzyme-linked immunosorbent assay was used to assess IL-6 expression in whole blood after being challenged with LPS. From the results it emanated that HHP caused in a change in LPS structure which resulted in a decreased IL-6 expression in whole blood, indicating that structural adaptation of the cell membrane in response to HHP influenced the ability of LPS to stimulate macrophages and monocytes. Therefore, further research and development would be required to evaluate the influence of post HHP LPS on human IL-6 expression. When comparing the porcine IL-6 with the LAL no correlation in toxicity could be established in any of the treatment parameters. Finally it can be concluded that HHP had an influence in the structural morphology of LPS. These structural changes could result in LPS being more toxic, it could also have an effect on the accuracy of immunological assessments, the ability to form biofilm, and susceptibility to phages.

Este trabalho teve como objetivo avaliar o efeito de revestimentos comestíveis na qualidade de mamão \'Formosa\' minimamente processado durante armazenamento a 5°C por 15 dias. Os tratamentos foram: o controle, e os seguintes revestimentos: amido de arroz 3%, alginato de sódio 0,5% e carboximetilcelulose 0,25%. O uso de revestimentos causou alterações nos parâmetros físicos, físico-químicos e microbiológicos do mamão minimamente processado, quando comparado ao controle. As alterações mais importantes foram: menor contagem de coliformes totais; menor respiração dos mamões tratados com amido de arroz e maior dos tratados com carboximetilcelulose, ao longo do tempo; menor descoloração da polpa dos frutos ao longo do armazenamento; maior manutenção da firmeza das amostras tratadas com carboximetilcelulose; e redução do teor de sólidos solúveis e aumento da acidez titulável. Os revestimentos não afetaram os atributos sensoriais. Como a maioria dos efeitos positivos das coberturas ocorreu no 12° e 15° dias e, considerando o custo da tecnologia relacionado ao preço dos revestimentos, a melhor opção, até 9 dias de armazenamento, consiste em fazer apenas uma boa sanitização dos frutos, como feito no controle. No entanto, se o interesse for preservar a vida útil dos mamões por um período maior, até 15 dias, os revestimentos testados podem ser utilizados com resultados satisfatórios. / This study aimed to evaluate the effect of edible coatings on the quality of minimally processed \'Formosa\' papaya during storage at 5°C for 15 days. The treatments were: the control, and the following coatings: rice starch 3%, sodium alginate 0.5% and carboxymethylcellulose 0.25%. The use of coatings caused changes in the physical, physicochemical and microbiological parameters of minimally processed papaya, when compared to control. The most important changes were: lower counts of total coliforms; lower respiration of papayas treated with rice starch and higher of those treated with carboxymethylcellulose over time; less fruit pulp discoloration during storage, increased firmness maintenance of samples treated with carboxymethylcellulose; and reduction of soluble solids and increased acidity. The coatings did not affect the sensory attributes. Since most of the positive effects of the coatings occurred at the 12th and 15th days, and considering the technology cost related to the price of coatings, the best option, until 9 days of storage, is just to do a good sanitization of fruits such as that of control samples. However, if the interest is to preserve the shelf life of papayas for a longer period, up to 15 days, the coatings tested could be used with satisfactory results.

O presente estudo teve como objetivo avaliar a utilização de campo magnético pulsado (CMP) de baixa intensidade na preservação da qualidade microbiológica, cor e estabilidade oxidativa de carne bovina moída durante armazenamento aeróbio refrigerado. Amostras moídas de peixinho bovino (músculo Supraspinatus) foram expostas a CMP por 2 horas às frequências de 1, 30 ou 60 Hz ou, em outra etapa, expostas a CMP de 1 Hz de frequência por 2 horas ou continuamente por 12 dias. Amostras controle não foram expostas ao CMP. As amostras foram armazenadas a 4ºC por até 12 dias, e avaliadas a cada seis dias por meio de análise microbiológica de contagem total de bactérias mesófilas aeróbias, e a cada dois dias por meio de análises físico-químicas e bioquímicas: pH, cor instrumental (escala CIELAB), mioglobina e oxidação lipídica. A exposição ao CMP de 1 Hz por 2 horas reduziu a contagem de mesófilos aeróbios com relação ao controle em 1,3 ciclos logarítmicos no 12º dia de armazenamento refrigerado. Os conteúdos de metamioglobina das amostras expostas por 2 horas ao CMP, independente da frequência de pulso, foram significativamente menores com relação ao controle no 6º dia de armazenamento refrigerado. Os demais parâmetros de qualidade não sofreram alteração significativa com relação ao controle durante o armazenamento e não foi verificado efeito das diferentes frequências de CMP. Conclui-se que campo magnético pulsado de baixa intensidade (ordem de mili Tesla) apresenta potencial para ser utilizado como tecnologia inovadora, em combinação com a refrigeração, na preservação de carnes frescas. Todavia, mais estudos são necessários para melhor entendimento dos mecanismos de ação de campo magnético, principalmente em alimentos. / This study aimed to evaluate the use of low intensity pulsed magnetic field (PMF) in the preservation of microbiological quality, color and oxidative stability of ground beef during aerobic refrigerated storage. Ground beef samples of chuck tender (Supraspinatus muscle) were exposed to PMF for 2 hours at frequencies of 1, 30 and 60 Hz or, in another step, they were exposed to a 1 Hz PMF for 2 hours or continuously for 12 days. Control samples were not exposed to PMF. Samples were stored at 4ºC for up to 12 days, and evaluated every six days through microbiological analysis of total aerobic mesophilic bacteria count, and every two days through physicochemical and biochemical analysis of pH, instrumental color (CIELAB scale), myoglobin and lipid oxidation. Exposure to 1 Hz PMF for 2 hours reduced the growth of aerobic mesophiles in relation to the control by 1.3 logarithmic cycles in the 12th day of refrigerated storage. Metmyoglobin content of samples exposed to the PMF for 2 hours, regardless of the pulse frequency, were significantly lower compared to the control in the 6th day of refrigerated storage. The other quality parameters did not change significantly during storage compared to the control and it was not observed effect of different PMF frequencies. We concluded that low intensity pulsed magnetic field (order of mili Tesla) has the potential to be used as innovative technology, in combination with refrigeration, in fresh meat preservation. However, more studies are needed to better understand the mechanisms of action of magnetic field, mainly in foods.

A água de coco é considerada uma bebida isotônica, nutritiva e pouco calórica. A sua composição química é bastante complexa, alguns dos principais constituintes são açúcares e minerais e, em menores quantidades, Iipídeos e compostos nitrogenados. Um grande desafio é preservar a água de coco por longo período de tempo fora do fruto, mantendo as suas características físicas e organolépticas. A pasteurização é um dos processos de conservação que vem sendo utilizado com esse propósito. No entanto, pouco se sabe a respeito da influência desse processo de conservação na composição química da água de coco. Nesse sentido, a proposta desse trabalho foi investigar as espécies químicas de Cu e Zn presentes na água de coco, bem como avaliar a influência do processo de pasteurização sobre essas espécies. Para esse estudo foram feitas medidas de pH e da concentração hidrogeniônica, extração em ponto nuvem, extração por solvente, ultrafiltrações e determinação da concentração total de proteínas visando a separação com eletroforese em gel de poliacrilamida com dodecil sulfato de sódio (SOS-PAGE), e cromatografia por filtração em gel. As determinações de Cu e Zn foram feitas na água de coco total e nas frações por espectrometria de absorção atômica com atomização eletrotérmica (ETAAS). Os resultados das determinações totais de Cu e Zn, e de proteínas mostraram que a composição dessas espécies varia muito entre os diferentes frutos. A combinação dos resultados obtidos pelas diferentes técnicas indicou que o Cu está, preferencialmente, associado às moléculas de maiores pesos moleculares, enquanto que o Zn encontra-se associado a pequenas moléculas. A pasteurização não afetou o pH, a concentração total dos elementos e de proteínas. Porém, a partir dos resultados da cromatografia por filtração em gel e da determinação de Cu e Zn nas frações coletadas do eluente, foi possível observar que a pasteurização provocou alterações nos pesos moleculares das proteínas e, possivelmente nos elementos associados a elas. As mudanças observadas indicam quebra de ligações fracas, provavelmente dissulfeto, rompendo aglomerados protéicos (maior massa molecular) e aumentando a abundância de proteínas mais leves (menor massa molecular). / Coconut water is a natural isotonic, nutritive and low caloric drink. Its chemical composition is quite complex, some of the main compounds are sugars and minerais and, in smaller amounts fat and compounds of nitrogen. The coconut water preservation outside the fruit, maintaining its physical and organolépticas properties is a big challenge. Pasteurization has been used as one of the most common preservation processes. However, little knowledge exists about the influence of preservation processes over coconut water chemical composition. This way, the aim of this work was to investigate the chemical species of Cu and Zn in coconut water and evaluate the influence of pasteurization over these species. For this, many procedures such as, pH measurements, c10ud point extractions, solvent extraction, ultrafiltration, measurement of total protein concentration, sodium dodecil sulphate poliacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography were executed. The Cu and Zn determinations were made in a whole coconut water and in its different fractions, obtained by the separation techniques by using electrothermal atomic absorption spectrometry. The results of Cu, Zn and protein determinations showed that there is a big variation between different fruits. Results obtained by ali techniques used showed that Cu is, preferentially Iinked to big molecules and Zn is associated to small molecules. The results of gel filtration chromatography associated to the concentration of Cu and Zn in the collected fractions showed the strong possibility of Iinkage of these elements with proteins. The pasteurization did not cause significant changes in the total proteins concentration, however, the changes observed indicated the break in week chemical connections, probably in proteins (agglomerations of high molecular mass), increasing the abundance of small proteins (Iow molecular mass).

Nos países em desenvolvimento, como o Brasil, a secagem de produtos agrícolas com uso de secador solar representa uma alternativa promissora de baixo custo, reduzindo perdas e agregando valor aos produtos. Porém, devido à natureza periódica da radiação solar e das condições do tempo, nem sempre é viável sua utilização. Dessa forma, o objetivo do trabalho foi a modelagem de um sistema auxiliar de armazenagem de energia térmica (SAET) em um secador solar, cuja finalidade é armazenar energia durante o dia para ser utilizada conforme necessário. Com base em registros de temperatura e umidade relativa, ambas do ar, de um secador solar, foi feito um estudo da termodinâmica dos processos envolvidos, a fim de propor meios para o dimensionamento do SAET. Foram explorados a estimativa do fluxo de massa de ar no secador, a modelagem da temperatura em função da radiação, e o dimensionamento para diferentes modos de operação do SAET, considerando o sistema ideal. Este dimensionamento tratou tanto do caso de fornecimento contínuo de fluxo de água preaquecida, como de uso de automação para controlar o fluxo. A estimativa de fluxo de ar no secador se aproximou de valores típicos encontrados na literatura. O dimensionamento do sistema, embora considerado ideal, mostra que a utilização do SAET melhora o desempenho do secador, servindo como parâmetro para melhor compreender o comportamento das variáveis durante seu funcionamento. / In developing countries such as Brazil, drying of agricultural products by using solar dryer is a promising low cost alternative to reduce losses and add value to products. However, due to periodic behavior of solar radiation and weather conditions, the use of solar drier is not always feasible. The objective of this study is to model an auxiliary thermal energy storage (ATES) in a solar drier, aiming to store energy during the day to be used as needed. Based on both air temperature and relative humidity records of a solar dryer, the thermodynamics of the underlying processes was studied in order to propose means for designing the ATES. It was addressed the estimative of the air mass flow in the dryer, the modeling of the temperature as a function of the radiation, and the designing of the ATES for different modes of operation, considering the optimal system. The designing dealt with both the continuous supply of preheated water flow and the use of automation for controlling the flow. The estimated air flow in the dryer approached typical values found in the literature. The designing of the system, although considered ideal, shows that the use of ATES improves the drying performance, serving as a parameter to better understand the behavior of variables during operation.

The current trend of increasing demand for minimally processed food requires more effective preservation technologies than are presently used. In this study, an investigation has been made into a novel strategy to control some common foodborne pathogens, and therefore, to provide an alternative means for enhancing the safety and extending the shelf lives of food products. Modified atmosphere is able to extend the shelf life of seafood and meat products. In this study, a simulated controlled atmosphere (CA) broth system was used to investigate the potential of a modified atmosphere rich in CO2 at a concentration of 40%, supplemented with N2, to control common foodborne pathogens, such as Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Vibrio parahaemolyticus. Controlled atmosphere significantly reduced the exponential growth rates of all tested pathogens, while the effects on other growth parameters (eg. lag phase duration and maximum population density) depended on the individual species and the specific growth conditions. The CA significantly extended the lag phase durations of S. aureus and V. parahaemolyticus at 20 degrees C at both pH 6.3 and 6.8, and that of L. monocytogenes at both 7 degrees C and 20 degrees C, and at both pH 6.3 and 6.8. The CA also significantly lowered the maximum population densities of S. aureus and V. parahaemolyticus at 20 degrees C, at pH 6.3 and 6.8, S. Typhimurium at pH 6.8, and L. monocytogenes at pH 6.3 and 7 degrees C. E. coli O157:H7 and S. Typhimurium were more resistant to the inhibitory effect of the CA, while S. aureus and V. parahaemolyticus were most sensitive. The inhibitory effect of CA was due mainly to the extensions of the lag phase duration and the reduction of the exponential growth rates of the test pathogens. This study confirms other studies that CA as a means for food preservation provides potential to control foodborne pathogens and therefore enhance the safety of a food product. The use of lactic acid bacteria (LAB) in controlling spoilage microorganisms and pathogens in foods has been a popular research theme worldwide. In this study, the antimicrobial effects of 18 lactic acid bacteria strains were evaluated in vitro, with emphasis on the most effective strain, the newly characterised Lactobacillus reuteri DPC16. The results demonstrated antagonistic effects of many strains against L. monocytogenes, E. coli O157:H7, S. Typhimurium and S. aureus. L. reuteri DPC16 showed the strongest antimicrobial activity against the tested pathogens including both Gram-positive and Gram-negative bacteria. Co-cultivation of L. reuteri DPC16, and co-incubation of its spent culture supernatant (DPC16-SCS), with the pathogens have demonstrated that the antimicrobial effect is bactericidal and valid at pH 4 - 6.5 and at a temperature as low as 10 degrees C. Further characterisation of the antimicrobial effect of L. reuteri DPC16 showed it to be mainly due to the presence of reuterin (ß-hydroxypropionaldehyde), although lactic acid may have also played a role. These characteristics of L. reuteri DPC16 and its metabolite reuterin make it an unique and potent candidate as a biopreservative to control both Gram-positive and Gram-negative bacteria in foods. The combination of L. reuteri DPC16 and CA was assessed for its inhibitory effect on L. monocytogenes using DPC16-SCS and the fermentative supernatant of L. reuteri DPC16 from a glycerol-water solution (DPC16-GFS). The results showed that both of these supernatants, at 25 AU/mL, in combination with CA (60% CO2:40% N2) had a combined inhibitory effect on L. monocytogenes which could not be achieved by any one of the individual factors alone. Analysis of the levels of expression of some stress response genes of L. monocytogenes, after growth in the presence of L. reuteri DPC16 supernatant and/or CA, showed that the expression of some genes was affected including genes betL, gbuA and opuCA responsible for osmosis adaptation and genes gadA, gadB and gadC responsible for acid tolerance. Induction of gbuA, gadB and gadC by the culture supernatant suggests activation of osmotic and acid adaptation and that these genes play a major role in the culture supernatant-induced stresses. An investigation was also carried out to determine if the changes in gene expression conferred a cross-protection to heat. The result showed that the survival of L. monocytogenes grown in the presence of the culture supernatant and CA was significantly increased after exposure to heat treatment at 56oC, suggesting that a cross-protection to thermal stress had been induced. Based on these findings it is proposed that a comprehensive novel strategy incorporating both L. reuteri DPC16 or its fermentative products and a modified atmosphere rich in CO2 could be developed to potentially control foodborne pathogens in food products.

This study investigated the quality and safety of solar dried fruits and vegetables produced by households in three locations in the Butha-Buthe district of Lesotho from November 2002 to March 2003. The aim of the study was to enhance year round availability of fruits and vegetables and reduce post-harvest losses, contributing to increased food availability and accessibility in the district. The study analysed the quality and safety of dried fruits and vegetables by assessing the processing techniques applied by the respondents during the production of dried fruits and vegetables, analysing the quality of dried fruits and vegetable samples produced by the study respondents using Appropriate Technology Section (ATS) solar driers, and by identifying the constraints that hamper the improvement of quality and safety of solar dried fruits and vegetables in the study area. Data was collected through focus group discussions, interviews, and laboratory food quality analysis of dried fruit and vegetable samples provided by the respondents. The dried fruits and vegetables produced by the respondents were of low quality due to poor processing techniques and unhygienic practices that increased chances of contamination and deterioration during processing and storage. Lack of processing skills and information, particularly on quality and safety standards, and weak extension support contributed to poor product. For the respondents to improve the quality and safety of dried fruits and vegetables, they need training and support with respect to quality and safety that includes training on the importance of food safety, best processing and storage practices and marketing of dried produce. / Thesis (M.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Submitted by JESSELEINE CRISTINE MONTEIRO DA SILVA null (jesse_cris@hotmail.com) on 2017-09-20T20:56:09Z No. of bitstreams: 1 Dissertação final Jesseleine.pdf: 1516064 bytes, checksum: 56e50bf83bbdb465716b33121512f13f (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-27T17:48:51Z (GMT) No. of bitstreams: 1 silva_jcm_me_araiq.pdf: 1516064 bytes, checksum: 56e50bf83bbdb465716b33121512f13f (MD5) / Made available in DSpace on 2017-09-27T17:48:51Z (GMT). No. of bitstreams: 1 silva_jcm_me_araiq.pdf: 1516064 bytes, checksum: 56e50bf83bbdb465716b33121512f13f (MD5) Previous issue date: 2017-09-06 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Devido ao crescente aumento de doenças transmitidas por alimentos, a segurança microbiológica se torna uma questão de saúde pública pelas suas características de endemicidade, alta morbidade e pela dificuldade da adoção de medidas de controle desses microrganismos. Diante deste fato, o objetivo deste trabalho foi sintetizar e caracterizar os análogos peptídicos LeuB e LeuC-1 derivados de bacteriocinas naturais denominadas Leucocinas. Os peptídeos foram sintetizados manualmente pelo método de síntese em fase sólida, submetidos à desproteção total e clivagem, com liberação dos peptídeos brutos. Foram realizadas as análises comparativas usando HPLC e ESI-MS, e com os respectivos peptídeos puros foram feitos os ensaios antimicrobiano, enzimático, permeabilização, antioxidante, hemolítico e de espectroscopia de dicroísmo circular. Com isso, observou-se que o método de síntese dos análogos foi adequado e o processo de purificação possibilitou a obtenção dos peptídeos com alto grau de pureza. O peso molecular teórico dos peptídeos foi confirmado por espectrometria de massas. O LeuB apresentou uma maior capacidade em inibir o crescimento de Escherichia coli O157:H7 e em Salmonella sorovar Typhimurium, enquanto que LeuC-1 apresentou efeito de inibição de crescimento de Listeria monocytogenes e também de S. sorovar Typhimurium. É importante destacar que todas essas bactérias são de interesse na área de alimentos, já que são as causadoras da maioria dos casos de infecção alimentar. O ensaio de inibição enzimática com DNA girase e Topoisomerase IV mostrou que apenas o peptídeo LeuB possui capacidade de inibição destas enzimas bacterianas, sugerindo um possível mecanismo de ação deste derivado de Leucocina. Este peptídeo também apresentou a capacidade de permeabilizar miméticos de membrana bacteriana composto de POPC/POPG (75/25). Por sua vez, o peptídeo LeuC-1 não apresentou capacidade significativa de inibição da atividade das enzimas DNA girase e Topoisomerase IV e também não apresentou capacidade de permeabilização de miméticos de membrana. Porém, LeuC-1 apresentou uma boa atividade antioxidante, obtida pelo método de ABTS. Ambos os peptídeos apresentaram baixa toxicidade em eritrócitos, comprovadas pelos ensaios hemolíticos. Estruturalmente, os peptídeos LeuB e LeuC-1 tendem a se estruturar em α-hélice. Assim sendo, este trabalho possibilitou a obtenção de dois peptídeos com potencial de aplicação como conservantes alimentares a partir de mecanismos distintos de ação sem apresentar citotoxicidade para células vermelhas do sangue. LeuB possui uma suposta atuação como inibidor de topoisomerases bacterianas e capacidade de permeabilização de miméticos de membrana. LeuC-1 possivelmente atua em diferentes vias metabólicas da bactéria, porém ainda não foi possível elucidar o mecanismo alvo deste mimético peptídico. / Due to the increase of foodborne diseases, microbiological safety becomes a public health issue due to its characteristics of endemicity, high morbidity and the difficulty of adopting control measures of these microorganisms. In view of this fact, the objective of this work was to synthesize and characterize LeuB and LeuC-1 peptidics analogues derived from natural bacteriocins called Leucocins. The peptides were synthesized manually by the solid phase synthesis method, subjected to total deprotection and cleavage, with release of the crude peptides. Comparative analyzes were performed using HPLC and ESI-MS, and with the respective pure peptides the antimicrobial, enzymatic, permeabilization, antioxidant, hemolytic and circular dichroism spectroscopy. With this, it was observed that the method of synthesis of the analogs was adequate and the purification process allowed to obtain the peptides with high purity. The theoretical molecular weight of the peptides was confirmed by mass spectrometry. LeuB showed a greater capacity to inhibit the growth of Escherichia coli O157: H7 and Salmonella serovar Typhimurium, whereas LeuC-1 presented inhibition effect of growth of Listeria monocytogenes and also of S. serovar Typhimurium. It is important to highlight that all these bacteria are interesting in the area of food, since they are the cause of most cases of food infection. The enzyme inhibition assay with DNA gyrase and Topoisomerase IV showed that only the LeuB peptide has the ability to inhibit these bacterial enzymes, suggesting a possible mechanism of action of this Leucocin derivative. This peptide also showed the ability to permeabilize bacterial membrane mimetics composed of POPC/POPG (75/25). On the other hand, the LeuC- 1 peptide did not present significant capacity to inhibit the activity of the enzymes DNA gyrase and Topoisomerase IV and also did not present permeabilization capacity of membrane mimetics. However, LeuC-1 presented a good antioxidant activity, obtained by the ABTS method. Both peptides had low erythrocyte toxicity, as demonstrated by hemolytic assays. Structurally, the LeuB and LeuC-1 peptides tend to be α-helix structured. Therefore, this work enabled two peptides with application potential as food preservatives to be obtained from distinct mechanisms of action without presenting red blood cell cytotoxicity. LeuB has a supposed action as inhibitor of bacterial topoisomerases and permeabilization capacity of membrane mimetics. LeuC-1 possibly acts on different metabolic pathways of the bacterium, but it has not yet been possible to elucidate the target mechanism of this peptidic mimetic. / CNPq: 150928/2015-7