A quem a correspondência deve ser enviada. RESUMO Cubos de melão de 20mm da variedade, cultivar Gold Mine foram desidratados osmoticamente com o objetivo de se estudar a cinética de transferência de massa durante o processo. As amostras foram imersas em soluções hipertônicas de sacarose ou maltose nas concentrações de 40 a 60°Brix e a desidratação foi conduzida por 8 horas com temperatura controlada (30 ou 40°C) e agitação de 120rpm. Perda de água e incorporação de sólidos na fruta foram avaliados ao longo do processo em função da temperatura de tratamento, tipo e concentração da solução. Os coeficientes de difusão para a água e os açúcares foram estimados através de um modelo empírico da literatura, baseado na equação de Fick. Para todos os ensaios, a perda de água aumentou significativamente com a elevação da temperatura e da concentração da solução desidratante, entretanto, os ensaios com maltose promoveram uma maior taxa de saída de água da fruta e menor ganho de sólidos. O modelo empírico utilizado se ajustou adequadamente aos dados experimentais, apresentando valores do coeficiente de correlação (R ) superiores a 0,92. desidratação osmótica; melão; difusividade efetiva; perda de água; ganho de sólidos. Cucumis melo inodorus2 Palavras-chave: SUMMARYMASS TRANSFER KINETICS OF OSMODEHYDRATED MELON WITH SUCROSE AND MALTOSE SOLUTIONS. Melon cubes of 20mm from the variety, Gold Mine cultivar were osmotically dehydrated with the aim of studying the mass transfer kinetics during the process. The samples were immersed in hypertonic solution of sucrose or maltose with different concentrations (40 to 60°Brix) and the osmotic dehydration was carried out for eight hours under controlled temperature (30°C or 40°C) and agitation (120rpm). Water loss and solids gain were evaluated throughout the process as a function of temperature, osmotic agent and solution concentration. The diffusion coefficients for water and sugar were estimated using an empiric model from literature based on Fick´s unsteady law of diffusion. For all treatments, water removal increased at a significant level for higher temperature and solution concentrations, but the greatest water loss rate and lowest sugar uptake was verified when using maltose solutions. The empiric model showed a good fit to experimental values with a high degree of correlation (R > 0,92). Cucumis melo inodorus2 Keywords: osmotic dehydration; melon; effective diffusivity; water loss; solids gain. -INTRODUÇÃOO Brasil é atualmente um dos maiores produtores de melão do mundo, sendo a Região Nordeste responsável por 95% da produção nacional. O estado do Rio Grande do Norte concentra cerca de 65% da produção total brasileira, além de se destacar como um dos maiores pólos exportadores de melão do país e, em seguida, estão os estados do Ceará, Bahia e Pernambuco [1].Apesar de ser considerado um produto de elevado valor comercial e ser apreciado por suas características sensoriais, o melão apresenta uma vida útil pós-colheita relativamente curta à temperatura ambiente, o que tem dificult...
This study evaluated if Carbon dioxide (CO2) (λ 10.6 μm) laser irradiation combined with acidulated phosphate fluoride gel application (APF gel) enhances "CaF2" uptake by demineralized enamel specimens (DES) and inhibits enamel lesion progression. Thus, two studies were conducted and DES were subjected to APF gel combined or not with CO2 laser irradiation (11.3 or 20.0 J/cm(2), 0.4 or 0.7 W) performed before, during, or after APF gel application. In study 1, 165 DES were allocated to 11 groups. Fluoride as "CaF2 like material" formed on enamel was determined in 100 DES (n = 10/group), and the surface morphologies of 50 specimens were evaluated by scanning electron microscopy (SEM) before and after "CaF2" extraction. In study 2, 165 DES (11 groups, n = 15), subjected to the same treatments as in study 1, were further subjected to a pH-cycling model to simulate a high cariogenic challenge. The progression of demineralization in DES was evaluated by cross-sectional microhardness and polarized light microscopy analyses. Laser at 11.3 J/cm(2) applied during APF gel application increased "CaF2" uptake on enamel surface. Laser irradiation and APF gel alone arrested the lesion progression compared with the control (p < 0.05). Areas of melting, fusion, and cracks were observed. CO2 laser irradiation, combined with a single APF application enhanced "CaF2" uptake on enamel surface and a synergistic effect was found. However, regarding the inhibition of caries lesion progression, no synergistic effect could be demonstrated. In conclusion, the results have shown that irradiation with specific laser parameters significantly enhanced CaF2 uptake by demineralized enamel and inhibited lesion progression.
Extracted human teeth are frequently used for research or educational purposes. Therefore, it is necessary to store them in disinfectant solutions that do not alter dental structures. Thus, this study evaluated the influence of storage solution on enamel demineralization. For that purpose, sixty samples were divided into the following groups: enamel stored in formaldehyde (F1), stored in thymol (T1), stored in formaldehyde and submitted to pH cycling (F2), stored in thymol and submitted to pH cycling (T2). All samples were evaluated by cross-sectional microhardness analysis and had their percentage of mineral volume versus micrometer (integrated area) determined. Differences between groups were found up to 30-µm depth from the enamel surface (p < 0.05), where samples from group T2 were more demineralized. It was concluded that the storage solution influenced the reaction of a dental substrate to a cariogenic challenge, suggesting that formaldehyde may increase enamel resistance to demineralization, when compared to demineralization occurring in enamel stored in thymol solution.
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