Orientador: Theo Guenter Kieckbusch / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenahria Quimica / Made available in DSpace on 2018-08-13T23:26:51Z (GMT). No. of bitstreams: 1 Grunennvaldt_FernandaLourdes_M.pdf: 2198505 bytes, checksum: 816de96976ad169bef8ef5d6a11eeda8 (MD5) Previous issue date: 2009 / Resumo: Amostras de chocolate amargo produzidas com misturas binárias de manteiga de cacau e gorduras alternativas foram avaliadas quanto aos atributos físicos e sensoriais assim como sua estabilidade ao desenvolvimento de fat bloom. Todas as quatro formulações de chocolate (F1 a F4) estudadas continham 10% de fase gordurosa total e 43% de líquor de cacau além de açúcar (46,5%), emulsificantes (0,5%) e aroma. A fase gordurosa de F1 era constituída somente de manteiga de cacau; F2 continha 30% de gordura de cupuaçu neutralizada; F3 continha 30% de gordura CBR low trans (gordura de palma) enquanto que a fase gordurosa de F4 continha 5% de CBS (gordura de palmiste). O chocolate foi produzido em planta piloto, segundo procedimentos padronizados. Para atingir as especificações de desempenho tecnológico, entretanto, foi necessário otimizar individualmente as condições de temperagem (temperatura Tc e tempo tc) para cada formulação, através de um planejamento experimental fatorial. Com uma taxa de resfriamento da massa uniforme de 2,0°C/min, os ensaios realizados em reator encamisado dotado de agitação mecânica a 96rpm indicaram para F1, Tc=28,8°C e tc=6,5min; para F2, Tc=27,5°C e tc=6,5min; para F3, Tc=24,5°C e tc=7min, e para F4, Tc=25,5°C e tc=5min. Essas condições garantiram um Índice de Temperagem em torno de 5,0, viscosidade plástica de Casson do chocolate a 31°C variando de 5,37 a 6,35 Pa.s e tensão de ruptura das barras (snap test) variando de 1,93 a 2,88 kgf/cm2. Uma análise sensorial das amostras não encontrou diferenças significativas em relação aos atributos dureza, derretimento na boca e residual gorduroso. Ensaios de armazenamento por 90 dias a temperatura constante (23°C) confirmou uma excelente estabilidade das amostras de todas as formulações. O armazenamento sob uma variação cíclica de temperatura (entre 20 e 30°C), porém, indicou que apenas as amostras da Formulação F2 (com gordura de cupuaçu) se mostraram resistentes ao desenvolvimento de fat bloom. A superfície das amostras da Formulação F3 desenvolveu densa cobertura de coloração esbranquiçada já a partir do vigésimo dia de armazenamento enquanto que as Formulações F1 e F4 apresentaram apenas leve deterioração da superfície ao fim do ensaio. Palavras-chave: chocolate amargo, cacau, cupuaçu, gordura low/zero trans, fat bloom / Abstract: Samples of dark chocolate produced with binary mixtures of cocoa butter and alternative fats were evaluated with respect to physical and sensorial attributes and their stability to the development of fat bloom. All four chocolate formulations (F1 to F4) were composed by 10% of total fat phase, 43% of cocoa liquor, 46.5% of sucrose, emulsifiers (0.5%) and aroma. The fatty phase of F1 was pure cocoa butter; F2 contained 30% neutralized cupuassu fat; F3 had 30% CBR low trans (palm fat) and F4 contained 5% CBS (palm kernel fat). The chocolates were produced in a pilot plant according to standard procedures. To achieve suitable processing specifications, however, the tempering conditions (temperature Tc and time tc) had to be individually optimized for each formulation through an experimental factorial planning. Maintaining an uniform cooling rate of the mass (0.5°C/min), runs conducted in a glass jacketed reactor equipped with a mechanical agitator (96rpm) indicated, for F1, Tc=29°C and tc=6.5min; for F2, Tc=28°C and tc= 6.5min; for F3, Tc=26°C and tc=7min; and for F4, Tc=25.5 and tc=5min.These conditions ensured an Temperindex around 5.0, Casson plastic viscosity (measured at 31°C) ranging from 5.37 to 6.35 Pa.s and snap test tensions of the bars varying between 1.93 and 2.88 kgf/cm2. A sensorial analysis could not point out significant differences among the samples for the attributes hardness, mouth melting and waxt residual. Storage tests for 90 days at a constant temperature of 23°C confirmed an excellent stability of the samples of all formulations. When stored under cycling temperatures between 20 and 30°C, however, only the samples made with Formulation F2 exhibit fat bloom resistance. An intense whitish film started to cover the surface of F3 samples just after 20 days of storage and chocolates made with Formulations F1 and F4 presented mild surface deterioration at the end of the test. Key words: dark chocolate, cocoa, cupuassu, fat low/zero trans, fat bloom / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

In a context of international reduction of greenhouse gases emissions, CCS (ce{CO2} Capture and Storage) appears as a particularly interesting midterm solution. Indeed, geological storage capacities may raise to several millions of tons of ce{CO2} injected per year, allowing to reduce substantially the atmospheric emissions of this gas. One of the most interesting targets for the development of this solution are the deep saline aquifers. These aquifers are geological formations containing brine whose salinity is often higher than sea water's, making it unsuitable for human consumption. However, this solution has to cope with numerous technical issues, and in particular, the precipitation of salt initially dissolved in the aquifer brine. Consequences of this precipitation are multiple, but the most important is the modification of the injectivity i.e. the injection capacity. Knowledge of the influence of the precipitation on the injectivity is particularly important for both the storage efficiency and the storage security and durability. The aim of this PhD work is to compare the relative importance of negative (clogging) and positive (fracturing) phenomena following ce{CO2} injection and salt precipitation. Because of the numerous simulations and modelling results in the literature describing the clogging of the porosity, it has been decided to focus on the mechanical effects of the salt crystallization and the possible deformation of the host rock. A macroscopic and microscopic modelling has then been developed, taking into account two possible modes of evaporation induced by the spatial distribution of residual water, in order to predict the behavior of a porous material subjected to the drying by carbon dioxide injection. Results show that crystallization pressure created by the growth of a crystal in a confined medium can reach values susceptible to locally exceed the mechanic resistance of the host rock, highlighting the importance of these phenomena in the global mechanical behavior of the aquifer. At the experimental level, the study of a rock core submitted to the injection of supercritical carbon dioxide has been proceeded on a new reactive percolation prototype in order to obtain the evolution of permeabilities in conditions similar to these of a deep saline aquifer

Dans un contexte de réduction internationale des émissions de gaz à effet de serre, les techniques de Captage Transport et Stockage de ce{CO2} (CTSC) apparaissent comme une solution à moyen terme particulièrement efficace. En effet, les capacités de stockage géologique pourraient s'élever jusqu'à plusieurs millions de tonnes de ce{CO2} injectées par an, soit une réduction substantielle des émissions atmosphériques de ce gaz. Une des cibles privilégiées pour la mise en place de cette solution sont les aquifères salins profonds. Ces aquifères sont des formations géologiques contenant une saumure dont la salinité est souvent supérieure à celle de la mer la rendant impropre à la consommation. Cependant, cette technique fait face à de nombreux défis technologiques; en particulier la précipitation des sels, dissous dans l'eau présente initialement dans l'aquifère cible, suite à son évaporation par le ce{CO2} injecté. Les conséquences de cette précipitation sont multiples, mais la plus importante est une modification de l'injectivité, c'est-à-dire des capacités d'injection. La connaissance de l'influence de la précipitation sur l'injectivité est particulièrement importante tant au niveau de l'efficacité du stockage et de l'injection qu'au niveau de la sécurité et de la durabilité du stockage. Le but de ces travaux de thèse est de comparer l'importance relative des phénomènes négatif (colmatage) et positif (fracturation) consécutifs à l'injection de ce{CO2} et à la précipitation des sels. Au vu des nombreux résultats de simulations et de modélisation dans la littérature décrivant le colmatage de la porosité, il a été décidé de porter l'accent sur les effets mécaniques de la cristallisation des sels et la possible déformation de la roche mère. Une modélisation macroscopique et microscopique, tenant compte de deux modes possibles d'évaporation induits par la distribution spatiale de l'eau résiduelle a donc été développée afin de prédire le comportement mécanique d'un matériau poreux soumis à un assèchement par injection de ce{CO2}. Les résultats montrent que la pression de cristallisation consécutive à la croissance d'un cristal en milieu confiné peut atteindre des valeurs susceptibles localement de dépasser la résistance mécanique du matériau, soulignant ainsi l'importance de ces phénomènes dans le comportement mécanique global de l'aquifère. Sur le plan expérimental, les travaux ont porté sur l'utilisation d'un nouveau prototype de percolation réactive afin de reproduire le comportement d'une carotte de roche soumise à l'injection et ainsi obtenir l'évolution des perméabilités dans des conditions similaires à celle d'un aquifère / In a context of international reduction of greenhouse gases emissions, CCS (ce{CO2} Capture and Storage) appears as a particularly interesting midterm solution. Indeed, geological storage capacities may raise to several millions of tons of ce{CO2} injected per year, allowing to reduce substantially the atmospheric emissions of this gas. One of the most interesting targets for the development of this solution are the deep saline aquifers. These aquifers are geological formations containing brine whose salinity is often higher than sea water's, making it unsuitable for human consumption. However, this solution has to cope with numerous technical issues, and in particular, the precipitation of salt initially dissolved in the aquifer brine. Consequences of this precipitation are multiple, but the most important is the modification of the injectivity i.e. the injection capacity. Knowledge of the influence of the precipitation on the injectivity is particularly important for both the storage efficiency and the storage security and durability. The aim of this PhD work is to compare the relative importance of negative (clogging) and positive (fracturing) phenomena following ce{CO2} injection and salt precipitation. Because of the numerous simulations and modelling results in the literature describing the clogging of the porosity, it has been decided to focus on the mechanical effects of the salt crystallization and the possible deformation of the host rock. A macroscopic and microscopic modelling has then been developed, taking into account two possible modes of evaporation induced by the spatial distribution of residual water, in order to predict the behavior of a porous material subjected to the drying by carbon dioxide injection. Results show that crystallization pressure created by the growth of a crystal in a confined medium can reach values susceptible to locally exceed the mechanic resistance of the host rock, highlighting the importance of these phenomena in the global mechanical behavior of the aquifer. At the experimental level, the study of a rock core submitted to the injection of supercritical carbon dioxide has been proceeded on a new reactive percolation prototype in order to obtain the evolution of permeabilities in conditions similar to these of a deep saline aquifer