https://repositorio.ufpb.br/jspui/handle/123456789/11874 PPGEQ Thu, 12 Mar 2026 03:56:46 GMT 2026-03-12T03:56:46Z https://repositorio.ufpb.br/jspui/handle/123456789/37361 Título: Obtenção da levedura Saccharomyces cerevisiae em pó pelo método da secagem em camada de espuma Autor(es): Melo, Geniellen Maria Paiva Costa de Orientador: Cavalcante, Josilene de Assis Abstract: The yeast Saccharomyces cerevisiae is an importantraw material in the food and beverageindustry, generating large amounts of residual biomass. In order to add value to this residue, this study proposes the use of the foam layer drying technique to produce yeast powder from biomass discarded from the fermentation of cachaça. This technique employs thickening and stabilizing agents to form a stable foam that resists dehydration under increasing temperature. The study also aims to evaluate the physicochemical characteristics of the yeast powder obtained by this technique. The foam production followed a 2³ +3 centrais points factorial experimental design that evaluated the influence of biomass dilution, foaming agent concentration (Porto gel) and agitation time on the physical characterization of the foam. The results indicated that the optimal combination to obtain a stable and high-quality foam is: ½ dilution, 20% foaming agent concentration and agitation time of 16 minutes. Under these conditions, the foam showed excellent properties, including air entrainment of 283%, density of 0.232 g/cm³ and excellent stability, with no collapse after 2 hours. Furthermore, an inverse relationship was observed between foam density and air entrainment, suggesting that lighter and more porous foams tend to be more stable. For powder production, since dilution is a crucial factor in foam production, a new 22 + 2 centrais points factorial experimental design was designed, setting the maximum dilution at 1:2 and the agitation time at 16 minutes, with the foaming agent concentration and drying temperature as inputs variables and the drying time and final moisture content as response variables. The experiments performed showed that temperature is the main factor influencing the drying kinetics of Saccharomyces cerevisiae yeast powder. Comprehensive physical-chemical tests were performed to characterize the powder obtained after drying, including analyses of moisture, soluble solids, water activity, pH, ash content, lipids, proteins, carbohydrates, granulometry and process yield. The results showed that the material presented low moisture content of 7.06% and water activity of 0.195 at a temperature of 45ºC, indicating stability for prolonged storage, average content of 13% proteins, 12% lipids and 38% carbohydrates suggesting potential as a nutritional supplement for animals and high ash content (20%), indicating the presence of mineral salts and vitamins essential for animal diet. The granulometric analysis classified the yeast powder as ultrafine. The results achieved define a new paradigm for the use of yeast biomass in drying processes and create promising perspectives for applications such as animals nutritional supplementation. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 26 Feb 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/37361 2025-02-26T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/37161 Título: Avaliação da formação de etringita por modelagem termodinâmica do sistema CAO–Al₂O₃–CaSO₄–NaCl em ambiente com CO₂ Autor(es): Texeira, Alan Henrique Orientador: Rojas, Leopoldo Oswaldo Alcázar Abstract: Portland cement is the primary material used in civil construction, accounting for approximately 90% of buildings worldwide. During hydration, clinquer forms phases such as C-S-H, portlandite, and ettringite, which are essential for the mechanical development of concrete. Ettringite plays a dual role: when formed in a controlled manner at early ages, it enhances initial strength and microstructural densification; however, its delayed or excessive formation—especially in environments with high humidity, extreme temperatures, or the presence of ions such as carbonate and chloride—can lead to expansion, cracking, and premature deterioration. This study investigates, through thermodynamic modeling using the GEMS software, the factors that govern the formation and stability of ettringite, with emphasis on the effects of minor compounds such as carbonates and chlorides. The simulations are based on Gibbs free energy minimization, enabling the prediction of stable solid phases and dissolved species. Results indicated that the highest ettringite formation (~41 g) occurs at the 2:5:4 mass ratio of the CaO–Al₂O₃–CaSO₄ system. The addition of CO₂ promotes the dissolution of carbonate species and shifts the pH toward favorable conditions for ettringite formation, although with no significant increase in its quantity. The approach based on Taylor’s (1997) stability criteria demonstrated the robustness of the model, revealing the influence of salts on the formation of new phases and on the reduction of ettringite. These findings reinforce the potential of thermodynamic modeling as a predictive and strategic tool for optimizing performance and durability in cementitious systems. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 30 Jul 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/37161 2025-07-30T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/36661 Título: Fluidos de perfuração emulsionados com óleos vegetais e tensoativo derivado de óleo de coco: uma avaliação para altas pressões e altas temperaturas Autor(es): Queiroz Neto, José Cavalcante de Orientador: Curbelo, Fabíola Dias da Silva Abstract: The use of drilling fluids is essential for pressure control, formation stabilization, cuttings transport, and operational safety, particularly in high-pressure and high-temperature environments. Although oil-based fluids are effective under these conditions, environmental concerns and health risks have encouraged the search for more sustainable alternatives. This study proposed the development of emulsified drilling fluids formulated with vegetable oils and a surfactant derived from coconut oil, aiming to reduce environmental impact while meeting API specifications for high-pressure and high-temperature applications. The surfactant used, saponified coconut oil (SCO), was obtained from coconut oil with a saponification index of 267.47 ± 1.72 mg KOH/g. Four emulsions (E1 to E4) were developed with varying proportions of aqueous, surfactant, and oil phases: 75/15/10 (E1 and E2) and 90/5/5 (E3 and E4). The formulations differed by oil type (pine oil in E1 and E2; coconut oil in E3 and E4) and aqueous phase composition (distilled water in E1 and E3; glycerol solution in E2 and E4). All emulsions exhibited high stability, with negative zeta potentials below -25 mV and surface tensions under 39.3 mN/m. The emulsions were converted into drilling fluids (F1 to F4) through the addition of specific additives: calcium carbonate and carboxymethylcellulose for filtrate control, xanthan gum and bentonite as rheological modifiers, barite as a weighting agent, and sodium chloride as an electrolyte. These additives were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential analysis, and were used in standardized concentrations across all formulations. The fluids were adjusted to a pH range of 10-11 and a density of 1.0 g/cm3. The fluids were evaluated according to API standards, through rheology and filtration tests under low-pressure and low-temperature (LPLT) conditions, dynamic aging at 66 °C for 16 hours, and high-pressure and hightemperature conditions. Under LPLT conditions, the fluids followed the Herschel-Bulkley rheological model, with coefficients of determination above 0.988 and flow behavior indices below 0.54. The presence of glycerol increased apparent viscosity and yield stress, while plastic viscosity remained constant due to the uniform solid composition. F1 and F2 showed superior filtration performance under LPLT, with filtrate volumes below 0.3 mL and thinner filter cakes. After aging, the fluids without glycerol exhibited more significant changes. F3 and F4 showed an increase in gel strength and a reduction in apparent viscosity, plastic viscosity, and yield stress. Under high-pressure and high-temperature conditions, F1 and F2 experienced a marked reduction in rheological properties due to the increased pressure and temperature, whereas F4 maintained good performance, forming a filter cake with a thickness of 1.45 mm and a filtrate volume of 5.5 mL. The results indicate that F3 and F4 are promising and environmentally viable alternatives to conventional oil-based fluids for use under extreme conditions. Editor: Universidade Federal da Paraíba Tipo: Dissertação Thu, 27 Feb 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/36661 2025-02-27T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/36283 Título: Estudo da produção e análise físico-química de aguardente mista de abacaxi e algaroba Autor(es): Mendonça, Izabella Rayana Prado de Orientador: Lopes, Julice Dutra Abstract: Brazil stands out as one of the world's leading fruit producers, ranking just behind China and India. In the region of Paraíba, there are vast pineapple plantations, making this fruit an important source of income for the local population and a significant economic activity. However, a considerable portion of the production is lost due to the fruits ripening before they are sold. The algaroba is a plant commonly found in semi-arid regions, known for its richness in nutrients and sugars that contribute to the alcoholic fermentation process. Based on this scenario, the objective of this study was to develop and characterize a mixed spirit made from pineapple and algaroba. The pineapple was sourced from a local market in João Pessoa, the algaroba pods were collected in the semi-arid region of Paraíba, and the yeasts were purchased commercially. The juices of the pineapple and algaroba were extracted using a manually operated hydraulic press with a capacity of 30 tons from the brand POTENTE. To optimize and determine the best conditions for the fermentation process, a complete factorial planning 22 + 3 was conducted, involving different yeasts, namely Saccharomyces bayanus and Saccharomyces cerevisiae. The concentrations of yeast and the proportion between pineapple juice and algaroba juice were varied, considering them as the input variables. The alcoholic fermentation of the experimental planning was conducted in a total of fourteen trials and in a batch system. The independent variables evaluated were conversion percentage, productivity, and yield of biomass and product relative to the substrate. After the alcoholic fermentation, calculations were performed, and the best response was found at the central point, with a yeast concentration of 0.3 g/L and equal proportions of algaroba and pineapple. Based on the results obtained, the tests conducted with Saccharomyces cerevisiae and Saccharomyces bayanus showed conversion percentages of 82.23% and 98.87%, productivity rates of 0.637 and 0.944 g/L.h, biomass yield relative to the substrate (Yx/s) of 0.004 and 0.016 gx/gs, and product yield relative to the substrate (Yp/s) of 0.422 and 0.447 gp/gs, respectively. Thus, the best conditions were established for a fermentation process designed to produce a larger quantity of the spirit. A study of the distillation of the alcoholic fermentation was conducted, resulting in a heart fraction with an alcohol content of 34.5° GL for the spirit produced with Saccharomyces bayanus and 38° GL for the spirit produced with Saccharomyces cerevisiae. After resting, the alcohol contents were 35.6° GL and 40.5° GL, respectively. The maturation of the spirits was expedited using oak wood chips over a period of one month. The identity and quality parameters of the produced spirits were analyzed and compared with the current legislation for fruit spirits, where the spirits yielded similar results within the standards established by MAPA, and it was verified that the spirit using Saccharomyces cerevisiae showed better performance than that using Saccharomyces bayanus. Editor: Universidade Federal da Paraíba Tipo: Dissertação Wed, 26 Feb 2025 00:00:00 GMT https://repositorio.ufpb.br/jspui/handle/123456789/36283 2025-02-26T00:00:00Z