Efeito de parâmetros de extrusão na cor E propriedades de pasta da farinha de mandioquinha-salsa (Arracacia xanthorrhiza)

Processou-se neste trabalho a farinha de mandioquinha-salsa (Arracacia xanthorrhiza Bancr.) em uma linha de extrusão (mono rosca) variando as condições operacionais: umidade da farinha (11-19%), temperatura de extrusão (86-154ºC) e taxa de rotação da rosca (136-272rpm). Os parâmetros de cor analisados foram luminosidade (L*) e os componentes de cromaticidade a* e b*. Os parâmetros de propriedade de pasta analisados foram viscosidade inicial, pico de viscosidade, quebra de viscosidade, tendência a retrogradação e viscosidade final. Os resultados obtidos mostraram que a umidade da matéria-prima interferiu nos componentes de cor das farinhas com efeito significativo sobre a luminosidade e croma a*, e a temperatura interferiu no croma b* . Quanto ao efeito dos parâmetros de processo sobre as propriedades de pasta, a umidade interferiu nas viscosidades inicial e final dos produtos, pico e quebra de viscosidade, enquanto a temperatura de extrusão e a rotação da rosca tiveram influência sobre a tendência a retrogradação e viscosidade final dos produtos.

Efeito da concentração de fibra e parâmetros operacionais de extrusão sobre as propriedades de pasta de misturas de fécula de mandioca e polpa cítrica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propriedades de pasta e concentração de amido resistente em duas variedades de féculas de raízes de mandioca em diferentes estágios de desenvolvimento

The objective of this work was to analyze the profiles of the concentrations of resistant starch and respective properties of paste of two cassava varieties with different development stages. For the evaluation of the profile of the concentration of resistant starch and paste properties, the starches of the cassava varieties were used IAC 576/70 and Fécula Branca, which were collected with different times of cultivation (10, 11, 12, 13, 14 and 15 months), and the use of these times were according the crop of cassava variety IAC 576/70. For the analysis of paste property the apparel was used RVA and for analysis of resistant starch the enzymatic method was used. The results showed for the paste properties happened significant differences among the two varieties of cassava starch, and in some months they there wasn't differences, and as the results of resistant starch happened differences among the starches the months of July and August, and as for the different development stages only the starch of Fécula Branca that happened significant differences.

Composição química e propriedades de pasta de farinhas de mandioca

This work aimed to analyze the chemical composition and paste properties of cassava flours, from several producers and classifications, marked in different Brazilian cities. Flours were characterized to moisture, ash, fibers, protein, lipids, total sugars and starch. The paste properties were analyzed in RVA. The results showed significant differences to chemical components in cassava flours. The moisture ranged from 4.39 to 10.26, starch (82.19 to 88.90%), ash (0.48 to 1.07%), fiber (3.23 to 6.41%), protein (1.15 to 2.13%), total sugar (0.05 to 0.56%) and lipids (0.40 to 1.24). These differences can be due the variations of raw material and process. The paste properties of flours were different, with viscosity peak ranged from 73.33 to 387.08 RVU, breakdown (2.42 to 248.83RVU, final viscosity (154.92 to 275.5 RVU) and retrogradation tendency (50.75 to 132.5 RVU), showing the influence of kind of processing on flour viscosity.

Propriedades de pasta e térmicas de misturas instantâneas de farinha de soja, fécula e farelo de mandioca

The application of extrusion technology in the food industry has enabled the development of new commercial products of fast preparation, and maintaining the nutritional characteristics after the process. During this process there are changes in raw material due to the action of temperature, humidity and mechanical friction resulting in a modified product which can be used in various industrial applications. This work aimed to evaluate the effect of the composition of the raw material and operating conditions of the extrusion process on the properties of paste and thermal properties in the development of a functional instant flour of cassava and soybean. The results showed significant effects of all operating parameters on the rheological properties studied. The extruded flours showed no residual gelatinization enthalpy, suggesting that the starch in the samples was gelatinized. The experimental conditions of the smallest percentages of cassava residue (10%) and high soybean flour (25%) mixed with cassava starch, extrusion temperature of 75ºC and low screw speed (170rpm) leads to obtain instant flour with desirable characteristics.

Avaliação clínica da pasta de metronidazol a 10% e lidocaína a 2% no tratamento da alveolite

Pós-graduação em Odontologia - FOA

Efeitos de tratamentos hidrotérmicos nas propriedades viscográficas e amidos resistentes em féculas de mandioca

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Composição físico-química e propriedades tecnológicas da farinha de folhas de mandioca

Cassava leaves can be considered an important nutritional source when compared to other commonly consumed vegetables leaves. Cassava leaves have high levels of protein, fiber and minerals, and arestill underexplored due to the lack of information regarding the use of them as afood product, as well as, their use as an industrial raw material. The consumption of cassava leaves in fresh form is impractical due to the presence of cyanide, thereby it is required a pretreatment to be performed to reduce this component. The objective of this study was to produce and characterize the four made with cassava leaves as its chemical composition, color, indices of absorption and water solubility, and pasting properties, aiming to provide information of interest for possible application as an ingredient in the food industry. Cassava leaf flour showed low moisture content (6.6 %)and significant amounts of fiber (30.68 %), protein (23.00 %), and total carbohydrate (22.27%). Drying and milling processes allowed to obtain a flour with a low content of total cyanide (0.3 mg 100g-1 ), and the presence of vitamin C (56.6 mg 100g-1 ) and β –carotene (38 mg 100g- 1 ). The color analysis of cassava leaf flour showed low lightness with, predominantly, green and yellow pigments. The cassava leaf flour presented good solubility (14.85 %) and water absorption (6.87 g gel. g-1 ). Pasting properties showed a low peak of viscosity and a higher final viscosity with a retrogradation tendency, indicating a low capacity of this flour to form gel. The flour of cassava leaves can be a good source of nutrition when used as a food ingredient in soups and pasta. However, it is not indicated to products that require high gel formation.

Efeitos de modificações físicas sobre as propriedades de amido de tuberosas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação de compatibilidade entre pasta de cimento e fluido de perfuração não-aquoso utilizados em poços petrolíferos

Compatibility testing between a drilling fluid and a cement slurry is one of the steps before an operation of cementing oil wells. This test allows us to evaluate the main effects that contamination of these two fluids may cause the technological properties of a cement paste. The interactions between cement paste and drilling fluid, because its different chemical compositions, may affect the cement hydration reactions, damaging the cementing operation. Thus, we carried out the study of the compatibility of non-aqueous drilling fluid and a cement slurry additives. The preparation procedures of the non-aqueous drilling fluid, the cement paste and completion of compatibility testing were performed as set out by the oil industry standards. In the compatibility test is evaluated rheological properties, thickening time, stability and compressive strength of cement pastes. We also conducted analyzes of scanning electron microscopy and X-ray diffraction of the mixture obtained by the compatibility test to determine the microstructural changes in cement pastes. The compatibility test showed no visual changes in the properties of the cement paste, as phase separation. However, after the addition of nonaqueous drilling fluid to cement slurry there was an increased amount of plastic viscosity, the yield point and gel strength. Among the major causative factors can include: chemical reaction of the components present in the non-aqueous drilling fluid as the primary emulsifier, wetting agent and paraffin oil, with the chemical constituents of the cement. There was a reduction in the compressive strength of the cement paste after mixing with this drilling fluid. Thickening test showed that the oil wetting agent and high salinity of the non-aqueous fluid have accelerating action of the handle of the cement paste time. The stability of the cement paste is impaired to the extent that there is increased contamination of the cement slurry with the nonaqueous fluid. The X-ray diffraction identified the formation of portlandite and calcium silicate in contaminated samples. The scanning electron microscopy confirmed the development of the identified structures in the X-ray diffraction and also found the presence of wells in the cured cement paste. The latter, formed by the emulsion stability of the drilling fluid in the cement paste, corroborate the reduction of mechanical strength. The oil wetting agent component of the non-aqueous drilling fluid, the modified cement hydration processes, mainly affecting the setting time.

Modificação da pasta kraft de eucalipto para novas aplicações

Este trabalho constou num estudo da modificação da pasta kraft de eucalipto, utilizando uma técnica de processamento por alta pressão hidrostática com o intuito de melhorar a sua performance para novas aplicações tal como o papel tissue ou o papel para embalagens. Para tal pretendia-se melhorar algumas propriedades da pasta com a utilização da técnica de alta pressão hidrostática. Realizou-se um estudo preliminar onde se submeteu uma pasta branqueada A, não refinada, a um tratamento hiperbárico (TH) numa gama de pressões de 5000-8000 bar. Para uma pressão de 6000 bar constatou-se uma melhoria de cerca de 16 % no alongamento percentual na rotura, 17 % na resistência à tração, 27 % no índice de rebentamento e cerca de 19 % no índice de rasgamento. Posteriormente, e tendo em conta os resultados positivos verificados na pasta A, estudou-se o efeito do TH numa pasta branqueada B variando a consistência de tratamento (1,5% ou 3%) e o tempo de processamento (5 ou 10 minutos). Foi estudado também o efeito do TH quando aplicado antes e após a refinação da pasta. A pasta branca foi submetida à refinação num moinho PFI entre 1000 e 3000 rotações. Os resultados obtidos mostram que o TH realizado a menores consistências apresenta um efeito mais significativo nas propriedades físico-mecânicas de pastas e que o efeito é distinto quando o processamento é aplicado antes e depois da refinação, tendo-se registado melhoramentos das propriedades mecânicas apenas quando o TH ocorre após a refinação. A pasta kraft foi também modificada com anidrido alquenil succínico (ASA). A modificação da pasta de celulose com ASA resultou numa diminuição das propriedades mecânicas e para além disso não gerou qualquer alteração na termoplasticidade do material, no entanto registou-se um aumento na resistência à molhabilidade. Concluiu-se que o TH conduz a alterações ao nível de propriedades mecânicas e estruturais da pasta de interesse para a aplicação em papéis tissue no caso da pasta B. Para além disso a modificação da pasta com ASA resultou em alterações de interesse particular para papéis de embalagem.

Formulação de pastas cimentícias com adição de suspensões de quitosana para cimentação de poços de petróleo

Primary cementing is one of the main operations in well drilling responsible for the mechanical stability and zonal isolation during the production of oil. However, the cement sheath is constantly under mechanical stresses and temperature variations caused by the recovery of heavy oil. In order to minimize fracture and wear of the cement sheath, new admixtures are developed to improve the properties of Portland cement slurries and avoid environmental contamination caused by leaking gas and oil. Polymers with the ability to form polymeric films are candidates to improve the properties of hardened cement slurries, especially their fracture energy. The present study aimed at evaluating the effect of the addition of a chitosan suspension on cement slurries in order to improve the properties of the cement and increase its performance on heavy oil recovery. Chitosan was dissolved in acetic ac id (0.25 M and 2 M) and added to the formulation of the slurries in different concentrations. SEM analyses confirmed the formation of polymeric films in the cementitious matrix. Strength tests showed higher fracture energy compared to slurries without the addition of chitosan. The formation of the polymeric films also reduced the permeability of the slurry. Therefore, chitosan suspensions can be potentially used as cementing admixtures for heavy oil well applications

Adição de resíduo cerâmico em pastas geopoliméricas para cimentação de poços de petróleo

The development of activities the of oil and gas sector have promoted the search for suitable materials for cementing oil wells. In the state of the Rio Grande do Norte, the integrity of the cement sheath tends to be impaired during steam injection, a procedure necessary to increase oil recovery in reservoirs with low-viscosity oil. The geopolymer is a material that can be used as alternative cement, since it has been used in the production of fire-resistant components, building structures, and for the control of toxic or radioactive residues. Geopolymers result from condensation polymer alkali aluminosilicates and silicates resulting three-dimensional polymeric structures. They are produced in a manner different from that of Portland cement, which is made an activating solution that is mixed with geopolymer precursor. Among the few works studied allowed us to conclude that the pastes prepared with metakaolin as precursor showed better performance of its properties. Several studies show the addition of waste clay as a means of reducing cost and improving end of the folder properties. On this basis, the goal is to study the influence of the addition of ceramic waste in geopolymer paste. To develop the study of rheology tests were carried out, filtered, thickening time, compressive strength, free water, specific gravity and permeability, according to the American Pretoleum Institute (API). The results for all formulations studied show that the folders have high mechanical strength to a light paste; low filtrate volume, absence of free water, very low permeability, slurry, consistent with a light paste, and thickening time low that can be corrected with the use of a retardant handle. For morphological characterization, microstructural, physical, chemical and thermal tests were carried out by XRD, MEV, DTA, TG, FTIR. In the trial of XRD, it was found that geopolymer is an amorphous material, with a peak of crystalline kaolinite. In tests of TG / DTA, revealed the presence of a significant event, which represents the mass loss related to water, and also observed the reduction of weight loss by increasing the concentration of ceramic waste. In the trial of MEV, we found a uniform matrix without the presence of other phases. In the trial of FT-IR, we observed the presence of the band related to water. From all results it was determined that the optimum concentration range of use is between 2.5 and 5% of waste ceramic

Desenvolvimento de sistemas de pastas leves para aplicação em cimentação de poços petrolíferos com baixo gradiente de fratura

All around the world, naturally occurring hydrocarbon deposits, consisting of oil and gas contained within rocks called reservoir rocks , generally sandstone or carbonate exists. These deposits are in varying conditions of pressure and depth from a few hundred to several thousand meters. In general, shallow reservoirs have greater tendency to fracture, since they have low fracture gradient, ie fractures are formed even with relatively low hydrostatic columns of fluid. These low fracture gradient areas are particularly common in onshore areas, like the Rio Grande do Norte basin. During a well drilling, one of the most favorable phases for the occurrence of fractures is during cementing, since the cement slurry used can have greater densities than the maximum allowed by the rock structure. Furthermore, in areas which are already naturally fractured, the use of regular cement slurries causes fluid loss into the formation, which may give rise to failures cementations and formation damages. Commercially, there are alternatives to the development of lightweight cement slurries, but these fail either because of their enormous cost, or because the cement properties were not good enough for most general applications, being restricted to each transaction for which the cement paste was made, or both reasons. In this work a statistical design was made to determine the influence of three variables, defined as the calcium chloride concentration, vermiculite concentration and nanosilica concentration in the various properties of the cement. The use of vermiculite, a low density ore present in large amounts in northeastern Brazil, as extensor for cementing slurries, enabled the production of stable cements, with high water/cement ratio, excellent rheological properties and low densities, which were set at 12.5 lb / gal, despite the fact that lower densities could be achieved. It is also seen that the calcium chloride is very useful as gelling and thickening agent, and their use in combination with nanosilica has a great effect on gel strength of the cement. Hydrothermal Stability studies showed that the pastes were stable in these conditions, and mechanical resistance tests showed values of the order of up to 10 MPa

Desenvolvimento de misturas instantâneas de mandioca e caseína: efeito do teor de proteína e parâmetros de extrusão sobre a viscosidade

O interesse da indústria de alimentos por produtos desenvolvidos a partir de farinhas acrescidas de proteína não se deve somente às suas características nutricionais, senão também às suas propriedades funcionais e reológicas, as quais definem as suas aplicações comerciais. Este trabalho teve por objetivo avaliar o efeito de parâmetros operacionais do processo de extrusão sobre as propriedades de pasta de misturas de farinha de mandioca e caseína. O processo de extrusão seguiu o delineamento 'central composto rotacional' para três fatores: teor de proteína (2,5 a 9,5%), umidade (14,5 a 19,5%) e temperatura de extrusão (65 a 135 ºC). As misturas antes e após a extrusão foram analisadas no Rapid Visco Analyser (RVA) quanto a: viscosidade inicial, pico de viscosidade, quebra de viscosidade, viscosidade final e tendência à retrogradação. Os resultados obtidos nas misturas antes da extrusão mostraram aumento dos valores de viscosidade com o aumento da concentração de proteína até o ponto central (6%) e, nos teores mais elevados de proteína, ocorreu redução destes. Após a extrusão, observou-se que o teor de proteína foi a variável de maior efeito sobre as propriedades de pasta, seguida pela umidade das misturas.