Thesis--Johns Hopkins University. / Vita.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted.

Thesis--Johns Hopkins University. / Vita.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--Johns Hopkins University. / Biography. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2007 / The rheological behaviour of non-Newtonian, highly concentrated and non-transparent fluids used in industry have so far been analysed using commercially available instruments, such as conventional rotational rheometers and tube viscometers. When dealing with the prediction of non-Newtonian flows in pipes, pipe fittings and open channels, most of the models used are empirical in nature. The fact that the fluids or slurries that are used normally are opaque, effectively narrows down the variety of applicable in-line rheometers even further, as these instruments are normally based on laser or visible light techniques, such as Laser Doppler Anemometry. Electrical Resistance Tomography is a non-invasive method used to look into opaque suspensions during pipe flow, but cannot be used to measure in-line rheometry. In this research, an Ultrasound Pulsed Echo Doppler Velocity Profile technique (UVP), in combination with a pressure difference (PD) was tested to provide in-line measurement of rheological parameters. The main objective ofthis research was to evaluate the capabilities of the UVP-PD technique for rheological characterisation of different concentrations of non-transparent non-Newtonian slurries. A unique pipe viscometer was designed and constructed. It consisted of four pipes, one of stainless steel and three of PVC, linked to an in-line mass-flow meter and equipped with two different ranges of pressure transducers on each pipe. The stainless steel pipe, with an inner diameter of 16 mm, was equipped with a specially designed flow adapter for in-line rheological characterisation using the UVP-PD method. The three PVC pipes with different diameters of 9 mm, 13 mm and 16 mm served as a tube viscometer for in-line rheological characterisation of mineral suspensions.

No description available.

No description available.

Orientador: Mirna Lucia Gigante / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T19:15:17Z (GMT). No. of bitstreams: 1 Salles_AntonioSergio_M.pdf: 233527 bytes, checksum: 23062b9d3bdc093e7873c5ea4165382b (MD5) Previous issue date: 2003 / Resumo: O Cream Cheese é um queijo obtido por coagulação ácida de alto teor de umidade que apresenta como principal defeito a sinérese, ou exudação do soro durante o período de armazenamento. O objetivo deste trabalho foi avaliar o efeito da adição do sorbato de potássio, sobre a estabilidade do Cream Cheese e da solução de goma locusta. Os queijos foram fabricados a partir de leite padronizado, homogeneizado, tratado termicamente e fermentado com cultura tipo ¿O¿, composta de Lactococcus lactis subsp. lactis e Lactococcus lactis subsp. cremoris. A massa obtida após fermentação foi dividida em duas porções para fabricação de queijos com e sem adição de sorbato de potássio. Os queijos de cada processo foram divididos em dois lotes e armazenados a 4°C ou a 20°C. Amostras de Cream Cheese foram randomicamente escolhidas após 4, 10, 17, 24, 31, 38, 45, 52 e 59 dias de armazenamento e analisadas quanto ao pH, quantidade de fase aquosa obtida por centrifugação, contagem total de microrganismos e de bolores e leveduras. A fase aquosa foi avaliada quanto ao teor de sólidos totais e parâmetros reológicos. O delineamento experimental utilizado foi Split-Split-Plot em blocos com três repetições. O efeito dos tratamentos, da temperatura e do tempo de armazenamento sobre as características estudadas foi avaliado por análise de variância. Para avaliar o efeito da adição de sorbato sobre o comportamento reológico da solução de goma locusta esta foi dissolvida em água destilada a 80°C, adicionada ou não de sorbato de potássio, tendo sido o pH ajustado para 4,60 ± 0,05. Soluções com e sem sorbato de potássio foram armazenadas a 4°C ou a 20°C. Amostras foram escolhidas após 4, 11, 18, 25, 32, 39, 46, 53, 60 e 67 dias de armazenamento e avaliadas quanto ao pH, contagem total de microrganismos, bolores e leveduras e parâmetros reológicos. A adição de sorbato de potássio não afetou a composição dos queijos, exceto o pH que foi mais alto no queijo com sorbato. A capacidade de retenção de água do Cream Cheese diminuiu significativamente durante o período de armazenamento e diminuiu mais rapidamente quando o queijo foi armazenado a 20°C. As contagens total e de bolores e leveduras aumentaram linearmente e significativamente durante o período de armazenamento e foram maiores para os queijos fabricados sem adição de sorbato e armazenados a 20°C. À medida que a contagem microbiológica aumentou, ocorreu a redução da viscosidade aparente da fase aquosa e, à medida que a viscosidade diminuiu, observou-se a redução da capacidade de retenção de água do Cream Cheese. A avaliação do efeito da adição de sorbato de potássio sobre o comportamento reológico da solução de goma locusta mostrou que durante o período de armazenamento não houve crescimento expressivo de microrganismos e nem alteração da viscosidade das soluções, o que indica que a capacidade de retenção de água da goma não foi alterada. Estes resultados sugerem que a manutenção da viscosidade da fase aquosa do Cream Cheese é consequência do retardamento do crescimento microbiano e contribui para minimizar a sinérese melhorando a capacidade de retenção de água e a qualidade do produto final / Abstract: Cream cheese is a product of high moisture content obtained by acid coagulation, the main defect being syneresis or whey exudation during the storage period. The objective of this study was to evaluate the effects of the addition of potassium sorbate on the stability of cream cheese and on a solution of locust bean gum. The cheeses were prepared from standardized homogenized milk, heat treated and fermented with an ¿O¿ type culture. The mass obtained after fermentation was divided into two parts to manufacture the cheeses with and without potassium sorbate. The cheeses from each process were divided into two batches and stored at 4 or 20°C. Samples of cream cheese were taken at random after 4, 10, 17, 24, 31, 38, 45, 52 and 59 days of storage and analyzed for pH, amount of aqueous phase obtained by centrifugation, total microbial count and yeast and mold count. The aqueous phase was evaluated for total solids and rheological parameters. A Split-Split-Plot block experimental design was used with three repetitions. The effect of the treatments, the temperature and time of storage on the characteristics under study was evaluated by the analysis of variance. To evaluate the effect of the addition of sorbate on the rheological behavior of a solution of locust bean gum, the latter was dissolved in distilled water at 80°C, with or without the addition of potassium sorbate, the pH having been previously adjusted to 4.60 ± 0.05. Solutions with and without potassium sorbate were stored at 4 or 20°C. Samples were taken after 4, 11, 18, 25, 32, 39, 46, 53, 60 and 67 days of storage and evaluated for pH, total microbial count, yeast and mold count and the rheological parameters. The addition of potassium sorbate did not affect the composition of the cheeses, with the exception of the pH, which was higher in the cheese with sorbate. The water holding capacity of the cream cheese decreased significantly during the storage period, decreasing quicker when stored at 20°C. The total and yeast and mold counts increased linearly and significantly during the storage period and were higher in the cheeses manufactured without the addition of potassium sorbate and stored at 20°C. As the microbial count increased so the apparent viscosity of the aqueous phase reduced, and as the viscosity reduced there was a reduction in the water holding capacity of the cream cheese. The evaluation of the effect of the addition of potassium sorbate on the rheological behavior of the locust bean gum solution showed that during the storage period there was no expressive growth of microorganisms nor alterations in the viscosity of the solutions, indicating that the water holding capacity of the gum was unaltered. These results suggest that the maintenance of the viscosity of the aqueous phase of the cream cheese is a consequence of retarding microbial growth and contributes to minimize syneresis, improving the water holding capacity and quality of the final product / Mestrado / Mestre em Tecnologia de Alimentos