Thesis. 1977. M.C.P.--Massachusetts Institute of Technology. Dept. of Urban Studies and Planning. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography : leaf 75. / by Stephen Klein. / M.C.P.

The purpose of this research was to determine whether or not canning fruit using fluoridated water made a difference in the fluoride contents of the juice and the pulp. Four cities in Utah were chosen. Two cities were fluoridated (Brigham City and Helper) and two cities were not fluoridated (North Ogden and Price). Three homes were chosen within each city, and three jars of canned fruit (one jar each of apricots, cherries, and peaches) were selected from each home. The fruit samples were freeze-dried, and then the fluoride was measured with a fluoride ion electrode. A difference was found in the fluoride level of the juice and the pulp when canning using fluoridated water. However, this difference was not statistically significant and did not greatly contribute to the overall dietary fluoride intake.

Heat transfer to canned particulate laden Newtonian fluids was studied during free axial agitation thermal processing in a pilot STOCK retort which was modified to simulate the can motion in continuous turbo cookers. Evaluation of heat transfer coefficients (overall, U and fluid to particle, hfp) associated with canned liquid/particle mixtures, while they are subjected to free axial motion is difficult because of the problems involved with attaching temperature measuring devices to liquid and particles without affecting their normal motion. A new methodology was developed to evaluate U and hfp in Newtonian liquids. The methodology involved first correlating U and hfp as a function of input variables for cans in fixed axial mode of rotation in which both particle and fluid temperatures were measured using thin wire thermocouples. Subsequently, only liquid temperatures were measured in cans using wireless sensors in the free axial mode, and hfp values were empirically computed from the developed correlations and the measured temperatures. An L-16 orthogonal experimental design of experiment was carried out to select system and product parameters that significantly influence hfp and U for particles in the Newtonian liquid. With significant parameters selected, a response surface methodology and two full factorial experimental designs were used to relate U and hfp to process variables in each mode of rotation (fixed and free axial modes). / Dimensionless correlations were then developed using the evaluated data for heat transfer coefficients (U and hfp), in canned high viscosity Newtonian liquids (with and without particles) using stepwise multiple non-linear-regressions of significant dimensionless groups. In free axial mode, combining the natural and forced convection, Nu = A 1(GrxPr)A2+ A3(Re) A4 (Pr)A5 FrA 6 (rhop/rhop1)A 7 (e/100-e)A8 (dp/Dc) A9 (Kp/K1)A10 yielded a higher R2 (0.93) than using a pure forced convection model when particles were present in the can. Even in the absence of particles, and with the end-over-end mode of agitation where forced convection dominates, introducing natural convection term (GrxPr), improvedR2 from 0.81 to 0.97. Artificial neural network (ANN) models were also developed for heat transfer coefficient predictions and the trained models gave better predictions than dimensionless correlations. All ANN models developed could be implemented easily in a spreadsheet as either matrices or a set of equations.

No description available.

The feasibility of using Artificial Neural Network (ANN) models for application in thermal process calculations was studied. / For a better understanding of the effect of process parameters on the evaluation of thermal process, the accuracy of several formula methods (Steele & Board, Ball, Stumbo and Pham) were studied over a wide range of commercial conditions. A computer simulation based on finite difference method of numerical solutions of heat transfer to packaged foods in cylindrical containers was applied to obtain the time-temperature data for designed conditions (retort and initial temperatures, thermal diffusivity, package sizes and processing time). Moreover, the process time and process lethality from this simulation were used as the reference values for the purpose of comparison. The accuracy of methods was evaluated based on the variation of each parameter over the range of conditions employed in the study. / As the final goal of the study, a multi-layer ANN model was developed as an alternative to thermal process calculations. (Abstract shortened by UMI.)

Graduation date: 1938

Graduation date: 1936

Graduation date: 1991

Orientador: Flávio Luis Schmidt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T02:07:59Z (GMT). No. of bitstreams: 1 Silva_ElaineBergesda_D.pdf: 4524403 bytes, checksum: aabc8930b1bedbdff633b05a11eb22e7 (MD5) Previous issue date: 2011 / Resumo: Os alimentos enlatados sob alto vácuo, também conhecidos como solid pack, contêm aproximadamente 10% de líquido em relação ao volume da embalagem e reduzem as trocas de massa por osmose entre o produto e a salmoura. Este trabalho de pesquisa teve como objetivo estudar o processamento térmico de fundos de alcachofra (Cynara cardunculus scolymus L.) sob alto vácuo em salmoura convencional (CV) e solid pack (SP). Os objetivos específicos foram: avaliar o efeito de antioxidantes na inibição do escurecimento enzimático e determinar: os parâmetros cinéticos para degradação térmica da textura; perfil de temperatura e pressão, os parâmetros de penetração de calor; letalidade; características físico-químicas e sensoriais. Foi determinado o índice de escurecimento (IE) em amostras pré-tratadas com L-cisteína (LC), ácidos cítrico (AC) e escórbico (AA) e branqueadas em água em ebulição nos tempos 0 a 20 minutos. A textura das amostras tratadas nas temperaturas 80 a 100oC foi determinada em texturômetro (força de penetração) em função do tempo. Os fundos branqueados foram acondicionadas em latas ¿abre-fácil¿, fechadas sob vácuo mecânico (mínimo 20 pol Hg) e processadas termicamente em autoclave por cascata de água a 128 oC por 210 s, sob agitação ¿end over end¿ de 20 rpm. Foi determinado o perfil de temperatura e pressão utilizando termopares e transmissores de pressão. As amostras processadas foram avaliadas sensorialmente quanto à aceitação e intenção de compra. Foi determinada a força de penetração das amostras processadas utilizando o texturômetro. A acidez titulável, pH, sólidos solúveis, composição centesimal, minerais e fenóis totais foram determinados. Na condição mais drástica de tratamento (AA1%, AC1%, LC1%) foi obtido o menor valor de k (0,0283). Foram obtidos os valores de Ea (20,76 kcal.mol-1), z (29,22oC) e Q10 (2,2) para degradação térmica da textura. Os valores de fh obtidos foram, respectivamente 7,01 e 7,82 minutos para CV e SP e o jc e jh variaram em torno de 1. O Fo obtido foi 5,76 e 7,04, para os processos CV e SP. Nos dois processos a degradação da textura foi de 1 ciclo log, sendo considerada sensorialmente aceitável. Os resultados médios dos atributos odor, sabor e aceitação global variaram em torno de 5, correspondendo a ¿não gostei/nem desgostei¿. A amostra in natura apresentou o maior conteúdo de fenóis totais (272 ± 11,74 mg/100 g), seguido pela SP (104 ± 3,79 mg/100g) e CV (85 ± 4,54 mg/100g). As cinzas, minerais, sólidos solúveis e fenóis totais foi significativamente maior (p<0,05) para SP em comparação à CV. O pré-tratamento com antioxidantes é recomendado para retardar o escurecimento antes do branqueamento. Temperaturas mais elevadas de processo por tempo mais curto minimizam a destruição térmica da textura. O tratamento térmico a 116,88 ºC por 6,66 minutos é o limite mínimo de processo capaz de garantir a estabilidade microbiológica do produto sem comprometer a textura dos fundos de alcachofra. A alcachofra in natura apresentou quantidades importantes de cálcio e zinco, além de ser fonte de ferro. O processo solid pack reduziu as trocas osmóticas entre o vegetal e a salmoura / Abstract: Canned foods under high vacuum, also known as solid pack type food contain approximately 10% of the recipient volume in liquid, which reduces the mass transfer by osmosis between the product and brine. This research aimed to study the thermal processing of artichoke (Cynara cardunculus scolymus L.) under high vacuum. The specific objectives were to assess the effect of antioxidants in inhibiting enzymatic browning and determine: the kinetic parameters for the thermal degradation of texture, temperature and pressure profile, the heat penetration parameters, lethality, and physico-chemical and sensorial characteristics of the conventional artichoke processed in brine (CV) and those of the solid pack (SP) one. The browning index (BI) of samples pretreated with solutions of L-cysteine (LC) and citric acid (CA) and ascorbic acid (AA) and blanched in boiling water from 0 up to 20 minutes were determined. The texture of the samples treated at temperatures of 80, 90 and 100oC were measured using the texturometer (penetration force) versus time. The blanched samples were packaged in "easy-open" cans, closed under mechanical vacuum (minimum 20 in Hg), and thermally processed in an water cascade autoclave at 128oC for 210 s with 20 rpm "end-over-end" agitation. The temperature and pressure profiles were determined using thermocouples and pressure transmitters, respectively. The processed samples were evaluated by sensory acceptance and attitude purchase. The penetration force of the processed samples were determined using the texturometer. The acidity, pH, soluble solids content, chemical composition, minerals and phenols were determined in the physical-chemical characterization of samples. The more drastic treatment (AA1% AC1% LC1%) provided the lowest value for k (0.0283). Values of Ea (20.76 kcal.mol-1), z (29.22°C) and Q10 (2.2) were obtained for thermal degradation of the texture. fh values obtained were respectively 7.01 and 7.82 minutes for CV and SP and jc and the jh varied around 1. The Fo obtained was 5.76 and 7.04 for CV and SP processes. In both cases the degradation of texture was 1 log cycle, and it was considered acceptable in sensory aspect. The average scores for odor, flavor and overall acceptability were around 5 corresponding to "neither liked nor disliked¿. The fresh sample showed the highest content of total phenols (272 ± 11.74 mg/100 g), followed by SP (104 ± 3.79 mg/100g) and CV (85 ± 4.54 mg/100g). The ash, minerals, phenols and total soluble solids were significantly higher (p <0.05) for the SP as compared to CV. Pre-treatment with antioxidants is recommended to control the browning before the heat blanching. Higher temperatures for shorter procedures minimize the thermal destruction of the texture. The thermal treatment at 116.88°C for 6.66 minutes is the minimum process capable of ensuring the microbiological stability of the product without compromising the texture of the artichoke hearts. The artichoke is a fresh source of copper and iron, and presents significant amounts of calcium and zinc. The physical-chemical results showed that the solid pack process reduced osmotic exchanges between the plant and brine / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

Electric machines are being deployed in industrial applications where previously only mechanical systems were considered, as environmental concerns from burning fossil fuels and energy costs are becoming a more dominant factor in system design considerations. Electric machines offer greater operational flexibility and typically higher efficiencies. There has therefore been a growing demand to develop electric machines to replace traditional mechanical systems in a number of industrial applications. One such suitable electric machine topology is the 'direct-drive' machine. These machines can be used where implementation does not require a high operating speed, therefore eliminating the necessity of a gearbox. Furthermore, direct-drive machines offer a number of advantages including reductions in through-life costs, noise and vibration, and overall system volume. This thesis explores the development of direct-drive rim-driven machines, constructed by integrating a propeller with the electric machine that is driving it, by mounting the machine directly around the outside of the propeller. A novel machine topology was developed by integrating a conducting-can onto the rotor structure capable of producing induction torque, to create a motor that can start directly from the main electric supply. This eliminated the need for a power electronic converter, gearbox and complicated drive shafts arrangement, for use in applications where only a low duty cycle of operation was required such as secondary propulsion systems for marine applications or where safety and reliability is of significant importance. A number of other industrial applications that may benefit from this canned rim-driven topology were also identified including seal-less pumps and 'run-of-the-river' generators. Permanent-magnet and induction motor topologies operating in fluid environments were investigated, using finite element analysis and thermal analysis techniques, to examine and optimise the design of the rim-driven topology for a specific operational requirement, in each industrial application area identified. A 30 kW canned line-start rim-drive induction motor was designed and developed for use as a bi-directional thruster on-board a tidal stream turbine. A novel induction motor topology was developed utilising only a conducting-can on the rotor, which eliminated the need for a traditional squirrel-cage, due to the ratio of the relatively large mean air-gap diameter to the small output power requirement; creating a simple yet reliable direct-drive canned induction motor. The design of this motor was manufactured and successfully tested to validate the design process.