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Orientador: Vivaldo Silveira Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T22:00:11Z (GMT). No. of bitstreams: 1 CasteliniNeto_Armando_M.pdf: 13618067 bytes, checksum: 5304d293b5811c2a4c8041f27a9a74c0 (MD5) Previous issue date: 2006 / Resumo: O trabalho consistiu em avaliar a linearidade do processo de pasteurização HTST na seção de aquecimento, verificar a diferença de sintonia entre as estratégias de controles convencionais (PID) e não convencionais (fuzzy/PID) e avaliar e comparar a eficiência desses controladores quando processados em fluidos newtoniano e não-newtoniano. O pasteurizador utilizado foi a placas de 3 seções (regeneração, aquecimento com retenção e resfriamento). O fluido newtoniano utilizado foi água e o não-newtoniano uma solução aquosa de 0,5% m/m de Carboximetilcelulose (CMC) sódica. Os binômios tempo/temperatura foram aferidos para cada fluido envolvido no processo com base nas limitações do trocador de calor e do controle das utilidades. Para a avaliação qualitativa da linearidade, as curvas de reação do processo foram analisadas pelo método da superposição sugeridos por Ogata (1985), subsidiado pela análise do fator de sensibilidade do coeficiente global de transferência de calor ¿U¿, avaliando a variação das propriedades termofísicas da água e solução aquosa de CMC frente às mudanças das temperaturas de entrada e de saída desses fluidos na seção de aquecimento. Ambos os processos apresentaram comportamento não linear; porém, o processo é mais nãolinear quando utilizada a solução de CMC sódica. A partir das curvas de resposta, foram obtidos os parâmetros de sintonia do PID/feedback pelo método de Aström e Hägglund (1984) e com esses foram obtidos os parâmetros de sintonia do controle fuzzy/PID pelo método de Li (1997). A variável controlada foi a temperatura de pasteurização na saída do tubo de retenção e a manipulada a vazão de água quente no trocador. Os controles foram testados, avaliados e comparados através dos índices de erros absolutos IAE, ITAE e ISE, fazendo-se perturbações de set-point na temperatura de saída da seção de aquecimento, com a seção de regeneração desativada para teste de eficiência de sintonia; e perturbações de carga na temperatura de entrada dos produtos no pasteurizador com as seções de regeneração e aquecimento integradas. Especificamente para o fluido não-newtoniano, também foi alterada sua concentração de entrada. Os valores obtidos dos parâmetros da sintonia foram diferentes para cada um dos fluidos pasteurizados. O controle PID teve bom desempenho para ambas as perturbações de setpoint e de carga no caso da água, o que não aconteceu quando se utilizou a solução de CMC sódica, principalmente no caso da perturbação da sua concentração.de entrada. Este desempenho inferior foi superado pelo uso do controle Fuzzy/PID que mostrou melhor desempenho perante às perturbações de carga e set-point / Abstract: The goal of this work was to evaluate the pasteurization process linearity in heat and cooling sections, to check if it would have tuning differences between conventional (PID) and non-conventional (fuzzy) control strategies and evaluate and compare these controllers performance when processed a Newtonian and a non-Newtonian fluid. A Plate Heat Exchanger with three sections (regeneration, heating with retention and cooling) was used. The Newtonian fluid used was water and the non-Newtonian fluid was a 0,5% w/w water based solution of Sodium Carboxymethyl cellulose (CMC). The temperature/time residence was achieved to both fluids based on the limitations of the heat exchange and the utilities control. To qualitative linearity evaluation, the gain curves were analyzed by the superposition method suggested by Ogata (1985), subsided by the sensibility factor analysis of the heat transfer global coefficient ¿U¿, evaluating the thermo physical properties variation in addiction to inlet and outlet temperature changes of this fluids in the heating section. The analysis showed that both systems presented nonlinear behavior; however, the most non-linear process was the one that sodium CMC was used. The PID/feedback tuning parameters were obtained from the gain curves, using Aström e Hägglund (1984) method and these parameters were used to obtain the fuzzy/PID/feedback tuning parameters by Li (1997) method. The controlled variable was the pasteurization temperature and the manipulated variable was the hot water flow. The controls were evaluated and compared through the absolute errors indexes IAE, ITAE e ISE indexes, by doing set point disturbances in the outlet heating section temperature, with the regenaration section turned off to tuning efficiency test and changing the inlet fluid temperature with both regeneration and heating section turned on. In the non-newtonian fluid case, the inlet concentration was also modified. The presented tuning parameters were different to both pasteurized fluids. The PID/feedback strategy had good performance after disturbances in the inlet temperature in the case of water, what did not happened when CMC water based solution was used. This lower performance was supplied by the use of the PID/Fuzzy/feedback strategy, that showed better performances after set-point and charge disturbances / Mestrado / Mestre em Engenharia de Alimentos

This study assessed losses of the linoleic, alpha-linolenic, arachidonic and docosahexaenoic fatty acids, vitamin B2 and total vitamin C during storage of human milk, pasteurized and unpasteurized. The volatile compounds’ pattern change was monitored. The storage conditions were 8 days at 4oC and 6 months at -20oC and at -80oC, with and without limitation of oxygen. Fatty acids were analyzed by GC-FID; vitamins - by HPLC; volatile compounds’ concentration patterns were obtained using the e-nose machine; ANOVA tests were applied, with the statistical significance assigned to P<0.05. The official recommendations for human milk storage of 5-8 days at 4oC and of 6 or more months at -20oC are appropriate in regard to the analyzed nutrients and can be extended for pasteurized human milk storage. Oxygen limitation and -80oC temperature have no clear benefit for nutrient preservation. The evaluation of the odour cannot be based exclusively on the e-nose analysis.

Two outbreaks of salmonellosis were linked to the consumption of raw California almonds in 2001 and 2004. Current federal regulations mandate that all almonds grown in California are to be treated with a process that results in a 4-log reduction of Salmonella. Since four out of the five approved technologies to pasteurize almonds rely on the application of heat to control Salmonella, the evaluation of alternative technologies against heat resistant Salmonella Senftenberg was imminent. In this study, almonds that were inoculated with S. Enteritidis PT 30 and S. Senftenberg, were treated with electron beam irradiation (e-beam), blanching and oil roasting. The thermal death time (D-value) for S. Enteritidis PT 30 when treated with e-beam was 0.90 kGy, 15 s when subjected to blanching at 88 degrees C, and 13 s when treated with oil at 127 degrees C. Irradiation and thermal resistance of S. Senftenberg was not significantly different (P > 0.05) from S. Enteritidis PT 30. The commercial application of e-beam as a pathogen intervention was assessed through Monte Carlo simulations (MCS) and experimental measurements. The sensory characteristics of almonds commercially treated by e-beam, blanching and roasting were assessed by a consumer panel. Irradiated and blanched almonds did not differ in consumer overall like (P > 0.05). Bitterness and rancidity attributes of irradiated almonds were between a "dislike slightly" and "dislike moderately", whereas blanched and roasted almonds were between "neither like nor dislike" and "like slightly". Almonds commercially irradiated, blanched and roasted were subjected to an accelerated shelf-life test (ASLT) evaluating percentage free fatty acids, peroxide value, and 2-thiobarbituric acid reactive substances (TBARs). No clear differences between treatments were observed at any given point in time in any of the chemical tests. A gas chromatography-mass-spectrometry-olfactometry (MDGC-MS-O) technology was used to compare full aroma and flavor profiles from raw and e-beam irradiated almonds. Differences in the aroma/odor profile and the taste analysis revealed that the difference between raw and irradiated almonds is extremely subtle. In conclusion, e-beam may be a feasible technology to control Salmonella in almonds if used at low doses, as a part of a series of interventions.

This study assessed losses of the linoleic, alpha-linolenic, arachidonic and docosahexaenoic fatty acids, vitamin B2 and total vitamin C during storage of human milk, pasteurized and unpasteurized. The volatile compounds’ pattern change was monitored. The storage conditions were 8 days at 4oC and 6 months at -20oC and at -80oC, with and without limitation of oxygen. Fatty acids were analyzed by GC-FID; vitamins - by HPLC; volatile compounds’ concentration patterns were obtained using the e-nose machine; ANOVA tests were applied, with the statistical significance assigned to P<0.05. The official recommendations for human milk storage of 5-8 days at 4oC and of 6 or more months at -20oC are appropriate in regard to the analyzed nutrients and can be extended for pasteurized human milk storage. Oxygen limitation and -80oC temperature have no clear benefit for nutrient preservation. The evaluation of the odour cannot be based exclusively on the e-nose analysis.

A continuous flow microwave heating system was set up by using one domestic microwave oven (1000W nominal output at 2450MHz). Water was run through the coil centrally located inside the oven cavity for microwave heating. Microwave absorption efficiency was evaluated by measuring inlet and outlet temperatures of coil as a function of system variables. In order to optimize the coil configuration, the influence of tube diameter (6.4, 7.9 and 9.7mm); initial temperature (10, 20 and 30 ºC); number of turns (3.5, 4.5 and 5.5); coil diameter (61.5, 88, 102, 121 and 153 mm) and pitch (16, 18, 20, 22 and 24mm) were evaluated, respectively at different flow rates (240, 270, 300, 330 and 360ml/min). In helical systems, Dean number is used as a measure of secondary flow which enhances mixing of the fluid providing uniform heating even under laminar flow conditions. Results showed that microwave absorption efficiency was a compromise between coil volume and Dean number. Therefore, a helical coil (110 mm high) with a coil diameter of 108 mm, tube diameter of 8.2 mm, 5.5 turns demonstrated the highest efficiency, fast heating rate, more uniform heating and less temperature fluctuations. The optimized coil configuration parameters were used subsequently to set up continuous-flow microwave heating system.

Filtered bright and unfiltered hazy lager beer samples were either treated with high hydrostatic pressure (200, 250, 300, 350 MPa for 3, 5 and 10 min at 10&deg / C and 20&deg / C) or conventional heat pasteurization (60&deg / C for 15 min). Treatments did not affect ethanol, extract, fermentation degree, density and pH in comparison with untreated beers. Both treatments produced microbiologically stable products. Bitterness, color, protein sensitivity and chill haze parameters were affected by both the HHP and heat treatment. A storage period of 56 days showed that HHP and heat pasteurization had similar results in terms of pH and color. However, HHP treated samples had lower bitterness and protein sensitivity and higher chill haze values than the heat pasteurized samples which indicates HHP treatment had a positive effect on bitterness and protein sensitivity at the end of the storage period. The microbiological stability of HHP treated beers was comparable with heat-treated beers, and the development of both lactic and acetic acid bacteria was inhibited for 56 days of storage. Unfiltered beer samples had 7. 48, 7.15 and 2.64 log10cfu/ml of total yeasts, total aerobic and lactic acid bacteria counts, respectively. No colony formation of lactic acid bacteria was observed when the samples were pressurized at pressures equal to or higher than 300 MPa at 10&deg / C and 20&deg / C for 5 and 10 min. Total aerobic and total yeasts counts demonstrated more than 6 and 7 log-cycle reduction when pressurized at 350 MPa at 10&deg / C and 20&deg / C for 10 min, respectively. Heat treatment gave similar results in terms of log reductions as HHP.

Orientador : Jose Satiro de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos e Agricola / Made available in DSpace on 2018-07-17T16:26:26Z (GMT). No. of bitstreams: 1 Prata_LuizFrancisco_M.pdf: 25047113 bytes, checksum: 929fcb9f022bcc9e6a2e25a2e4738ae7 (MD5) Previous issue date: 1984 / Resumo: Partindo-se da importância do controle microbiológico do leite recebido na plataforma das indústrias de laticínios, a pesquisa de provas específicas que ofereçam resultados rápidos e compatíveis com a perecibilidade do produto, tem sido o objetivo do serviço de inspeção sanitária. Nesse aspecto, não encontramos, sendo utilizado em nosso meio, um teste que ofereça resultados que permitam o controle efetivo da matéria prima antes que esta entre na linha de processamento.No presente trabalho foi, então, estudado o método de contagem microscópica de microrganismos, com a intenção de comprovar a sua aplicabilidade como método rápido para o controle microbiológico do leite ao chegar à plataforma. Os resultados alcançados permitiram concluir que esse método se correlacionou muito bem com a contagem padrão em placas, tendo se comportado, também, de forma semelhante ao método de redução do azul de metileno. A aplicação do método microscópico na avaliação da qualidade microbiológica de 319 amostras de leite cru, incluindo leite tipo ¿B¿ apresentou resultados que permitiram recomendá-lo como teste rápido para o controle de qualidade a nível de plataforma das indústrias de laticínios. Mostrou-se útil, também, no fornecimento de informações adicionais importantes, como por exemplo na detecção de leite mastítico. Ressalta-se, ainda, que sua aplicação a leite pasteurizado permitiu uma indicação da qualidade microbiológica do leite antes de ser submetido ao tratamento térmico / Abstract: The microbiological quality is the starting point for the milk quality control in the receiving platform of the dairy industry, therefore the search for specific rapid tests has been the airn of resarchers envolved in milk quality inspection. In Brazil we have not found a microbiological test being used which could effectively evaluate the raw milk quality before it enters the processing line. In the present research work it was studied the direct microscopic count method to show its applications as a rapid test for contoling the milk quality in our brazilian industrues. The results indicated a very good correlation between the microscopic. Count and the standard plate count. As a quality control test the microscopic method was equivalent to the methylene blue reduction test. In assessing the microbiological quality of 319 samples of raw milk, including also type B milk, the microscopic count method proved to be a very good rapid test for controlling the raw milk quality in the dairy industry. This method also gave additional informations regarding the milk quality, like for instance the indication of mastitic milk. It could also be pointed that the microscopic count when applied to pasteurized milk gives a good idea of the microbiological quality of this milk right before it's pasteurization / Mestrado / Mestre em Tecnologia de Alimentos

The objective of this study was to determine the effect of aging on the tenderness and palatability of beef from the semitendinosus muscle of the round. Tenderness may be affected by the length of the aging period and the aging temperature. Steaks from the semitendinosus muscle were stored for 0, 3, 6, 9, 12, and 24 hr at two temperatures, 43.3°C and 2.2°C. Ultra high temperature (UHT) pasteurization was accomplished by subjecting the meat to 1100°C for 20 seconds. UHT pasteurization denatures surface proteins, destroys vegetative pathogens, and eliminates some spoilage organisms from the surface of the meat. UHT -treated steaks were cooked in a microwave oven to an internal temperature of 71.1°C. Two cores were taken from the center of each cooked steak. Shear values (lb) were determined on the cores using a Warner Bratzler shear. The results of the study showed that the UHT-treated steaks that were stored at 43.3°C were significantly more tender than those that were refrigerated at 2.2°C regardless of the length of the aging period up to 24 hr. Additional tenderness at 2.2°C when the aging period exceeds 24 hr may be possible. Total plate count (TPC) of raw and UHT-treated steaks was determined using the standard plate count method. The average TPC for the raw steaks was significantly higher than the UHT-treated steaks. The TPC was not significantly different between the UHT- treated steaks that were aged and those that were not aged. A trained panel was used for sensory evaluation to evaluate the moistness, tenderness, and flavor of the steaks using a 9-point hedonic scale. Sensory scores of the UHT-treated steaks revealed that steaks stored at 43.3°C had significantly more moisture and were more tender than those stored at 2.2°C. The panel noted more spoiled flavor among the steaks stored at 43.3°C than 2.2°C. Steaks stored at 2.2°C received significantly higher flavor scores than those stored at 43.3°C.

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