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| Fraiha,Marcos; Ferraz,Antonio Carlos de Oliveira; Biagi,João Domingos. |
| The aim of this experiment was to evaluate how susceptible spores become to mechanical damage during food extrusion after being submitted to CO2. B. stearothermophilus spores sowed to corn and soy mix were submitted to 99% CO2 for 10 days and extruded in a single-screw extruder. The treatments were: T1 - spore-containing samples, extruded at screw rotational speed of 65 rpm and barrel wall temperature of 80 °C; T2 - as T1, except for screw rotational speed of 150 rpm; and T3 - as T2, except that samples were submitted to the modified atmosphere. The results for cell viability, minimum and maximum residence times, and static pressure were T1 - 19.90 ± 3.24%, 123.3 ± 14.50 seconds; 203.3 ± 14.05 seconds; 2.217 ± 62 kPa; T2 - 21.42 ± 8.24%, 70.00 ± 5.77... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Shear; Feed; Bacillus stearothermophilus. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612011000100024 |
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| Fraiha,Marcos; Biagi,João Domingos; Ferraz,Antonio Carlos de Oliveira. |
| Foods behave as non-Newtonian fluids, but little is known about how corn and soybean mix behave under viscometric flow. In order to characterize the rheological behavior of animal feed under viscometric flow, a 70:30 (mass:mass) mixture of ground corn and soybean grains was submitted to a capillary rheometer at 3 different temperatures (80, 120, and 160 °C), different moisture levels (26.5 ± 0.08; 30.4 ± 0.31, and 33.4 ± 0.05%), and 4 shear rates (30.4; 72.9; 304.3, and 728.6/second). Different strain rates and die dimensions were used to obtain the target shear rates. The resulting data were fitted to Power Law, Casson, and Bingham models. Based on experimental data, water content, mass temperature, and the effects of shear rate on the apparent shear... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Viscometric flow; Shear; Shear-thinning; Capillary rheometer. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612011000100018 |
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| Fraiha,Marcos; Ferraz,Antonio Carlos de Oliveira; Biagi,João Domingos. |
| In order to determine thermobacteriological parameters for B. stearothermophilus spores, they were diluted in a saline solution medium and in ground corn-soybean mix, distributed in TDT tube, and submitted to heat for a specific period of time. The D value (time to reduce 1 log cycle of microbial count under a certain temperature) and z value (variation of temperature to cause 10-fold change in D value) were estimated. To estimate their dimensions, the spores were visualized by using a scanning electron microscope. D121.1 ºC and z values for these spores, as determined in the saline solution, were 8.8 minutes and 12.8 ºC, respectively. D121,1 ºC and z values determined in the corn-soy mix were 14.2 minutes and 23.7 ºC, respectively. The micrographs... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Thermobacteriology; Feed; D value; Z value; Spore size. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612010000400032 |
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| Fraiha,Marcos; Biagi,João Domingos; Ferraz,Antonio Carlos de Oliveira; Sverzut,Claudio. |
| O princípio da reometria é relativamente simples, e a construção de equipamentos para avaliação do comportamento reológico de materiais pode ser realizada com poucos investimentos. O presente trabalho teve por objetivos projetar e construir um reômetro capilar para caracterizar ingredientes e misturas utilizadas em alimentação animal. Durante os testes, observou-se atrito desprezível (0,20 a 0,01% da força aplicada) entre pistão e cilindro e não se observou refluxo de amostra. A força necessária para o escoamento das amostras através do capilar foi de 986,02±52,05; 559,60±52,24 e 338,25±45,86N, para as amostras com 29,04±0,08, 31,91±1,01 e 34,98±0,30% de umidade, respectivamente. A partir da fundamentação teórica de reologia de materiais, foi possível... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Taxa de cisalhamento; Reologia; Propriedades mecânicas de materiais. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782010000900023 |
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