Rheological Behavior Of Corn And Soy Mix As Feed Ingredients [comportamento Reológico De Mistura De Milho E Soja Para Produção De Rações]

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 viscosity of corn-soy mix were fitted to a single expression (p < 0.001, R2 = 0.93): η = 18,769.7 (γ)-0.86 e(-9.34 U + 935 T), where γ is shear rate, U is sample moisture, and T is sample temperature in Kelvin scale. As expected, such mixture presented a pseudoplastic (shear-thinning) behavior.311129134Alavi, S.H., Chen, K.H., Rizvi, S.S.H., Rheological characteristics of intermediate moisture blends of pregelatinized and raw wheat starch (2002) Journal of Agricultural Food Chemistry, 50, pp. 6740-6745Method of determining and expressing fineness of feed materials by sieving. ANSI/ASAE S319.3 (2004) ASAE. Agricultural engineers yearbook of standard, pp. 578-581. , AMERICAN SOCIETY OF, 51th ed. St. Joseph: ASAE, In:(1984) Official methods of analysis, p. 1141. , ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS-AOAC, 14th ed. Washington, DC: AOACBagley, E.B., Dintzis, F.R., Chakrabarti, S., Experimental and conceptual problems in the rheological characterization of wheat flour doughs (1998) Rheologica Acta, 37, pp. 556-565Padmanabhan, M., Bhattacharya, M., Flow behavior and exit pressures of corn meal under high-shear-high temperature extrusion conditions using a slit die (1991) Journal of Rheology, 35 (3), pp. 315-342Carvalho, C.W.P., Ascheri, J.L.R., Mitchell, J.R., Capillary rheometry of maize and wheat: Effect of sugar and temperature (2004) Alimentaria, pp. 109-118Darby, R., (1979) Viscoelastic fluids, an introduction to their properties and behavior, p. 638. , New York: Marcel DekkerEerikainen, T., Linko, P., Extrusion cooking modeling, control and optimization (1998) Extrusion cooking, american association of cereal chemists, pp. 157-204. , In: MERCIER, C. et al, MinnesotaFraiha, M., Projeto e construção de reômetro capilar (2007) Congresso Brasileiro de Engenharia Agrícola, 36. , In:, Bonito. Anais... Sociedade Brasileira de Engenharia Agrícola, 2007Harper, J.M., Rhodes, T.P., Wanninger, L.A., Viscosity model for cooked cereal doughs (1971) AIChE Symposium Series, 67, pp. 40-43Li, P.X., Campanella, O.H., Hardacre, A.K., Using a in-line slit-die viscometer to study the effects of extrusion parameters on corn melt rheology (2004) Cereal Chemistry, 81 (1), pp. 70-76McKey, K., Rheological modeling of potato flour during extrusion cooking (1989) Journal of Food Processing Engineering, 12, pp. 1-11Mohsenin, N.N., (1986) Physical properties of plant and animal materials, p. 734. , 2nd ed. New York: Gordon and Breach ScienceNguyen, Q.D., Boger, D.V., Measuring the flow properties of yield stress fluids (1992) Annual Review of Fluid Mechanics, 24, pp. 47-85Pimenova, N.V., Hanley, T.R., Effect of corn stover concentration on rheological characteristics (2004) Applied Biochemistry and Biotechnology, 113, pp. 347-360Rao, M.A., Anantheswaran, R.C., Rheology of fluids in food processing (1982) Food TechnologyRauwendaal, C., (1994) Polymer extrusion, p. 568. , 3rd ed. New York: Hanser Gardner PublishersRemsen, C.H., Clark, J.P., A viscosity model for a cooking dough (1978) Journal of Food Processing Engineering, 2, pp. 39-64Sandoval, A.J., Barreiro, J.A., Off-line capillary rheometry of corn starch: Effects of temperature, moisture content and shear rate (2007) Food Science and Technology, 40, pp. 43-48Senouci, A., Smith, A.C., An experimental study of food melt rheology: I. Shear viscosity using a slit die viscometer and a capillary rheometer (1998) Rheologica Acta, 27, pp. 546-554Servais, C., Jones, R., Roberts, I., The influence of particle size distribution on the processing of food (2002) Journal of Food Engineering, 51, pp. 201-208(2007) Perfil 2007, , http://www.sindiracoes.org.br/imagens/UserFiles/Image/Sindiraes/Perfil/P erfil_2006_2E_Produc_Bras_15.gif, SINDIRAÇÕES, Disponível em:, Acesso em: decSingh, N., Smith, A.C., Rheological behavior of different cereals using capillary rheometry (1999) Journal of Food Engineering, 39, pp. 203-209Steffe, J.F., (1996) Rheological methods in food process engineering, p. 417. , 2nd ed. Freeman Press: East LansingStickel, J.J., Powell, R.L., Fluid mechanics and rheology of dense suspensions (2005) Annual Reviews in Fluid Mechanics, 37, pp. 129-149Tin, C., Guo, J., Uhlherr, P.H.T., Yielding behaviour of viscoplastic materials (2006) Journal of Industrial and Engineering Chemistry, 12, pp. 653-662Viamajala, S., Rheology of corn stover slurries at high solids concentrations-Effects of saccharification and particle size (2009) Bioresource Technology, 100, pp. 925-93

Pre-treatment Of Thermoduric Spores In Co2 Modified Atmosphere And Their Survivability During Food Extrusion [pré-tratamento De Esporos Termodúricos Em Atmosfera Modificada De Co2 E Sua Sobrevivência Ao Processo De Extrusão]

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 seconds; 170.00 ± 4.67 seconds; 2.310 ± 107 kPa; and T3 - 11.06 ± 2.46%, 86.00 ± 7.23 seconds; 186.00 ± 7.50 seconds; 2.403 ± 93 kPa, respectively. It was concluded that the extrusion process did reduce the cell count. However, screw rotational speed variation or CO2 pre-treatment did not affect cell viability.311167171Method of determining and expressing fineness of feed materials by sieving. ANSI/ASAE S319.3 (2004) Agricultural Engineers Yearbook of Standard, pp. 578-581. , AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS, In: AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS, 51th. ed. St. Joseph: ASAEBearman, T.C., Bacterial spore heat resistance correlated with water content, wet density, and protoplast/sporoplast volume ratio (1982) Journal of Bacteriology, 150 (2), pp. 870-877Black, S.H., Gerhardt, P., Permeability of bacterial spores: III. Permeation relative to germination (1962) Journal of Bacteriology, 83 (2), pp. 301-308Bouveresse, J.A., Influence of extrusion cooking on the thermal destruction of Bacillus stearothermophilus spores in a starch-protein-sucrose mix (1982) Lebensmittel-Wissenschaft und-Technologie, 15, pp. 135-138Bulut, S., Waites, W.M., Mitchell, J.R., Effects of combined shear and thermal forces on destruction of Microbacterium lacticum (1999) Applied Environmental Microbiology, 65 (10), pp. 4464-4469Debs-Louka, E., Effect of compressed carbon dioxide on microbial cell viability (1999) Applied and Environmental Microbiology, 65 (2), pp. 626-631Dixon, N.M., Kell, D.B., The inhibition by CO2 of the growth and metabolism of micro-organisms (1989) Journal of Applied Bacteriology, 67, pp. 109-136Fraiha, M., (2008) Efeitos da temperatura, pressão e taxa de cisalhamento sobre a viabilidade de esporo termodúrico durante a extrusão de alimentos para animais, p. 197. , Tese (Doutorado em Tecnologia Pós-Colheita)-Escola de Engenharia Agrícola, Universidade Estadual de Campinas, Campinas, 2008Fraiha, M., Ferraz, A.C.O., Biagi, J.D., Determination of shear effects on the viability of thermoduric spores inoculated in animal feed using a capillary rheometer (2008) International Grain Quality and Technology Congress, , In:, Chicago. Proceedings... Urbana Champaign: Illinois Un., 2008Hotchkiss, J., Werner, B.G., Lee, E.Y.C., Addition of carbon dioxide to dairy products to improve quality: A comprehensive review (2006) Comprehensive Reviews in Food Science and Food Safety, 5, pp. 158-169Kauffman, K.B., Hatch, R.T., Shear effects on cell viability during extrusion of semi-moist foods (1977) Journal of Food Science, 42 (4), pp. 906-910Kelley, T.R., Walker, P.M., Bacterial concentration reduction of food waste amended animal feed using a single-screw dry-extrusion process (1999) Bioresource Technology, 67, pp. 247-253Kelley, T.R., Walker, P.M., Bacterial concentration reduction in swine waste amended livestock feed using a single-screw dryextrusion process (2000) Bioresource Technology, 75, pp. 189-195Likinami, T.A., Methodology to determine destruction of bacterial spores during extrusion cooking (1990) Journal of Food Science, 55 (5), pp. 1388-1393Lilliefore, H.W., On the Kolmogorov-Smirnov Test for Normality with mean and variance unknown (1967) Journal of the American Statistical Association, 62, pp. 399-402Lin, H.M., Disintegration of yeast cells by pressurized carbon dioxide (1991) Biotechnology Progress, 7 (3), pp. 201-214Lin, H.M., Yang, Z., Chen, L.F., An improved method for disruption of microbial cells with pressurized carbon dioxide (1992) Biotechnology Progress, 8 (2), pp. 165-166Okelo, P.O., Optimization of extrusion conditions for elimination of mesophilic bacteria during thermal processing of animal feed mash (2006) Animal Feed Science and Technology, 129, pp. 116-137Orson, K.E., Sorrels, K.M., Thermophilic Anaerobic Sporeformers (1992) Compendium of methods for the microbiological examination of foods, , In: VANDERZANT, C.SPLITTSTOESSER, D. F., 3th ed. Washington: American Public Health AssociationQuéguiner, C., Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties (1989) International Journal of Food Science and Technology, 24, pp. 601-612Seker, M., Distribution of the residence time in a single-screw extruder with differing numbers of mixing elements (2004) International Journal of Food Science and Technology, 39, pp. 1053-1060Shimoda, M., The influence of dissolved CO2 concentration on the death kinetics of Saccharomyces cerevisiae (2001) Journal of Applied Microbiology, 91, pp. 306-31

Reflections on Mind in Nature

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. D<inf>1211°C</inf> and z values for these spores, as determined in the saline solution, were 8.8 minutes and 12.8°C, respectively. D<inf>121 1°C</inf> and z values determined in the corn-soy mix were 14.2 minutes and 23.7°C, respectively. The micrographs indicated that the spores have homogeneous shape and size, with length and diameter of 2 and 1 μm, respectively. These results confirm that the spore is highly thermal-resistant, and it is a good biological indicator to evaluate the extrusion process as a feed sterilizer.30410411045Bouveresse, J.A., Infuence of extrusion cooking on the thermal destruction of Bacillus stearothermophilus spores in a starch-protein-sucrose mix (1982) Lebensmittel-Wissenschaf Und-Technologie, 15, pp. 135-138Bulut, S., Waites, W.M., Mitchell, J.R., Efects of combined shear and thermal forces on destruction of Microbacterium lacticum (1999) Applied Environmental Microbiology, 65 (10), pp. 4464-4469Feeherry, F., Munsey, D., Rowley, D.B., Termal inactivation and injury of Bacillus stearothermophilus spores (1987) Applied Environmental Microbiology, 53 (2), pp. 365-370Iciek, J., Papiewska, A., Molska, M., Inactivation of Bacillus stearothermophilus spores during thermal processing (2006) Journal of Food Engineering, 77 (3), pp. 406-410Kauffman, K.B., Hatch, R.T., Shear efects on cell viability during extrusion of semi-moist foods (1977) Journal of Food Science, 42 (4), pp. 906-910Kumar, S., Nussinov, R., How do thermophilic proteins deal with heat (2001) Cellular and Molecular Life Sciences, 58, pp. 1217-1233Leitão, M.F.F., Junqueira, V.C.A., Microbiologia aplicada à esterilização de alimentos (1995) Princípios De Esterilização De Alimentos, 10, pp. 3-22. , In: GERMER, S. P. M. et al, 2. ed. Campinas: ITAL, Manual técnicoLequérinel, I., Couvert, O., Mafart, P., Modelling the infuence of the sporulation temperature upon the bacterial spore heat resitance, application to heating process calculation (2007) International Journal of Food Microbiology, 114 (1), pp. 100-104Letrari, J., Lima, H.O.S., Vanin, M., Esterilização térmica e parâmetros de morte microbiana do Bacillus stearothermophilus ATCC 7953 (2006) Anais, , In: ENTEC, 4.WORKSHOP DA UTFPR, 2., 2006, Campo Mourão, Campo MourãoOkelo, P.O., Optimization of extrusion conditions for elimination of mesophilic bacteria during thermal processing of animal feed mash (2006) Animal Feed Science and Technology, 129, pp. 116-137Orson, K.E., Sorrels, K.M., Termophilic anaerobic sporeformers (1992) Compendium of Methods For the Microbiological Examination of Foods, pp. 245-248. , VANDERZANT, C., SPLITTSTOESSER, D. F, 3. ed. Washington American Public Health AssociationPenna, T.C.V., Machoshvili, I.A., Esterilização térmica: Conceitos básicos da morte microbiana (1997) Revista Farmácia Bioquímica Da Universidade De São Paulo, pp. 1-5. , Suplemento 1Pinho, C., Cristianini, M., Three-dimensional mathematical modeling of microbiological destruction of Bacillus stearothermophilus in conductive baby food packed in glass container (2005) International Journal of Food Engineering, 2, p. 1Segner, W.P., Frazier, W.C., Calbert, H.E., Thermal inactivation of heat-resistant bacterial spores in milk concentrate at ultra-high temperatures (1963) Journal of Dairy Science, 46 (9), pp. 891-896Stumbo, C.R., (1965) Termobacteriology In Food Processing, p. 236. , Academic Press: Nova IorqueYoo, J.A., Hardin, M.T., Chen, X.D., Te infuence of milk composition on the growth of Bacillus stearothermophilus (2006) Journal of Food Engineering, 77 (1), pp. 96-102Zheng, X., Chiang, W.C., Wang, S.S., Efect of shear energy on size reduction of starch granules in extrusion (1995) Starch/Stärke, 47 (4), pp. 146-151Zheng, X., Wang, S.S., Shear induced starch conversion during extrusion (1994) Journal of Food Science, 59 (5), pp. 1137-114

O PÊNDULO DEFASADO: um exemplo de sistema caótico para estudantes do ciclo inicial do curso de graduação em Física

Neste trabalho é apresentado um estudo realizado por estudantes ingressantes do curso de Física da Universidade Federal do Pará com o objetivo de se analisar os estados de estabilidade de um pêndulo cujo pivô está em movimento circular uniforme (MCU). O modelo teórico foi desenvolvido utilizando-se a descrição de Lagrange da Mecânica Clássica. Após a modelagem, comparou-se as previsões teóricas com um aparato experimental, afim de se observar os casos de estabilidade. O projeto foi desenvolvido em uma disciplina piloto que se utilizou de uma metodologia ativa, baseada na indagação, em particular com o uso de problemas em aberto, para desenvolver nos estudantes habilidades e competências ligadas ao processo investigativo em ciências exatas, contribuindo também indiretamente para o entendimento da natureza da ciências