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The moisture adsorption isotherms of pineapple processing waste – shell and central cylinder – were determined at 40, 50, 60 and 70C using a gravimetric method. The sorption data were fitted to six well-known sorption isotherm models. The Guggenheim–Anderson–de Boer model was found to be the most satisfactory to represent the equilibrium moisture content data for the pineapple shells and central cylinders. The thermodynamic properties – differential enthalpy and entropy – were estimated by the Clausius–Clapeyron method. The differential enthalpy of the pineapple shells and central cylinders ranged between 11.486 to 1.671 kJ/mol and 23.655 to −0.945 kJ/mol, respectively. The differential entropy had minimum values at 0.04 and 0.005 kgwater/kgdry solids for the pineapple shells and central cylinders, respectively. The pineapple shells presented two lines of compensation, one controlled by entropy and the other controlled by enthalpy and the pineapple central cylinders showed only one zone controlled by enthalpy mechanisms. Practical Applications This work presents information about the moisture sorption characteristics of pineapple processing waste. This kind of information is important for designing the unit operations necessary in the waste process use. In addition, knowledge of the moisture sorption characteristics is useful with respect to selection of packaging materials and storage stability. In general, this work gives relationship between water activity, entropy, enthalpy and moisture content of pineapple processing waste.

Brazil is considered one of the largest producers and consumers of tropical fruits. Green coconut (Cocos nucifera L.) stands out not only for its production and consumption, but also for the high amount of waste produced by coconut water industry and in natura consumption. Therefore, there is a need for utilization of this by-product. This study aims to study the adsorption isotherms of green coconut pulp and determine its isosteric heat of sorption. The adsorption isotherms at temperatures of 30, 40, 50, 60, and 70 °C were analyzed, and they exhibit type III behavior, typical of sugar rich foods. The experimental results of equilibrium moisture content were correlated by models present in the literature. The Guggenheim, Anderson and De Boer (GAB) model proved particularly good overall agreement with the experimental data. The heat of sorption determined from the adsorption isotherms increased with the decrease in moisture content. The heat of sorption is considered as indicative of intermolecular attractive forces between the sorption sites and water vapor, which is an important factor to predict the shelf life of dried products.O Brasil é considerado um dos maiores produtores e consumidores de frutas tropicais. O coco verde (Cocos nucifera L.) se destaca tanto em termos de produção e consumo quanto em quantidade de resíduos gerada por indústrias de água de coco e pelo consumo in natura. Portanto, existe uma necessidade de aproveitamento deste subproduto. Este trabalho teve por objetivo estudar as isotermas de adsorção da polpa de coco verde e determinação do calor isostérico de sorção. As isotermas de adsorção para as temperaturas de 30, 40, 50, 60 e 70 °C foram analisadas e evidenciaram curvas do tipo III, típicas de alimentos ricos em açúcares. Os dados experimentais de umidade de equilíbrio foram correlacionados por modelos da literatura. O modelo de GAB apresentou melhor concordância com os dados experimentais, entre os modelos avaliados. O calor isostérico de sorção é considerado um indicativo de forças atrativas intermoleculares entre os sítios de sorção de vapor de água, consequentemente, um importante fator para predizer a vida de prateleira de produtos desidratados.

The rheological behavior and density of goat milk was studied as a function of solids concentration (10.5 to 50.0%) and temperature (273 to 331 k). Newtonian behavior was observed for values of total solids (TS) between 10.5 and 22.0% and temperatures from 276 to 331 k changing to pseudoplastic behavior without yield stress for TS from 25.0 to 39.4% at the same range of temperature. Goat milk with TS between 44.3 to 50.0% and temperatures of 273 to 296 k showed yield stress in addition to pseudoplastic behavior. At 303 to 331 k the power law model was observed again, without yield stress. The density of goat milk ranged from 991.7 to 1232.4 kg.m-3.Estudou-se o comportamento reológico do leite de cabra em função da concentração (10,5 a 50,0%) e da temperatura (273 a 331 k). O comportamento Newtoniano foi obtido para valores de sólidos totais (ST) entre 10,5 e 22,0% e temperaturas entre 276 e 331 k, mudando para o comportamento pseudoplástico sem tensão residual para ST entre 25,0 e 39,4% na mesma faixa de temperatura. Leite de cabra com ST entre 44,3 e 50,0% e temperaturas entre 273 e 296 k apresentaram comportamento pseudoplástico com tensão residual. O modelo da lei da potência foi observado novamente sem tensão residual entre 303 e 331 k. Os valores experimentais de densidade do leite de cabra variaram entre 991,7 e 1232,4 kg.m-3.

Summary In this study, physical characteristics of goat milk powder produced with the addition of soy lecithin at levels of 0 (control), 0.4, 0.8 and 1.0 g lecithin/100 g of total solids in concentrated milk before the spray drying process were investigated. Goat milk was pasteurised, concentrated at 40% of total solids, spray dried and packed in plastic bags under vaccum conditions. Lecithin addition decreased the wetting time of milk powders, although no influence was observed on dispersibility, water sorption, water activity and particle size distribution of the powders. Powders with higher levels of lecithin showed significantly lower brightness, with a greater intensity of yellow colour. It was concluded that lecithin addition before spray drying process at the minimal proportion in concentrated milk of 0.4 g lecithin/100 g of total solids in concentrated milk is useful for achieving more rapid wetting time of goat milk powder.

En este trabajo fueron determinados experimentalmente el calor específico, conductividad térmica, difusividad térmica y densidad del jugo de lulo en el rango de contenido de agua de 0.55 a 0.90 (p/p en base húmeda) y en temperaturas variando de 4 a 78.6 °C. La conductividad térmica y el calor específico fueron obtenidos utilizando el mismo aparato - una célula constituida de dos cilindros concéntricos - operando en estado estacionario y no- estacionario, respectivamente. La difusividad térmica fue obtenida a través del método de Dickerson y la densidad determinada por picnometria. Tanto la temperatura como el contenido de agua presentaron una fuerte influencia en los datos experimentales de las propiedades termofísicas del jugo de lulo. Los resultados obtenidos fueron utilizados para obtener modelos matemáticos y predecir estas propiedades en función de la concentración y la temperatura.Neste trabalho, foram determinados experimentalmente o calor específico, a condutividade térmica, difusividade térmica e densidade de suco de lulo na faixa de conteúdo de água entre 0,55 e 0,90 (p/p em base úmida) e em temperaturas entre 4 e 78,6 °C. A condutividade térmica e o calor específico foram obtidos utilizando-se o mesmo equipamento - uma célula constituída de dois cilindros concêntricos - operando em estado estacionário e não estacionário, respectivamente. A difusividade térmica foi obtida através do método de Dickerson e a densidade determinada por picnometria. Tanto a temperatura como o conteúdo de água apresentaram grande influência nos dados experimentais das propriedades termofísicas do suco de lulo. Os resultados obtidos foram utilizados na obtenção de modelos matemáticos para predizer estas propriedades em função da concentração e temperatura.

Datos de humedad de equilibrio de polvo de pulpa de lulo (PL) con y sin aditivos - 58% de maltodextrina (MD) o 58% de goma Arábiga (GA) - fueran determinados en las temperaturas de 20, 30, 40 y 50 °C utilizando el método estático gravimétrico para un rango de actividades de agua entre 0.06 y 0.90. Las isotermas presentaran formato sigmoidal del tipo III, y el modelo de Guggenhein-Anderson-de Boer (GAB) fue ajustado satisfactoriamente a los datos experimentales de humedad de equilibrio en función de la actividad de agua. La adición de encapsulantes afecto las isotermas de tal manera que en la misma actividad de agua, las muestras PL + GA y PL + MD presentaron un menor contenido de humedad de equilibrio y no fueron afectadas por la variación de temperatura. Los calores isostéricos de sorción de las pulpas en polvo con encapsulantes fueron mayores (menos negativos) con relación a las pulpas de lulo en polvo, sugiriendo la existencia de sitios polares más activos en el producto sin adición de GA o MD. Una relación exponencial empírica fue utilizada para describir la dependencia del calor de sorción con el contenido de humedad del material.Dados de umidade de equilíbrio de polpa de lulo em pó (PL) com e sem aditivos - 58% de maltodextrina (MD) ou 58% de goma Arábica (GA) - foram determinados nas temperaturas de 20, 30, 40 e 50 °C, utilizando-se o método estático gravimétrico numa faixa de atividade de água de 0,06 a 0,90. As isotermas apresentaram formato sigmoidal do tipo III e o modelo de Guggenhein-Anderson-de Boer (GAB) ajustou satisfatoriamente os dados experimentais de umidade de equilíbrio em função da atividade de água. A adição de encapsulantes afetou as isotermas de tal maneira que na mesma atividade de água, as amostras PL + GA y PL + MD apresentaram um menor conteúdo de umidade de equilíbrio e não foram afetadas pela variação de temperatura. Os calores isostéricos de sorção das polpas em pó com encapsulantes foram maiores (menos negativos) em relação à polpa de lulo em pó, sugerindo a existência de sítios polares mais ativos no produto sem adição de GA ou MD. Uma relação exponencial empírica foi utilizada para descrever a dependência do calor de sorção com o conteúdo de umidade do material.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:11Z No. of bitstreams: 0 Made available in DSpace on 2013-08-22T18:53:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-01 Made available in DSpace on 2013-09-30T19:44:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:11:44Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T15:11:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-01 Dados de umidade de equilíbrio de polpa de lulo em pó (PL) com e sem aditivos - 58% de maltodextrina (MD) ou 58% de goma Arábica (GA) - foram determinados nas temperaturas de 20, 30, 40 e 50 °C, utilizando-se o método estático gravimétrico numa faixa de atividade de água de 0,06 a 0,90. As isotermas apresentaram formato sigmoidal do tipo III e o modelo de Guggenhein-Anderson-de Boer (GAB) ajustou satisfatoriamente os dados experimentais de umidade de equilíbrio em função da atividade de água. A adição de encapsulantes afetou as isotermas de tal maneira que na mesma atividade de água, as amostras PL + GA y PL + MD apresentaram um menor conteúdo de umidade de equilíbrio e não foram afetadas pela variação de temperatura. Os calores isostéricos de sorção das polpas em pó com encapsulantes foram maiores (menos negativos) em relação à polpa de lulo em pó, sugerindo a existência de sítios polares mais ativos no produto sem adição de GA ou MD. Uma relação exponencial empírica foi utilizada para descrever a dependência do calor de sorção com o conteúdo de umidade do material. Datos de humedad de equilibrio de polvo de pulpa de lulo (PL) con y sin aditivos - 58% de maltodextrina (MD) o 58% de goma Arábiga (GA) - fueran determinados en las temperaturas de 20, 30, 40 y 50 °C utilizando el método estático gravimétrico para un rango de actividades de agua entre 0.06 y 0.90. Las isotermas presentaran formato sigmoidal del tipo III, y el modelo de Guggenhein-Anderson-de Boer (GAB) fue ajustado satisfactoriamente a los datos experimentales de humedad de equilibrio en función de la actividad de agua. La adición de encapsulantes afecto las isotermas de tal manera que en la misma actividad de agua, las muestras PL + GA y PL + MD presentaron un menor contenido de humedad de equilibrio y no fueron afectadas por la variación de temperatura. Los calores isostéricos de sorción de las pulpas en polvo con encapsulantes fueron mayores (menos negativos) con relación a las pulpas de lulo en polvo, sugiriendo la existencia de sitios polares más activos en el producto sin adición de GA o MD. Una relación exponencial empírica fue utilizada para describir la dependencia del calor de sorción con el contenido de humedad del material. Universidad Nacional de Colombia Departamento de Física e Química Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade de São Paulo Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos

The rise in boiling point of blackberry juice was experimentally measured at soluble solids concentrations in the range of 9.4 to 58.4°Brix and pressures between 4.9 × 103 and 9.0 × 104 Pa (abs.). Different approaches to representing experimental data, including the Duhring's rule, a model similar to Antoine equation and other empirical models proposed in the literature were tested. In the range of 9.4 to 33.6°Brix, the rise in boiling point was nearly independent of pressure, varying only with juice concentration. Considerable deviations of this behavior began to occur at concentrations higher than 39.1°Brix. Experimental data could be best predicted by adjusting an empirical model, which consists of a single equation that takes into account the dependence of rise in boiling point on pressure and concentration.

Data on pressure drop were obtained in stainless steel, sanitary fittings and valves during laminar and turbulent flow of aqueous suspensions of sucrose and bentonite. The rheological properties of these suspensions were determined and the Bingham model provided the best fitting with the experimental data. Friction losses were measured in fully- and partially-open butterfly and plug valves, bends and union. Values of loss coefficients (kf) were calculated and correlated as functions of the classical Reynolds number and the Reynolds number proposed by Govier and Aziz (1972) for viscoplastic fluids. The two-k method and a new proposed model presented the best adjustments for the Govier and Aziz Reynolds number, and Hedstrom and classical Reynolds numbers, respectively. On a obtenu des donnees sur la perte de charge dans des ajustages et des vannes sanitaires en acier inoxydable pour l'ecoulement laminaire et turbulent de suspensions aqueuses de sucrose et bentonite. Les proprietes rheologiques de ces suspensions ont ete determinees, et le modele de Bingham fournit le meilleur calage des donnees experimentales. Les pertes de friction ont ete mesurees dans des vannes a papillon et a opercule pleinement et partiellement ouvertes, les coudes et les raccords. Les valeurs des coefficients de pertes (kf) ont ete calculees et correlees en fonction du nombre de Reynolds classique et du nombre de Reynolds propose par Govier et Aziz (1972) pour des fluides viscoelastiques. La methode des deux k et un nouveau modele propose presentent les meilleurs ajustements pour le nombre de Reynolds de Govier et Aziz, et les nombres de Reynolds d'Hedstrom et classique, respectivement.

Sorption isotherms of lemon juice (LE) powders with and without additives—18% maltodextrin (MA) or 18% gum Arabic (GA)—were determined at 20–50°C. Addition of additives was shown to affect the isotherms in such a way that, at the same water activity, samples LE + GA and LE + MA presented lower equilibrium moisture content and were not so affected by varying temperature. The net isosteric heats of sorption of juice powders with additives were higher (less negative) than those of lemon juice powders, suggesting that there are more active polar sites in the product without addition of GA or MA. In general, the quality properties decreased with the addition of maltodextrin and gum arabic and it was obtained similar values for LE + GA and LE + MA.

Rheological and thermophysical properties were determined for blackberry juice, which was produced from blackberry fruit at 9.1 ± 0.5 °Brix and density of 1.0334 ± 0.0043 g cm-3. The concentration process was performed using a roto evaporator, under vacuum, to obtain concentrated juice at about 60 °Brix. In order to obtain different concentrations, concentrated juice was diluted with distilled water. Rheological measurements were carried out using a Rheotest 2.1 Searle type rheometer. In the tested ranges, the samples behaved as pseudoplastic fluids, and the Power-Law model was satisfactorily fitted to the experimental data. The friction factor was measured for blackberry juice in laminar flow conditions of pseudoplastic behavior. Thermal conductivity, thermal diffusivity and density of blackberry juice at 9.4 to 58.4 °Brix were determined, in triplicate, at 0.5 to 80.8 °C. Polynomial regression was performed to fit experimental data obtaining a good fit. Both temperature and concentration showed a strong influence on thermophysical properties of blackberry juice. Calculated apparent specific heat values varied from 2.416 to 4.300 kJ.kg-1 °C in the studied interval.As propriedades reológicas e termofísicas foram determinadas para suco de amora produzido a partir da fruta com 9.1 ± 0.5 °Brix e densidade de 1,0334 ± 0,0043 g cm-3. O processo de concentração foi realizado utilizando-se um roto evaporador, sob vácuo, obtendo-se o suco concentrado em aproximadamente 60 °Brix. As diferentes concentrações foram obtidas a partir da diluição do suco concentrado em água destilada. As medidas reológicas foram conduzidas utilizando-se o reômetro Rheotest 2.1 do tipo Searle. Em todos os experimentos as amostras apresentaram um comportamento pseudoplástico, e o modelo da Lei da Potência foi ajustado satisfatoriamente aos dados experimentais. O fator de atrito foi medido para o suco em regime laminar com comportamento pseudoplástico. A condutividade térmica, a difusividade térmica e a densidade foram determinadas em triplicata para o suco de amora nas faixas de 9,4 a 58,4 °Brix e de 0,5 a 80,8 °C. A temperatura e a concentração mostraram forte influência nas propriedades termofísicas do suco de amora. Os valores do calor específico aparente variaram de 2,416 a 4,300 kJ.kg-1 °C.

Moisture equilibrium data of pineapple pulp (PP) powders with and without additives – 18% maltodextrin (MD) or 18% gum Arabic (GA) – were determined at 20, 30, 40 and 50 °C by using the static gravimetric method in a water activity range of 0.06–0.90. The obtained isotherms were sigmoid, typical type III, and the Guggenhein–Anderson–de Boer (GAB) model was fitted to the experimental data of equilibrium moisture content versus water activity. Addition of additives was shown to affect the isotherms in such a way that, at the same water activity, samples PP + GA and PP + MD presented lower equilibrium moisture content and were not so affected by varying temperature. The net isosteric heats of sorption of pulp powders with additives were higher (less negative) than those of pineapple pulp powders, suggesting that there are more active polar sites in the product without addition of GA or MD. An empirical exponential relationship could describe the heat of sorption dependence on the material moisture content.

Pressure drop and minimum fluidization velocity were experimentally studied in a vibro-fluidized bed of inert particles subjected to different vibration intensities during drying of soursop pulp. Maltodextrin was added to the pulp in order to prevent stickiness between particles and the consequent bed collapse. Pulps were initially concentrated, resulting in pastes with different soluble solids content, and a constant fraction of maltodextrin was guaranteed in the final pulp samples. The pulp rheological behavior as affected by temperature and total soluble solids content, including maltodextrin, was evaluated and the effect of pulp apparent viscosity on pressure drop and minimum vibro-fluidization velocity were investigated. Two types of inert particles – 3.6 mm glass beads and 3 mm Teflon cylinders (length and diameter) – were tested and, due to lower pressure drop presented by Teflon cylinders during operation of the dry vibro-fluidized bed, these particles were adopted for pulp drying process. Increasing pulp apparent viscosity caused a considerable increase in the vibro-fluidized bed pressure drop during pulp drying and, as a consequence resulted in a larger value of minimum vibro-fluidization velocity. On the other hand, the negative effect of increasing apparent viscosity could be attenuated by increasing the fluidized bed vibration intensity, which could prevent stickiness between particles.

Pressure drop and minimum fluidization velocity were experimentally studied in a vibro-fluidized bed of inert particles subjected to different vibration intensities during drying of guava pulp. Maltodextrin was added to the pulp in order to prevent stickiness between particles and the consequent bed collapse. Pulps were initially concentrated, resulting in pastes with different soluble solids content, and a constant fraction of maltodextrin was guaranteed in the final pulp samples. The pulp rheological behavior as affected by temperature and total soluble solids content, including maltodextrin, was evaluated and the effect of pulp apparent viscosity on pressure drop and minimum vibro-fluidization velocity were investigated. Two types of inert particles – 3.6 mm glass beads and 3 mm Teflon cylinders – were tested and, due to lower pressure drop presented by Teflon cylinders during operation of the dry vibro-fluidized bed, these particles were adopted for pulp drying process. Increasing pulp apparent viscosity caused a considerable increase in the vibro-fluidized bed pressure drop during pulp drying and, as a consequence resulted in a larger value of minimum vibro-fluidization velocity. On the other hand, the negative effect of increasing apparent viscosity could be attenuated by increasing the fluidized bed vibration intensity, which could prevent stickiness between particles.

The rise in boiling point of grapefruit juice was experimentally measured at soluble solids concentrations in the range of 9.3�60.6 °Brix and pressures between °6.0 × 10 3 and 9.0 × 104 Pa. Different approaches to represent experimental data, including the Duhring's rule, the Antoine equation and empirical models proposed in the literature were tested. In the range of 9.3�29.0 °Brix, the rise in boiling point was nearly independent of pressure, varying only with juice concentration. Considerable deviations of this behavior began to occur at concentrations higher than 29.0 °Brix. Experimental data could be best predicted by adjusting an empirical model, which consisted of a single equation that takes into account the dependence of rise in boiling point on pressure and concentration. The rise in boiling point of grapefruit juice was experimentally measured at soluble solids concentrations in the range of 9.3�60.6 °Brix and pressures between °6.0 × 10 3 and 9.0 × 104 Pa. Different approaches to represent experimental data, including the Duhring's rule, the Antoine equation and empirical models proposed in the literature were tested. In the range of 9.3�29.0 °Brix, the rise in boiling point was nearly independent of pressure, varying only with juice concentration. Considerable deviations of this behavior began to occur at concentrations higher than 29.0 °Brix. Experimental data could be best predicted by adjusting an empirical model, which consisted of a single equation that takes into account the dependence of rise in boiling point on pressure and concentration. The rise in boiling point of grapefruit juice was experimentally measured at soluble solids concentrations in the range of 9.3�60.6 °Brix and pressures between °6.0 × 10 3 and 9.0 × 104 Pa. Different approaches to represent experimental data, including the Duhring's rule, the Antoine equation and empirical models proposed in the literature were tested. In the range of 9.3�29.0 °Brix, the rise in boiling point was nearly independent of pressure, varying only with juice concentration. Considerable deviations of this behavior began to occur at concentrations higher than 29.0 °Brix. Experimental data could be best predicted by adjusting an empirical model, which consisted of a single equation that takes into account the dependence of rise in boiling point on pressure and concentration.

Experimental viscosity values of sucrose, glucose, and fructose aqueous solutions in a large range of temperatures (0 to 85°C) and concentrations (10 to 60% w/w) that might be encountered in food processes were obtained in order to contribute to extending the available database of food properties. The temperature dependence of viscosity could be adequately described by the Arrhenius model, and the activation energy was well represented by a unique function of the solute volume fraction, valid for sucrose, glucose, and fructose solutions.

The freezing point depression of mango and papaya pulps was measured by using a simple apparatus, consisting of two major sections: a freezing vessel and a data acquisition system. The thermal conductivity of both pulps as a function of frozen water fraction and temperature was also investigated by using a coaxial dual-cylinder apparatus. Thermal conductivity above the initial freezing point was well fitted by polynomial equations. Below the freezing point, the thermal conductivity was strongly affected by both the frozen water fraction and temperature. Simple equations in terms of frozen water fraction and temperature could be fitted to the experimental data of freezing point depression and thermal conductivity.

Density, heat capacity and thermal conductivity of liquid egg products, such as egg white, egg yolk, whole egg and various white and yolk blends, were determined as affected by temperature and water content ranging from 273 to 311 K and 51.8 to 88.2% (mass), respectively. Polynomial models fitted the experimental data very well, showing a linear relationship both for temperature and water content.

The rheological behavior of egg yolk was studied at a range of temperatures (277–333 K) using a concentric cylinder viscometer. Rheological behavior was pseudoplastic and flow curves fitted by the power law model. The consistency and behavior indexes, dependent on temperature, were expressed by an Arrhenius-type equation. The rheological parameters, together with experimental values of pressure loss in tube flow were used to calculate friction factors. The good agreement between predicted and observed values confirmed the reliability of the equations proposed for describing the flow behavior of the egg yolk.

This article presents empirical correlations to predict the density, specific heat, thermal conductivity and rheological power-law parameters of liquid egg yolk over a temperature range compatible with its industrial thermal processing (0-61C). Moreover, a mathematical model for a pasteurizer that takes into account the spatial variation of the overall heat transfer coefficient throughout the plate heat exchanger is presented, as are two of its simplified forms. The obtained correlations of thermophysical properties are applied for the simulation of the egg yolk pasteurization, and the obtained temperature profiles are used for evaluating the extent of thermal inactivation. A detailed simulation example shows that there is a considerable deviation between the designed level of heat treatment and that this is predicted through process simulation. It is shown that a reliable mathematical model, combined with specialized thermophysical property correlations, provide a more accurate design of the pasteurization equipment that ensures effective inactivation, while preserving nutritional and sensorial characteristics.

Mechanical properties of food products and biological materials are greatly affected by the drying process and are considered one of the most important quality attributes of dehydrated products. The aim of this work was to review theoretical principles and mathematical modeling, analyzing the measurement techniques and major experimental results that exist in the literature about rheological properties of dehydrated foods and biological materials. Different methods of measuring rheological parameters (fundamental and empiric or imitative) are discussed and major experimental results, as well as the rheological models used in their analysis, published in recent years are presented.

Drying kinetics of tomato was studied by using heat pump dryer (HPD) and electric resistance dryers with parallel and crossed airflow. The performance of both systems was evaluated and compared and the influence of temperature, air velocity, and tomato type on the drying kinetics was analyzed. The use of HPD showed to be adequate in the drying process of tomatoes, mainly in relation to the conversion rate of electric energy into thermal energy. The heat pump effective coefficient of performance (COPHT,EF) was between 2.56 and 2.68, with an energy economy of about 40% when compared to the drying system with electric resistance. The Page model could be used to predict drying time of tomato and statistical analysis showed that the model parameters were mainly affected by drying temperature.

Realizou-se a modelagem da degradação de vitamina C em ameixas desidratadas e submetidas a diferentes condições de temperatura e umidade relativa, com o auxílio da equação de Bigelow. As ameixas in natura foram liofilizadas e acondicionadas em dessecadores contendo diferentes soluções salinas saturadas na temperatura de 4ºC. Após atingir o equilíbrio, os dessecadores foram submetidos a temperaturas na faixa que variou entre 40 e 80ºC. A degradação de vitamina C foi analisada ao longo de 5 dias, aplicando-se o método de titulação com solução padronizada de 2,6-diclorofenolindofenol 0,01%. As amostras apresentaram os seguintes conteúdos de umidade: 0,05; 0,11; 0,18; 0,38 e 1,40g água/g sólido seco. A partir dos parâmetros da equação de Bigelow, tempo de redução decimal (D T) e valor z, os resultados indicaram que as amostras submetidas à faixa de temperatura entre 40 - 60ºC apresentaram uma perda mais lenta de vitamina C (D T no conteúdo de umidade de 0,05 apresentou valores na faixa de 1672 - 275h). Por outro lado, em altas temperaturas a degradação do ácido ascórbico ocorreu mais rapidamente (D T para X = 0,05 forneceu valores entre 110 e 47h). Os parâmetros z e D T apresentaram uma dependência linear e quadrática com o conteúdo de umidade das amostras, respectivamente. De modo geral, em altos teores de umidade, houve uma maior perda de vitamina C, devido a sua alta solubilidade.The degradation of vitamin C in prunes submitted to different conditions of temperature and moisture content was modeling by using the Bigelow equation. Firstly, plums were freeze-dried and conditioned in dessecators with different saturated salt solutions at 4ºC. After reaching the equilibrium, dessecators were submitted to a range of temperature between 40 to 80ºC. The vitamin C degradation was analyzed during 5 days, by applying the titration method with patronized solution of 2,6-dichlorophenolindophenol 0.01%. Samples presented the following moisture contents: 0.05; 0.11; 0.18; 0.38 and 1.40 g water/g dry solid. From the parameters of Bigelow equation, reducing decimal time (D T) and z-value, the results showed that the samples submitted to a temperature range of 40 - 60ºC, presented loss of vitamin C slower than at high temperatures (D T at the moisture content of 0.05 presented a range of 1672 - 275h and 110 e 47h, respectively). Parameters z-value and D T showed a linear and quadratic dependence with the moisture content of the samples, respectively. In general, at high moisture content, it occurs more pronounced ascorbic acid degradation, due to its high solubility.

Rheological properties of rehydrated prunes were obtained applying compression–relaxation tests by using a Texture Analyzer TAXT2i. A mathematical development was adopted to determine the stress and area, along the deformation. Experimental data of stress versus time was fitted by using three different rheological models: generalized Maxwell, Normand & Peleg and Maxwell. Results showed that generalized Maxwell model can be used to describe the viscoelastic behavior of the samples. The rheological parameters obtained indicated that prunes exhibited elastic behavior more pronounced at low moisture content and drying air temperature. At high moisture content and temperature the sample became a more viscous and less rigid.

Sorption isotherms were determined for salted alligator's meat at four different temperatures (10°C, 15°C, 25°C and 35°C), using a standard gravimetric method. The goodness of fit of five sorption models to experimental data was determined. Five models, namely the GAB, the BET, the Halsey, the Henderson and the Hailwood and Horrobin, were evaluated to determine the best fit for the experimental data. The GAB was the best fitted model for the data of salted alligator's meat with an average error less than 10% for temperature of 10°C and less than 5% for the others temperatures. The coefficients of determination ( r 2 ) were 0.99 for all temperatures considered. The monolayer values decreased as temperature increased. The other four models were not appropriated to fit the data because of the high error values, although the r 2 were also similar to the GAB model. The net isosteric heat of sorption was estimated from equilibrium sorption data, using the Clausis–Clapeyron equation. Isosteric heats of sorption were found to increase with increasing temperature and could be well adjusted by an exponential relationship.

Univ Estadual Paulista, Dept Engn & Tecnol Alimentos, BR-15054000 Sao Jose do Rio Preto, SP, Brazil

Specific heat, thermal conductivity, thermal diffusivity, and density of coffee extract were experimentally determined in the range of 0.49 to 0.90 (wet basis) water content and at temperatures varying from 30 to 82°C. Thermal conductivity and specific heat were measured by means of the same apparatus‐ a cell constituted of two concentric cylinders ‐ operating at steady and unsteady state, respectively. The thermal diffusivity was measured by the well‐known Dickerson's method and density was determined by picnometry. The results obtained were used to derive mathematical models for predicting these properties as a function of concentration and temperature.

Moisture equilibrium data of persimmon skin and pulp were determined using the static gravimetric method. Adsorption and desorption isotherms were obtained in the range of 20–70°C, to water activities ( a w ) from 0.02 to 0.85. The application of the GAB model to the experimental results, using direct nonlinear regression analysis, provided a good agreement between experimental and calculated values. The net isosteric heat of sorption was estimated from equilibrium sorption data, using the Clausius–Clapeyron equation. Isosteric heats of sorption were found to increase with increasing temperature and could be well adjusted by an exponential relationship. The enthalpy–entropy compensation theory was applied to sorption isotherms and plots of Δ H versus Δ S for skin and pulp provided the isokinetic temperatures, indicating an enthalpy controlled sorption process.

The effects of chemical pretreatment and air drying temperature on drying kinetics, shrinkage, density and rehydration ratio of grapes were determined at various moisture contents. It was observed that the chemical pretreatment employed - a solution of 2% CaCCb with 0 to 3% ethyl oleate - increased considerably the drying rate. It was established that the shrinkage increased with drying temperature between 40 to 80°C and decreased with increasing concentration of ethyl oleate in the chemical pretreatment solution.

The enthalpy-entropy compensation theory was applied to water sorption for grapes of Italy variety. The moisture sorption isotherms were analyzed using the static gravimetric method at 35, 40, 50, 60, 70 and 75° C. For isotherms construction, the skin and pulp of the grape were used separately and it was possible to observe significant differences. The GAB equation was fitted to the experimental data, using direct nonlinear regression analysis; the agreement between experimental and calculated values was satisfactory. The net isosteric heat or enthalpy of water sorption, determined from the equilibrium sorption data, showed a different behavior when compared with other works, as it was obtained for skin and pulp separately. Plots of Ah vs AS for skin and pulp provided the isokinetic temperatures TBS = 423.2 ± 27.6 K and TBP = 424.5 ± 25.3 K, respectively, indicating an enthalpy-controlled desorption process over the whole range of moisture content considered.

The specific heat, thermal conductivity, thermal diffusivity and density of Brazilian orange juice were determined between 0.34 and 0.73 (w/w) water content and with temperatures from 0.5 to 62 °C. The experimental data were fitted as functions of temperature and water content and all properties showed a linear dependency with these variables. In the tested range, the water content exhibited a greater influence on the analyzed properties than temperature.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:15Z No. of bitstreams: 1 S0101-20612012000200026.pdf: 269353 bytes, checksum: d6b7d133de9d26a0deb2051761fcf381 (MD5) Made available in DSpace on 2013-08-22T18:53:15Z (GMT). No. of bitstreams: 1 S0101-20612012000200026.pdf: 269353 bytes, checksum: d6b7d133de9d26a0deb2051761fcf381 (MD5) Previous issue date: 2012-06-01 Made available in DSpace on 2013-09-30T19:44:48Z (GMT). No. of bitstreams: 2 S0101-20612012000200026.pdf: 269353 bytes, checksum: d6b7d133de9d26a0deb2051761fcf381 (MD5) S0101-20612012000200026.pdf.txt: 23320 bytes, checksum: 9914ff1a9bcfb5cc3be5f13a4e0d58f2 (MD5) Previous issue date: 2012-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:01:56Z No. of bitstreams: 2 S0101-20612012000200026.pdf: 269353 bytes, checksum: d6b7d133de9d26a0deb2051761fcf381 (MD5) S0101-20612012000200026.pdf.txt: 23320 bytes, checksum: 9914ff1a9bcfb5cc3be5f13a4e0d58f2 (MD5) Made available in DSpace on 2014-05-20T14:01:56Z (GMT). No. of bitstreams: 2 S0101-20612012000200026.pdf: 269353 bytes, checksum: d6b7d133de9d26a0deb2051761fcf381 (MD5) S0101-20612012000200026.pdf.txt: 23320 bytes, checksum: 9914ff1a9bcfb5cc3be5f13a4e0d58f2 (MD5) Previous issue date: 2012-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Estudou-se o comportamento reológico do leite de cabra em função da concentração (10,5 a 50,0%) e da temperatura (273 a 331 k). O comportamento Newtoniano foi obtido para valores de sólidos totais (ST) entre 10,5 e 22,0% e temperaturas entre 276 e 331 k, mudando para o comportamento pseudoplástico sem tensão residual para ST entre 25,0 e 39,4% na mesma faixa de temperatura. Leite de cabra com ST entre 44,3 e 50,0% e temperaturas entre 273 e 296 k apresentaram comportamento pseudoplástico com tensão residual. O modelo da lei da potência foi observado novamente sem tensão residual entre 303 e 331 k. Os valores experimentais de densidade do leite de cabra variaram entre 991,7 e 1232,4 kg.m-3. The rheological behavior and density of goat milk was studied as a function of solids concentration (10.5 to 50.0%) and temperature (273 to 331 k). Newtonian behavior was observed for values of total solids (TS) between 10.5 and 22.0% and temperatures from 276 to 331 k changing to pseudoplastic behavior without yield stress for TS from 25.0 to 39.4% at the same range of temperature. Goat milk with TS between 44.3 to 50.0% and temperatures of 273 to 296 k showed yield stress in addition to pseudoplastic behavior. At 303 to 331 k the power law model was observed again, without yield stress. The density of goat milk ranged from 991.7 to 1232.4 kg.m-3. Universidade de São Paulo Faculdade de Zootecnia e Engenharia de Alimentos Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos FAPESP: 07/02688-9

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:13Z No. of bitstreams: 0 Made available in DSpace on 2013-08-22T18:53:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-01 Made available in DSpace on 2013-09-30T19:44:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:11:45Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T15:11:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-01 Item merged in doublecheck by Felipe Arakaki (fe.arakaki@gmail.com) on 2015-11-17T19:39:41Z Item was identical to item(s): 27637, 21449 at handle(s): http://hdl.handle.net/11449/28138, http://hdl.handle.net/11449/21887 Neste trabalho, foram determinados experimentalmente o calor específico, a condutividade térmica, difusividade térmica e densidade de suco de lulo na faixa de conteúdo de água entre 0,55 e 0,90 (p/p em base úmida) e em temperaturas entre 4 e 78,6 °C. A condutividade térmica e o calor específico foram obtidos utilizando-se o mesmo equipamento - uma célula constituída de dois cilindros concêntricos - operando em estado estacionário e não estacionário, respectivamente. A difusividade térmica foi obtida através do método de Dickerson e a densidade determinada por picnometria. Tanto a temperatura como o conteúdo de água apresentaram grande influência nos dados experimentais das propriedades termofísicas do suco de lulo. Os resultados obtidos foram utilizados na obtenção de modelos matemáticos para predizer estas propriedades em função da concentração e temperatura. En este trabajo fueron determinados experimentalmente el calor específico, conductividad térmica, difusividad térmica y densidad del jugo de lulo en el rango de contenido de agua de 0.55 a 0.90 (p/p en base húmeda) y en temperaturas variando de 4 a 78.6 °C. La conductividad térmica y el calor específico fueron obtenidos utilizando el mismo aparato - una célula constituida de dos cilindros concéntricos - operando en estado estacionario y no- estacionario, respectivamente. La difusividad térmica fue obtenida a través del método de Dickerson y la densidad determinada por picnometria. Tanto la temperatura como el contenido de agua presentaron una fuerte influencia en los datos experimentales de las propiedades termofísicas del jugo de lulo. Los resultados obtenidos fueron utilizados para obtener modelos matemáticos y predecir estas propiedades en función de la concentración y la temperatura. Universidade Nacional de Colômbia Departamento de Física e Química Universidade de São Paulo Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:02:15Z No. of bitstreams: 1 S0104-66322009000200006.pdf: 156913 bytes, checksum: 77757574175a16038c62ce1b5613b4b9 (MD5) Made available in DSpace on 2013-08-22T19:02:15Z (GMT). No. of bitstreams: 1 S0104-66322009000200006.pdf: 156913 bytes, checksum: 77757574175a16038c62ce1b5613b4b9 (MD5) Previous issue date: 2009-06-01 Made available in DSpace on 2013-09-30T20:03:02Z (GMT). No. of bitstreams: 2 S0104-66322009000200006.pdf: 156913 bytes, checksum: 77757574175a16038c62ce1b5613b4b9 (MD5) S0104-66322009000200006.pdf.txt: 47816 bytes, checksum: 050d3555f14b12e5724ae20d8c47a844 (MD5) Previous issue date: 2009-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:16:09Z No. of bitstreams: 2 S0104-66322009000200006.pdf: 156913 bytes, checksum: 77757574175a16038c62ce1b5613b4b9 (MD5) S0104-66322009000200006.pdf.txt: 47816 bytes, checksum: 050d3555f14b12e5724ae20d8c47a844 (MD5) Made available in DSpace on 2014-05-20T15:16:09Z (GMT). No. of bitstreams: 2 S0104-66322009000200006.pdf: 156913 bytes, checksum: 77757574175a16038c62ce1b5613b4b9 (MD5) S0104-66322009000200006.pdf.txt: 47816 bytes, checksum: 050d3555f14b12e5724ae20d8c47a844 (MD5) Previous issue date: 2009-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses. Universidade Estadual de Campinas Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade de São Paulo Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos FAPESP: 02/02461-0

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:46:54Z No. of bitstreams: 1 S0100-204X2006000300018.pdf: 1044776 bytes, checksum: ee79336d82f27f2159bc0793d6b39821 (MD5) Made available in DSpace on 2013-08-22T18:46:54Z (GMT). No. of bitstreams: 1 S0100-204X2006000300018.pdf: 1044776 bytes, checksum: ee79336d82f27f2159bc0793d6b39821 (MD5) Previous issue date: 2006-03-01 Made available in DSpace on 2013-09-30T19:36:29Z (GMT). No. of bitstreams: 2 S0100-204X2006000300018.pdf: 1044776 bytes, checksum: ee79336d82f27f2159bc0793d6b39821 (MD5) S0100-204X2006000300018.pdf.txt: 27137 bytes, checksum: 88734d558353220710ce1fcf1fa51a5c (MD5) Previous issue date: 2006-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:09:49Z No. of bitstreams: 2 S0100-204X2006000300018.pdf: 1044776 bytes, checksum: ee79336d82f27f2159bc0793d6b39821 (MD5) S0100-204X2006000300018.pdf.txt: 27137 bytes, checksum: 88734d558353220710ce1fcf1fa51a5c (MD5) Made available in DSpace on 2014-05-20T15:09:49Z (GMT). No. of bitstreams: 2 S0100-204X2006000300018.pdf: 1044776 bytes, checksum: ee79336d82f27f2159bc0793d6b39821 (MD5) S0100-204X2006000300018.pdf.txt: 27137 bytes, checksum: 88734d558353220710ce1fcf1fa51a5c (MD5) Previous issue date: 2006-03-01 O objetivo deste trabalho foi selecionar o pré-tratamento químico mais apropriado para a secagem de uvas cv. Rubi para a produção de passas. Foram obtidas curvas de secagem convectiva com ar a 50ºC, em um secador de bandejas, para uvas submetidas a pré-tratamentos químicos com diferentes concentrações de carbonato de potássio e azeite de oliva, e diferentes tempos de imersão, de acordo com planejamentos fatoriais. Também foram obtidas curvas de secagem convectiva, para uvas pré-tratadas em suspensões aquosas de lecitina de soja, em várias concentrações de lecitina e diferentes tempos de imersão. O modelo de Page foi ajustado às curvas de secagem experimental, e os tempos de secagem calculados mostraram que o melhor pré-tratamento consistiu na imersão das uvas por 2 minutos, em uma emulsão de 5% de azeite de oliva e 6% de K2CO3, a 50ºC, o que resultou em tempos de secagem próximos aos do pré-tratamento com 2,5% de azeite de oliva, mas com um menor consumo dessa substância. Além disso, a imersão das uvas em uma suspensão aquosa de 2% de lecitina de soja, a 50ºC, por 5 minutos, resultou em um tempo de secagem total apenas levemente superior ao do pré-tratamento mais efetivo. The objective of this work was to determine the most appropriated chemical treatment to be used to dry grapes cv. Rubi for raisin production. Drying curves for convective drying with air at 50ºC, in a tray drier, were obtained for grapes submitted to chemical pretreatments with different concentrations of potassium carbonate and olive oil, and different dipping times, according to factorial designs. Convective drying curves were also obtained for grapes pretreated in aqueous suspensions of soybean lecithin, at varied lecithin concentrations and dipping times. Page model was adjusted to the experimental drying curves, and the calculated drying times showed that the best pretreatment consisted in dipping grapes for 2 minutes in a 5% olive oil and 6% K2CO3 emulsion, at 50ºC, which resulted in a drying time close to that of the pretreatment with 2.5% of olive oil, but with a lower consumption of this substance. In addition, the immersion of grapes in an aqueous suspension of 2% soy lecithin, at 50ºC, for 5 minutes, resulted in a total drying time slightly higher than the most effective pretreatment. Universidade Estadual Paulista Júlio de Mesquita Filho Dep. de Engenharia e Tecnologia de Alimentos Universidade de São Paulo Fac. de Zootecnia e Engenharia de Alimentos Dep. de Engenharia de Alimentos Universidade Estadual Paulista Júlio de Mesquita Filho Dep. de Engenharia e Tecnologia de Alimentos

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:04Z No. of bitstreams: 1 S0101-20612005000200020.pdf: 275892 bytes, checksum: a16f2bafb7103eacbe7eb952e4b1417e (MD5) Made available in DSpace on 2013-08-22T18:53:04Z (GMT). No. of bitstreams: 1 S0101-20612005000200020.pdf: 275892 bytes, checksum: a16f2bafb7103eacbe7eb952e4b1417e (MD5) Previous issue date: 2005-06-01 Made available in DSpace on 2013-09-30T19:44:34Z (GMT). No. of bitstreams: 2 S0101-20612005000200020.pdf: 275892 bytes, checksum: a16f2bafb7103eacbe7eb952e4b1417e (MD5) S0101-20612005000200020.pdf.txt: 25884 bytes, checksum: 2caf79e975d7a88c945cb46673d6ed17 (MD5) Previous issue date: 2005-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:11:42Z No. of bitstreams: 2 S0101-20612005000200020.pdf: 275892 bytes, checksum: a16f2bafb7103eacbe7eb952e4b1417e (MD5) S0101-20612005000200020.pdf.txt: 25884 bytes, checksum: 2caf79e975d7a88c945cb46673d6ed17 (MD5) Made available in DSpace on 2014-05-20T15:11:42Z (GMT). No. of bitstreams: 2 S0101-20612005000200020.pdf: 275892 bytes, checksum: a16f2bafb7103eacbe7eb952e4b1417e (MD5) S0101-20612005000200020.pdf.txt: 25884 bytes, checksum: 2caf79e975d7a88c945cb46673d6ed17 (MD5) Previous issue date: 2005-06-01 Dados de equilíbrio da umidade da polpa de manga foram determinados utilizando-se o método estático gravimétrico. As isotermas de adsorção e dessorção foram obtidas na faixa de 30-70 ºC e as atividades de água (a w) de 0,02 a 0,97. A utilização do modelo de GAB nos resultados experimentais, através da análise de regressão não linear, proporcionou um bom ajuste entre os dados experimentais e os valores calculados. O calor isostérico de sorção foi estimado a partir dos dados de equilíbrio de sorção, utilizando-se a equação de Clausius-Clayperon. Notou-se que os calores isostéricos de sorção crescem com o aumento da temperatura e pode ser bem ajustado através de uma relação exponencial. A teoria da compensação entalpia-entropia foi aplicada às isotermas de sorção e gráficos deltaH versus deltaS forneceram as temperaturas isocinéticas, indicando um processo de sorção entalpicamente controlado. Moisture equilibrium data of mango pulp were determined using the static gravimetric method. Adsorption and desorption isotherms were obtained in the range of 30-70 ºC, to water activities (a w) from 0.02 to 0.97. The application of the GAB model to the experimental results, using direct nonlinear regression analysis, provided agreement between experimental and calculated values. The net isosteric heat of sorption was estimated from equilibrium sorption data, using the Clausius-Clapeyron equation. Isosteric heats of sorption were found to increase with increasing temperature and could be well adjusted by an exponential relationship. The enthalpy-entropy compensation theory was applied to sorption isotherms and plots of deltaH versus deltaS provided the isokinetic temperatures, indicating an enthalpy controlled sorption process. Universidade Estadual Paulista Depto. de Engenharia e Tecnologia de Alimentos Universidade Estadual de Campinas Depto. de Engenharia de Alimentos Universidade de São Paulo Depto. de Engenharia de Alimentos Universidade Estadual Paulista Depto. de Engenharia e Tecnologia de Alimentos

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:02Z No. of bitstreams: 1 S0101-20612003000400013.pdf: 560827 bytes, checksum: f9234424f30a1752cc5fc57a02c0efea (MD5) Made available in DSpace on 2013-08-22T18:53:02Z (GMT). No. of bitstreams: 1 S0101-20612003000400013.pdf: 560827 bytes, checksum: f9234424f30a1752cc5fc57a02c0efea (MD5) Previous issue date: 2003-12-01 Made available in DSpace on 2013-09-30T19:44:31Z (GMT). No. of bitstreams: 2 S0101-20612003000400013.pdf: 560827 bytes, checksum: f9234424f30a1752cc5fc57a02c0efea (MD5) S0101-20612003000400013.pdf.txt: 24400 bytes, checksum: 8c249bf9acb60695347d43fbfb85c66a (MD5) Previous issue date: 2003-12-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:11:41Z No. of bitstreams: 2 S0101-20612003000400013.pdf: 560827 bytes, checksum: f9234424f30a1752cc5fc57a02c0efea (MD5) S0101-20612003000400013.pdf.txt: 24400 bytes, checksum: 8c249bf9acb60695347d43fbfb85c66a (MD5) Made available in DSpace on 2014-05-20T15:11:41Z (GMT). No. of bitstreams: 2 S0101-20612003000400013.pdf: 560827 bytes, checksum: f9234424f30a1752cc5fc57a02c0efea (MD5) S0101-20612003000400013.pdf.txt: 24400 bytes, checksum: 8c249bf9acb60695347d43fbfb85c66a (MD5) Previous issue date: 2003-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Realizou-se a modelagem da degradação de vitamina C em ameixas desidratadas e submetidas a diferentes condições de temperatura e umidade relativa, com o auxílio da equação de Bigelow. As ameixas in natura foram liofilizadas e acondicionadas em dessecadores contendo diferentes soluções salinas saturadas na temperatura de 4ºC. Após atingir o equilíbrio, os dessecadores foram submetidos a temperaturas na faixa que variou entre 40 e 80ºC. A degradação de vitamina C foi analisada ao longo de 5 dias, aplicando-se o método de titulação com solução padronizada de 2,6-diclorofenolindofenol 0,01%. As amostras apresentaram os seguintes conteúdos de umidade: 0,05; 0,11; 0,18; 0,38 e 1,40g água/g sólido seco. A partir dos parâmetros da equação de Bigelow, tempo de redução decimal (D T) e valor z, os resultados indicaram que as amostras submetidas à faixa de temperatura entre 40 - 60ºC apresentaram uma perda mais lenta de vitamina C (D T no conteúdo de umidade de 0,05 apresentou valores na faixa de 1672 - 275h). Por outro lado, em altas temperaturas a degradação do ácido ascórbico ocorreu mais rapidamente (D T para X = 0,05 forneceu valores entre 110 e 47h). Os parâmetros z e D T apresentaram uma dependência linear e quadrática com o conteúdo de umidade das amostras, respectivamente. de modo geral, em altos teores de umidade, houve uma maior perda de vitamina C, devido a sua alta solubilidade. The degradation of vitamin C in prunes submitted to different conditions of temperature and moisture content was modeling by using the Bigelow equation. Firstly, plums were freeze-dried and conditioned in dessecators with different saturated salt solutions at 4ºC. After reaching the equilibrium, dessecators were submitted to a range of temperature between 40 to 80ºC. The vitamin C degradation was analyzed during 5 days, by applying the titration method with patronized solution of 2,6-dichlorophenolindophenol 0.01%. Samples presented the following moisture contents: 0.05; 0.11; 0.18; 0.38 and 1.40 g water/g dry solid. From the parameters of Bigelow equation, reducing decimal time (D T) and z-value, the results showed that the samples submitted to a temperature range of 40 - 60ºC, presented loss of vitamin C slower than at high temperatures (D T at the moisture content of 0.05 presented a range of 1672 - 275h and 110 e 47h, respectively). Parameters z-value and D T showed a linear and quadratic dependence with the moisture content of the samples, respectively. In general, at high moisture content, it occurs more pronounced ascorbic acid degradation, due to its high solubility. Universidade Estadual de Campinas Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos

The net isosteric heat and entropy of water sorption were calculated for plum, based on sorption iso- therms obtained by the static gravimetric method at different temperatures (20 to 70 °C). The Guggenheim-Anderson- deBoer model was applied to the experimental data giving a good agreement between experimental and calculated values. The net isosteric heat of water sorption, estimated by applying Claussius-Clapeyron equation to sorption isotherms, was found to be different for plum skin and pulp, mainly at low moisture contents, and could be well adjusted by an empirical exponential relationship. Plots of enthalpy in contrast to entropy provided the isokinetic temperatures for skin and pulp, indicating an enthalpy-controlled sorption process. Thermodynamic data on water sorption for plums are not found in literature, as opposed to prunes for which the data are abundant.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:53:06Z No. of bitstreams: 1 S0101-20612007000300025.pdf: 227717 bytes, checksum: 94a891ff68bca2bc3b4bc9e1777eeeed (MD5) Made available in DSpace on 2013-08-22T18:53:06Z (GMT). No. of bitstreams: 1 S0101-20612007000300025.pdf: 227717 bytes, checksum: 94a891ff68bca2bc3b4bc9e1777eeeed (MD5) Previous issue date: 2007-09-01 Made available in DSpace on 2013-09-30T19:44:38Z (GMT). No. of bitstreams: 2 S0101-20612007000300025.pdf: 227717 bytes, checksum: 94a891ff68bca2bc3b4bc9e1777eeeed (MD5) S0101-20612007000300025.pdf.txt: 34344 bytes, checksum: 14063461c79756627d759e39b9b76b8c (MD5) Previous issue date: 2007-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:01:55Z No. of bitstreams: 2 S0101-20612007000300025.pdf: 227717 bytes, checksum: 94a891ff68bca2bc3b4bc9e1777eeeed (MD5) S0101-20612007000300025.pdf.txt: 34344 bytes, checksum: 14063461c79756627d759e39b9b76b8c (MD5) Made available in DSpace on 2014-05-20T14:01:55Z (GMT). No. of bitstreams: 2 S0101-20612007000300025.pdf: 227717 bytes, checksum: 94a891ff68bca2bc3b4bc9e1777eeeed (MD5) S0101-20612007000300025.pdf.txt: 34344 bytes, checksum: 14063461c79756627d759e39b9b76b8c (MD5) Previous issue date: 2007-09-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) As propriedades reológicas e termofísicas foram determinadas para suco de amora produzido a partir da fruta com 9.1 ± 0.5 °Brix e densidade de 1,0334 ± 0,0043 g cm-3. O processo de concentração foi realizado utilizando-se um roto evaporador, sob vácuo, obtendo-se o suco concentrado em aproximadamente 60 °Brix. As diferentes concentrações foram obtidas a partir da diluição do suco concentrado em água destilada. As medidas reológicas foram conduzidas utilizando-se o reômetro Rheotest 2.1 do tipo Searle. em todos os experimentos as amostras apresentaram um comportamento pseudoplástico, e o modelo da Lei da Potência foi ajustado satisfatoriamente aos dados experimentais. O fator de atrito foi medido para o suco em regime laminar com comportamento pseudoplástico. A condutividade térmica, a difusividade térmica e a densidade foram determinadas em triplicata para o suco de amora nas faixas de 9,4 a 58,4 °Brix e de 0,5 a 80,8 °C. A temperatura e a concentração mostraram forte influência nas propriedades termofísicas do suco de amora. Os valores do calor específico aparente variaram de 2,416 a 4,300 kJ.kg-1 °C. Rheological and thermophysical properties were determined for blackberry juice, which was produced from blackberry fruit at 9.1 ± 0.5 °Brix and density of 1.0334 ± 0.0043 g cm-3. The concentration process was performed using a roto evaporator, under vacuum, to obtain concentrated juice at about 60 °Brix. In order to obtain different concentrations, concentrated juice was diluted with distilled water. Rheological measurements were carried out using a Rheotest 2.1 Searle type rheometer. In the tested ranges, the samples behaved as pseudoplastic fluids, and the Power-Law model was satisfactorily fitted to the experimental data. The friction factor was measured for blackberry juice in laminar flow conditions of pseudoplastic behavior. Thermal conductivity, thermal diffusivity and density of blackberry juice at 9.4 to 58.4 °Brix were determined, in triplicate, at 0.5 to 80.8 °C. Polynomial regression was performed to fit experimental data obtaining a good fit. Both temperature and concentration showed a strong influence on thermophysical properties of blackberry juice. Calculated apparent specific heat values varied from 2.416 to 4.300 kJ.kg-1 °C in the studied interval. Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos Universidade Nacional de Colômbia IIDepartamento de Física e Química Universidade de São Paulo Departamento de Engenharia de Alimentos Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos

A presente tese apresenta a utilização da fibra da casca do coco verde como reforço de matriz cimentícia para produção de fibrocimentos. Embora orgânico, o resíduo do coco verde apresenta difícil degradação e diminuí da vida útil de aterros sanitários e lixões. Para viabilizar o uso do resíduo do coco verde (fibra), como reforço de compósitos, optou-se por realizar tratamentos físico-químicos nas fibras e, substituir parcialmente o cimento Portland por material pozolânico de alta reatividade (cinza da casca de arroz (CCA)) para diminuir o ataque alcalino da matriz sobre a fibra vegetal. O experimento foi dividido em duas etapas, a primeira avaliou a fibra de coco verde com e sem tratamentos e os compósitos produzidos com elas. A segunda etapa analisou a influência de diferentes níveis de substituição do cimento Portland pela cinza da casca de arroz (CCA). Para preparação dos compósitos foi utilizada a técnica de dispersão das matérias-primas em solução aquosa, seguida de drenagem e prensagem, como uma simulação simplificada do processo Hatschek de fabricação industrial. Os compósitos foram analisados aos 28 dias (período de cura úmida) e após os processos de envelhecimento, 100 ciclos de imersão-secagem e 28 dias em banho térmico (65°C). Ensaios físicos e mecânicos avaliaram o desempenho, a resistência e a ductilidade dos compósitos. A termogravimetria permitiu observar o consumo da portlandita e a queda da alcalinidade da matriz com 50% de substituição do cimento Portland pela CCA, sem afetar a resistência do material. Os resultados obtidos indicam que a fibra do coco verde tem grande potencial para ser utilizada como reforço de fibrocimentos, desde que seja incorporada a uma matriz de alcalinidade reduzida. This thesis studies the use of green coconut fiber as a reinforcer in the matrix cement for the production of fibre-cement. Besides being an organic material, the green coconut residues are not easily degradable, but can reduce the landfills lifespan. To evaluate the possibility of use of coconut residue fiber, as reinforcer in composites, physical-chemical treatments were carried out on the fibers, and partially replacing Portland cement with pozzolanic materials for high reactivity (rice husk ash (RHA)) was also added to decrease the alkaline attack matrix on the plant fiber. The experiment was divided into two stages: the first assessed the green coconut fiber with and without treatment and the composites produced with them. The second stage examined the influence reinforcer high reactivity to allow the use of coconut fiber as reinforcement in cementitious matrix. In the preparation of the composites, the technique of dispersing the materials in aqueous solution was used, followed by draining and pressing, as a simplified simulation Hatschek process of industrial manufacture. The composites were analyzed after 28 days and after an aging process, with 100 cycles of immersion-drying or heating in water for 28 days at 65°C). Physical and mechanical tests were used to e valuated the performance, traction resistance and ductility of the composites. A thermogravimetry test allowed the observation of the use of portlandita and the alkalinity reduction of the matrix with the addition of RHA, without affecting the resistance of the material. The results obtained indicate that the green coconut fiber has great potential to be used as a fibre-cement reinforcer, as long it is included in a matrix with reduced alkalinity.

No presente trabalho, diferentes condições de pasteurização foram estudadas a fim de desenvolver um purê de manga para pronto consumo, sem adição de açúcares e de conservantes, com estabilidade microbiológica, físico-química e sensorial. A qualidade e a vida de prateleira do purê foram avaliadas por meio de análises físico-químicas, microbiológicas, enzimáticas, reológicas e sensoriais. Na primeira etapa do trabalho, foram estudadas temperaturas de pasteurização entre 65 e 85 °C, em trocador de calor a placas e tubular. Os ensaios mostraram que o trocador tubular foi o mais indicado para a pasteurização do purê de manga. A inativação térmica da peroxidase, uma das enzimas mais termorresistentes encontradas naturalmente em mangas, foi utilizada como parâmetro de pasteurização. Os parâmetros cinéticos para inativação da enzima foram calculados: D77,2 ºC e z iguais a 4,4 s e 14,3 ºC, respectivamente. Na segunda etapa, duas condições de pasteurização, P1 (70ºC/13s) e P2 (75 ºC/13s), foram selecionadas para determinação da vida de prateleira do purê. A pasteurização nestas condições, combinada ao armazenamento refrigerado, foi eficiente para manter a qualidade microbiológica, físico-química e sensorial do purê por 17 semanas. Análises microbiológicas indicaram que os maiores contaminantes do purê cru foram os microrganismos mesófilos e os bolores e leveduras. Com a pasteurização, houve redução significativa destes microrganismos e de coliformes fecais. Todas as características físico-químicas (pH, acidez titulável, teor de sólidos totais, sólidos solúveis, ácido ascórbico e cor) foram influenciadas significativamente pelo tempo de armazenamento. Foi observada diferença significativa do pH a partir da 17ª semana de armazenamento e a perda de ácido ascórbico foi de aproximadamente 45 % após 20 semanas. As medidas reológicas mostraram a natureza pseudoplástica do purê de manga: os valores de n variaram entre 0,27 e 0,29 e os valores de K entre 5,00 e 7,16 Pa.sn. O tempo de armazenamento praticamente não influenciou os parâmetros reológicos dos purês pasteurizados. Na análise sensorial, notas superiores a 6,7 foram obtidas, indicando que o produto teve boa aceitação durante as 17 semanas de armazenamento. O tempo de armazenamento não influenciou significativamente os atributos sensoriais, exceto no purê processado na condição P1. In this work, different pasteurization conditions were studied in order to develop a ready-to-serve mango purée, with microbiological safety and physical-chemical and sensorial stability. Physical-chemical, microbiological, enzymatic and sensory analyses and rheological measurements were carried out to evaluate quality and shelf life of mango purée. Two types of heat exchanger were used to pasteurize mango purée: a plate heat exchanger and a double pipe heat exchanger. Pasteurization temperatures ranged from 65 to 85ºC. The double pipe exchanger showed to be more suitable for the process, due to characteristics of purée. Thermal inactivation of peroxidase, one of most thermostable enzymes naturally present in mangoes, was used as indicator of pasteurization. Kinetic parameters were calculated: D77.2 ºC = 4.4 s and z = 14.3 ºC. Two pasteurization conditions P1 (70 °C / 13s) and P2 (75 °C / 13s) were selected in order to determine shelf life of mango purée. Pasteurization, combined to refrigerated storage, was effective to maintain microbiological, physical, chemical and sensory quality of purée for 17 weeks. Microbiological analysis showed that the main contaminants of raw purée were mesophilic microorganisms and yeast and moulds. After pasteurization, there was significant reduction of these microorganisms and of thermo-tolerant coliforms. All physical-chemical attributes (pH, titratable acidity, total solids, soluble solids, ascorbic acid and color) were affected significantly by storage time. It was observed significant difference in pH after 17 weeks of storage and ascorbic acid loss was approximately 45 % after 20 weeks. Rheological measurements showed shear thinning nature of mango purée: n values varied from 0.27 to 0.29 and K values from 5.00 to 7.16 Pa.sn. Storage time did not affect significantly rheological parameters of pasteurized purées. Sensory analysis of pasteurized mango purée indicated that the product has good acceptance (scores \'> or =\' 6,7) over 17 weeks of refrigerated storage. Storage time did not affect significantly sensory attributes, except color of P1 mango purée.