Muitas foram as pessoas que, direta ou indiretamente, contribuíram para a realização deste trabal... more Muitas foram as pessoas que, direta ou indiretamente, contribuíram para a realização deste trabalho, em especial gostaria de agradecer: Ao meu orientador, João Borges Laurindo, por acreditar na minha capacidade, pelo apoio dispensado no decorrer desses anos, pela paciência e amizade, permitindo que eu crescesse tanto profissionalmente quanto pessoalmente. Ao Prof. Alfredo por sempre estar valorizando o meu trabalho e pelas discussões que proporcionaram uma melhor compreensão sobre assuntos relacionados ao mesmo.
The aim of this work was to develop cassava starch biocomposites with varius concentrations of gr... more The aim of this work was to develop cassava starch biocomposites with varius concentrations of grape skin (Gr) and acerola (Ac) residues (0.1, 1.0, 5.0 and 10.0 wt%) using extrusion and injection molding processes. Grape residue had the highest concentration of total monomeric anthocyanin (ANC) and Ac had the highest concentration of total phenolic content (TPC) and total sugars. The starch and fruit residues had thermal degradation onset temperatures above the processing temperature profile of polymer biocomposites. The results showed that the antioxidant, physicochemical, mechanical, and morphological properties of these biocomposites were influenced by the type and concentration of the fruit residues. The addition of grape skins and acerola residues to the cassava thermoplastic starch resulted in better antioxidant characteristics, indicating the potential of these formulations for the development of new bioactive packaging obtained by large-scale processes.
A fibrous residue rich in non-extracted starch (bagasse) obtained from the industrial production ... more A fibrous residue rich in non-extracted starch (bagasse) obtained from the industrial production of cassava starch was used to obtain a composite that is similar to cardboard, through a technique used in small scale artisan production of recycled paper. A mixture of 90% cassava bagasse and 10% of Kraft paper was used for the production of these composites. Kraft paper was added as a source of long fibres, in order to improve the mechanical properties of the material. The prepared material has similar characteristics to the molded fibre packaging made using recycled paper, as used in egg boxes. However, cassava bagasse has advantages over recycled paper, in view of the fact that it is obtained from known and renewable sources. The impregnated and non-impregnated materials were submitted to tests of tensile strength and to direct contact with water by complete immersion of the samples. The cassava bagasse-Kraft paper composites obtained had a slight resistance to direct contact with water. The water mass absorbed by the materials impregnated with starch acetate was approximately half that of the materials without impregnation. However, the impregnation had little influence on the tensile strength of the tested samples. Starch acetate is therefore an attractive additive for use in the manufacture of waterproof materials, such as disposable trays.
Enzymes from coconut water such as peroxidase (POD) and polyphenol oxidase (PPO) when in contact ... more Enzymes from coconut water such as peroxidase (POD) and polyphenol oxidase (PPO) when in contact with oxygen begin reactions causing nutritional and color losses. Solutions simulating the chemical constituents of coconut water were submitted to a batch process in a microwave oven. PPO and POD inactivation data could be characterized by: PPO/water D 93 1C ¼ 16.5 s (z ¼ 35.5 1C); PPO/sugars D 91 1C ¼ 18 s (z ¼ 331C); POD/water D 91.5 1C ¼ 44 s (z ¼ 24 1C) and POD/sugars D 92 1C ¼ 20.5 s (z ¼ 19.5 1C). The contact between salts and enzymes promoted a drastic reduction of the initial activity. After the incidence of microwave energy at temperatures above 90 1C, enzymes activity was not detected. These results can indicate an adequate choice of temperature conditions to inactivate coconut water enzymes. The knowledge of how green coconut water constituents influence POD and PPO activity will supply useful information about microwave processing of coconut water.
O processamento industriai da mandioca para a obtencao de fecula gera uma grande variedade e quan... more O processamento industriai da mandioca para a obtencao de fecula gera uma grande variedade e quantidade de residuos, sendo o bagaco o principal residuo solido produzido nas fecularias. Esse material, quando descartado, alem de poluir o meio ambiente, representa desperdicio de uma materia-prima que poderia ser mais bem aproveitada. Neste trabalho, o bagaco de mandioca foi misturado a fibras vegetais para a preparacao de compositos, que foram utilizados como materia-prima para a producao de bandejas descartaveis. A tecnica empregada na producao de bandejas de polpa moldada para acondicionamento de ovos foi adaptada para a fabricacao dos compositos e das bandejas. As bandejas de bagaco de mandioca adicionado de 10% de papel Kraft sao semelhantes as de papelao, produzidas a partir de papel reciclado (bandejas de papel para ovos). As bandejas obtidas em laboratorio foram resistentes o suficiente para permitir a sua utilizacao no acondicionamento de frutas e hortalicas. Assim, a utilizaca...
Microwave heating, also known as dielectric heating, is a direct process, that is, energy is tran... more Microwave heating, also known as dielectric heating, is a direct process, that is, energy is transferred directly to the food by molecular interaction with the electromagnetic field. Thus a greater penetration is achieved resulting in faster reaching of the temperature of interest and more uniform heat distribution. To correctly design processing equipment, it is essential to understand and determine the dielectric properties of the food and so ensure microwave incidence to obtain the required processing conditions. In order to obtain the dielectric properties of the food, it is important to consider its shape, moisture content, specific gravity, conductivity, and diffusivity, as well as process variables like maximum temperature and frequency. In this chapter, application of microwaves in various conservation methods applied to fruits will be presented such as blanching, drying, pasteurization, and sterilization. The advantages and disadvantages of employing microwaves to perform t...
In this work, physical, chemical and morphological modifications of three different polyamide 6.6... more In this work, physical, chemical and morphological modifications of three different polyamide 6.6 (PA6.6) fabrics were investigated using double barrier dielectric (DBD) plasma treatment. Several techniques of characterization were used to study the effects caused by the interaction between plasma discharge and polyamide fabrics, such as: contact angle, water drop adsorption, Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), whiteness by Berger degree and tensile strength. All analyses performed in this study showed that DBD plasma discharge, when applied on PA6.6 fiber, produces significant modifications on the surface of this substrate, without altering its intrinsic properties, thus proving the effectiveness of this important technology to the textile industry.
The industrial processing of cassava to obtain starch generates a great variety of residues, with... more The industrial processing of cassava to obtain starch generates a great variety of residues, with bagasse being the main solid residue produced. The improper disposal of this material represents an environmental problem and could be avoided by using this residue as a raw material to obtain biodegradable products. The bagasse produced during the process to obtain starch from cassava was used to prepare composites for disposable trays. Samples of the composites were impregnated with cassava starch acetate at atmospheric pressure and under vacuum condition. Moisture isotherms were determined and adjusted by GAB model. It was observed that the impregnation promoted an important decrease in sample higroscopicity, mainly at high relative humidities. These results suggest that starch acetate impregnation can be an alternative to water proofing biological materials like the composites obtained in this work.
This study describes the use of cassava starch acetate (CSA) to impregnate Kraft paper and its in... more This study describes the use of cassava starch acetate (CSA) to impregnate Kraft paper and its influence on the water vapor permeability (K w). This barrier property depends on the water vapor diffusion coefficient (D eff) and the material hygroscopicity properties (adsorptivity, b). The influences of D eff and b on the K w value were studied. Kraft paper samples were impregnated at atmospheric pressure and under vacuum. The results showed an important decrease on the K w values, which was associated with two factors: (a) the partial filling of the Kraft paper superficial and internal pores by the impregnated CSA, reducing the K w ; (b) as CSA is much less hygroscopic than paper, its adsorptivity is reduced significantly by impregnation. This paper demonstrates that CSA impregnation of Kraft paper is an interesting alternative for the improvement of the hygroscopic properties and water vapor permeability of the Kraft paper.
The inactivation kinetics of enzymes polyphenol oxidase (PPO) and peroxidase (POD) was studied fo... more The inactivation kinetics of enzymes polyphenol oxidase (PPO) and peroxidase (POD) was studied for the batch (discontinuous) microwave treatment of green coconut water. Inactivation of commercial PPO and POD added to sterile coconut water was also investigated. The complete time-temperature profiles of the experimental runs were used for determination of the kinetic parameters D-value and z-value: PPO (D 92.20°C = 52 s and z = 17.6°C); POD (D 92.92°C = 16 s and z = 11.5°C); PPO/sterile coconut water: (D 84.45°C = 43 s and z = 39.5°C) and POD/sterile coconut water: (D 86.54°C = 20 s and z = 19.3°C). All data were well fitted by a first order kinetic model. The enzymes naturally present in coconut water showed a higher resistance when compared to those added to the sterilized medium or other simulated solutions reported in the literature. The thermal inactivation of PPO and POD during microwave processing of green coconut water was significantly faster in comparison with conventional processes reported in the literature.
Determinação simultânea e contínua da densidade de líquidos e da concentração de suspensões líqui... more Determinação simultânea e contínua da densidade de líquidos e da concentração de suspensões líquidas, Laurindo et al. 1. Recebido para publicação em 25/09/2002. Aceito para publicação em 30/03/2004 (000998).
Brazilian Archives of Biology and Technology, 2004
Studies were carried out to produce biodegradable films from cassava starch. Two alternatives wer... more Studies were carried out to produce biodegradable films from cassava starch. Two alternatives were investigated. In the first, films were obtained by starch gelatinization followed by thermopressing and glycerol was used at different concentrations as a plasticizer. In the second, starch acetate films were obtained by solubilization of cassava starch acetate in organic solvents, followed by casting on a glass plate and drying at room temperature. The films obtained by gelatinization were transparent and resistant to traction. The starch acetate films were also transparent but breakable. The use of these starch acetate films in paper impregnation improved the mechanical properties of the paper.
Brazilian Archives of Biology and Technology, 2004
Studies were carried out to produce biodegradable films from cassava starch. Two alternatives wer... more Studies were carried out to produce biodegradable films from cassava starch. Two alternatives were investigated. In the first, films were obtained by starch gelatinization followed by thermopressing and glycerol was used at different concentrations as a plasticizer. In the second, starch acetate films were obtained by solubilization of cassava starch acetate in organic solvents, followed by casting on a glass plate and drying at room temperature. The films obtained by gelatinization were transparent and resistant to traction. The starch acetate films were also transparent but breakable. The use of these starch acetate films in paper impregnation improved the mechanical properties of the paper.
Kraft paper is widely used in the manufacture of packing, but its hygroscopic properties and wate... more Kraft paper is widely used in the manufacture of packing, but its hygroscopic properties and water vapor barrier are not suitable for the storage of dehydrated products for long periods. The objective of this work was to study the influence of the impregnation of ...
Muitas foram as pessoas que, direta ou indiretamente, contribuíram para a realização deste trabal... more Muitas foram as pessoas que, direta ou indiretamente, contribuíram para a realização deste trabalho, em especial gostaria de agradecer: Ao meu orientador, João Borges Laurindo, por acreditar na minha capacidade, pelo apoio dispensado no decorrer desses anos, pela paciência e amizade, permitindo que eu crescesse tanto profissionalmente quanto pessoalmente. Ao Prof. Alfredo por sempre estar valorizando o meu trabalho e pelas discussões que proporcionaram uma melhor compreensão sobre assuntos relacionados ao mesmo.
The aim of this work was to develop cassava starch biocomposites with varius concentrations of gr... more The aim of this work was to develop cassava starch biocomposites with varius concentrations of grape skin (Gr) and acerola (Ac) residues (0.1, 1.0, 5.0 and 10.0 wt%) using extrusion and injection molding processes. Grape residue had the highest concentration of total monomeric anthocyanin (ANC) and Ac had the highest concentration of total phenolic content (TPC) and total sugars. The starch and fruit residues had thermal degradation onset temperatures above the processing temperature profile of polymer biocomposites. The results showed that the antioxidant, physicochemical, mechanical, and morphological properties of these biocomposites were influenced by the type and concentration of the fruit residues. The addition of grape skins and acerola residues to the cassava thermoplastic starch resulted in better antioxidant characteristics, indicating the potential of these formulations for the development of new bioactive packaging obtained by large-scale processes.
A fibrous residue rich in non-extracted starch (bagasse) obtained from the industrial production ... more A fibrous residue rich in non-extracted starch (bagasse) obtained from the industrial production of cassava starch was used to obtain a composite that is similar to cardboard, through a technique used in small scale artisan production of recycled paper. A mixture of 90% cassava bagasse and 10% of Kraft paper was used for the production of these composites. Kraft paper was added as a source of long fibres, in order to improve the mechanical properties of the material. The prepared material has similar characteristics to the molded fibre packaging made using recycled paper, as used in egg boxes. However, cassava bagasse has advantages over recycled paper, in view of the fact that it is obtained from known and renewable sources. The impregnated and non-impregnated materials were submitted to tests of tensile strength and to direct contact with water by complete immersion of the samples. The cassava bagasse-Kraft paper composites obtained had a slight resistance to direct contact with water. The water mass absorbed by the materials impregnated with starch acetate was approximately half that of the materials without impregnation. However, the impregnation had little influence on the tensile strength of the tested samples. Starch acetate is therefore an attractive additive for use in the manufacture of waterproof materials, such as disposable trays.
Enzymes from coconut water such as peroxidase (POD) and polyphenol oxidase (PPO) when in contact ... more Enzymes from coconut water such as peroxidase (POD) and polyphenol oxidase (PPO) when in contact with oxygen begin reactions causing nutritional and color losses. Solutions simulating the chemical constituents of coconut water were submitted to a batch process in a microwave oven. PPO and POD inactivation data could be characterized by: PPO/water D 93 1C ¼ 16.5 s (z ¼ 35.5 1C); PPO/sugars D 91 1C ¼ 18 s (z ¼ 331C); POD/water D 91.5 1C ¼ 44 s (z ¼ 24 1C) and POD/sugars D 92 1C ¼ 20.5 s (z ¼ 19.5 1C). The contact between salts and enzymes promoted a drastic reduction of the initial activity. After the incidence of microwave energy at temperatures above 90 1C, enzymes activity was not detected. These results can indicate an adequate choice of temperature conditions to inactivate coconut water enzymes. The knowledge of how green coconut water constituents influence POD and PPO activity will supply useful information about microwave processing of coconut water.
O processamento industriai da mandioca para a obtencao de fecula gera uma grande variedade e quan... more O processamento industriai da mandioca para a obtencao de fecula gera uma grande variedade e quantidade de residuos, sendo o bagaco o principal residuo solido produzido nas fecularias. Esse material, quando descartado, alem de poluir o meio ambiente, representa desperdicio de uma materia-prima que poderia ser mais bem aproveitada. Neste trabalho, o bagaco de mandioca foi misturado a fibras vegetais para a preparacao de compositos, que foram utilizados como materia-prima para a producao de bandejas descartaveis. A tecnica empregada na producao de bandejas de polpa moldada para acondicionamento de ovos foi adaptada para a fabricacao dos compositos e das bandejas. As bandejas de bagaco de mandioca adicionado de 10% de papel Kraft sao semelhantes as de papelao, produzidas a partir de papel reciclado (bandejas de papel para ovos). As bandejas obtidas em laboratorio foram resistentes o suficiente para permitir a sua utilizacao no acondicionamento de frutas e hortalicas. Assim, a utilizaca...
Microwave heating, also known as dielectric heating, is a direct process, that is, energy is tran... more Microwave heating, also known as dielectric heating, is a direct process, that is, energy is transferred directly to the food by molecular interaction with the electromagnetic field. Thus a greater penetration is achieved resulting in faster reaching of the temperature of interest and more uniform heat distribution. To correctly design processing equipment, it is essential to understand and determine the dielectric properties of the food and so ensure microwave incidence to obtain the required processing conditions. In order to obtain the dielectric properties of the food, it is important to consider its shape, moisture content, specific gravity, conductivity, and diffusivity, as well as process variables like maximum temperature and frequency. In this chapter, application of microwaves in various conservation methods applied to fruits will be presented such as blanching, drying, pasteurization, and sterilization. The advantages and disadvantages of employing microwaves to perform t...
In this work, physical, chemical and morphological modifications of three different polyamide 6.6... more In this work, physical, chemical and morphological modifications of three different polyamide 6.6 (PA6.6) fabrics were investigated using double barrier dielectric (DBD) plasma treatment. Several techniques of characterization were used to study the effects caused by the interaction between plasma discharge and polyamide fabrics, such as: contact angle, water drop adsorption, Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), whiteness by Berger degree and tensile strength. All analyses performed in this study showed that DBD plasma discharge, when applied on PA6.6 fiber, produces significant modifications on the surface of this substrate, without altering its intrinsic properties, thus proving the effectiveness of this important technology to the textile industry.
The industrial processing of cassava to obtain starch generates a great variety of residues, with... more The industrial processing of cassava to obtain starch generates a great variety of residues, with bagasse being the main solid residue produced. The improper disposal of this material represents an environmental problem and could be avoided by using this residue as a raw material to obtain biodegradable products. The bagasse produced during the process to obtain starch from cassava was used to prepare composites for disposable trays. Samples of the composites were impregnated with cassava starch acetate at atmospheric pressure and under vacuum condition. Moisture isotherms were determined and adjusted by GAB model. It was observed that the impregnation promoted an important decrease in sample higroscopicity, mainly at high relative humidities. These results suggest that starch acetate impregnation can be an alternative to water proofing biological materials like the composites obtained in this work.
This study describes the use of cassava starch acetate (CSA) to impregnate Kraft paper and its in... more This study describes the use of cassava starch acetate (CSA) to impregnate Kraft paper and its influence on the water vapor permeability (K w). This barrier property depends on the water vapor diffusion coefficient (D eff) and the material hygroscopicity properties (adsorptivity, b). The influences of D eff and b on the K w value were studied. Kraft paper samples were impregnated at atmospheric pressure and under vacuum. The results showed an important decrease on the K w values, which was associated with two factors: (a) the partial filling of the Kraft paper superficial and internal pores by the impregnated CSA, reducing the K w ; (b) as CSA is much less hygroscopic than paper, its adsorptivity is reduced significantly by impregnation. This paper demonstrates that CSA impregnation of Kraft paper is an interesting alternative for the improvement of the hygroscopic properties and water vapor permeability of the Kraft paper.
The inactivation kinetics of enzymes polyphenol oxidase (PPO) and peroxidase (POD) was studied fo... more The inactivation kinetics of enzymes polyphenol oxidase (PPO) and peroxidase (POD) was studied for the batch (discontinuous) microwave treatment of green coconut water. Inactivation of commercial PPO and POD added to sterile coconut water was also investigated. The complete time-temperature profiles of the experimental runs were used for determination of the kinetic parameters D-value and z-value: PPO (D 92.20°C = 52 s and z = 17.6°C); POD (D 92.92°C = 16 s and z = 11.5°C); PPO/sterile coconut water: (D 84.45°C = 43 s and z = 39.5°C) and POD/sterile coconut water: (D 86.54°C = 20 s and z = 19.3°C). All data were well fitted by a first order kinetic model. The enzymes naturally present in coconut water showed a higher resistance when compared to those added to the sterilized medium or other simulated solutions reported in the literature. The thermal inactivation of PPO and POD during microwave processing of green coconut water was significantly faster in comparison with conventional processes reported in the literature.
Determinação simultânea e contínua da densidade de líquidos e da concentração de suspensões líqui... more Determinação simultânea e contínua da densidade de líquidos e da concentração de suspensões líquidas, Laurindo et al. 1. Recebido para publicação em 25/09/2002. Aceito para publicação em 30/03/2004 (000998).
Brazilian Archives of Biology and Technology, 2004
Studies were carried out to produce biodegradable films from cassava starch. Two alternatives wer... more Studies were carried out to produce biodegradable films from cassava starch. Two alternatives were investigated. In the first, films were obtained by starch gelatinization followed by thermopressing and glycerol was used at different concentrations as a plasticizer. In the second, starch acetate films were obtained by solubilization of cassava starch acetate in organic solvents, followed by casting on a glass plate and drying at room temperature. The films obtained by gelatinization were transparent and resistant to traction. The starch acetate films were also transparent but breakable. The use of these starch acetate films in paper impregnation improved the mechanical properties of the paper.
Brazilian Archives of Biology and Technology, 2004
Studies were carried out to produce biodegradable films from cassava starch. Two alternatives wer... more Studies were carried out to produce biodegradable films from cassava starch. Two alternatives were investigated. In the first, films were obtained by starch gelatinization followed by thermopressing and glycerol was used at different concentrations as a plasticizer. In the second, starch acetate films were obtained by solubilization of cassava starch acetate in organic solvents, followed by casting on a glass plate and drying at room temperature. The films obtained by gelatinization were transparent and resistant to traction. The starch acetate films were also transparent but breakable. The use of these starch acetate films in paper impregnation improved the mechanical properties of the paper.
Kraft paper is widely used in the manufacture of packing, but its hygroscopic properties and wate... more Kraft paper is widely used in the manufacture of packing, but its hygroscopic properties and water vapor barrier are not suitable for the storage of dehydrated products for long periods. The objective of this work was to study the influence of the impregnation of ...
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