In this work, Cassava starch acetate (CSA) with a high degree of substitution films (DS = 2.9) and composite materials consisting of CSA resin supported on Kraft paper were developed. As a previous step, the synthesis of high degree acetate was carried out by using methylsulfonic acid as a catalyst. The characterization of the mechanical and barrier properties of the films obtained was performed. Acetylated cassava starch films were homogeneous and continuous, with plastic appearance, but brittle. The addition of 50% plasticizer allowed to obtain films with good mechanical properties (tensile strength at break 17,5 MPa and deformation 8,2%) but with storage, they became waxy and brittle. The films composed of Kraft paper -cassava starch acetate - have lower water vapor permeability values (up to 51%) than untreated papers, and their mechanical properties are better (tensile strength at break 33- 42 MPa and deformation 2 - 4%). Therefore, the development of biodegradable packages based on acetylated starch-cellulose materials seems a good option for the replacement of packages that are not environmentally compatible.

En este trabajo se desarrollaron películas de acetato de almidón de mandioca (AAM) de alto grado de sustitución (DS = 2,9) y materiales compuestos consistentes de la resina AAM soportada en papel Kraft. Como un paso previo, la síntesis del acetato de alto grado fue llevada a cabo empleando ácido metilsulfónico como catalizador. Se realizó la caracterización de las propiedades mecánicas y de barrera de las películas obtenidas. Las películas de almidón de mandioca acetilado resultaron homogéneas y continuas, de apariencia plástica, pero frágiles. El agregado de 50% de plastificante permitió obtener películas con buenas propiedades mecánicas (tensión de rotura 17,5 MPa y deformación de rotura de 8,2%) pero que, con el almacenamiento, se volvieron cerosas y frágiles. Las películas compuestas de papel Kraft - acetato de almidón de mandioca tienen valores de permeabilidad al vapor de agua menores (hasta el 51%) que los papeles sin tratar, a la vez que sus propiedades mecánicas son mejores (tracción de rotura 33 - 42 MPa y elongación 2 - 4%). Por lo tanto, el desarrollo de envases biodegradables basados en materiales de almidón acetilado - celulosa parece una buena opción para el reemplazo de envases que no son ambientalmente compatibles.

The aim of this study was to evaluate the effect of drying conditions on water loss and color changes of Diospyros kaki var Fuyu fruit. The conditions were: i) drying with constant air flow rate (1,1 m/s) and temperature (45, 60 and 75 °C) (SAC), ii) intermittent drying with cicles of heat application/tempering time for 45/45 min (SAC INT), at the same temperatures, iii) Osmotic dehydration in sucrose solution at 50 and 60 °Brix before drying at 60 °C (DO + SAC). In order to describe the water loss the Page model was used. The n parameter values of SAC at 45 and 60 °C,SAC INT and DO + SAC were not significantly different (p> 0.05). The k values increased with temperature in SAC and SAC INT. L* and b* color parameters decreased during drying. The color difference ΔE was not affected by INT SAC.

El objetivo fue evaluar el efecto de las condiciones de deshidratacion sobre la perdida de agua y los cambios de color en Dyospiros kaki var ‘Fuyu’. Las condiciones fueron: i) Secado con aire a velocidad (1,1 m/s) y temperatura (45, 60 y 75 .C) constantes (SAC), ii) Secado intermitente con ciclos de flujo de aire/reposo de 45/45 minutos (SAC INT), a las mismas temperaturas, iii) Deshidratacion osmotica en solucion de sacarosa a 50 y 60 .Brix y secado con aire a 60 .C (DO+SAC). El modelo de Page fue utilizado para describir la perdida de agua. Los valores de n para SAC a 45 y 60 .C, SAC INT y DO+SAC no presentaron diferencias significativas (p>0,05). Los valores de k aumentaron con la temperatura en SAC y SAC INT. Los parametros L* y b* disminuyeron durante el secado. El ΔE no fue afectado por el SAC INT.

In this work, the effect of operating conditions during calcium pretreatment on the calcium uptake and the compression resistance of papaya bits in syrup was studied. The papaya fruit was cut into cylinders of approximately 10 mm in length and 25 mm in diameter. An aqueous solution of calcium hydroxide was used as impregnation medium. Different conditions of calcium pre-treatment were applied. A three-factor two-level factorial design was chosen to evaluate the combined effect of three independent impregnation variables: concentration solution, temperature and impregnation time. The system response was measured in terms of calcium gain in the fruit and mechanical property values of processed food. The results showed that the solution concentration and the impregnation time were the most relevant variables on the hardness of papaya in syrup. The greatest calcium content (116.7 mg/100 g fresh fruit) was reached by fruit impregnation in 1.5% Ca(HO)2-solution at 40°C for 4.5 h.

En el presente trabajo se estudió el efecto de las condiciones de operación del pre-tratamiento de impregnación con calcio sobre el incremento del mineral y sobre la resistencia a la compresión de mamón en almíbar. La fruta de mamón se seccionó en cilindros de aproximadamente 10 mm de longitud y 25 mm de diámetro. Una solución acuosa de hidróxido de calcio se utilizó como medio de impregnación. Se aplicaron diferentes condiciones de pretratamiento. Se eligió un diseño factorial de tres factores en dos niveles para evaluar el efecto combinado de tres variables independientes de impregnación: concentración, temperatura y tiempo de impregnación. La respuesta del sistema se midió en función de la incorporación de calcio en la fruta y valores de las propiedades mecánicas del alimento elaborado. Los resultados indicaron que la concentración de la solución y el tiempo de inmersión son las variables de mayor relevancia sobre la dureza del mamón en almíbar. El mayor contenido de calcio (116,7 mg/100 g de fruta fresca) se alcanzó por inmersión de frutas en solución de Ca(OH)2 al 1,5% y 40 °C, durante 4,5 horas.

A perda da água, o ganho do sacarose e a variação na concentração de outros açúcares naturais de fruta (glucose e fructose) foram estudados durante a desidratação osmótica de fatias de abacaxi, com 0.6 milímetro espessura, em solução de sacarose (60 % w/w) em três temperaturas (30, 40 e 50ºC). Como a temperatura foi elevada de 30 a 50ºC, as difusividades aparentes da água e da sacarose (Dw e Ds) aumentaram 3.8 e 2.8 vezes, respectivamente; conseqüentemente, o índice da eficiência da desidratação (Dw/Ds) aumentou com a temperatura. A perda de glucose e de fructose aumentou com temperatura. O índice do soluto é uma função linear do índice de umidade e esta relação nao é funcão da temperatura durante os primeiros 600 minutos da desidratação. As experiências da desidratação osmótica foram realizadas em 40°C com fatias de 10 milímetros de espessura para determinar os perfis da concentração da água e da sacarose em função da posição para valores diferentes de tempos da imersão.

Water loss, sucrose gain and the variation in concentration of other natural fruit sugars (glucose and fructose) were studied during osmotic dehydration of pineapple slices (0.6 mm thick) in sucrose solution (60 % w/w) at three temperatures (30, 40 and 50ºC). As temperature increased from 30 to 50ºC, the apparent moisture and sucrose diffusivities (Dw and Ds) increased 3.8 and 2.8 times, respectively; therefore, the dehydration efficiency index (Dw/Ds) increased with temperature. The loss of glucose and fructose increased with temperature too. It was found that the solute content was a linear function of the moisture content and this relation was independent of the temperature during the first 600 minutes of dehydration.

O objetivo desta pesquisa foi estudar a cinética de degradação de dimetoato em plantas de erva-mate (Ilex paraguariensis Saint Hilaire) e durante o processamento destas. Para determinar a concentração de dimetoato foi empregada a técnica de cromatografia gasosa capilar, com uso de detector seletivo de massas. O tempo de meia vida nas plantas variou entre 9.8 e 11.8 dias. Durante o processamento, com branqueamento (sapeco) e duas etapas da secagem, a concentração de dimetoato foi reduzida a 22.7% do valor inicial (base seca), enquanto que, durante o estacionamento (a 45°C), o tempo de meia vida foi de 17.3 dias. Com estes valores, foi determinado o intervalo de segurança.

The objective of this research was to study degradation kinetics of dimethoate in plants of Ilex paraguariensis Saint Hilaire (or yerba maté) and during its processing. To determine dimethoate concentration, a capillary gas chromatography technique with a mass selective detector was used. Half-life times in plants ranked between 9.8 and 11.8 days. During processing, with a blanching and two drying steps, dimethoate concentration decayed to a 22.7% of its initial value (in dry basis); while during seasoning step (at 45°C), half-life time was 17.3 days. With these values, preharvest safety interval was determined.