Rodajas de peras fortificadas con calcio y zinc para la elaboración de un tentempié
Date
2021-09-24
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Escuela de Posgrado - UTN FRBA
Abstract
El objetivo fue obtener peras de la variedad Packham’s Triumph secadas por microondas en simultáneo con convección con aire caliente (secado combinado), previo pretratamiento por impregnación con calcio y zinc para mejorar su valor nutricional, su textura y alcanzar una adecuada humedad que permitiese extender su vida útil. Las rodajas de peras se sumergieron en una solución acuosa que contenía sales de lactato de calcio y de acetato de zinc. Se determinó la concentración de Calcio y Zinc en el producto durante el tiempo de impregnación por espectrofotometría de absorción atómica de llama y por ICP/POES, respectivamente. Para lograr extender la vida útil del tentempié, se tomó la muestra osmodeshidratada/impregnada durante 1h y posteriormente, se secó mediante secado combinado. Se realizaron pruebas a diferentes potencias de microondas y tiempos. Este método de secado combinado se comparó con el secado por convección con aire caliente solo, y presentó la ventaja de reducir los tiempos de exposición y obtener un producto de mejores características organolépticas. El producto obtenido luego del secado combinado presentó algunas propiedades texturales que requirieron mejora, mediante un secado convectivo final con aire caliente. Los procesos de deshidratación osmótica/impregnación, secado combinado y de convección con aire caliente se modelaron matemáticamente mediante modelos empíricos y uno del tipo fenomenológico basado en la segunda Ley de Fick de la difusión como el de Crank que se utilizó para calcular los coeficientes de difusión efectivos. La microestructura de las peras frescas y tratadas se analizó por microscopía electrónica de barrido y la concentración de minerales superficial se determinó por espectroscopía de dispersión de rayos X. Se realizó el análisis sensorial para determinar las muestras de mejores características organolépticas. Finalmente, se determinó la concentración de calcio y de zinc en el producto final elegido, luego de todos los tratamientos, con el fin de conocer el aporte que una porción de fruta deshidratada de 25 g cubre de los porcentajes requeridos de estos minerales para una dieta diaria de 2000 Kcal. Palabras claves: peras fortificadas, peras secadas por microondas y convección, secado combinado de peras, peras impregnadas con Ca y Zn, peras deshidratadas osmóticamente.
The aim of this thesis is to obtain pears (var. Packham ´s Triumph) dried by a combined method (microwave and hot air convection), pretreated by osmotic dehydration/impregnation process with calcium and zinc. The main purpose is to improve the nutritional value, the characteristic texture and reach an adequate humidity which allows a stable shelf product. The pear slices were immersed in an aqueous solution, which contained lactate calcium and acethate zinc. The calcium and zinc concentrations were measured by a flame atomic absorption spectrophotometer and by ICP / POES, respectively. The impregnation with minerals was analysed in relation to time. In order to extend the useful life of the snack, the osmodehydrated / impregnated sample was taken for 1h and subsequently, it was dried by combined drying. Tests were carried out at different microwave powers and times. This combined drying method was compared to convection drying with hot air alone, and had the advantage of reducing exposure times and obtaining a product with better organoleptic characteristics. The product obtained after combined drying showed some textural properties that required improvement, by means of a final convective drying with hot air. The processes of osmotic dehydration / impregnation, combined drying and convection with hot air were mathematically modeled using empirical models and one of the phenomenological type based on Fick's second Law of diffusion such as Crank's that was used to calculate the effective diffusion coefficients. The microstructure of fresh and treated pears was analyzed by scanning electron microscopy. Mineral concentration at the surfaces of these samples was determined by X-ray dispersion spectroscopy. Afterwards, these samples were studied by sensorial analysis with the aim to know the contribution that a portion of 25 g, cover a percentage of these minerals (Ca and Zn) for a daily diet of 2000 kcal. Keywords: fortified pears, pears dried by microwave and convection, combined drying of pears, pears impregnated with Ca and Zn, osmotically dehydrated pears.
The aim of this thesis is to obtain pears (var. Packham ´s Triumph) dried by a combined method (microwave and hot air convection), pretreated by osmotic dehydration/impregnation process with calcium and zinc. The main purpose is to improve the nutritional value, the characteristic texture and reach an adequate humidity which allows a stable shelf product. The pear slices were immersed in an aqueous solution, which contained lactate calcium and acethate zinc. The calcium and zinc concentrations were measured by a flame atomic absorption spectrophotometer and by ICP / POES, respectively. The impregnation with minerals was analysed in relation to time. In order to extend the useful life of the snack, the osmodehydrated / impregnated sample was taken for 1h and subsequently, it was dried by combined drying. Tests were carried out at different microwave powers and times. This combined drying method was compared to convection drying with hot air alone, and had the advantage of reducing exposure times and obtaining a product with better organoleptic characteristics. The product obtained after combined drying showed some textural properties that required improvement, by means of a final convective drying with hot air. The processes of osmotic dehydration / impregnation, combined drying and convection with hot air were mathematically modeled using empirical models and one of the phenomenological type based on Fick's second Law of diffusion such as Crank's that was used to calculate the effective diffusion coefficients. The microstructure of fresh and treated pears was analyzed by scanning electron microscopy. Mineral concentration at the surfaces of these samples was determined by X-ray dispersion spectroscopy. Afterwards, these samples were studied by sensorial analysis with the aim to know the contribution that a portion of 25 g, cover a percentage of these minerals (Ca and Zn) for a daily diet of 2000 kcal. Keywords: fortified pears, pears dried by microwave and convection, combined drying of pears, pears impregnated with Ca and Zn, osmotically dehydrated pears.
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Tecnología de los Alimentos, Peras fortificadas, Peras secadas por microondas y convección, Secado combinado de peras, Peras impregnadas con Ca y Zn, Peras deshidratadas osmóticamente
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