Estudio de las propiedades físicas de frutillas (Fragaria ananassa) deshidratadas mediante liofilización atmosférica en lecho de impacto y mediante microondas
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Date
2012
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Universidad de Concepción
Abstract
La frutilla es altamente demandada a nivel mundial debido a su calidad organoléptica y su valor nutricional. La mayor parte de las exportaciones se hacen en congelado, método que eleva considerablemente los costos de transporte y almacenamiento. Métodos de deshidratación como la liofilización convencional pueden ser una alternativa para mantener la calidad de las frutillas. Sin embargo, los sistemas de liofilización convencional son complejos y costosos; el proceso es lento y las capacidades de procesamiento son limitadas. El objetivo es evaluar distintos métodos de deshidratación sobre la calidad de algunas propiedades físicas de frutillas.
Se hizo una deshidratación convencional a 5 variedades de frutillas (Albion, Monterrey, Camarosa, San Andreas y Portola). Se seleccionó una variedad y se realizaron distintos métodos de deshidratación no convencional. Los parámetros a medir fueron: color, textura, estructura, geometría y rehidratación. La variedad escogida fue San Andreas, que se deshidrató más rápido. Deshidratación por microondas redujo en menor tiempo la humedad hasta 27,92% para frutillas enteras y hasta 3,84% para cubos. El color de frutillas enteras cambió menos que el color de frutillas liofilizadas. La rehidratación fue de 12,16% para frutillas enteras y 19,57% para cubos. El método de deshidratación en lecho de impacto redujo la humedad de cubos 2 hasta 46,76% pero la rehidratación no superó el 11%. Las condiciones con las que se llevó a cabo la deshidratación por microondas son adecuadas para obtener un producto de buena calidad aunque menor a la calidad de frutillas liofilizadas convencionalmente. Aún se puede mejorar las condiciones del equipo de microondas, automatizando el sistema para tener un mejor control de la temperatura y así aumentar la calidad del producto.
Strawberries are highly demanded worldwide due to their sensory quality and nutritional value. Short shelf life of strawberries results into their exportation in frozen state raising significantly storage and transport costs. Dehydration such as conventional freeze-drying can be an alternative to maintain strawberry quality. However, conventional freeze-drying systems are complex and expensive; it is a time consuming process with limited processing capacities. The main objective of this study was to evaluate different methods of dehydration on the quality of some physical properties of strawberries. Conventional dehydration of five cultivars of strawberries (Albion, Monterrey, Camarosa, San Andreas and Portola) was done. Afterwards one cultivar was chosen according to overall dehydration performance followed by unconventional dehydration study. To assess the effect on the quality of strawberries, the following parameters were measured: color, texture, structure, geometry and rehydration. The cultivar of San Andreas was chosen, because of high dehydration rate. Vacuum microwave dehydration was able to reduce in less time moisture of whole strawberries until 27.92% and up to 3.84% for strawberries cubes. These strawberries showed less color change compared to lyophilized strawberries. Rehydration was 12.16% for whole strawberries and 19.57% for strawberries cubes. Impingement drying diminished moisture of cubes to 46.76%, where their rehydration did not exceed 11%. The operating conditions of vacuum microwave dehydration were correct to get a good product quality, although worse than conventionally lyophilized strawberries. However, operational conditions of microwave equipment can still be improved by automation that results into a better temperature control and thus improving dehydrated product quality.
Strawberries are highly demanded worldwide due to their sensory quality and nutritional value. Short shelf life of strawberries results into their exportation in frozen state raising significantly storage and transport costs. Dehydration such as conventional freeze-drying can be an alternative to maintain strawberry quality. However, conventional freeze-drying systems are complex and expensive; it is a time consuming process with limited processing capacities. The main objective of this study was to evaluate different methods of dehydration on the quality of some physical properties of strawberries. Conventional dehydration of five cultivars of strawberries (Albion, Monterrey, Camarosa, San Andreas and Portola) was done. Afterwards one cultivar was chosen according to overall dehydration performance followed by unconventional dehydration study. To assess the effect on the quality of strawberries, the following parameters were measured: color, texture, structure, geometry and rehydration. The cultivar of San Andreas was chosen, because of high dehydration rate. Vacuum microwave dehydration was able to reduce in less time moisture of whole strawberries until 27.92% and up to 3.84% for strawberries cubes. These strawberries showed less color change compared to lyophilized strawberries. Rehydration was 12.16% for whole strawberries and 19.57% for strawberries cubes. Impingement drying diminished moisture of cubes to 46.76%, where their rehydration did not exceed 11%. The operating conditions of vacuum microwave dehydration were correct to get a good product quality, although worse than conventionally lyophilized strawberries. However, operational conditions of microwave equipment can still be improved by automation that results into a better temperature control and thus improving dehydrated product quality.
Description
Tesis presentada para optar al título de Ingeniero Agroindustrial
Keywords
Diseño, Industria del vino, Jugo de uva