Pineapple shell, considered a waste in the juice industry, was used as a reinforcement material to produce biodegradable foam trays (FTs) based on cassava starch by a compression molding process. These foams were prepared with different starch/fiber ratios and then were characterized according to their microstructure and physical and mechanical properties. The starch/fiber ratio of 95/5 showed the lowest values of thickness and density (2.58 mm and 367 kg m−3, respectively). There was a good distribution of the pineapple shell fiber throughout the polymeric matrix. All FTs showed a semicrystalline structure and 95/5 ratio showed the highest crystallinity index (CI) value (39%). In addition, this ratio improved the tensile strength of the FTs, obtaining similar values to expanded polystyrene (EPS) samples, used as the reference material. Nevertheless, all FTs reinforced with pineapple shell fiber showed high water absorption capacity (WAC); therefore, future studies should focus on to improve the physicochemical and structural properties of the cassava starch-based foams, considering the promising potential of this novel biodegradable material for dry food packaging, such as a viable alternative to reduce the use of petroleum-based materials such as commercial EPS trays.

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Recibido 02 febrero 2010; aceptado 30 marzo 2010Resumen El objetivo de este estudio fue comparar la pérdida de vitamina C de la chalarina después de aplicar cuatro métodos de deshidratación: deshidratación osmótica a vacío combinada con secado convectivo, secado convectivo, deshidratación osmótica a vacío combinada con liofilización, y liofilización. La chalarina fresca fue acondicionada en forma de cubos de 1 cm de arista; se determinó el contenido de vitamina C y otras propiedades químicas de la pulpa. Los polvos obtenidos fueron caracterizados: contenido de vitamina C, contenido de humedad, a w , densidad, ángulo de fluencia y compresibilidad. La pulpa de chalarina fresca presentó un contenido de vitamina C de 29.75 mg/100g. La deshidratación osmótica a vacío redujo este contenido hasta 15.75 mg/100g, que combinado con secado convectivo se llega a 9.31 mg/100g; en tanto, combinado con liofilización se obtuvo 14.98 mg/100g. Aplicando sólo secado convectivo se obtuvo 7.05 mg de vitaminaC/100g de polvo de chalarina, mientras que aplicando sólo liofilización se obtuvo 23.63 mg/100g. Se concluye que el polvo obtenido por deshidratación osmótica a vacío -secado convectivo presenta mejores características fisicoquímicas que los polvos obtenidos con los otros métodos de deshidratación. Palabras clave: Chalarina, vitamina C, deshidratación osmótica, liofilización AbstractThe aim of this study was to compare the loss of chalarina vitamin C after applying four methods of dehydration: vacuum osmotic dehydration combined with convective drying, convective drying, osmotic dehydration combined with vacuum freeze-drying, and freeze-drying. The fresh chalarina was fitted into cubes of 1 cm; we determined the vitamin C content and other chemical properties of the pulp. The powders were characterized: vitamin C, moisture content, a w , density, angle of flow and compressibility. Fresh chalarina pulp has a vitamin C content of 29.75 mg/100g. Osmotic dehydration and vacuum reduced to 15.75 mg/100g this content; combined with convective drying is reached 9.31 mg/100g; if combined with freeze-drying is obtained 14.98 mg/100g. Applying convective drying was obtained only 7.05 mg of vitaminaC/100g chalarina powder, while by applying only freeze-drying was obtained 23.63 mg/100g. We conclude that the powder obtained by vacuum osmotic dehydration -convective drying has better physical and chemical characteristics of powders obtained with other methods of dehydration.