Process of physical separation and dryong of inulin obtained from (cichorium intybus L.). / Processos de separação fisica e secagem de inulina obtida a partir de raizes de chicoria (Cichorium intybus L.).

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Inulin is a polysaccharide, which can be found in several vegetable products, in which it acts as a reserve carbohydrate. Amongst these vegetables, chicory roots are outlined for inulin production in industrial scale. The application of this carbohydrate at the food industry is related to its ability for substituting sugar and fat, with the advantage of presenting a very low caloric value. Besides this, inulin acts at the human digestive system in a similar way to the dietary fibers, contributing to the bifido bacteria increment. For this reason, it can be applied as a functional ingredient in several foodstuffs and formulations. Chemically, inulin is a polysaccharide consisting in a chain of fructose molecules with a terminal glucose molecule (GFn). The number of fructose molecules varies with a various factors, in such a way that the polymerization degree can vary from 2 to 60. Inulin solubility in water is strongly dependent of the temperature. In this research work, it has been carried through a study of a process of physical separation of an inulin concentrated solution extracted from chicory roots by means of lowering temperature (16 to -24ºC) followed by centrifugation and of the process of obtaining powder inulin by spray drying inulin precipitated in a laboratorial dryer. The results of phases separation process had been evaluated through the response surface method and it was observed that freezing the concentrated inulin extract at -24ºC and, after that, centrifuging it at 10,000rpm during 15 minutes of time interval leads to the precipitation of a heterogeneous paste like substance, with high concentration of soluble solids, composed for granules of varied sizes. The precipitated inulin at the best condition of physical separation had been characterized in accordance with its density, soluble solids concentration, total solids concentration and the rheological behavior. It was observed that it is a highly shear thinning material, with a high flowing resistance at low shear rates followed by a breaking of its structure with increasing the intensity of shear. Due to the very high apparent viscosity values of the inulin precipitated obtained under the best physical separation process conditions, mainly at low shear rate conditions, it could not be applied at the feeding of the spray dryer, for obtaining inulin in powder. The spray drying process of inulin precipitated was carried through with the material that resulted from freezing the inulin concentrated extract at ?24ºC. It had been evaluated the effect of the inulin precipitated at the feeding of the spray dryer, the drying temperature and the speed of rotation of the peristalsis pump on the mass production rate of the process. The obtained results were evaluated by means of response surface methodology and it was observed that, inside the studied range of values, the best drying condition was the feeding of the inulin precipitated at room temperature (25ºC) under 5% of the maximum speed of allowed rotation of peristalsis pump and with a drying temperature of 210ºC. The powder obtained under these conditions has a microstructure composed by spherical particles with variable diameters and smooth surfaces. It was studied the influence of the powder moisture on its own microstructure, by storing it under different relative moisture conditions, at 25ºC, and it was observed that when the material reaches 8% of moisture level, its structure is totally modified by water absorption.

ASSUNTO(S)

water activity microestrutura spray dryer secagem por atomizador atividade de agua reologia microestructure rheology

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