The application of inulin in food and pharmaceutical industries is associated to the possibility of substituting sugar or fat, with a low caloric contribution, and of formulating medicine and functional foods, as it acts in the human organism in a similar way to dietary fibers. Inulin is mostly commercialized as a powder, which provides easier manipulation, transportation, storage and consumption. Thus, it is of great importance to know the behavior of inulin powder when stored under different relative humidity conditions. The objective of this work was to evaluate the influence of moisture on the microstructure of inulin powder, obtained from spray drying an inulin concentrate extract from chicory roots. The analysis of the structure of the material in a scanning electron microscope demonstrated its high higroscopicity. In environments with water activity (a w) higher than 0.3085, inulin presented alterations in its microstructure that compromised its quality. When inulin was stored in an environment with a w = 0.5285, the material lost its powder characteristics, due to particle agglomeration associated to moisture absorption, and it turned into a solid mass. This characteristic was aggravated with the increase of the relative humidity of the environment.
scanning electron microscopy; water activity; spray dryer
