Evaluation of the physical properties and conservation of the antioxidants content, employing inulin and maltodextrin in the spray drying of blueberry juice.

In this work, two carbohydrate polymers, inulin (I) and maltodextrin (MX), were compared as carrying agents in the spray drying of blueberry juice (BJ). The physicochemical properties and the conservation of the antioxidants content were characterized. Both systems, showed non-agglomerated particles and light-purple color appearance. Powders were subjected to the adsorption of water, and the glass transition temperature (Tg) decreased with the water activity. The evolution of the microstructure in the MX-BJ remained unchanged, while the I-BJ presented an abrupt change from amorphous to crystalline. This was corroborated by scanning electron microscopy (SEM), observing in the I-BJ system, the change from spherical into irregular shape particles. In the conservation of the antioxidants content, the MX-BJ showed a better performance. Anyhow, the performance of both carbohydrate polymers as carrying agents in the spray drying of BJ was effective.

Physical properties of inulin and inulin-orange juice: physical characterization and technological application.

In this work two systems based on a carbohydrate polymer were studied: inulin as model system and inulin-orange juice as complex system. Both system were stored at different water activity conditions and subsequently characterized. Water adsorption isotherms type II were fitted by the GAB model and the water monolayer content was determined for each system. From thermal analyzes it was found that at low water activities (aw) systems were fully amorphous. As aw increased, crystallinity was developed. This behavior was corroborated by X-ray diffraction. In the inulin-orange juice system, crystallization appears at lower water activity caused by the intensification of the chemical interaction of the low molecular weight species contained in orange juice. Glass transition temperature (Tg), determined by modulated differential scanning calorimeter, decreased with aw. As water is adsorbed, the physical appearance of samples changed which could be observed by optical microscopy and effectively related with the microstructure found by scanning electron microscopy.