Co-crystallization is an encapsulation process where a second ingredient is incorporated in a porous conglomerate of sucrose microcrystals formed by spontaneous crystallization. The process is carried out by concentrating a sucrose syrup until supersaturation and, then, adding the core material, with the mixture being submitted to an intensive agitation that leads to nucleation and product agglomeration. In the present work, encapsulation of passion fruit concentrated juice by co-crystallization with sucrose was evaluated by determining the effects of added juice fraction and juice pH on moisture content, solubility, apparent density and repose angle of final product, as well as by following the co-crystallization kinetics in a rheo-reactor, constituted of a crystallizer adapted to a concentric cylinders rotational rheometer, in which an agitator substitutes for the internal cylinder. The cocrystallization kinetics was described by an empirical model fitted to experimental data and the crystallization rate was accelerated with increasing pH and decreasing added juice fraction. The co-crystallized products presented lower moisture content and higher solubility at lower juice fractions. Apparent density and repose angle were similar to those reported for the encapsulating matrix and were in the range of values reported for most of food powders.
microencapsulation; fruit juice; sugar; food powders; apparent viscosity
