State diagrams of freeze-dried camu-camu (Myrciaria dubia (HBK) Mc Vaugh) pulp with and without maltodextrin addition

The state diagram for freeze-dried natural camu-camu pulp and for pulp with 30% maltodextrin DE 20 were determined by differential scanning calorimetry (DSC). Freeze-dried samples were equilibrated at 25 °C over saturated salt solutions in order to achieve water activities between 0.11 and 0.90. Higher water activities were obtained by direct water addition on the freeze-dried product. Gordon–Taylor model was able to predict the plasticizing effect of water in the low and intermediate moisture content range. In the high moisture domain (aw > 0.90), Tg was practically constant, representing the glass transition temperature of the maximally concentrated phase (Tg′), which were −58.8 °C and −40.1 °C for natural pulp and pulp with maltodextrin, respectively.