SPRAY DRYING OF AÇAI (EUTERPE OLERACEAE MART.) JUICE: EFFECT OF INLET AIR TEMPERATURE AND TYPE OF CARRIER AGENT

ABSTRACT Physical and morphological characteristics of powdered açai juice were evaluated in this work. Powders produced by spray drying at different temperatures (140, 170 and 200C) using different carrier agents (maltodextrin 10DE, maltodextrin 20DE and gum Arabic) were evaluated for moisture content, water activity, hygroscopicity, bulk density, particle size distribution and morphology. Sorption isotherms were also constructed. The samples produced with maltodextrin 10DE showed the highest moisture content, water activity and mean diameter and were the less hygroscopic. The increase in drying temperature resulted in particles with lower moisture content, water activity and bulk density. Moreover, powders produced at higher temperatures were more hygroscopic and exhibited a greater number of particles with smooth surface. Sorption isotherms were of type III and showed a better fit to Guggenheim-Anderson-de Boe and Brunauer-Emmett-Teller models. PRACTICAL APPLICATIONS The present study provides useful information about the production of powdered açai juice by spray drying. In this process, the addition of a carrier agent is normally necessary in order to avoid problems like stickiness on the dryer wall, which would be negative to process yield and product quality. Moreover, among the process variables related to spray drying, the inlet air temperature can be considered very important, since it is directly related with powder quality, as well as with energy saving/wasting. Thus, in this work, the effect of three different types of carrier agents and three inlet air temperatures on the physicochemical properties of spray-dried açai juice was evaluated. The results can be useful for food and cosmetic companies looking for novel and inexpensive sources of natural pigments, to be used as colorants and flavorings.