Physical properties of spray sdryed Stenocereus griseus pitaya juice powder

The aim of this work was to analyze the effect of spray drying conditions on the physical properties of pitaya juice powder using a 23 factorial design. Independent variables were inlet air temperature (150 and 180°C), feed flow rate (1.5 and 2 L/hr), and the amount of encapsulants (60 and 90%). The spray process was performed on pilot-scale spray dryer and maltodextrin/pectin combination was used as encapsulating material. Moisture content, yield, color, water adsorption, glass transition temperature, and morphology of pitaya juice powders were analyzed. Critical conditions of storage, at which the glass transition occurs were determined. Experimental results showed that all the individual factors had a significant effect on moisture content and color, however, yield was only affected by feed flow rate and percentage of encapsulants. Lower drying temperatures (150°C) favored higher yield of 59% and privileged red-violet color retention during spray drying. The GAB and Gordon-Taylor models gave good fit for the experimental data of adsorption isotherms and glass transition temperatures, respectively.

Practical Applications
In this work betalains with compounds including nutraceutical properties, which can be used as a dye, were encapsulated. The knowledge of the properties of natural products, with potential either as an additive or as a colorant, is of great significance for applications in both the food and pharmaceutical industry. The efficiency, color, morphology of powders, and properties influencing hygroscopicity, collapse, compression, and agglomeration were determined. These factors control the processability, handling properties, and the stability of pitaya powders.