Spray-drying optimization for red pitaya peel (Hylocereus polyrhizus)

Optimization for the spray-drying of pitaya peel (Hylocereus polyrhizus) was carried out using the central composite design (CCD) of the response surface methodology to study the effect of inlet air temperature (155–175 °C), outlet air temperature (75–85 °C), and maltodextrin DE10 concentration (8–22% w/w) on the pitaya peel powder characteristics. Spray-dried pitaya peel powders had high betacyanin retention and low water activity and had desirable color, solubility, and hygroscopicity properties. Significant (p 0.85) ranging from 0.896 to 0.979 fitted for the experimental data were obtained. The linear term of maltodextrin concentration was found to be the most significant (p < 0.05) variable influencing the powder characteristics, and the outlet temperature had the least effect. The overall optimum region for the spray-drying of the desirable pitaya peel powder was predicted at a combined parameter of inlet air temperature at 165 °C, outlet air temperature at 80 °C, and maltodextrin DE10 at 15% (w/w)